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INTERNET-DRAFT J. Loughney (Editor)
Internet Engineering Task Force Nokia
G. Sidebottom, Guy Mousseau
Issued: 20 July 2001 Nortel Networks
Expires: 20 January 2002 S. Lorusso
Unisphere Solutions
L. Coene, G. Verwimp
Siemens
J. Keller
Tekelec
F. Escobar
Ericsson
W. Sully, S. Furniss
Marconi
SS7 SCCP-User Adaptation Layer (SUA)
<draft-ietf-sigtran-sua-07.txt>
Status of This Memo
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC 2026.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet-
Drafts.
Internet-Drafts are draft documents valid for a maximum of six
months and may be updated, replaced, or obsoleted by other documents
at any time. It is inappropriate to use Internet-Drafts as
reference material or to cite them other than as 'work in progress.'
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
This draft expires on 20 January 2002
Abstract
This Internet Draft defines a protocol for the transport of any SS7
SCCP-User signaling (e.g., TCAP, RANAP, etc.) over IP using the
Stream Control Transport Protocol. The protocol should be modular
and symmetric, to allow it to work in diverse architectures, such as
a Signaling Gateway to IP Signaling Endpoint architecture as well as
a peer-to-peer IP Signaling Endpoint architecture. Protocol
elements are added to allow seamless operation between peers in the
SS7 and IP domains.
Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001
Abstract.............................................................1
1. Introduction......................................................3
1.1 Scope...........................................................3
1.2 Terminology.....................................................3
1.3 Signaling Transport Architecture................................5
1.4 Services Provided by the SUA Layer.............................12
1.5 Internal Functions Provided in the SUA Layer...................14
1.6 Definition of SUA Boundaries...................................16
2 Conventions.......................................................17
3 Protocol Elements.................................................17
3.1 Common Message Header..........................................17
3.2 SUA Connectionless Messages....................................21
3.3 Connection Oriented Messages...................................23
3.4 Signaling Network Management Messages..........................32
3.5 Application Server Process State Maintenance Messages..........37
3.6 ASP Traffic Maintenance Messages...............................40
3.7 SUA Management Messages........................................43
3.8 Common Parameters..............................................44
3.9 SUA-Specific parameters........................................53
4 Procedures........................................................64
4.1 SCCP � SUA Interworking at the SG..............................65
4.2 Primitives received from the local SUA-user....................67
4.3 Layer Management Procedures....................................67
4.4 SUA Management Procedures......................................68
5 Examples of SUA Procedures........................................76
5.1 SG Architecture................................................76
5.2 IP-IP Architecture.............................................78
6 Security..........................................................80
6.1 Introduction...................................................80
6.2 Threats........................................................80
6.3 Protecting Confidentiality.....................................81
7 IANA Considerations...............................................81
7.1 SCTP Payload Protocol ID.......................................81
7.2 Port Number....................................................81
7.3 Protocol Extensions............................................81
8 Timer Values......................................................83
9 Acknowledgements..................................................83
10 Authors' Addresses...............................................83
11 References.......................................................84
Copyright Statement.................................................87
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Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001
1. Introduction
1.1 Scope
There is on-going integration of SCN networks and IP networks.
Network service providers are designing all IP architectures that
include support for SS7 and SS7-like signaling protocols. IP
provides an effective way to transport user data and for operators
to expand their networks and build new services. In these networks,
there may be some need for interworking between the SS7 and IP
domains.
This document details the delivery of SCCP-user messages (MAP & CAP
over TCAP, RANAP, etc.) and new third generation network protocol
messages over IP between two signaling endpoints. Consideration is
given for the transport from an SS7 Signaling Gateway (SG) to an IP
signaling node (such as an IP-resident Database) as described in the
Framework Architecture for Signaling Transport [2719]. This protocol
can also support transport of SCCP-user messages between two
endpoints wholly contained within an IP network.
The delivery mechanism addresses the following criteria:
* Support for transfer of SCCP-User Part messages (TCAP, RANAP,
etc.)
* Support for SCCP connectionless service.
* Support for SCCP connection oriented service.
* Support for the seamless operation of SCCP-User protocol
peers.
* Support for the management of SCTP transport associations
between a SG and one or more IP-based signaling nodes).
* Support for distributed IP-based signaling nodes.
* Support for the asynchronous reporting of status changes to
management.
The protocol is modular in design, allowing different
implementations to be made, based upon the environment that needs to
be supported. Depending upon the upper layer protocol supported, the
SUA will need to support SCCP connectionless service, SCCP connect-
oriented service or both services.
1.2 Terminology
Signaling Gateway (SG) - Network element that terminates SCN
signaling and transports SCCP-User signaling over IP to an IP
signaling endpoint. A Signaling Gateway could be modeled as one or
more Signaling Gateway Processes, which are located at the border of
the SS7 and IP networks.
Application Server (AS) - A logical entity serving a specific
Routing Key. An example of an Application Server is a virtual IP
Loughney (editor) [Page 3]
Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001
database element handling all requests for a SCCP-user. The AS
contains a set of one or more unique Application Server Processes,
of which one or more is normally actively processing traffic.
Application Server Process (ASP) - An Application Server Process
serves as an active or backup process of an Application Server
(e.g., part of a distributed signaling node or database element).
Examples of ASPs are MGCs, IP SCPs, or IP-based HLRs. An ASP
contains an SCTP end-point and may be configured to process traffic
within more than one Application Server.
IP Server Process (IPSP) - A process instance of an IP-based
application. An IPSP is essentially the same as an ASP, except that
it uses SUA in a peer-to-peer fashion. Conceptually, an IPSP does
not use the services of a Signaling Gateway.
Signaling Gateway Process (SGP) - A process instance of a Signaling
Gateway. It serves as an active, standby or load-sharing process of
a Signaling Gateway.
Signaling Process - A process instance that uses SUA to communicate
with other signaling process. An ASP, a SGP and an IPSP are all
signaling processes.
Association - An association refers to an SCTP association. The
association provides the transport for the delivery of SCCP-User
protocol data units and SUA layer peer messages.
Routing Key - The Routing Key describes a set of SS7 parameters
and/or parameter-ranges that uniquely defines the range of signaling
traffic configured to be handled by a particular Application Server.
An example would be where a Routing Key consists of a particular SS7
SCCP SSN plus an identifier to uniquely mark the network that the
SSN belongs to, for which all traffic would be directed to a
particular Application Server. Routing Keys are mutually exclusive
in the sense that a received SS7 signaling message cannot be
directed to more than one Routing Key. Routing Keys can be
provisioned, for example, by a MIB.
Routing Context - An Application Server Process may be configured to
process traffic within more than one Application Server. In this
case, the Routing Context parameter is exchanged between the SGP and
the ASP (or between two ASPs), identifying the relevant Application
Server. From the perspective of an SGP/ASP, the Routing Context
uniquely identifies the range of traffic associated with a
particular Application Server, which the ASP is configured to
receive. There is a 1:1 relationship between a Routing Context value
and a Routing Key within an AS. Therefore the Routing Context can
be viewed as an index into an AS Table containing the AS Routing
Keys. The Routing Context also uniquely identifies an SS7 entity
(point code) into a SS7 network, as presented by the SG.
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Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001
Address Mapping Function (AMF) - The AMF is an implementation
dependent function that is responsible for resolving the address
presented in the incoming SCCP/SUA message to correct SCTP
association for the desired endpoint. The AMF MAY use routing
context / rouging key information as selection criteria for the
appropriate SCTP association.
Fail-over - The capability to re-route signaling traffic as required
to an alternate Application Server Process, or group of ASPs, within
an Application Server in the event of failure or unavailability of a
currently used Application Server Process. Fail-over may apply upon
the return to service of a previously unavailable Application Server
Process.
Network Byte Order - Most significant byte first, a.k.a. Big Endian.
Layer Management - Layer Management is a nodal function that handles
the inputs and outputs between the M3UA layer and a local management
entity.
Host - The computing platform that the SGP or ASP process is running
on.
Stream - A stream refers to an SCTP stream; a uni-directional
logical channel established from one SCTP endpoint to another
associated SCTP endpoint, within which all user messages are
delivered in-sequence except for those submitted to the un-ordered
delivery service.
Transport address - an address that serves as a source or
destination for the unreliable packet transport service used by
SCTP. In IP networks, a transport address is defined by the
combination of an IP address and an SCTP port number. Note, only
one SCTP port may be defined for each endpoint, but each SCTP
endpoint may have multiple IP addresses.
1.3 Signaling Transport Architecture
The framework architecture that has been defined for SCN signaling
transport over IP [2719] uses multiple components, including an IP
transport protocol, a signaling common transport protocol and an
adaptation module to support the services expected by a particular
SCN signaling protocol from its underlying protocol layer.
In general terms, the SUA architecture can be modeled as a peer-to-
peer architecture. The first section considers the SS7-IP
interworking architectures for connectionless and connection-
oriented transport. For this case, it is assumed that the ASP
initiates the establishment of the SCTP association with SG.
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Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001
1.3.1 Protocol Architecture for Connectionless Transport
In this architecture, the SCCP and SUA layers interface in the SG.
There needs to be interworking between the SCCP and SUA layers to
provide for the seamless transfer of the user messages as well as
the management messages. For messages destined for an ASP, there
are two scenarios.
******** SS7 *************** IP ********
* SEP *---------* *--------* *
* or * * SG * * ASP *
* STP * * * * *
******** *************** ********
+------+ +------+
| SUAP | | SUAP |
+------+ +------+------+ +------+
| SCCP | | SCCP | SUA | | SUA |
+------+ +------+------+ +------+
| MTP3 | | MTP3 | | | |
+------| +------+ SCTP | | SCTP |
| MTP2 | | MTP2 | | | |
+------+ +------+------+ +------+
| L1 | | L1 | IP | | IP |
+------+ +------+------+ +------+
| | | |
+---------------+ +------------+
SUAP - SCCP/SUA User Protocol (TCAP, for example)
STP - SS7 Signaling Transfer Point
1.3.1.1 SG as endpoint
In this case, the connectionless SCCP messages are routed on PC and
SSN. The subsystem identified by SSN and Routing Context is
regarded as local to the SG. This means from SS7 point of view, the
SCCP-user is located at the SG.
By means of configuration, the SG knows the local SCCP-user is
actually represented by an AS, and serviced by a set of ASPs working
in n+k redundancy mode. An ASP is selected and a CLDT message is
sent on the appropriate SCTP association/stream.
The selection criterion can be based on a round robin mechanism, or
any other method that guarantees a balanced load sharing over the
active ASPs. However, when TCAP messages are transported, load
sharing is only possible for the first message in a TCAP dialogue
(TC_Begin, TC_Query, TC_Unidirectional). All other TCAP messages in
the same dialogue are sent to the same ASP that was selected for the
first message, unless the ASPs are able to share state and maintain
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Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001
in sequence delivery. To this end, the SGP needs to know the TID
allocation policy of the ASPs in a single AS:
- State sharing
- Fixed range of TIDs per ASP in the AS
This information may be preconfigured in the SG, or may be
dynamically exchanged via the ASP_Active message.
An example for a INAP/TCAP message exchange between SEP and ASP is
given below.
Address information in CLDT message (e.g. TC_Query) from SGP to ASP,
with association ID = SG-ASP, Stream ID based on SLS and possibly
other parameters, e.g. OPC or Network ID:
- Routing Context: based on SS7 Network ID and AS membership,
so that the message can be transported to the correct ASP.
- Source address: valid combination of SSN, PC and GT, as
needed for back routing to the SEP.
- Destination address: at least SSN, to select the SCCP/SUA-
user at the ASP.
Address information in CLDT message (e.g. TC_Response) from ASP to
SG, with association ID = ASP-SG, stream ID selected by
implementation dependent means with regards to in-sequence-delivery:
- Routing Context: as received in previous message.
- Source address: unique address provided so that when used as
the SCCP called party address in the SEP, it MUST yield the
same AS, the SSN might be sufficient.
- Destination address: copied from source address in received
CLDT message.
Further messages from the SEP belonging to the same TCAP transaction
will now reach the same ASP.
1.3.1.2 SG as relay-point
A Global Title translation is executed at the SG, before the
destination of the message can be determined. The actual location
of the SCCP-user is irrelevant to the SS7 network. GT Translation
yields an "SCCP entity set", which now may contain one or more AS�s.
Selection of the AS is thus based on the SCCP called party address
(and possibly other SS7 parameters depending on the implementation).
Basically this means splitting the SS7 traffic over different AS�s
based on GT information. After this, the same as in 1.3.1.1
applies.
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Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001
1.3.2 Protocol Architecture for Connection-Oriented Transport
In this architecture, the SCCP and SUA layers interface in the SGP
to associate the two connection sections needed for the connection-
oriented data transfer between SEP and ASP. Both connection
sections are setup when routing the Connect Request messages from
SEP via SGP to ASP or the other way. The routing of the Connect
Request message is done in the same way as described in 1.3.1.
Further messages for this connection are routed on DPC in the SS7
connection section (MTP routing label), and on IP address in the IP
connection section (SCTP header). No other routing information is
present in the SCCP or SUA messages themselves. Resources are kept
within the SG to forward messages from one section to another and to
populate the MTP routing label or SCTP header, based on the
destination local reference of these messages (Connect Confirm, Data
Transfer, ...)
This means that in the SG, two local references are allocated, one
3-byte value used for the SS7 section and one 4 byte value for the
IP section. Also a resource containing the connection data for both
sections is allocated, and either of the two local references can be
used to retrieve this data e.g. for an incoming DT1 or CODT, for
example.
******** SS7 *************** IP ********
* SEP *---------* *--------* *
* or * * SG * * ASP *
* STP * * * * *
******** *************** ********
+------+ +------+
| SUAP | | SUAP |
+------+ +------+------+ +------+
| SCCP | | SCCP | SUA | | SUA |
+------+ +------+------+ +------+
| MTP3 | | MTP3 | | | |
+------| +------+ SCTP | | SCTP |
| MTP2 | | MTP2 | | | |
+------+ +------+------+ +------+
| L1 | | L1 | IP | | IP |
+------+ +------+------+ +------+
| | | |
+---------------+ +------------+
SUAP - SCCP/SUA Application Protocol (e.g. - RANAP/RNSAP)
STP - SS7 Signaling Transfer Point
The above architecture may simplify, in some cases, to carrying SS7
application protocols between two IP based endpoints. In this
Loughney (editor) [Page 8]
Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001
scenario, full SG functionality is not needed. This architecture is
considered in the next section.
1.3.3 All IP Architecture
This architecture can be used to carry a protocol that uses the
transport services of SCCP, but is contained with an IP network.
This allows extra flexibility in developing networks, especially
when interaction between legacy signaling is not needed. The
architecture removes the need for signaling gateway functionality.
******** IP ********
* *--------* *
* IPSP * * IPSP *
* * * *
******** ********
+------+ +------+
| SUAP | | SUAP |
+------+ +------+
| SUA | | SUA |
+------+ +------+
| SCTP | | SCTP |
+------+ +------+
| IP | | IP |
+------+ +------+
| |
+----------------+
SUAP - SCCP/SUA Application Protocol (e.g. - RANAP/RNSAP)
In the case where a collision occurs during initiation, there exist
two possible solutions: 1) if there are sufficient resources, both
initiations could be accepted; 2) both ASPs should back-off and
after some amount of time, later re-establish an initiation.
1.3.4 Generalized Peer-to-Peer Network Architecture
Figure 1 shows an example network architecture that can support
robust operation and failover. There need to be some management
resources at the AS to manage traffic.
Loughney (editor) [Page 9]
Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001
***********
* AS1 *
* +-----+ * SCTP Associations
* |ASP1 +-------------------+
* +-----+ * | ***********
* * | * AS3 *
* +-----+ * | * +-----+ *
* |ASP2 +-----------------------------------------+ASP1 | *
* +-----+ * | * +-----+ *
* * | * *
* +-----+ * | * +-----+ *
* |ASP3 | * +--------------------------+ASP2 | *
* +-----+ * | | * +-----+ *
*********** | | ***********
| |
*********** | | ***********
* AS2 * | | * AS4 *
* +-----+ * | | * +-----+ *
* |ASP1 +--------------+ +---------------------+ASP1 | *
* +-----+ * * +-----+ *
* * * *
* +-----+ * * +-----+ *
* |ASP2 +-----------------------------------------+ASP1 | *
* +-----+ * * +-----+ *
* * ***********
* +-----+ *
* |ASP3 | *
* +-----+ *
* *
***********
Figure 1: Generalized Architecture
In this example, the Application Servers are shown residing within
one logical box, with ASPs located inside. In fact, an AS could be
distributed among several hosts. In such a scenario, the host
should share state as protection in the case of a failure.
Additionally, in a distributed system, one ASP could be registered
to more than one AS. This draft should not restrict such systems -
though such a case in not specified.
1.3.5 Signaling Gateway Network Architecture
When interworking between SS7 and IP domains is needed, the SGP acts
as the gateway node between the SS7 network and the IP network. The
SGP will transport SCCP-user signaling traffic from the SS7 network
to the IP-based signaling nodes (for example IP-resident Databases).
The Signaling Gateway can be considered as a group of Application
Servers with additional functionality to interface towards an SS7
network.
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Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001
The SUA protocol should be flexible enough to allow different
configurations and transport technology to allow the network
operators to meet their operation, management and performance
requirements.
An ASP may be connected to multiple SGPs (see figure 2). In such a
case, a particular SS7 destination may be reachable via more than
SG, therefore, more than one route. Given that proper SLS selection,
loadsharing, and SG selection based on point code availability is
performed at the ASP, it will be necessary for the ASP to maintain
the status of each distant SGPs to which it communicates on the
basis of the SG through which it may route.
Signaling Gateway
SCTP Associations
+----------+ **************
| SG1 | * AS3 *
| ******** | * ******** *
| * SGP11+--------------------------------------------+ ASP1 * *
| ******** | / * ******** *
| ******** | | * ******** *
| * SGP12+--------------------------------------------+ ASP2 * *
| ******** | \ / | * ******** *
+----------+ \ | | * . *
\ | | * . *
+----------+ \ | | * . *
| SG2 | \ | | * . *
| ******** | \ | | * ******** *
| * SGP21+---------------------------------+-+ * * ASPN * *
| ******** | \ * ******** *
| ******** | \ **************
| * SGP22+---+--+ \
| ******** | | | \ **************
+----------+ | | \ * AS4 *
| | \ * ******** *
| +-------------------------------------+ ASP1 * *
| * ******** *
| * . *
| * . *
| * *
| * ******** *
+----------------------------------------+ ASPn * *
* ******** *
**************
Figure 2: Signaling Gateway Architecture
The pair of SGs can either operate as replicated endpoints or as
replicated relay points from the SS7 network point of view.
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Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001
Replicated endpoints: the coupling between the SGs and the ASPs when
the SGs act as replicated endpoints is an implementation issue.
Replicated relay points: in normal circumstances, the path from SEP
to ASP will always go via the same SGP when in-sequence-delivery is
requested. However, linkset failures may cause MTP to re-route to
the other SG.
1.3.6 ASP Fail-over Model and Terminology
The SUA protocol supports ASP fail-over functions to support a high
availability of transaction processing capability.
An Application Server can be considered as a list of all ASPs
configured/registered to handle SCCP-user messages within a certain
range of routing information, known as a Routing Key. One or more
ASPs in the list may normally be active to handle traffic, while
others may be inactive but available in the event of failure or
unavailability of the active ASP(s).
1.4 Services Provided by the SUA Layer
1.4.1 Support for the transport of SCCP-User Messages
The SUA needs to support the transfer of SCCP-user messages. The SUA
layer at the SG needs to seamlessly transport the user messages.
1.4.2 SCCP Protocol Class Support
Depending upon the SCCP-users supported, the SUA shall support the 4
possible SCCP protocol classes transparently. The SCCP protocol
classes are defined as follows:
* Protocol class 0 provides unordered transfer of SCCP-user
messages in a connectionless manner.
* Protocol class 1 allows the SCCP-user to select the in-
sequence delivery of SCCP-user messages in a connectionless
manner.
* Protocol class 2 allows the bi-directional transfer of SCCP-
user messages by setting up a temporary or permanent
signaling connection.
* Protocol class 3 allows the features of protocol class 2 with
the inclusion of flow control. Detection of message loss or
mis-sequencing is included.
Protocol classes 0 and 1 make up the SCCP connectionless service.
Protocol classes 2 and 3 make up the SCCP connection-oriented
service.
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Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001
1.4.3 Native Management Functions
The SUA layer provides the capability to indicate errors associated
with the SUA-protocol messages and to provide notification to local
management and the remote peer as is necessary.
1.4.4 Interworking with SCCP Network Management Functions
SUA uses the existing ASP management messages for ASP status
handling. The interworking with SCCP management consists on the
sending of DUNA, DAVA, DAUD, DRST or SCON messages on receipt of
SSP, SSA, SST or SSC to the appropriate ASPs. See also chapter
1.4.5. The primitives below are considered to be sent between the
SCCP and SUA management functions in the SG to trigger events in the
IP and SS7 domain.
Generic |Specific |
Name |Name |ANSI/ITU Reference
----------+-----------+---------------------------------------------
N-State |Request |ITU-Q.711 Chap 6.3.2.3.2 (Tab 14/Q.711)
|Indication |ANSI-T1.112 Chap 2.3.2.3.2 (Tab 8E/T1.112.1)
----------+-----------+---------------------------------------------
N-Pcstate |Indication |ITU-Q.711 Chap 6.3.2.3.3 (Tab 15/Q.711)
| |ANSI-T1.112 Chap 2.3.2.3.4 (Tab 8G/T1.112.1)
1.4.5 Support for the management between the SGP and ASP.
The SUA layer should provide interworking with SCCP management
functions at the SG for seamless inter-operation between the SCN
network and the IP network. It should:
* Provide an indication to the SCCP-user at an ASP that a SS7
endpoint/peer is unreachable.
* Provide an indication to the SCCP-user at an ASP that a SS7
endpoint/peer is reachable.
* Provide congestion indication to SCCP-user at an ASP.
* Provide the initiation of an audit of SS7 endpoints at the
SG.
1.4.6 Relay function
For network scalability purposes, the SUA may be enhanced with a
relay functionality to determine the next hop SCTP association
towards the destination SUA endpoint.
The determination of the next hop may be based on Global Title
information (e.g. E.164 number), in analogy with SCCP GTT in SS7
networks, modeled in [ITU-T Q.714]. It may also be based on Hostname
information, IP address, or pointcode contained in the called party
address.
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Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001
This allows for greater scalability, reliability and flexibility in
wide-scale deployments of SUA. The usage of a relay function is a
deployment decision.
1.5 Internal Functions Provided in the SUA Layer
To perform its addressing and relaying capabilities, the SUA makes
use of a Address Mapping Function (AMF). This function is considered
part of SUA, but the way it is realized is left implementation /
deployment dependent (local tables, DNS (ENUM), LDAP, etc.)
The AMF is invoked when a message is received at the incoming
interface. The AMF is responsible for resolving the address
presented in the incoming SCCP/SUA message to SCTP associations to
destinations within the IP network. The AMF will select the
appropriate SCTP association based upon routing context / routing
key information available. The destination might be the end SUA node
or a SUA relay node. The Routing Keys reference an Application
Server, which will have one or more ASPs processing traffic for the
AS. The availability and status of the ASPs is handled by SUA ASP
management messages.
Possible SS7 address/routing information that comprise a Routing Key
entry includes, for example, OPC, DPC, SIO found in the MTP3 routing
label, SCCP subsystem number, or Transaction ID. IP addresses and
host names can also be used as Routing Key Information.
It is expected that the routing keys be provisioned via a MIB or
external process, such as a database.
1.5.1 Address Mapping at the SG
Normally, one or more ASPs are active in the AS (i.e., currently
processing traffic) but in certain failure and transition cases it
is possible that there may not be an active ASP available. The SGP
will buffer the message destined for this AS for a time t(r) or
until an ASP becomes available. When no ASP becomes available before
expiry of t(r), the SGP will flush the buffered messages and
initiate the appropriate return or refusal procedures.
If there is no match for an incoming message, a default treatment
MUST be specified. Possible solutions are to provide a default
Application Server to direct all unallocated traffic to a (set of)
default ASP(s), or to drop the messages and provide a notification
to management. The treatment of unallocated traffic is
implementation dependent.
1.5.2 Address Mapping at the ASP
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Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001
To direct messages to the SS7 network, the ASP MUST perform an
address mapping to choose the proper SGP for a given message. This
is accomplished by observing the Destination Point Code and other
elements of the outgoing message, SS7 network status, SGP
availability, and Routing Context configuration tables.
A Signaling Gateway may be composed of one or more SGPs. There is,
however, no SUA messaging to manage the status of an SGP. Whenever
an SCTP association to an SGP exists, it is assumed to be available.
Also, every SGP of one SG communicating with one ASP regarding one
AS provides identical SS7 connectivity to this ASP.
An ASP SHOULD send responses only to that SGP that it received
messages from; within the routing context which it is currently
active and receiving traffic. The routing context itself is
effectively used by the ASP to select the SGP.
1.5.3 Address Mapping Function at a Relay Node
The relay function is invoked when:
- Routing is on Global Title
- Routing is on Hostname
- Routing is on SSN+PC or SSN+IP Address and the address
presented is not the one of the relay node
Translation/resolution of the above address information yields one
of the following:
- Route on SSN: SCTP association ID towards the destination
node, SSN and optionally Routing Context and/or IP address.
- Route on GT: SCTP association ID towards next relay node,
(new) GT and optionally SSN and/or Routing Context.
- Routing on Hostname: SCTP association ID towards next relay
node, (new) Hostname and optionally SSN and/or Routing
Context.
- A local SUA-user (combined relay/end node)
To prevent looping, a hop counter is used. The originating end node
(be it an SS7 or an IP node) sets the value of the hop counter to
the maximum value (15 or less). Each time the relay function is
invoked within an intermediate (relay) node, the hop counter MUST be
decremented. When the value reaches zero, the return or refusal
procedures are invoked with reason "Hop counter violation".
1.5.4 SCTP Stream Mapping
The SUA supports SCTP streams. The SG/AS needs to maintain a list of
SCTP and SUA-users for mapping purposes. SCCP-users requiring
sequenced message transfer need to be sent over a stream supporting
sequenced delivery.
Loughney (editor) [Page 15]
Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001
SUA MUST use stream 0 for SUA management messages. It is recommended
that sequenced delivery be used to preserve the order of management
message delivery.
Stream selection based on protocol class:
- Protocol class 0: SUA SHOULD select an unordered stream.
- Protocol class 1: SUA MUST select an ordered stream, based on
a sequence parameter given by the upper layer over the
primitive interface.
- Protocol classes 2 and 3: SUA will select an ordered stream,
based on its own source local reference.
1.6 Definition of SUA Boundaries
1.6.1 Definition of the upper boundary
The following primitives are supported between the SUA and an SCCP-
user (a reference to ITU and ANSI sections where these primitives
and corresponding parameters are described, is also given):
Generic |Specific |
Name |Name |ANSI/ITU Reference
------------+----------+-------------------------------------------
N-Connect |Request |ITU-Q.711 Chap 6.1.1.2.2 (Tab 2/Q.711)
|Indication|ANSI-T1.112 Chap 2.1.1.2.2 (Tab 2/T1.112.1)
|Response |
|Confirm |
------------+----------+-------------------------------------------
N-Data |Request |ITU-Q.711 Chap 6.1.1.2.3 (Tab 3/Q.711)
|Indication|ANSI-T1.112 Chap 2.1.1.2.3 (Tab 3/T1.112.1)
------------+----------+-------------------------------------------
N-Expedited |Request |ITU-Q.711 Chap 6.1.1.2.3 (Tab 4/Q.711)
Data |Indication|ANSI-T1.112 Chap 2.1.1.2.3 (Tab 4/T1.112.1)
------------+----------+-------------------------------------------
N-Reset |Request |ITU-Q.711 Chap 6.1.1.2.3 (Tab 5/Q.711)
|Indication|ANSI-T1.112 Chap 2.1.1.2.3 (Tab 5/T1.112.1)
|Response |
|Confirm |
------------+----------+-------------------------------------------
N-Disconnect|Request |ITU-Q.711 Chap 6.1.1.2.4 (Tab 6/Q.711)
|Indication|ANSI-T1.112 Chap 2.1.1.2.4 (Tab 6/T1.112.1)
------------+----------+-------------------------------------------
N-Inform |Request |ITU-Q.711 Chap 6.1.1.3.1 (Tab 7/Q.711)
|Indication|ANSI-T1.112 Chap 2.1.1.2.5 (Tab 6A/T1.112.1)
------------+----------+-------------------------------------------
N-Unit Data |Request |ITU-Q.711 Chap 6.2.2.3.1 (Tab 10/Q.711)
|Indication|ANSI-T1.112 Chap 2.2.2.3.1 (Tab 8A/T1.112.1)
------------+----------+-------------------------------------------
N-Notice |Indication|ITU-Q.711 Chap 6.2.2.3.2 (Tab 11/Q.711)
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Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001
| |ANSI-T1.112 Chap 2.2.2.3.2 (Tab 8B/T1.112.1)
1.6.2 Definition of the lower boundary
The upper layer primitives provided by the SCTP are provided in
[SCTP].
2 Conventions
The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD,
SHOULD NOT, RECOMMENDED, NOT RECOMMENDED, MAY, and OPTIONAL, when
they appear in this document, are to be interpreted as described in
[RFC2119].
3 Protocol Elements
The general message format includes a Common Message Header together
with a list of zero or more parameters as defined by the Message
Type.
For forward compatibility, all Message Types may have attached
parameters even if none are specified in this version.
3.1 Common Message Header
The protocol messages for the SCCP-User Adaptation Protocol requires
a message structure which contains a version, message class, message
type, message length and message contents. This message header is
common among all signaling protocol adaptation layers:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Version | Reserved | Message Class | Message Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message Data |
Note that the 'data' portion of SUA messages SHALL contain SCCP-User
data, not the encapsulated SCCP message.
Optional parameters can only occur at most once in an SUA message.
3.1.1 SUA Protocol Version
The version field (ver) contains the version of the SUA adaptation
layer. The supported versions are:
1 SUA version 1.0
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Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001
3.1.2 Message Classes
Message Classes
0 SUA Management (MGMT) Message
1 Reserved
2 Signaling Network Management (SNM) Messages
3 ASP State Maintenance (ASPSM) Messages
4 ASP Traffic Maintenance (ASPTM) Messages
5 Reserved
6 Reserved
7 Connectionless Messages
8 Connection-Oriented Messages
9 - 127 Reserved by the IETF
128 - 255 Reserved for IETF-Defined Message Class Extensions
3.1.3 Message Types
SUA Management Messages
0 Error (ERR)
1 Notify (NTFY)
2 - 127 Reserved by the IETF
128- 255 Reserved for IETF-Defined Message Class Extensions
Signaling Network Management (SNM) Messages
0 Reserved
1 Destination Unavailable (DUNA)
2 Destination Available (DAVA)
3 Destination State Audit (DAUD)
4 Network Congestion (SCON)
5 Reserved
6 Destination Restricted (DRST)
7 - 127 Reserved by the IETF
128 - 255 Reserved for IETF-Defined Message Class Extensions
Application Server Process State Maintenance (ASPSM) Messages
0 Reserved
1 ASP Up (UP)
2 ASP Down (DOWN)
3 Heartbeat (BEAT)
4 ASP Up Ack (UP ACK)
5 ASP Down Ack (DOWN ACK)
6 Heartbeat Ack (BEAT ACK)
7 - 127 Reserved by the IETF
128 - 255 Reserved for IETF-Defined Message Class Extensions
ASP Traffic Maintenance (ASPTM) Messages
Loughney (editor) [Page 18]
Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001
0 Reserved
1 ASP Active (ACTIVE)
2 ASP Inactive (INACTIVE)
3 ASP Active Ack (ACTIVE ACK)
4 ASP Inactive Ack (INACTIVE ACK)
5 - 127 Reserved by the IETF
128 - 255 Reserved for IETF-Defined Message Class Extensions
Connectionless Messages
0 Reserved
1 Connectionless Data Transfer (CLDT)
2 Connectionless Data Response (CLDR)
3 - 127 Reserved by the IETF
128 - 255 Reserved for IETF-Defined Message Class Extensions
Connection-Oriented Messages
0 Reserved
1 Connection Request (CORE)
2 Connection Acknowledge (COAK)
3 Connection Refused (COREF)
4 Release Request (RELRE)
5 Release Complete (RELCO)
6 Reset Confirm (RESCO)
7 Reset Request (RESRE)
8 Connection Oriented Data Transfer (CODT)
9 Connection Oriented Data Acknowledge (CODA)
10 Connection Oriented Error (COERR)
11 Inactivity Test (COIT)
12 - 127 Reserved by the IETF
128 - 255 Reserved for IETF-Defined Message Class Extensions
3.1.4 Message Length
The Message Length defines the length of the message in octets,
including the header and including all padding bytes.
3.1.5 Tag-Length-Value Format
SUA messages consist of a Common Header followed by zero or more
parameters, as defined by the message type. The Tag-Length-Value
(TLV) parameters contained in a message are defined in a Tag-Length-
Value format as shown below.
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Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Parameter Tag | Parameter Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
\ \
/ Parameter Value /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Parameter Tag: 16 bits (unsigned integer)
Tag field is a 16-bit identifier of the type of parameter. It
takes a value of 0 to 65535.
Parameter Length: 16 bits (unsigned integer)
The Parameter Length field contains the size of the parameter in
bytes, including the Parameter Tag, Parameter Length, and
Parameter Value fields. The Parameter Length does not include any
padding bytes. However, composite parameters will contain all
padding bytes, since all parameters contained within this
composite parameter will be considered multiples of 4 bytes.
Parameter Value: variable-length.
The Parameter Value field contains the actual information to
be trasnfered in the parameter.
The total length of a parameter (including Tag, Parameter
Length and Value fields) MUST be a multiple of 4 bytes. If the
length of the parameter is not a multiple of 4 bytes, the
sender pads the parameter at the end (i.e., after the
Parameter Value field) with all zero bytes. The length of the
padding is NOT included in the parameter length field. A
sender should NEVER pad with more than 3 bytes. The receiver
MUST ignore the padding bytes.
Implementation note: the use of TLV in principle allows the
parameters to be placed in a random order in the message. However,
some guidelines should be considered for easy processing in the
following order:
- Parameters needed to correctly process other message
parameters, preferably should precede these parameters (such
as Routing Context).
- Mandatory parameters preferably SHOULD precede any optional
parameters.
- The data parameter will normally be the final one in the
message.
Loughney (editor) [Page 20]
Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001
- The receiver SHOULD accept parameters in any order, except
where explicitly mandated.
3.2 SUA Connectionless Messages
The following section describes the SUA Connectionless transfer
messages and parameter contents. The general message format
includes a Common Message Header together with a list of zero or
more parameters as defined by the Message Type. All Message Types
can have attached parameters.
3.2.1 Connectionless Data Transfer (CLDT)
This message transfers data between one SUA to another.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0006 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Routing Context /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0101 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0102 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Source Address /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0103 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Destination Address /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0003 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Data /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Parameters
Routing Context Mandatory
Flags Mandatory
Source Address Mandatory
Destination Address Mandatory
Data Mandatory
Loughney (editor) [Page 21]
Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001
Implementation note: This message covers the following SCCP
messages: unitdata (UDT), extended unitdata (XUDT), long unitdata
(LUDT).
3.2.2 Connectionless Data Response (CLDR)
This message is used as a response message by the peer to report
errors in the received CLDT message, when the return on error option
is set.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0006 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Routing Context /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0101 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0106 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SCCP Cause |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0102 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Source Address /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0103 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Destination Address /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0003 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Data /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Parameters
Routing Context Mandatory
Flags Mandatory
SCCP Cause Mandatory
Source Address Mandatory
Destination Address Mandatory
Data Optional
Loughney (editor) [Page 22]
Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001
Implementation note: This message covers the following SCCP
messages: unitdata service (UDTS), extended unitdata service (XUDTS)
and long unitdata service (LUDTS).
3.3 Connection Oriented Messages
3.3.1 Connection Oriented Data Transfer (CODT)
This message transfers data between one SUA to another for
connection-oriented service.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0006 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Routing Context /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0107 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0105 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination Reference Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0003 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Data /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Parameters
Routing Context Mandatory
Sequence number Mandatory *1
Destination Reference Number Mandatory
Data Mandatory
NOTE *1: This parameter is not present in case of Expedited Data
(ED).
Implementation note: This message covers the following SCCP
messages: DaTa form 1 (DT1), DaTa form 2 (DT2), Expedited Data (ED).
3.3.2 Connection Oriented Data Acknowledge (CODA)
This message is used to acknowledge receipt of data by the peer.
This message is used only with protocol class 3.
Loughney (editor) [Page 23]
Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0006 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Routing Context /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0105 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination Reference Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0108 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Receive Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x010A | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Credit |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Parameters
Routing Context Mandatory
Destination Reference Number Mandatory
Receive Sequence number Mandatory *1
Credit Mandatory *1
NOTE *1: Mandatory when representing Data Acknowledgement (AK).
Implementation note: This message covers the following SCCP
messages: data AcKnowledgement (AK), Expedited data Acknowledgement
(EA).
3.3.3 Connection Request (CORE)
This message is used for establishing a signaling connection between
two peer endpoints.
Loughney (editor) [Page 24]
Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0006 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Routing Context /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0101 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0104 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Reference Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0103 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Destination Address /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0102 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Source Address /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x010A | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Credit |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0003 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Data /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Parameters
Routing Context Mandatory
Flags Mandatory
Source Reference Number Mandatory
Destination Address Mandatory
Source Address Optional
Credit Mandatory, protocol class 3 only
Data Optional
Implementation note: This message covers the following SCCP message:
Connection Request (CR).
3.3.4 Connection Acknowledge (COAK)
Loughney (editor) [Page 25]
Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001
This message is used to acknowledge a connection request from the
peer endpoint.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0006 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Routing Context /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0101 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0105 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination Reference Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0104 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Reference Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x010A | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Credit |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0103 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Destination Address /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0003 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Data /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Parameters
Routing Context Mandatory
Flags Mandatory
Destination Reference Number Mandatory
Source Reference Number Mandatory
Credit Mandatory *2
Destination Address Optional *1
Data Optional
NOTE *1: Destination Address parameter will be present in case
that the received CORE message conveys the Source
Address parameter.
Loughney (editor) [Page 26]
Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001
NOTE *2: Only applicable for protocol class 3.
Implementation note: This message covers the following SCCP message:
Connection Confirm (CC).
3.3.5 Connection Refused (COREF)
This message is used to refuse a connection request between two peer
endpoints.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0006 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Routing Context /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0105 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination Reference Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0106 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SCCP Cause |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0103 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Destination Address /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0003 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Data /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Parameters
Routing Context Mandatory
Destination Reference Number Mandatory
SCCP Cause Mandatory
Destination Address Optional *1
Data Optional
Note *1: Destination Address parameter will be present in case
that the received CORE message conveys the Source Address
parameter.
Implementation note: This message covers the following SCCP message:
Connection REFused (CREF).
Loughney (editor) [Page 27]
Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001
3.3.6 Release Request (RELRE)
This message is used to request a signaling connection between two
peer endpoints be released. All associated resources can then be
released.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0006 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Routing Context /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0105 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination Reference Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0104 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Reference Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0106 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SCCP Cause |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0101 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0003 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Data /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Parameters
Routing Context Mandatory
Destination Reference Number Mandatory
Source Reference Number Mandatory
SCCP Cause Mandatory
Flags Optional
Data Optional
Implementation note: This message covers the following SCCP message:
connection ReLeaSeD (RLSD).
3.3.7 Release Complete (RELCO)
Loughney (editor) [Page 28]
Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001
This message is used to acknowledge the release of a signaling
connection between two peer endpoints. All associated resources
should be released.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0006 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Routing Context /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0105 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination Reference Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0104 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Reference Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Parameters
Routing Context Mandatory
Destination Reference Number Mandatory
Source Reference Number Mandatory
Implementation note: This message covers the following SCCP message:
ReLease Complete (RLC).
3.3.8 Reset Request (RESRE)
This message is used to indicate that the sending SCCP/SUA wants to
initiate a reset procedure (re-initialization of sequence numbers)
to the peer endpoint.
Loughney (editor) [Page 29]
Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0006 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Routing Context /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0105 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination Reference Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0104 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Reference Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0106 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SCCP Cause |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Parameters
Routing Context Mandatory
Destination Reference Number Mandatory
Source Reference Number Mandatory
SCCP Cause Mandatory
Implementation note: This message covers the following SCCP message:
ReSet Request (RSR).
3.3.9 Reset Confirm (RESCO)
This message is used to confirm the Reset Request.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0006 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Routing Context /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0105 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination Reference Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0104 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Reference Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001
Parameters
Routing Context Mandatory
Destination Reference Number Mandatory
Source Reference Number Mandatory
Implementation note: This message covers the following SCCP message:
ReSet Confirmation (RSC).
3.3.10 Connection Oriented Error (COERR)
The COERR message is sent to indicate a protocol data unit error.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0006 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Routing Context /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0105 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination Reference Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0106 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SCCP Cause |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Parameters
Routing Context Mandatory
Destination Reference Number Mandatory
SCCP Cause Mandatory
Implementation note: This message covers the following SCCP message:
Protocol Data Unit ERRor (ERR).
3.3.11 Connection Oriented Inactivity Test (COIT)
This message is used for auditing the signaling connection state and
the consistency of connection data at both ends of the signaling
connection.
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0006 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Routing Context /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0101 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0104 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Reference Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0105 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination Reference number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0107 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x010A | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Credit |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Parameters
Routing Context Mandatory
Flags Mandatory
Source Reference Number Mandatory
Destination Reference number Mandatory
Sequence number Mandatory *1
Credit Mandatory *1
NOTE *1: Information in these parameter fields reflects those
values sent in the last data form 2 or data
acknowledgement message. They are ignored if the protocol
class indicates class 2.
Implementation note: This message covers the following SCCP message:
Inactivity Test (IT).
3.4 Signaling Network Management Messages
3.4.1 Destination Unavailable (DUNA)
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In the scope of SUA, this message is covered by the PC- or N-state
indication passed between SCCP and local SCCP-user. The DUNA message
is sent from the SGP or relay node to all concerned ASPs (servicing
SCCP-users considered local to the SGP or relay node, see chapter
1.3.1.1), when a destination or SCCP-user has become unreachable.
The SUA-User at the ASP is expected to stop traffic to the affected
destination or SCCP-user through the SGP or relay node initiating
the DUNA.
The format for DUNA Message parameters is as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0006 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Routing Context /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0103 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Destination Address /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0004 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Info String /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Parameters
Routing Context Optional
Destination Address Mandatory *1
Info String Optional
Note 1: The destination address refers to the node that has
become unavailable. When the SSN is included in the
Destination Address parameter, the DUNA/DAVA/DRST/SCON
message corresponds to the SCCP N-STATE primitive. When
SSN is not included in the Destination Address parameter,
the DUNA/DAVA/DRST/SCON message corresponds to the
SCCP N-PCSTATE primitive.
3.4.2 Destination Available (DAVA)
In the scope of SUA, this message is covered by the PC- and N-state
indication passed between SCCP and local SCCP-user. The DAVA message
is sent from the SGP or relay node to all concerned ASPs (servicing
SCCP-users considered local to the SGP or relay node, see chapter
1.3.1.1) to indicate that a destination (PC or SCCP-user) is now
reachable. The ASP SUA-User protocol is expected to resume traffic
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Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001
to the affected destination through the SGP or relay node initiating
the DAVA.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0006 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Routing Context /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0103 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Destination Address /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0004 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Info String /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Parameters
Routing Context Optional
Destination Address Mandatory *1
Info String Optional
Note 1: The destination address refers to the node that has
become unavailable. When the SSN is included in the
Destination Address parameter, the DUNA/DAVA/DRST/SCON
message corresponds to the SCCP N-STATE primitive. When
SSN is not included in the Destination Address parameter,
the DUNA/DAVA/DRST/SCON message corresponds to the
SCCP N-PCSTATE primitive.
3.4.3 Destination State Audit (DAUD)
The DAUD message can be sent from the ASP to the SGP (or relay node)
to query the availability state of the routes to an affected
destination. A DAUD may be sent periodically after the ASP has
received a DUNA, until a DAVA is received. The DAUD can also be sent
when an ASP recovers from isolation from the SGP (or relay node).
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Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0001 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0006 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Routing Context /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Destination Address /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0004 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Info String /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Parameters
Routing Context Optional
Destination Address Mandatory *1
Info String Optional
Note 1: The destination address refers to the node that has
become unavailable. When the SSN is included in the
Destination Address parameter, the DUNA/DAVA/DRST/SCON
message corresponds to the SCCP N-STATE primitive. When
SSN is not included in the Destination Address parameter,
the DUNA/DAVA/DRST/SCON message corresponds to the
SCCP N-PCSTATE primitive.
3.4.4 Network Congestion (SCON)
The SCON message can be sent from the SGP or relay node to all
concerned ASPs to indicate that the congestion level in the SS7
network to a specified destination has changed.
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0001 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0006 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Routing Context /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Destination Address /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x000F | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Congestion Level |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0004 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Info String /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Parameters
Routing Context Optional
Congestion Level Mandatory
Destination Address Mandatory *1
Info String Optional
Note 1: The destination address refers to the node that has
become unavailable. When the SSN is included in the
Destination Address parameter, the DUNA/DAVA/DRST/SCON
message corresponds to the SCCP N-STATE primitive. When
SSN is not included in the Destination Address parameter,
the DUNA/DAVA/DRST/SCON message corresponds to the
SCCP N-PCSTATE primitive.
3.4.5 Destination Restricted (DRST)
The DRST message is optionally sent from the SGP to all concerned
ASPs to indicate that the SGP has determined that one or more
destinations are now restricted from the point of view of the SGP,
or in response to a DAUD message if appropriate. The SUA layer at
the ASP is expected to send traffic to the affected destination via
an alternate SGP of equal priority, but only if such an alternate
route exists and is available. If the affected destination is
currently considered unavailable by the ASP, the MTP3-User should be
informed that traffic to the affected destination can be resumed.
In this case, the SUA layer should route the traffic through the SGP
initiating the DRST message.
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Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001
This message is optional for the SGP to send and it is optional for
the ASP to act on any information received in the message.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0001 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0006 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Routing Context /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Destination Address /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0004 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Info String /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Parameters
Routing Context Optional
Destination Address Mandatory *1
Info String Optional
Note 1: The destination address refers to the node that has
become unavailable. When the SSN is included in the
Destination Address parameter, the DUNA/DAVA/DRST/SCON
message corresponds to the SCCP N-STATE primitive. When
SSN is not included in the Destination Address parameter,
the DUNA/DAVA/DRST/SCON message corresponds to the
SCCP N-PCSTATE primitive.
3.5 Application Server Process State Maintenance Messages
3.5.1 ASP Up (UP)
The ASP UP (UP) message is used to indicate to a remote SUA peer
that the Adaptation layer is up and running.
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x000E | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ASP Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0109 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ASP Capabilities |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0004 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Info String /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Parameters
ASP Identifier Optional *1
ASP Capabilities Optional
Info String Optional
Note 1: ASP Identifier MUST be used where the IPSP/SGP cannot
identify the ASP by pre-configured address/port number
information (e.g., where an ASP is resident on a Host using
dynamic address/port number assignment).
3.5.2 ASP Up Ack (UP ACK)
The ASP UP Ack message is used to acknowledge an ASP-Up message
received from a remote SUA peer.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x000E | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ASP Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0109 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ASP Capabilities |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0004 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Info String /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Parameters
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Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001
ASP Identifier Optional *1
ASP Capabilities Optional
Info String Optional
Note 1: ASP Identifier MUST be used where the IPSP/SGP cannot
identify the ASP by pre-configured address/port number
information (e.g., where an ASP is resident on a Host using
dynamic address/port number assignment).
3.5.3 ASP Down (DOWN)
The ASP Down (DOWN) message is used to indicate to a remote SUA peer
that the adaptation layer is not running.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0004 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Info String /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Parameters
Info String Optional
3.5.4 ASP Down Ack (DOWN ACK)
The ASP DOWN Ack message is used to acknowledge an ASP-Down message
received from a remote SUA peer.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0004 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Info String /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Parameters
Info String Optional
Note: ASP DOWN ACK will always be sent to acknowledge an ASP DOWN.
3.5.5 Heartbeat (BEAT)
The Heartbeat message is optionally used to ensure that the SUA
peers are still available to each other.
The format for the BEAT message is as follows:
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Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0009 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Heartbeat Data /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Parameters
Heartbeat Data Optional
3.5.6 Heartbeat Ack (BEAT ACK)
The Heartbeat ACK message is sent in response to a BEAT message. A
peer MUST send a BEAT ACK in response to a BEAT message. It includes
all the parameters of the received Heartbeat message, without any
change.
The format for the BEAT ACK message is as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0009 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Heartbeat Data /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Parameters
Heartbeat Data Optional
3.6 ASP Traffic Maintenance Messages
3.6.1 ASP Active (ACTIVE)
The ASPAC message is sent by an ASP to indicate to a remote SUA peer
that it is Active and ready to process signaling traffic for a
particular Application Server.
The format for the ACTIVE message is as follows:
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Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x000B | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Traffic Mode Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0006 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Routing Context /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0004 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Info String /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Parameters
Traffic Mode Type Mandatory
Routing Context Optional
Info String Optional
3.6.2 ASP Active Ack (ACTIVE ACK)
The ASPAC Ack message is used to acknowledge an ASP-Active message
received from a remote SUA peer.
The format for the ACTIVE Ack message is as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x000B | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Traffic Mode Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0006 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Routing Context /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0004 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Info String /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Parameters
Traffic Mode Type Mandatory
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Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001
Routing Context Optional
Info String Optional
The value of the Traffic Mode Type and Routing Context parameters is
the same as for the ASP-Active message.
The value of the optional Info String parameter is the same as for
the ASP-Active message.
3.6.3 ASP Inactive (INACTIVE)
The INACTIVE message is sent by an ASP to indicate to a remote SUA
peer that it is no longer processing signaling traffic within a
particular Application Server.
The format for the ASPIA message parameters is as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0006 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Routing Context /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0004 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ INFO String /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Parameters
Routing Context Optional
INFO String Optional
3.6.4 ASP Inactive Ack (INACTIVE ACK)
The INACTIVE Ack message is used to acknowledge an ASP-Inactive
message received from a remote SUA peer.
The format for the INACTIVE Ack message is as follows:
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Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0006 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Routing Context /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0004 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ INFO String /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Parameters
Routing Context Optional
INFO String Optional
The value of the optional Info String parameter is the same as for
the ASP-Active message.
3.7 SUA Management Messages
These messages are used for managing SUA and the representations of
the SCCP subsystems in the SUA layer.
3.7.1 Error (ERR)
The ERR message is sent between two SUA peers to indicate an error
situation. The Data parameter is optional, possibly used for error
logging and/or debugging.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x000C | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Error Code |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0007 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Diagnostic Info /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Parameters
Error Code Mandatory
Diagnostic Info Optional
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3.7.2 Notify (NTFY)
The Notify message used to provide an autonomous indication of SUA
events to an SUA peer.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x000D | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Status |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x000E | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ASP Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0006 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Routing Context /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0004 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Info String /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The NTFY message contains the following parameters:
Parameters
Status Mandatory
ASP Identifier Optional *1
Routing Context Optional
Info String Optional
Note 1: ASP Identifier MUST be used where the IPSP/SGP cannot
identify the ASP by pre-configured address/port number
information (e.g., where an ASP is resident on a Host using
dynamic address/port number assignment).
3.8 Common Parameters
These TLV parameters are common across the different adaptation
layers.
Parameter Name Parameter ID
============== ============
Reserved 0x0000
Not used in SUA 0x0001
Not used in SUA 0x0002
Data 0x0003
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Info String 0x0004
Affected Point Code 0x0005
Routing Context 0x0006
Diagnostic Info 0x0007
Not used in SUA 0x0008
Heartbeat Data 0x0009
Reason 0x000A
Traffic Mode Type 0x000B
Error Code 0x000C
Status 0x000D
ASP Identifier 0x000E
Congestion Level 0x000F
3.8.1 Not Used
Use of Parameter ID 0x0001 in SUA messages is not supported.
3.8.2 Not used
Use of Parameter ID 0x0002 in SUA messages is not supported.
3.8.3 Data
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0003 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Data /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Data parameter field contains the SS7 SCCP-User application
message, for example an INAP/TCAP message.
3.8.4 Info String
The INFO String parameter can carry any meaningful 8-BIT ASCII
character string along with the message. Length of the INFO String
parameter is from 0 to 255 characters. No procedures are presently
identified for its use but service providers may use the INFO String
for debugging purposes.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0004 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Info String /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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3.8.5 Affected Point Code
The Affected Point Code parameter contains one or more Affected
Destination Point Codes, each a three-octet parameter to allow for
14-, 16- and 24-bit binary formatted SS7 Point Codes. Affected
Point codes that are less than 24-bits, are padded on the left to
the 24-bit boundary.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0005 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Mask | Affected PC 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ . . . /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The encoding is shown below for ANSI and ITU Point Code examples.
ANSI 24-bit Point Code:
0 1 2 3-->
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Mask | Network | Cluster | Member |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|MSB-----------------------------------------LSB|
ITU 14-bit Point Code:
0 1 2 3-->
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Mask |0 0 0 0 0 0 0 0 0 0|Zone | Region | SP |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|MSB--------------------LSB|
It is optional to send an Affected Point Code parameter with more
than one Affected PC but it is mandatory to receive it. All the
Affected PCs included MUST be within the same Routing Context.
Including multiple Affected PCs may be useful when reception of a
management message or a linkset event simultaneously affects the
availability status of a list of destinations at an SG.
Mask: 8-bits
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The Mask parameter can be used to identify a contiguous range of
Affected Destination Point Codes, independent of the point code
format. Identifying a contiguous range of Affected PCs may be
useful when reception of an MTP3 management message or a linkset
event simultaneously affects the availability status of a series of
destinations at an SG.
The Mask parameter is an integer representing a bit mask that can be
applied to the related Affected PC field. The bit mask identifies
how many bits of the Affected PC field are significant and which are
effectively "wild-carded". For example, a mask of "8" indicates
that the last eight bits of the PC is "wild-carded". For an ANSI
24-bit Affected PC, this is equivalent to signaling that all PCs in
an ANSI Cluster are unavailable. A mask of "3" indicates that the
last three bits of the PC is "wild-carded". For a 14-bit ITU
Affected PC, this is equivalent to signaling that an ITU Region is
unavailable.
For use in SUA, the mask parameter MUST always be coded zero and
there MUST be only a single point code present.
3.8.6 Routing Context
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0006 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Routing Context /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Routing Context parameter contains (a list of) 4-byte unsigned
integers indexing the Application Server traffic that the sending
ASP is configured/registered to receive. There is a one-to-one
relationship between an index entry and a Routing Key or AS Name.
An Application Server Process may be configured to process traffic
for more than one logical Application Server. From the perspective
of an ASP, a Routing Context defines a range of signaling traffic
that the ASP is currently configured to receive from the SG.
Additionally, the Routing Context parameter identifies the SS7
network context for the message, for the purposes of logically
separating the signaling traffic between the SGP and the Application
Server Process over a common SCTP Association, when needed. An
example is where an SGP is logically partitioned to appear as an
element in several different national SS7 networks. It implicitly
defines the SS7 Point Code format used, the SS7 Network Indicator
value and SCCP protocol type/variant/version used within a separate
SS7 network. It also defines the network context for the PC and SSN
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Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001
values. Where an SGP operates in the context of a single SS7
network, or individual SCTP associations are dedicated to each SS7
network context, this functionality is not needed.
Where the optional Routing Context parameter is present, it SHOULD
be the first parameter in the message as it defines the format
and/or interpretation of the parameters containing a PC or SSN
value.
3.8.7 Diagnostic Information
The Diagnostic Information can be used to convey any information
relevant to an error condition, to assist in the identification of
the error condition. In the case of an Adaptation Layer Identifier
or Traffic Handling Mode, the Diagnostic Information includes the
received parameter. In the other cases, the Diagnostic information
may be the first 40 bytes of the offending message.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0007 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Diagnostic Information /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3.8.8 Not Used
Parameter ID 0x0008 is not used in SUA.
3.8.9 Heartbeat Data
The sending node defines the Heartbeat Data field contents. It may
include a Heartbeat Sequence Number and/or Timestamp, or other
implementation specific details.
The receiver of a Heartbeat message does not process this field as
it is only of significance to the sender. The receiver echoes the
content of the Heartbeat Data in a BEAT-Ack message.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0009 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Heartbeat Data /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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The data field can be used to store information in the heartbeat
message useful to the sending node (e.g. the data field can contain
a time stamp, a sequence number, etc.).
3.8.10 Reason
The Reason parameter indicates the reason why the remote SUA
adaptation layer is unavailable.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x000A | Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reason |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Reason: 32-bit (unsigned integer)
The valid values for Reason are shown in the following table.
0 Unspecified
1 User Unavailable
2 Management Blocking
3 ASP Fault
3.8.11 Traffic Mode Type
The Traffic Mode Type parameter identifies the traffic mode of
operation of the ASP within an AS.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x000B | Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Traffic Mode Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The valid values for Type are shown in the following table.
1 Over-ride
2 Load-share
3 Over-ride (Standby)
4 Loadshare (Standby)
Within a Routing Context, Over-ride and Loadshare Types cannot be
mixed. The Over-ride value indicates that the ASP is operating in
Over-ride mode, and the ASP wishes to take over all traffic for an
Application Server (i.e., primary/back-up operation), over-riding
any currently active ASP in the AS. In Load-share mode, the ASP
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Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001
wishes to share in the traffic distribution with any other currently
active ASPs. The Standby versions of the Over-ride and Loadshare
Types indicate that the ASP is declaring itself ready to accept
traffic but leaves it up to the sender as to when the traffic is
started. Over-ride (Standby) indicates that the traffic sender
continues to use the currently active ASP until it can no longer
send/receive traffic (i.e., the currently active ASP transitions to
Down or Inactive). At this point the sender may immediately move
the ASP to Active and commence traffic. Loadshare (Standby) is
similar - the sender continues to loadshare to the current ASPs
until it is determined that there is insufficient resources in the
Loadshare group. When there are insufficient ASPs, the sender may
immediately move the ASP to Active.
3.8.12 Error Code
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag =0x000C | Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Error Code |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Error Code parameter indicates the reason for the Error Message.
The Error parameter value can be one of the following values:
Invalid Version 0x01
n/a 0x02
Unexpected Message Class 0x03
Invalid Message Type 0x04
Unsupported Traffic Handling Mode 0x05
Unexpected Message 0x06
Protocol Error 0x07
Invalid Routing Context 0x08
Invalid Stream Identifier 0x09
Parameter Field Error 0x0B
Unexpected Parameter 0x0C
Duplicated Parameter 0x0D
Error - ASP Identifier Required 0x0E
Error - Invalid ASP Identifier 0x0F
Refused - ASP Identifier Required 0x10
The "Invalid Version" error would be sent if a message was received
with an invalid or unsupported version. The Error message would
contain the supported version in the Common header. The Error
message could optionally provide the supported version in the
Diagnostic Information area.
The "Invalid Routing Context" error would be sent by a SG if an ASP
sends a message with an invalid (unconfigured) Routing Context
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Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001
value. The Error message could optionally provide the invalid
Routing Context in the Diagnostic Information area.
The "Unexpected Message Class" error would be sent if a message with
an unsupported Message Class were received.
The "Unexpected Message Type" error would be sent if a message with
an unsupported Message Type were received.
The "Unsupported Traffic Handling Mode" error would be sent by a SGP
if an ASP sends an ASP Active with an unsupported Traffic Handling
Mode. An example would be a case in which the SGP did not support
load sharing.
The "Unexpected Message" error would be sent by an ASP if it
received a message that is unexpected in the ASP's current state.
The "Protocol Error" error would be sent for any protocol anomaly
(i.e. a bogus message).
The "Invalid Routing Context" error would be sent by a SGP if the
routing context cannot be supported, e.g. not unique.
The "Invalid Stream Identifier" error would be sent if a message was
received on an unexpected SCTP stream.
The "Parameter Field Error" would be sent if a message with a
parameter having a wrong length field.
The "Unexpected Parameter" error would be sent if a message contains
an invalid parameter.
The "Duplicated Parameter" error would be sent if a message contains
a parameter more than once.
To be sent in response to an ASPUP message which does not contain an
ASP Id parameter when the SGP requires one. Then, instead of simply
adding 8 bytes to ever ASPUP message as proposed, the ASP can go
around again a second time with an ASP ID.
3.8.13 Status
The Status parameter identifies the type of the status that is being
notified and the Status ID.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x000D | Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Status Type | Status ID |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The valid values for Status Type (16 bit unsigned integer) are:
1 Application Server state change (AS_State_Change)
2 Other
The Status ID parameter contains more detailed information for the
notification, based on the value of the Status Type.
If the Status Type is AS_STATE_CHANGE, then the Status ID (16 bit
unsigned integer) values are:
1 reserved
2 Application Server Inactive (AS-Inactive)
3 Application Server Active (AS-Active)
4 Application Server Pending (AS-Pending)
These notifications are sent from an SGP to an ASP upon a change in
status of a particular Application Server. The value reflects the
new state of the Application Server.
If the Status Type is �Other", then the following Status Information
values are defined:
1 Insufficient ASP resources active in AS
2 Alternate ASP Active
These notifications are not based on the SGP reporting the state
change of an ASP or AS. In the Insufficient ASP Resources case, the
SGP is indicating to an "Inactive" ASP(s) in the AS that another ASP
is required to handle the load of the AS (Load-sharing mode). For
the Alternate ASP Active case, an ASP is informed when an alternate
ASP transitions to the ASP-Active state in Over-ride mode.
3.8.14 ASP Identifier
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x000E | Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ASP Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
ASP Identifier field: 32-bits (unsigned integer)
The ASP Identifier field contains a unique value that is locally
significant amoung the ASPs that support an AS. The SGP should save
the ASP Identifier to be used, if necessary, with the Notify message
(see Section 3.7.2).
3.8.15 Congestion Level
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x000E | Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Congestion Level |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Congestion Level field: 8-bits (unsigned integer)
The valid values for the Congestion Level parameter range from 0 to
7, where 0 indicates least congested and 7 indicates most congested
subsystem.
3.9 SUA-Specific parameters
These TLV parameters are specific to the SUA protocol.
Parameter Name Parameter ID
============== ============
Flags 0x0101
Source Address 0x0102
Destination Address 0x0103
Source Reference Number 0x0104
Destination Reference Number 0x0105
SCCP Cause 0x0106
Sequence Number 0x0107
Receive Sequence Number 0x0108
ASP Capabilities 0x0109
Credit 0x010A
Reserved 0x010B
SMI / Subsystem 0x010C
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Destination/Source Address Sub-Parameters
===========================================
Global Title 0x8001
Point Code 0x8002
Subsystem Number 0x8003
IPv4 Address 0x8004
Hostname 0x8005
IPv6 Addresses 0x8006
3.9.1 Flags
The Flags parameter is a conglomerate of following parameters,
described in ITU-T Recommendation Q.713:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0101 | Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Seq. Control | Importance | Hop Counter | Protocol Cl. |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Sequence Control (1.1.2/Q.714)
Bits 1-5 are coded with the value of the sequence control
parameter associated with a group of messages and are chosen
so as to ensure proper loadsharing of message groups over SLS
values while ensuring that sequence control values within
message groups have the sequence control value coded with the
same value as the initial message of the message group.
Bits 6-8 are spare bits and should be coded zero.
Protocol class (3.6/Q.713)
Bits 1-2 indicate the protocol class.
Value Description
0 Class 0 (connectionless service)
1 Class 1 (connectionless service)
2 Class 2 (connection-oriented service)
3 Class 3 (connection-oriented service)
Bit 8 indicates the use of the return on error procedure.
Value Description
0x0 No special options
0x1 Return message on error
Bits 3-7 are spare and should be coded zero.
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Hop Counter (3.18/Q.713)
The value of the hop counter is decremented with each global
title translation, and should be in the range 15 to 1.
Importance (3.19/Q.713)
Bits 1-3 are coded to indicate the importance of the messages.
The values are between 0 and 7, where the value of 0 indicates
the least important and 7 indicates the most important.
Bits 4-8 are spare bits and should be coded zero.
3.9.2 Source Address
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0102 | Parameter Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Routing Indicator | Address Indicator |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Address parameter(s) /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Source Address field may contain the SCCP Calling Party Address.
See chapters 3.4 and 3.5 of ITU-T Recommendation Q.713.
The following combinations of address parameters are valid :
- Global Title (e.g. E.164 number) + optional PC and/or SSN,
SSN may be zero, when routing is done on Global Title
- SSN (non-zero) + optional PC and/or Global Title, when
routing is done on PC + SSN. The PC is mandatory in the
source address when sending from SGP to ASP, and in the
destination address when sending from ASP to SGP to reach the
SS7 SEP.
- Hostname + optional SSN, when routing is done by Hostname
- SSN (non-zero) and optional IP address (IPv4 or IPv6) when
routing is done on IP address + SSN
3.9.2.1 Routing Indicator
The following values are valid for the routing indicator :
Reserved 0
Route on Global Title 1
Route on SSN + PC 2
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Route on Hostname 3
Route on SSN + IP Address 4
The routing indicator determines which address parameters need to be
present in the address parameters field.
3.9.2.2 Address Indicator
This parameter is needed for interworking with SS7 networks. The
address indicator specifies what address parameters are actually
received in the SCCP address from the SS7 network, or are to be
populated in the SCCP address when the message is sent into the SS7
network. The value of the routing indicator needs to be taken into
account.
The address indicator is coded as follows:
Bit 1 is used to indicate inclusion of the SSN
0 Do not include SSN when optional
1 Include SSN
Bit 2 is used to indicate inclusion of the PC
0 Do not include PC, regardless of the routing indicator
value
1 Include PC
Bit 3 is used to indicate inclusion of the Global Title
0 Do not include GT when optional (routing indicator /= 1)
1 Include GT
Bits 4-8 are spare and should be coded zero.
3.9.2.3 Global Title
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x8001 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| No. Digits | Trans. type | Num. Plan | Nature of Add |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Global Title Digits |
/ /
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Number of Digits:
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This is the number of digits contained in the Global Title.
Translation type:
0 Unknown
1 - 63 International services
64 - 127 Spare
128 � 254 National network specific
255 Reserved
Numbering Plan:
0 unknown
1 ISDN/telephony numbering plan (Recommendations E.163 and
E.164)
2 generic numbering plan
3 data numbering plan (Recommendation X.121)
4 telex numbering plan (Recommendation F.69)
5 maritime mobile numbering plan (Recommendations E.210,
E.211)
6 land mobile numbering plan (Recommendation E.212)
7 ISDN/mobile numbering plan (Recommendation E.214)
8 - 13 spare
14 private network or network-specific numbering plan
15 - 126 spare
127 reserved.
Nature of Address:
0 unknown
1 subscriber number
2 reserved for national use
3 national significant number
4 international number
5 - 255 Spare
Global Title:
Octets contain a number of address signals and possibly filler as
shown:
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|2 addr.|1 addr.|4 addr.|3 addr.|6 addr.|5 addr.|8 addr.|7 addr.|
| sig. | sig. | sig. | sig. | sig. | sig. | sig. | sig. |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ............. |filler |N addr.| filler |
| |if req | sig. | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
All filler bits MUST be set to 0.
Address signals to be coded as defined in ITU-T Q.713 Section
3.4.2.3.1.
The actual Global Title format to be used for interworking with the
SS7 network is defined by the network ID, or is implicitly
understood if the SGP only operates in one SS7 network partition.
The formats are defined in chapter 3.4.2.3 of Q.713. The following
conversions of the Translation Type, Numbering Plan and Nature of
Address elements apply:
1) SS7 network uses GTI = 0001
Nature of Address is ignored. It is implicitly assumed that
Translation Type = Unknown and Numbering Plan = E.164 (value 1).
2) SS7 network uses GTI = 0010
This is most commonly used in North American networks. The
Translation Type implicitly determines Nature of Address and
Numbering Plan. This data can be configured in the SG. The number of
digits is always even and determined by the SCCP address length.
3) SS7 network uses GTI = 0011
Numbering Plan and Translation Type are taken over. It is implicitly
assumed that the Nature of Address = Unknown.
4) SS7 network uses GTI = 0100
This format is used in international networks and most commonly in
networks outside North America. All information to populate the
source address is present in the SCCP Address.
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3.9.2.4 Point Code
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x8002 | Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Point Code |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
See chapter 3.2.5 Affected Point Code for the layout of the Point
Code field.
3.9.2.5 Subsystem Number
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x8003 | Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| spare | SSN value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The internationally standardized SSN values are described in chapter
3.4.2.2 of Q.713.
3.9.2.6 IP Addresses
The IP address formats can use different tags. It should be noted
that if the source address is in a certain IP version, the
destination address should also be in the same IP version.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x8004/0x8006 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 or IPv6 Address |
/ /
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Note: The tag value 0x8004 is for an IPv4 address and 0x8006 is for
IPv6.
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3.9.2.7 Hostname
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x8005 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Host Name |
/ /
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
If the type of address is Host Name, then the labels in the host
name have to be reversed to obtain an efficient Host Name encoding
form for the Global title translation function.
hostname: zzzz.yyy....edc.ab
should be transformed to
HTname : ab.edc....yyy.zzzz
The labels of the Host Name are then encoded using the encoding
rules of the labels described in [IDNS]. The end of the Host name is
indicated by 0x00.
Example:
hostname = www.reindael.security.org
First the name has to be reverse to have the gTLD on the left side.
Global Title name: org.security.reindael.www
Then the result of applying the rules of the iDNS is:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
x | 3 | O | R | G |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+4 | 8 | S | E | C |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+8 | U | R | I | T |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+12| Y | 8 | R | E |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+16| I | N | D | A |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+20| E | L | 3 | W |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+24| W | W | 00 | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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3.9.3 Destination Address
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0103 | Parameter Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Routing Indicator | Address Indicator |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ address parameter(s) /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The format of this parameter is identical to the Source Address
parameter.
3.9.4 Source Reference Number
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0104 | Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Reference Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The source reference number is a 4 octet long integer. This is
allocated by the source SUA instance.
3.9.5 Destination Reference Number
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0105 | Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination Reference Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The destination reference number is a 4 octet long integer. This is
allocated by the destination SUA instance.
3.9.6 SCCP Cause
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0106 | Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Spare | Cause Type | Cause Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
This parameter bundles the SCCP parameters Release cause, Return
cause, Reset cause, Error cause and Refusal cause.
Cause Type can have the following values:
Return Cause 0x1
Refusal Cause 0x2
Release Cause 0x3
Reset Cause 0x4
Error Cause 0x5
Cause Value contains the specific cause value. Below gives examples
for ITU SCCP values. ANSI references can be found in ANSI T1.112.3
Cause value in Correspondence with Reference
SUA message SCCP parameter
------------------ ----------------- ---------
CLDR Return Cause ITU-T Q.713 Chap 3.12
COREF Refusal Cause ITU-T Q.713 Chap 3.15
RELRE Release Cause ITU-T Q.713 Chap 3.11
RESRE Reset Cause ITU-T Q.713 Chap 3.13
ERR Error Cause ITU-T Q.713 Chap 3.14
3.9.7 Sequence Number
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0107 | Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Spare | Rec Seq Num|M| Sent Seq Num |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
This parameter is used to indicate whether �more� data will follow
in subsequent CODT messages, and/or to number each CODT message
sequentially for the purpose of flow control. It contains the
received as well as the sent sequence number, P(R) and P(S) in
Q.713, chapters 3.7 and 3.9.
As such it can also be used to acknowledge the receipt of data
transfers from the peer in case of protocol class 3.
Sent Sequence Number is one octet and is coded as follows:
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Bits 2-8 are used to indicate the Send Sequence Number P(S).
Bit 1 (LSB) of octet 1 is spare.
Received Sequence Number is one octet, and is coded as follows:
Bits 2-8 are used to indicate the Received Sequence Number
P(R).
Bit 1 (LSB) is used for the more data indication, as follows:
0 no more data
1 more data
3.9.8 Receive Sequence Number
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0108 | Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| spare | Rec Seq Num |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
This parameter is used exclusively for protocol class 3 in the data
acknowledgment message to indicate the lower edge of the receiving
window. See Q.713, chapter 3.8.
It is a 1 octet long integer coded as follows:
Bits 8-2 are used to indicate the Receive Sequence Number P(R).
Bit 1 is spare.
3.9.9 ASP Capabilities
This parameter is used so that the ASP can report its capabilities
regarding SUA for supporting different protocol classes and
interworking scenarios.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x0109 | Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| spare |0 0 0 0|a|b|c|d| Interworking |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Flags
a - Protocol Class 3
b - Protocol Class 2
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c - Protocol Class 1
d - Protocol Class 0
It is mandatory to support at least Protocol Class 0.
Interworking
Values
0x0 indicates no interworking with SS7 Networks.
0x1 indicates IP Signaling Endpoint (ASP), interworking with SS7
networks.
0x2 indicates Signaling Gateway.
0x3 indicates relay node support.
3.9.10 Credit
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x010A | Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Credit |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The length of the credit field is is one octet. See ITU-T Q.713
Chapter 3.10. The parameter is used for protocol class 3
exclusively.
3.9.11 SMI / Subsystem
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag = 0x010C | Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SMI | Spare | SSN |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Subsystem Number (SSN) is one octet.
Subsystem Multiplicity Indicator (SMI) can have the following
values:
0x00 Reserved
0x01 Replicated
0x02 Solitary
0x03 Unknown
4 Procedures
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The SUA layer needs to respond to various local primitives it
receives from other layers as well as the messages that it receives
from the peer SUA layers. This section describes the SUA procedures
in response to these events.
4.1 SCCP � SUA Interworking at the SG
On the SG, the SCCP routing or interworking function determines that
the message is sent to an AS via the SUA stack, based on information
in the incoming message. The SUA Address Mapping Function identifies
the appropriate Application Server (AS) and selects an active ASP
from the list of ASPs servicing this AS. The appropriate ASP can be
determined based on the routing information in the incoming message,
local load sharing information, etc. The appropriate SUA message is
then constructed and sent to the appropriate endpoint, via the
correct SCTP association and stream.
The SGP MUST take care of any segmentation / reassembly issues at
the border of the SS7 and IP networks. The IPSP may not have any
knowledge about the requirements regarding the maximum supported
message length of the SS7 network to which it is sending. However,
since there is in principle no limit to the use of the more
indicator in SS7 networks, there is still need for connection-
oriented segmentation / reassembly procedures in the IPSP as well.
If a SGP is operated in mated pair configuration, and it receives a
non-first XUDT segment for which no reassembly process exists, it
should pass on this segment to it's mate; if the segment was already
received from the mated SGP or if no mated SGP is available, the
return on error procedures is invoked.
4.1.1 Connection Oriented Procedures
On receipt of a CR message from the SS7 network, a first connection
section is established between the SGP and SS7 originating node. A
second connection section is to be setup between the SGP and the
appropriate ASP, determined by the SUA outgoing mapping function.
Local resources and source local reference numbers are allocated to
keep/retrieve the required address information and the connection
state to format and route subsequent messages for the connection
based on reference numbers only. The existing SCCP procedures MAY be
deployed at the SGP to perform this coupling.
The same applies for a CORE message received from the IP network,
destined for an SS7 node. After allocating the necessary resources,
the SUA incoming mapping function formats the appropriate SCCP
message and passes it on to SCCP routing for further processing
(sending into the SS7 network).
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The SGP MUST take care of any segmentation / reassembly issues at
the border of the SS7 and IP networks. The IPSP may not have any
knowledge about the requirements regarding the maximum supported
message length of the SS7 network to which it is sending. However,
since there is in principle no limit to the use of the more
indicator in SS7 networks, there is still need for connection-
oriented segmentation / reassembly procedures in the IPSP as well.
4.1.2 Connectionless Procedures
The existing SCCP routing functions may be enhanced to support
interworking with the SUA layer. The function of SUA can be limited
to outgoing mapping (formatting of the CLDT or CLDR message) and
selection of the correct SCTP association (ASP) and stream. For the
direction ASP to SG, the SUA incoming mapping formats the
appropriate SCCP message (UDT(S), XUDT(S) or LUDT(S)) and passes it
on to SCCP routing for further processing.
4.1.3 SS7 Signaling Network Management Procedures
When an SCCP Subsystem Management (SCMG) message is received from
the SS7 network, the SGP needs to determine whether there are
concerned Application Servers interested in subsystem status
changes. The SUA management function is informed with the N-State
indication primitive upon which it formats and transfers the
applicable SNM message to the list of concerned ASPs using stream ID
"0".
When MTP-3 Management indications are received (MTP-PAUSE, MTP-
RESUME, MTP-STATUS), SCCP Subsystem Management determines whether
there are concerned local SCCP-users. When these local SCCP-users
are in fact Application Servers, serviced by ASPs, SUA management is
informed with the PC-State indication primitive upon which it
formats and transfers the applicable SNM message (DUNA, DAVA, DRST
or SCON) to the list of concerned ASPs using stream ID "0".
If an ASP receives a DUNA, DRST or SCON from a SGP, the SUA layer at
the ASP is expected to send traffic to the affected destination via
an alternate SGP of equal priority, but only if such an alternate
route exists and is available. The local ASP SHOULD maintain the
status of the possible routes to the peer endpoint in the SS7
network. By maintaining the status of the possible routes, the ASP
can determine if the remote peer is unavailable.
When the DAUD message is received at the SGP from an ASP, the SGP
checks the status of the specified SS7 destination and returns DAVA,
DUNA, DRST or SCON depending on the result of the check. The SGP
initiates SST (Subsystem Status Test) procedures by following the
SCCP procedures described in Q.714; the receipt of a DAUD message
does not trigger these.
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SCCP Subsystem Management procedures may also be triggered in case
of AS state changes, see chapter 4.4.1.2.
4.2 Primitives received from the local SUA-user
These support the SUA transport of SCCP-User/SCCP boundary
primitives. The same services as supported by SCCP (connectionless
and connection-oriented) are to be provided by SUA. The SCCP-users
at the SGP should be able to use the same primitive interface to
SCCP/SUA without any changes. The SCCP-SUA interworking function
takes care of selecting the appropriate stack.
The SUA needs to setup and maintain the appropriate SCTP association
to the selected endpoint. SUA also manages the usage of SCTP
streams.
The address information passed by the SUA-user at an ASP MUST
contain either:
- A valid SS7 address to reach a destination in the SS7 network
via the appropriate SCTP association to a SG.
- A valid IP address/hostname to reach another ASP in the IP
network via the appropriate SCTP association.
4.3 Layer Management Procedures
On receiving primitives from the local Layer Management, the SUA
layer will take the requested action and provide a response to Layer
Management.
An M-SCTP-ESTABLISH request from Layer Management will initiate the
establishment of an SCTP association. An M-SCTP-ESTABLISH confirm
will be sent to Layer Management when the initiated association set-
up is complete. An M-SCTP-ESTABLISH indication is sent upon
successful completion of an incoming SCTP association set-up from a
peer SUA node.
An M-SCTP-RELEASE request from Layer Management initiates the
teardown of an SCTP association. An M-SCTP-RELEASE confirm is sent
to Layer Management when the association teardown is complete. An M-
SCTP-RELEASE indication is sent to Layer Management upon successful
teardown of an SCTP association initiated by a peer SUA.
An M-SCTP-STATUS request supports a Layer Management query of the
local status of a particular SCTP association. The SUA responds with
the association status in an M-SCTP-STATUS confirm. No peer SUA
protocol is invoked.
An M-ASP-STATUS request supports a Layer Management query of the
status of a particular local or remote ASP. The SUA responds with an
M-ASP-STATUS confirm. No peer SUA protocol is invoked.
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An M-AS-STATUS request supports a Layer Management query of the
status of a particular AS. The SUA responds with an M-AS-STATUS
confirm. No peer SUA protocol is invoked.
M-ASP-UP, -DOWN, -ACTIVE and �INACTIVE request primitives allow
Layer Management at an IPSP to force state changes. Upon successful
completion, a corresponding confirm primitive is issued by SUA to
the Layer Management. If the invocation is unsuccessful, an Error
indication is provided.
SUA Management informs layer Management about AS/ASP state changes
with the corresponding indications. It is also informed of received
NTFY or ERR messages, see chapter 4.4.3.
4.4 SUA Management Procedures
This functionality comprises the handling of AS/ASP state and
traffic management messages, SUA peer management messages, SCTP
notifications and the interface with local Layer Management.
These procedures support the SUA management of SCTP Associations and
ASP paths between SGs and ASPs.
4.4.1 AS and ASP State and Traffic Management
The SUA layer on each IPSP (e.g. SG) needs to maintain the state of
each connected IPSP (e.g. ASP), as a way to manage the traffic to
these IPSPs and the (logical) ASs they service. In particular at a
SG, the state of each connected ASP is needed as input to the SGs
routing function.
4.4.1.1 ASP States
The state of each ASP is maintained in the SUA layer at the
controlling AS. The state of an ASP changes due to events. The
events include:
- ASP Management messages (ASP-Up, ASP-Down, ASP-Active, ASP-
Inactive).
- SCTP Communication Down Notification (SCTP CDI).
The state of the ASP within each AS is important in particular for
the routing function at the SG, to direct traffic for a specific
routing key (AS) to the appropriate ASP.
At an ASP, if it is connected to a set of redundant SGs, this set
can also be seen as an AS handling all traffic destined for the SS7
network.
The ASP state transition diagram is shown in Figure 4. The possible
states of an ASP are:
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ASP-DOWN: The Application Server Process is unavailable. Initially
all ASPs will be in this state.
ASP-UP: The Application Server Process is available but application
traffic is not possible. The ASP can only handle management
messages.
ASP-ACTIVE: The Application Server Process is available and
application traffic is possible. Whether traffic will be directed to
this ASP depends on the Traffic Mode Type (over-ride, loadshare with
or without Standby option).
+-------------+
| ASP-ACTIVE |
+----------------------| or |
| +------| ASP-STANDBY*|
| AS | +-------------+
| Override | ^ |
| | ASP | | ASP
| | Active | | Inactive
| | | v
| | +-------------+
| +------| |
| | ASP-INACTIVE|
| +-------------+
| ^ |
ASP Down | ASP | | ASP Down /
SCTP CDI | Up | | SCTP CDI
| | v
| +-------------+
| | |
+--------------------->| ASP-DOWN |
| |
+-------------+
* Note: ASP-ACTIVE and ASP-STANDBY differ only in whether the ASP is
currently receiving Data traffic within the AS.
Figure 4: ASP State Transition Diagram
SCTP CDI: The local SCTP layer's SHUTDOWN COMPLETE notification or
COMMUNICATION LOST notification. The shutdown of an SCTP association
may have been requested by local Layer Management, see chapter 4.3.
Local Layer Management
4.4.1.2 AS States
The AS is configured in the IPSP as a logical entity to handle
traffic for a specific (unique) routing key. The state of the AS is
maintained in the SUA layer, and can change due to following events:
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- ASP state changes: when the first ASP within an AS goes UP or
ACTIVE, or when the last ASP within an AS goes DOWN or
INACTIVE
- Recovery Timer expiry
The possible states of an AS are:
AS-DOWN: The Application Server is unavailable. This state implies
that all related ASPs are in the ASP-DOWN state for this AS.
Initially the AS will be in this state.
AS-UP: The Application Server is available but no application
traffic is possible (i.e. one or more related ASPs are in the ASP-UP
state, but none in the ASP-ACTIVE state).
AS-ACTIVE: The Application Server is available and application
traffic is possible. This state implies that at least one ASP is in
the ASP-ACTIVE state.
AS-PENDING: An active ASP has transitioned from active to inactive
or down and it was the last remaining active ASP in the AS. A
recovery timer T(r) will be started and all incoming SCN messages
will be queued by the SG. If an ASP becomes active before T(r)
expires, the AS will move to AS-ACTIVE state and all the queued
messages will be sent to the active ASP.
If T(r) expires before an ASP becomes active, the SGP stops queuing
messages and discards all previously queued messages. The AS will
move to AS-UP if at least one ASP is in ASP-UP state, otherwise it
will move to AS-DOWN state.
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+----------+ one ASP trans to ASP-ACTIVE +-------------+
| |---------------------------->| |
| AS-UP | | AS-ACTIVE |
| |<--- | |
+----------+ \ +-------------+
^ | \ Tr Expiry, ^ |
| | \ at least one | |
| | \ ASP in ASP-INACTIVE | |
| | \ | |
| | \ | |
| | \ | |
one ASP | | all ASP \ one ASP | | Last ACT.
trans | | trans to \ trans to | | ASP trans
to ASP- | | ASP-DOWN -------\ ASP-ACTIVE| | to ASP-
INACTIVE| | \ | | INACTIVE
| | \ | | or ASP-
| | \ | | DOWN
| | \ | |
| v \ | v
+----------+ \ +-------------+
| | --| |
| AS-DOWN | | AS-PENDING |
| | | (queuing) |
| |<----------------------------| |
+----------+ Tr Expiry no ASP +-------------+
in ASP-INACTIVEstate
Tr = Recovery Timer
Figure 5: AS State Transition Diagram
The SGP maintains the availability of the ASs, and will need to
issue the correct SCCP management message (where applicable) to the
SS7 node(s).
When an AS transitions to the UP or DOWN state, and it is the only
(or last) one handling traffic for a certain SSN, an SSP message is
broadcast to the concerned remote SCCP-users in the SS7 network.
When an AS transitions to the ACTIVE state, and it is the first one
handling traffic for a certain SSN, an SSA message is broadcast to
the concerned remote SCCP-users in the SS7 network.
4.4.2 AS/ASP Management procedures
Once an SCTP association is established between two IPSPs, one (or
both) side(s) might issue an ASP-UP message.
4.4.2.1 ASP-Up
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An ASP sends an ASP-UP to each communication partner. When the ASP-
UP message is received, the receiving IPSP can react in three
different ways:
- Mark the remote ASP Inactive and reply with an ASP-UP Ack
message in acknowledgement to every received ASP-UP, even if
the ASP is already marked as Inactive.
- If for any local reason (e.g. management lock-out) the IPSP
cannot respond with an ASP-UP Ack, it responds with an ASP-
DOWN Ack message.
- If an unknown version is received with the ASP-UP message,
the receiving end MUST respond with an Error message with
Error Code �Invalid Version�. The version field in the common
header will indicate to the sender which version(s) the
receiving node supports. This is useful when protocol version
upgrades are being performed. A node with the newer version
should support the older versions as well to fallback upon in
a subsequent ASP-UP message.
If the ASP does not receive any of the above reactions, the ASP may
resend ASP-Up messages until it receives a response. The ASP MUST
wait for the ASP-UP Ack message before sending any other messages.
If the remote peer receives any other SUA messages from an ASP,
before an ASP-UP is received and acknowledged, the message should be
discarded.
If the ASP Up message contains an ASP Identifier, the SGP should
save the ASP Identifier for that ASP, to be used in any Notify
messages, which are sent indicating a change in the state of the
ASP.
4.4.2.2 ASP-Down
The IPSP will mark an ASP as down if one of the following events
occur:
- An ASP Down (DOWN) message is received from the ASP.
- The ASP is locked by local Layer Management.
The IPSP sends an ASP DOWN Ack message in response to a received
ASP-DOWN message from the ASP even if the ASP is already marked as
Down.
The IPSP will send an ASP DOWN message whenever it wants to take
down an ASP. Since it is possible for ASP DOWN and ASP DOWN Ack
messages to be lost (for example, during a node failover), the IPSP
can send ASP DOWN messages repeatedly until the path comes down
(i.e. until it receives a ASP-DOWN message from the remote peer or
the SCTP association goes down).
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4.4.2.3 ASP-Active
When an ASP is ready to start processing traffic, it sends an ASP-
ACTIVE message to the remote peer. When an ASP-ACTIVE message is
received, the remote peer responds with an ASP-ACTIVE Ack. The ASP
cannot send any other messages until after the ASP-ACTIVE Ack is
received. If the ASP-ACTIVE Ack is not received within a certain
time, the ASP may resend the ASP-ACTIVE message.
The ASP-ACTIVE message optionally contains a list of one or more
Routing Contexts, indicating which Application Servers the ASP is
joining. If no Routing Contexts are present, then local
configuration data is used to determine to which Application
Server(s) the ASP belongs.
The Traffic Mode Type parameter in the ASP-ACTIVE message indicates
the traffic handling mode used in a particular Application Server,
either Over-ride, Over-ride (Standby), Load-share or Load-share
(Standby). If the remote peer determines that the mode indicated in
an ASP-ACTIVE is incompatible with the mode currently used in the
AS, the remote peer responds with an Error message indicating
"Invalid Traffic Handling Mode".
In the Over-ride mode, reception of an ASP-ACTIVE message at a
remote peer causes the all traffic for the AS to be sent to the ASP
that sent the ASP-ACTIVE. All previously active ASPs in the AS are
now considered Inactive and will no longer receive traffic for that
particular AS. The remote peer sends a Notify (Alternate ASP-
Active) to the previously active ASP in the AS, after stopping all
traffic to that ASP. All existing connections/transactions with the
previously active ASP should be terminated however.
In the Over-ride (Standby) mode, the actions are the same with the
exception that the traffic is not started to the ASP until the
previously active ASP transitions to the "Inactive or "Down" state.
At this point the ASP that sent the Over-Ride (Standby) ASP-ACTIVE
message takes over the traffic. No Notify messages are needed.
In the Load-share mode, reception of an ASP-ACTIVE message causes
the redistribution of traffic to the ASP sending the ASP-ACTIVE, in
addition to all the other ASPs that are currently active in the AS.
The algorithm at the SGP for load-sharing traffic within an AS to
all the active ASPs is implementation dependent. All ASPs marked for
load sharing should be able to handle any traffic within the AS, to
accommodate any potential fail-over or re-balancing of the offered
load.
In the Load-share (Standby) mode, the actions are the same as the
Load-share mode, with the exception that the traffic is not started
to the ASP until the remote peer determines that additional
resources are needed to service the AS. When needed, the ASP that
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sent the Loadshare (Standby) ASP-ACTIVE message is taken up in the
loadsharing scheme and traffic is started. No Notify messages are
needed to be sent.
A node that receives an ASP-ACTIVE with an incorrect Traffic Mode
Type for a particular Routing Context will respond with an Error
Message with Error Cause �Invalid Traffic Handling Mode�. A node
that receives an unknown Routing Context value responds with an
Error message with Error Cause �Invalid Routing Context�.
4.4.2.4 ASP-Inactive
When an ASP wishes to withdraw from handling traffic, it sends an
ASP-INACTIVE to the applicable remote peers, specifying the AS
(Routing Context) from which it is withdrawing. If the ASP is
withdrawing from more than one AS, then the ASP issues either
multiple ASP-INACTIVE messages, if multiple SCTP associations exist
to the remote ASPs; or a single ASP-INACTIVE message containing
multiple Routing Contexts.
The ASP could have been in one of two modes, Over-ride or Load-
sharing. In the Over-ride mode, the ASP that sent the ASP-INACTIVE
is marked as Inactive. No further traffic is sent from and to the
ASP marked Inactive. The remote peer now should notify the
remaining ASPs of situation.
In the Load-sharing mode, the peer marks the ASP as Inactive and re-
allocates the traffic to the remaining active ASPs. The load-sharing
mechanism used is outside of the scope of SUA. If there are
insufficient resources, a NTFY (Insufficient ASPs) may be sent to
all inactive ASPs within the AS. If a Loadshare (Standby) ASP is
available, it may be now immediately included in the loadshare group
and a Notify message MUST not be sent. An ASP-INACTIVE Ack message
is sent to the ASP after all traffic is halted.
In the case when no other ASPs are active or standby in the
Application Server, the remote peer should send a NTFY (AS-Pending)
to all inactive ASPs of the AS. The remote peer then either discards
all incoming messages for the AS or starts buffering the incoming
messages for T(r) seconds, after which messages will be discarded.
T(r) is configurable by the network operator.
If the remote peer receives an ASP-ACTIVE from an ASP in the AS
before expiry of T(r), the buffered traffic is directed to the ASP
and the timer is cancelled. If T(r) expires, the AS is moved to the
"Down" state.
4.4.3 SUA peer management messages
4.4.3.1 Notify
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A NTFY message reflecting a change in the AS state MUST be sent to
all ASPs in the AS, except those in the ASP-DOWN state, with
appropriate Status Type/ID and ASP Identifier of the failed ASP.
The Notify message MUST be sent after any ASP State or Traffic
Management acknowledgement messages (e.g., ASP Up Ack, ASP Down Ack,
ASP Active Ack, or ASP Inactive Ack).
In the case where a NTFY (AS-Pending) message is sent by an SGP that
now has no active ASPs to service the traffic, or a NTFY
(Insufficient ASPs) is sent in the Loadshare mode, the NTFY does not
explicitly force the ASP(s) receiving the message to become active.
The ASPs remain in control of what (and when) action is taken.
4.4.3.2 Error
The ERR message is used to signal invalid protocol behavior.
4.4.4 Heartbeat procedure
The optional Heartbeat message may be sent to query the status of
the remote peer. It is optional to send, but mandatory to
acknowledge. It MAY be used when operating over transport layers
that do not have their own heartbeat mechanism for detecting loss of
the transport association (i.e., other than SCTP).
After an ASP or IPSP has received an ASP Up Ack from an SUA peer in
response to an ASP Up message, either M3UA peer MAY optionally send
Heartbeat messages periodically, subject to a provisionable timer
T(beat). Upon receiving a Heartbeat message, the SUA peer MUST
respond with a Heartbeat ACK message.
If no Heartbeat Ack message (or any other SUA message) is received
from the peer within 2*T(beat), the remote peer is considered
unavailable. Transmission of Heartbeat messages is stopped and the
signaling process SHOULD attempt to re-establish communication, if
it is configured as the client for the disconnected M3UA peer.
The data field can be used to store information in the heartbeat
message useful to the sending node (e.g. the data field can contain
a time stamp, a sequence number, etc.). The data field MUST be
echoed back unchanged in the related Heartbeat Ack message. The
contents/format of the Heartbeat Data parameter is implementation-
dependent and only of local interest to the original sender. The ASP
sender, upon examining the contents of the returned Heartbeat Ack
message, MAY choose to consider the remote M3UA peer as unavailable.
Note: Heartbeat related events are not shown in the "ASP state
transition diagram".
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5 Examples of SUA Procedures
The following sequence charts overview the procedures of SUA. These
are meant as examples, they do not, in and of themselves, impose
additional requirements upon an instance of SUA.
5.1 SG Architecture
The sequences below outline logical steps for a variety of scenarios
within a SG architecture. Please note that these scenarios cover a
Primary/Backup configuration. Where there is a load-sharing
configuration then the SGP can declare availability when 1 ASP
issues ASPAC but can only declare unavailability when all ASPs have
issued ASPIA.
5.1.1 Establishment of SUA connectivity
The following is established before SUA/SCCP traffic can flow.
Each node is configured (via MIB, for example) with the connections
that need to be setup.
ASP-a1 ASP-a2 SG SEP
(Primary) (Backup)
|------Establish SCTP Association------|
|--Estab. SCTP Ass--|
|--Align SS7 link---|
Each ASP declares to the SGP that it is running.
+----------------ASP Up---------------->
<--------------ASP Up Ack--------------+
+------ASP Up------->
<---ASP Up Ack------+
The Primary ASP declares to the SGP that it is active.
The SGP notifies all ASPs.
+-------------ASP Active--------------->
<----------ASP Active Ack--------------+
<----------NTFY (ASP Active)-----------+
<-NTFY (ASP Active)-+
The SGP declares the availability of the signaling
user on ASP-a1 to the SEP. The SGP has been
configured (via a MIB) that the SEP is concerned
about its signaling users. The SGs SS7 address
is presented in the SSA, i.e. the SGP represents the
availability of ASP-a1 to the SEP.
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+--------SSA-------->
The SEP declares its availability to the SGP since
the SGP appears within its concerned list. Similarly,
the SGP informs the active ASP of the availability of
the SEP as dictated by SGs concerned list. N.B.
The SGP maps the SS7 address of the SEP to an
IP address that the SGP knows ASP-a1 will understand.
<--------SSA--------+
<-----------------DAVA-----------------+
Traffic can now flow. A connectionless flow is shown
for simplicity. Nevertheless, the SGP is responsible
for mapping IP to SS7 addresses and vice-versa. Only
the Routing Context for ASP-a1 persists from ASP-a1 to
SEP.
+-----------------CLDT----------------->
+--------UDT-------->
5.1.2 Failover scenarios
The following sequences address failover of SEP and ASP
5.1.2.1 SEP Failover
The SEP knows that the SGP is 'concerned' about its availability.
Similarly, the SGP knows that ASP-a1 is concerned about the SEPs
availability; therefore the incoming SSP is translated into DUNA.
ASP-a1 uses a DAUD to instruct the SGP to invoke the SS7 Sub-system
Test procedure.
ASP-a1 ASP-a2 SG SEP
(Primary) (Backup)
<--------SSP--------+
<-----------------DUNA-----------------+
+-----------------DAUD----------------->
+--------SST-------->
5.1.2.2 Successful ASP Failover scenario
The following is an example of a successful failover scenario, where
there is a failover from ASP-a1 to ASP-a2, i.e. Primary to Backup.
During the failover, the SGP buffers any incoming data messages from
the SEP, forwarding them when the Backup becomes available.
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Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001
ASP-a1 ASP-a2 SG SEP
(Primary) (Backup)
+-------------ASP Inactive------------->
<----------NTFY (ASP Inactive)---------+
<-NTFY (ASP Inact.)-+
+----ASP Active----->
<--ASP Active Ack---+
<-NTFY (ASP Active)-+
<----------NTFY (ASP Active)-----------+
5.1.2.3 Unsuccessful ASP Failover scenario
ASP-a1 ASP-a2 SG SEP
(Primary) (Backup)
+-------------ASP Inactive------------->
<----------NTFY (ASP Inactive)---------+
<-NTFY (ASP Inact.)-+
After some time elapses (i.e. timeout).
+--------SSP-------->
<--------SST--------+
5.2 IP-IP Architecture
The sequences below outline logical steps for a variety of scenarios
within an IP-IP architecture. Please note that these scenarios
cover a Primary/Backup configuration. Where there is a load-sharing
configuration then the AS can declare availability when 1 ASP issues
ASPAC but can only declare unavailability when all ASPs have issued
ASPIA.
5.2.1 Establishment of SUA connectivity
The following shows an example establishment of SUA connectivity.
In this example, each IPSP consists of an Application Server and two
ASPs.
The following is established before SUA traffic can flow. A
connectionless flow is shown for simplicity.
Each node is configured (via MIB, for example) with the connections
that need to be setup.
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Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001
IP SEP A IP SEP B
AS A AS B
ASP-a1 ASP-a2 ASP-b2 ASP-b1
(Primary) (Backup) (Backup) (Primary)
[Establish SCTP Connectivity]
|------------- Establish SCTP Association -------------|
|------------------ Establish SCTP Association ------------------|
|------- Establish SCTP Association --------|
|------------ Establish SCTP Association -------------|
[Establish SUA Connectivity]
+----------------------ASP Up-------------------------->
<--------------------ASP Up Ack------------------------+
+---------------------------ASP Up------------------------------->
<-------------------------ASP Up Ack-----------------------------+
<----------------ASP Up---------------------+
+----------------ASP Up Ack----------------->
+------------------------ASP Up----------------------->
<----------------------ASP Up Ack---------------------+
+---------------------------ACTIVE------------------------------->
<-------------------------ACTIVE Ack-----------------------------+
[Traffic can now flow directly between ASPs]
+-----------------------------CLDT------------------------------->
5.2.2 Failover scenarios
The following sequences address failover of ASP
5.2.2.1 Successful ASP Failover scenario
The following is an example of a successful failover scenario, where
there is a failover from ASP-a1 to ASP-a2, i.e. Primary to Backup.
Since data transfer passes directly between peer ASPs, ASP-b1 is
notified of the failover of ASP-a1 and buffers outgoing data
messages until ASP-a2 becomes available.
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Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001
IP SEP A IP SEP B
ASP-a1 ASP-a2 ASP-b2 ASP-b1
(Primary) (Backup) (Backup) (Primary)
+-----------------------------ASP Inact------------------------>
<---------------------------ASP Inact Ack----------------------+
<---------------NTFY (ASP-a1 Inactive)--------------+
+---------------------ASP Act----------------------->
<-------------------ASP Act Ack---------------------+
5.2.2.2 Unsuccessful ASP Failover scenario
The sequence is the same as 4.2.2.1 except that, since the backup
fails to come in then, the Notify messages declaring the
availability of the backup are not sent.
6 Security
6.1 Introduction
SUA is designed to carry signaling messages for telephony services.
As such, SUA involves the security needs of several parties: the end
users of the services; the network providers and the applications
involved. Additional security requirements may come from local
regulation. While having some overlapping security needs, any
security solution should fulfill all of the different parties'
needs.
6.2 Threats
There is no quick fix, one-size-fits-all solution for security. As
a transport protocol, SUA has the following security objectives:
* Availability of reliable and timely user data transport.
* Integrity of user data transport.
* Confidentiality of user data.
SUA runs on top of SCTP. SCTP provides certain transport related
security features, such as:
* Blind Denial of Service Attacks
* Flooding
* Masquerade
* Improper Monopolization of Services
When SUA is running in professionally managed corporate or service
provider network, it is reasonable to expect that this network
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includes an appropriate security policy framework. The "Site
Security Handbook" [2196] should be consulted for guidance.
When the network in which SUA runs in involves more than one party,
it may not be reasonable to expect that all parties have implemented
security in a sufficient manner. End-to-end security should be the
goal; therefore, it is recommended that IPSEC is used to ensure
confidentiality of user payload. Consult [2409] for more
information on configuring IPSEC services.
6.3 Protecting Confidentiality
Particularly for mobile users, the requirement for confidentiality
may include the masking of IP addresses and ports. In this case
application level encryption is not sufficient; IPSEC ESP should be
used instead. Regardless of which level performs the encryption, the
IPSEC ISAKMP service should be used for key management.
7 IANA Considerations
7.1 SCTP Payload Protocol ID
IANA has assigned a SUA value for the Payload Protocol Identifier in
the SCTP DATA chunk. The following SCTP Payload Protocol Identifier
is registered:
SUA "4"
The SCTP Payload Protocol Identifier value "4" SHOULD be included in
each SCTP DATA chunk, to indicate that the SCTP is carrying the SUA
protocol. The value "0" (unspecified) is also allowed but any other
values MUST not be used. This Payload Protocol Identifier is not
directly used by SCTP but MAY be used by certain network entities to
identify the type of information being carried in a DATA chunk.
The User Adaptation peer MAY use the Payload Protocol Identifier as
a way of determining additional information about the data being
presented to it by SCTP.A request will be made to IANA to assign CTP
Payload Protocol IDs.
7.2 Port Number
IANA has registered SCTP Port Number 14001 for SUA. This port
number is the port that the SGPs listen to when receiving SCTP
datagrams.
7.3 Protocol Extensions
This protocol may also be extended through IANA in three ways:
- Through definition of additional message classes.
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Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001
- Through definition of additional message types.
- Through definition of additional message parameters.
The definition and use of new message classes, types and parameters
is an integral part of SIGTRAN adaptation layers. Thus, these
extensions are assigned by IANA through an IETF Consensus action as
defined in [RFC2434].
The proposed extension MUST in no way adversely affect the general
working of the protocol.
7.3.1 IETF Defined Message Classes
The documentation for a new message class MUST include the following
information:
(a) A long and short name for the message class;
(b) A detailed description of the purpose of the message class.
7.3.2 IETF Defined Message Types
Documentation of the message type MUST contain the following
information:
(a) A long and short name for the new message type;
(b) A detailed description of the structure of the message.
(c) A detailed definition and description of intended use of each
field within the message.
(d) A detailed procedural description of the use of the new message
type within the operation of the protocol.
(e) A detailed description of error conditions when receiving this
message type.
When an implementation receives a message type which it does not
support, it MUST respond with an Error (ERR) message, with an Error
Code = Unsupported Message Type.
7.3.4 IETF-defined TLV Parameter Extension
Documentation of the message parameter MUST contain the following
information:
(a) Name of the parameter type.
(b) Detailed description of the structure of the parameter field.
This structure MUST conform to the general type-length-value
format described earlier in the document.
(c) Detailed definition of each component of the parameter value.
(d) Detailed description of the intended use of this parameter type,
and an indication of whether and under what circumstances
multiple instances of this parameter type may be found within
the same message type.
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Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001
8 Timer Values
Ta 2 seconds
Tr 2 seconds
T(ack) 2 seconds
T(ias) Inactivity Send timer 7 minutes
T(iar) Inactivity Receive timer 15 minutes
T(beat) Heartbeat Timer 30 seconds
9 Acknowledgements
The authors would like to thank Brian Bidulock, Martin Booyens,
Klaus Gradischnig, Miguel A. Garcia, Marja-Liisa Hamalainen, Sherry
Karl, Markus Maanoja, Chirayu Patel, Michael Purcell, Michael
Tuexen, Al Varney, Ben Wilson, Michael Wright and James Yu for their
insightful comments and suggestions.
Funding for the RFC editor function is currently provided by the
Internet Society.
10 Authors' Addresses
John Loughney
Nokia Research Center
PO Box 407
FIN-00045 Nokia Group
Finland
EMail: [email protected]
Greg Sidebottom
Kanata, Ontario
Canada
EMail: [email protected]
Guy Mousseau
Nortel Networks
3685 Richmond Rd
Nepean, Ontario,
Canada K2H 5B7
Stephen Lorusso
Unisphere Networks
10 Technology Park Drive
Westford, MA 01886
USA
Phone: +1 (978) 589-0533
EMail: [email protected]
Lode Coene
Siemens Atea
Atealaan 34
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Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001
B-2200 Herentals
Belgium
Phone: +32-14-252081
EMail: [email protected]
Gery Verwimp
Siemens Atea
34 Atealaan
PO 2200
Herentals
Belgium
Phone: +32 14 25 3424
EMail: [email protected]
Joe Keller
Tekelec
5200 Paramount Parkway
Morrisville, NC 27560
USA
EMail: [email protected]
Florencio Escobar Gonzalez
Ericsson Spain S.A.
Retama 7, 2nd floor
28045, Madrid
Spain
EMail: [email protected]
Steven Furniss
Marconi
New Century Park
Coventry CV3 1HJ
United Kingdom
EMail: [email protected]
William Sully
Marconi
New Century Park
Coventry CV3 1HJ
United Kingdom
EMail: [email protected]
11 References
[2196] RFC 2196, "Site Security Handbook", B. Fraser Ed.,
September 1997.
[2396] Berners-Lee, T., Fielding, R.T. and L. Masinter,
"Uniform Resource Identifiers (URI): Generic Syntax",
RFC 2396, August 1998.
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Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001
[2401] RFC 2401, "Security Architecture for the Internet
Protocol", S. Kent, R. Atkinson, November 1998.
[2434] RFC 2434 "Guidelines for Writing an IANA
Considerations Section in RFCs", T. Narten, H.
Alvestrand, October 1998.
[2719] RFC 2719, "Framework Architecture for Signaling
Transport"
[ANSI-MTP] ANSI T1.111 'Signaling System Number 7 - Message
Transfer Part'
[ANSI SCCP] ANSI T1.112 'Signaling System Number 7 - Signaling
Connection Control Part'
[ANSI TCAP] ANSI T1.114 'Signaling System Number 7 - Transaction
Capabilities Application Part'
[ENUM] RFC 2916 "E.164 number and DNS", P. Faltstrom,
September 2000.
[IDNS] Blanchet, M., Hoffman, P., "Internationalized domain
names using EDNS (IDNE)", <draft-ietf-idn-idne-
01.txt>, Work in progress, July 2000
[ITU-MTP] ITU-T Recommendations Q.701-Q.705, 'Signalling System
No. 7 (SS7) - Message Transfer Part (MTP)'
[ITU SCCP] ITU-T Recommendations Q.711-714, 'Signaling System
No. 7 (SS7) - Signaling Connection Control Part
(SCCP)'
[ITU TCAP] ITU-T Recommendation Q.771-775 'Signaling System No.
7 SS7) - Transaction Capabilities (TCAP)
[M3UA] MTP3-User Adaptation Layer <draft-ietf-sigtran-m3ua-
06.txt>, March 2001, Work in Progress.
[RANAP] 3G TS 25.413 V3.5.0 (2001-03) 'Technical
Specification 3rd Generation Partnership Project;
Technical Specification Group Radio Access Network;
UTRAN Iu Interface RANAP Signalling'
[SCTP] RFC 2960 "Stream Control Transport Protocol" R.
Stewart, et al, November 2000.
[UTRAN IUR] 3G TS 25.422 V3.5.0 (2000-12) "Technical
Specification 3rd Generation Partnership Project;
Technical Specification Group Radio Access Network;
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UTRAN Iur Interface Signaling Transport (Release
1999)"
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Copyright Statement
Copyright (C) The Internet Society (2000). All Rights Reserved.
This document and translations of it may be copied and furnished to
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or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
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are included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
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The limited permissions granted above are perpetual and will not be
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This document and the information contained herein is provided on an
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TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Loughney (editor) [Page 87]
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