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INTERNET-DRAFT L. Coene(Ed)
Internet Engineering Task Force Siemens
Issued: April 2002 J. Pastor
Expires: September 2002 Ericsson
Telephony Signalling Transport over SCTP applicability statement
<draft-ietf-sigtran-signalling-over-sctp-applic-05.txt>
Status of this Memo
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026. 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
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Internet-Drafts are draft documents valid for a maximum of six
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Abstract
This document describes the applicability of the new protocols
developed under the signaling transport framework[RFC2719]. A
description of the main issues regarding the use of the Stream
Control Transmission Protocol (SCTP)[RFC2960] and each adaptation
layer for transport of telephony signalling information over IP
infrastructure is explained.
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Table of contents
Telephony signalling over SCTP Applicability statement ......... ii
Chapter 1: Introduction ........................................ 2
Chapter 1.1: Scope ..... ....................................... 3
Chapter 1.2: Terminology ....................................... 3
Chapter 1.3: Contributors ...................................... 3
Chapter 2: SIGTRAN architecture ................................ 4
Chapter 2.1: Overview ......................................... 4
Chapter 3: Issues for transporting Telephony signalling
information over SCTP .......................................... 6
Chapter 3.1: Congestion control ................................ 6
Chapter 3.2: Detection of failures ............................. 6
Chapter 3.2.1: Retransmission TimeOut (RTO) calculation ........ 7
Chapter 3.2.2: Heartbeat ....................................... 7
Chapter 3.2.3: Maximum Number of retransmissions ............... 7
Chapter 3.3: Shorten end-to-end message delay ................. 7
Chapter 3.4: Bundling considerations ........................... 8
Chapter 3.5: Stream Usage ...................................... 8
Chapter 4: User Adaptation Layers............................... 8
Chapter 4.1: IUA (ISDN Q.921 User Adaptation) .................. 10
Chapter 4.2: V5UA (V5.2-User Adaptation) Layer ................. 11
Chapter 4.3: DUA (DPNSS/DASS User adaptation) Layer ............ 12
Chapter 4.4: M2UA (SS7 MTP2 User Adaptation) Layer ............. 12
Chapter 4.5: M2PA (SS7 MTP2-User Peer-to-Peer Adaptation) Layer. 13
Chapter 4.6: M3UA (SS7 MTP3 User Adaptation) Layer ............. 15
Chapter 4.7: SUA (SS7 SCCP User Adaptation) Layer .............. 16
Chapter 5: Security considerations ............................. 18
Chapter 6: References and related work ......................... 18
Chapter 7: Acknowledgments ..................................... 19
Chapter 8: Author's address .................................... 19
1 INTRODUCTION
This document intends to inform how to transport telephony
signalling protocols, used in classic telephony systems, over IP
networks. The whole architecture is called SIGTRAN (Signalling
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Transport) as described in RFC2719 and is composed of a transport
protocol(SCTP) and several User Adaptation (UAL) layers. The
transport protocol SCTP has been been developed to fulfill the
stringent requirements that telephony signalling networks have. The
set of User Adaptation layers have also been introduced to make it
possible that different signalling protocols can use the SCTP layer.
1.1 Scope
The scope of this document is to explain the way that user
adaptation layers and SCTP protocols have to be used to transport
Telephony signalling information over IP.
1.2 Terminology
The following terms are commonly identified in related work:
Association: SCTP connection between two endpoints.
Stream: A uni-directional logical channel established within an
association, within which all user messages are delivered in
sequence except for those submitted to the unordered delivery
service.
SPU: Signalling protocol user, the application on top of the User
adaptation layer.
CTSP: Classical Telephony Signalling protocol(examples: MTP level2,
MTP level 3, SCCP....).
UAL: User adaptation layer: the protocol that encapsulate the upper
layer telephony signalling protocols that are to be transported over
SCTP/IP.
ISEP: IP signalling endpoint: a IP node that implements SCTP and a
User adapatation layer.
SP: signalling point
1.3 Contributors
The following people contributed to the document: L. Coene(Editor),
M. Tuexen, G. Verwimp, J. Loughney, R.R. Stewart, Qiaobing Xie,
M. Holdrege, M.C. Belinchon, A. Jungmaier, J. Pastor and L. Ong.
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2 SIGTRAN architecture
The SIGTRAN architecture describes the transport of signalling
information over IP infrastructure.
Telephony Signalling transport over IP normally uses the following
architecture:
Telephony Signalling Application
|
+------------------------------------+
| Signalling Adaptation Layers |
+------------------------------------+
|
+------------------------------------+
|Stream Control Transmission Protocol|
| (SCTP) |
+------------------------------------+
|
Internet Protocol (IPv4/IPv6)
Figure 1.1: Telephony signalling transport protocol stack
The components of the protocol stack are :
(1) Adaptation modules are used when the telephony application needs
to preserve an existing primitive interface. (e.g. management
indications, data operation primitives, ... for a particular
user/application protocol).
(2) SCTP, specially configured to meet the telephony application
performance requirements.
(3) The standard Internet Protocol.
The telephony signalling protocols to be transported can be:
- SS7 MTP3 users: SCCP, ISUP, TUP...
- SS7 MTP2 users: MTP3
- SS7 SCCP users: RANAP, MAP(+TCAP), INAP(+TCAP)...
- ISDN Q.921 users: Q.931
- V5.2/DSS1
- ....
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Every classic telephony protocol can have a corresponding UAL
developed.
The user adaptation layers(UALs) are a set of protocols that
encapsulate a specific signalling protocol to be transported over
SCTP. The adapation is done in a way that the upper signalling
protocols that are relayed remain unaware that the lower layers are
different to the originail lower telephony signalling layers. In
that sense, the upper interface of the user adapatation layers need
to be the same as the upper layer interface to its original lower
layer. If a MTP user is being relayed over the IP network, the
related UAL used to transport the MTP user will have the same upper
interface as MTP has.
The Stream Control Transmission protocol was designed to fulfill the
stringent transport requirements that classical signalling protocols
have and is therefore the recommended transport protocol to use for
this purpose.
The following functions are provided by SCTP:
- Reliable Data Transfer
- Multiple streams to help avoid head-of-line blocking
- Ordered and unordered data delivery on a per-stream basis
- Bundling and fragmentation of user data
- Congestion and flow control
- Support continuous monitoring of reachability
- Graceful termination of association
- Support of multi-homing for added reliability
- Protection against blind denial-of-service attacks
- Protection against blind masquerade attacks
SCTP is used as the transport protocol for telephony signalling
applications. Message boundaries are preserved during data
transport by SCTP and so each UA can specify its own message
structure withing the SCTP user data. The SCTP user data can be
delivered by the order of transmission within a stream(in sequence
delivery) or unordered.
SCTP can be used to provide redundancy at the
transport layer and below. Telephony applications needing this level
of redundancy can make use of SCTP's multi-homing support.
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SCTP can be used for telephony applications where head-of-line
blocking is a concern. Such an application should use multiple
streams to provide independent ordering of telephony signalling
messages.
3 Issues for transporting telephony signalling over SCTP
Transport of telephony signalling requires special
considerations. In order to use SCTP, special care must be taken to
meet the performance, timing and failure management requirements.
3.1 Congestion Control
The basic mechanism of congestion control in SCTP have been
described in [RFC2960]. SCTP congestion control sometimes conflicts
with the timing requirements of telephony signalling application
messages which are transported by SCTP. During congestion, messages
may be delayed by SCTP, thus sometimes violating the timing
requirements of those telephony applications.
In an engineered network (e.g. a private intranet), in which network
capacity and maximum traffic are very well understood, some
telephony signalling applications may choose to relax the congestion
control rules of SCTP in order to satisfy the timing
requirements. In order to do this, they should employ their own
congestion control mechanisms. But this should be done without
destabilising the network, otherwise this would lead to potential
congestion collapse of the network.
Some telephony signalling applications may have their own congestion
control and flow control techniques. These techniques may interact
with the congestion control procedures in SCTP.
3.2 Detection of failures
Telephony systems often must have no single point of failure in
operation.
The UA must meet certain service availability and performance
requirements according to the classical signalling layers they are
replacing. Those requirements may be specific for each UA.
For example, telephony systems are often required to be able to
preserve stable calls during a component failure. Therefore error
situations at the transport layer and below must be detected quickly
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so that the UA can take approriate steps to recover and preserve the
calls. This poses special requirements on SCTP to discover
unreachablility of a destination address or a peer.
3.2.1 Retransmission TimeOut (RTO) calculation
The SCTP protocol parameter RTO.Min value has a direct impact on the
calculation of the RTO itself. Some telephony applications want to
lower the value of the RTO.Min to less than 1 second. This would
allow the message sender to reach the maximum
number-of-retransmission threshold faster in the case of network
failures. However, lowering RTO.Min may have a negative impact on
network behaviour [ALLMAN99].
In some rare cases, telephony applications might not want to use the
exponential timer back-off concept in RTO calculation in order to
speed up failure detection. The danger of doing this is that, when
network congestion occurs, not backing off the timer may worsen the
congestion situation. Therefore, this strategy should never be used
in public Internet.
It should be noted that not using delayed SACK will also help faster
failure detection.
3.2.2 Heartbeat
For faster detection of (un)availability of idle paths, the
telephony application may consider lowering the SCTP parameter
HB.interval. It should be noted this might result in a higher traffic
load.
3.2.3 Maximum number of retransmissions
Setting Path.Max.Retrans and Association.Max.Retrans SCTP parameters
to lower values will speed up both destination address and peer
failure detection. However, if these values are set too low, the
probability of false fault detections might increase.
3.3 Shorten end-to-end message delay
Telephony applications often require short end-to-end message
delays. The method described in section 3.2.1 on lowering RTO may
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be considered. The different paths within a single association will
have a different RTO, so using the path with the lowest RTO will
lead to a shorter end-to-end message delay for the application
running on top of the UA's.
3.4 Bundling considerations
Bundling small telephony signalling messages at transmission helps
improve the bandwidth usage efficiency of the network. On the
downside, bundling may introduce additional delay to some of the
messages. This should be taken into consideration when end-to-end
delay is a concern.
3.5 Stream Usage
Telephony signalling traffic is often composed of multiple,
independent message sequences. It is highly desirable to transfer
those independent message sequences in separate SCTP streams. This
reduces the probability of head-of-line blocking in which the
retransmission of a lost message affects the delivery of other
messages not belonging to the same message sequence.
4 User Adaptation Layers
Users Adaptation Layers have been defined to encapsulate different
signalling protocols in order to transport them over SCTP/IP.
There are UALs for both access signalling (DSS1) and trunk signalling
(SS7). A brief description of the standardized UALs follows in the
next sub-sections.
The delivery mechanism in the several UALs
- Supports seamless operation of UALs user peers over an IP network
connection.
- Supports the interface boundary that the UAL user had with the
traditional lower layer.
- Supports management of SCTP transport associations and traffic
between SGs and ISEPs or two ISEPs
- Supports asynchronous reporting of status changes to management.
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Two main scenarios have been developed for Signalling Transport:
- Intercommunication of traditional Signalling transport nodes and IP
based nodes.
Traditional Telephony
Telephony Signalling
******* Signalling ********** over IP ********
* SEP *----------------* SG *--------------* ISEP *
******* ********** ********
+-----+ +------+
| SPU | | SPU |
+-----+ +----+----+ +------+
| | | |UAL | | UAL |
| | | +----+ +------+
|CTSP | |CTSP|SCTP| | SCTP |
| | | +----+ +------+
| | | | IP | | IP |
+-----+ +---------+ +------+
SEP: Signalling Endpoint
SG: Signalling Gateway
ISEP: IP Signalling Endpoint
SPU: Signalling Protocol User
CTSP: Classical Telephony Signalling Protocol
UAL: User Adaptation Layer
SCTP: Stream Control Transport Protocol
It is also referred as SG to AS communication. AS is the name that
UAL usually gives to the ISEP nodes. It stands for Application
Server.
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- Communication inside the IP networks.
Telephony
Signalling
******** over IP ********
* ISEP *------------------* ISEP *
******** ********
+------+ +------+
| SPU | | SPU |
+------+ +------+
| UAL | | UAL |
+------+ +------+
| SCTP | | SCTP |
+------+ +------+
| IP | | IP |
+------+ +------+
This is also referred to as IPSP communication. IPSP is the name
given to the role that a UAL plays on an IP-based node. It stands
for IP Signalling Point.
4.1 IUA (ISDN Q.921 User Adaptation)
This protocol supports both ISDN Primary Rate Access (PRA) as well
as Basic Rate Access (BRA) including the support for both
point-to-point and point-to-multipoint modes of communication. This
support includes Facility Associated Signalling (FAS), Non-Facility
Associated Signalling (NFAS) and NFAS with backup D channel.
It implements the client/server architecture. The default
orientation is for the SG to take on the role of server while the
ISEP is the client. The SCTP (and UDP/TCP) Registered User Port
Number Assignment for IUA is 9900.
Examples of the upper layers to be transported are Q.931 and QSIG.
The main scenario supported by this UAL is the SG to ISEP
communication where the ISEP role is typically played by a node
called an MGC, as defined in [RFC2719].
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****** ISDN ****** IP *******
* EP *---------------* SG *--------------* MGC *
****** ****** *******
+-----+ +-----+
|Q.931| (NIF) |Q.931|
+-----+ +----------+ +-----+
| | | | IUA| | IUA |
| | | +----+ +-----+
|Q.921| |Q.921|SCTP| |SCTP |
| | | +----+ +-----+
| | | | IP | | IP |
+-----+ +-----+----+ +-----+
NIF - Nodal Interworking Function
EP - ISDN End Point
SCTP - Stream Control Transmission Protocol
IUA - ISDN User Adaptation Layer Protocol
The SCTP (and UDP/TCP) Registered User Port Number Assignment for
IUA is 9900.
The value assigned by IANA for the Payload Protocol Identifier in
the SCTP Payload Data chunk is "1".
4.2 V5UA (V5.2-User Adaptation) Layer
It is an extension from the IUA layer with the modifications needed
to support the differences between Q.921 / Q.931, and V5.2 layer 2 /
layer 3. It supports analog telephone access, ISDN basic rate access
and ISDN primary rate access over a V5.2 interface. It is typically
implemented in an interworking scenario with SG.
****** V5.2 ****** IP *******
* AN *---------------* SG *--------------* MGC *
****** ****** *******
+-----+ +-----+
|V5.2 | (NIF) |V5.2 |
+-----+ +----------+ +-----+
| | | |V5UA| |V5UA |
| | | +----+ +-----+
|LAPV5| |LAPV5|SCTP| |SCTP |
| | | +----+ +-----+
| | | | IP + | IP |
+-----+ +-----+----+ +-----+
AN - Access Network
NIF - Nodal Interworking Function
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LAPV5 - Link Access Protocol for the V5 channel
SCTP - Stream Control Transmission Protocol
The SCTP (and UDP/TCP) Registered User Port Number Assignment for
V5UA is 5675.
The value assigned by IANA for the Payload Protocol Identifier in
the SCTP Payload Data chunk is "6".
4.3 DUA (DPNSS/DASS 2 User Adaptation) Layer
The DUA is built on top of IUA and defines the necessary extensions
to IUA for a DPNSS/DASS2 transport. DPNSS stands for Digital Private
Network Signalling System and DASS2 for Digital Access Signalling
System No 2.
****** DPNSS ****** IP *******
*PBX *---------------* SG *--------------* MGC *
****** ****** *******
+-----+ +-----+
|DPNSS| (NIF) |DPNSS|
| L3 | | L3 |
+-----+ +----------+ +-----+
| | | | DUA| | DUA |
|DPNSS| |DPNSS+----+ +-----+
| L2 | | L2 |SCTP| |SCTP |
| | | +----+ +-----+
| | | | IP + | IP |
+-----+ +-----+----+ +-----+
PBX - Private Branch eXchange
NIF - Nodal Interworking function
SCTP - Stream Control Transmission Protocol
DUA - DPNSS User Adaptation Layer Protocol
The value assigned by IANA for the Payload Protocol Identifier in
the SCTP Payload Data chunk is "TBD".
4.4 M2UA (SS7 MTP2 User Adaptation) Layer
This protocol is typically used between a Signalling Gateway (SG) and
Media Gateway Controler (MGC). The SG will terminate up to MTP Level
2 and the MGC will terminate MTP Level 3 and above. In other words,
the SG will transport MTP Level 3 messages over an IP network to a
MGC.
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MTP3 and MTP3b are the only MTP2 Users that are transported by this
UAL.
The SG provides a interworking of transport functions with the IP
transport, to transfer the MTP2-User signalling messages with MTP2-
User at an application server(e.g. MGC).
****** SS7 ****** IP *******
*SEP *-----------* SG *-------------* MGC *
****** ****** *******
+----+ +----+
|S7UP| |S7UP|
+----+ +----+
|MTP + |MTP |
| L3 | (NIF) |L3 |
+----+ +----+----+ +----+
|MTP | |MTP |M2UA| |M2UA|
| | | +----+ +----+
| L2 | | L2 |SCTP| |SCTP|
| L1 | | L1 +----+ +----+
| | | |IP | |IP |
+----+ +---------+ +----+
MGC - Media Gateway Controler
SG - Signalling Gateway
SEP - SS7 Signalling Endpoint
NIF - Nodal Interworking Function
IP - Internet Protocol
SCTP - Stream Control Transmission Protocol
The SCTP (and UDP/TCP) Registered User Port Number Assignment for
M2UA is 2904.
The value assigned by IANA for the Payload Protocol Identifier in
the SCTP Payload Data chunk is "2".
4.5 M2PA (SS7 MTP2-User Peer-to-Peer Adaptation) Layer
This protocol is used between SS7 Signalling Points using the MTP
Level 3 protocol. The SS7 Signalling Points may also employ standard
SS7 links using the SS7 MTP Level 2 to provide transport of MTP
Level 3 signalling messages.
Both configurations: interworking of SS7 and IP with SG and
communication between ISEPs are possible.
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******** IP ********
* IPSP *--------* IPSP *
******** ********
+------+ +------+
| TCAP | | TCAP |
+------+ +------+
| SCCP | | SCCP |
+------+ +------+
| MTP3 | | MTP3 |
+------+ +------+
| M2PA | | M2PA |
+------+ +------+
| SCTP | | SCTP |
+------+ +------+
| IP | | IP |
+------+ +------+
IP - Internet Protocol
IPSP - IP Signalling Point
SCTP - Stream Control Transmission Protocol
******** SS7 *************** IP ********
* SEP *--------* SG *--------* IPSP *
******** *************** ********
+------+ +------+
| TCAP | | TCAP |
+------+ +------+
| SCCP | | SCCP |
+------+ +-------------+ +------+
| MTP3 | | MTP3 | | MTP3 |
+------+ +------+------+ +------+
| MTP2 | | MTP2 | M2PA | | M2PA |
+------+ +------+------+ +------+
| MTP1 | | MTP1 | SCTP | | SCTP |
| | | +------+ +------+
| | | | IP | | IP |
+------+ +------+------+ +------+
SEP - SS7 Signalling Endpoint
These figures are only an example. Other configurations are
possible.
The SCTP (and UDP/TCP) Registered User Port Number Assignment for
M2PA is TBD.
The value assigned by IANA for the Payload Protocol Identifier in
the SCTP Payload Data chunk is "5".
Differences between M2PA and M2UA include:
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a. M2PA: IPSP processes MTP3/MTP2 primitives.
M2UA: MGC transports MTP3/MTP2 primitives between the SG's MTP2
and the MGC's MTP3 (via the NIF) for processing.
b. M2PA: SG-IPSP connection is an SS7 link.
M2UA: SG-MGC connection is not an SS7 link. It is an
extension of MTP to a remote entity.
c. M2PA: SG is an SS7 node with a point code.
M2UA: SG is not necessarily an SS7 node and may not have a point code.
d. M2PA: SG can have upper SS7 layers, e.g., SCCP.
M2UA: SG does not have upper SS7 layers since it has no MTP3.
e. M2PA: relies on MTP3 for management procedures.
M2UA: uses M2UA management procedures.
4.6 M3UA (SS7 MTP3 User Adaptation) Layer
This adaptation layer supports the transport of any SS7 MTP3-User
signalling such as TUP, ISUP and SCCP over IP using the services of
SCTP.
This protocol allows both:
- Interworking of SS7 and IP nodes
- Communication between two IP nodes
******** SS7 ***************** IP ********
* SEP *---------* SGP *--------* ASP *
******** ***************** ********
+------+ +---------------+ +------+
| ISUP | | (NIF) | | ISUP |
+------+ +------+ +------+ +------+
| MTP3 | | MTP3 | | M3UA | | M3UA |
+------| +------+-+------+ +------+
| MTP2 | | MTP2 | | SCTP | | SCTP |
+------+ +------+ +------+ +------+
| L1 | | L1 | | IP | | IP |
+------+ +------+ +------+ +------+
SEP - SS7 Signalling End Point
SCTP - Stream Control Transmission Protocol
NIF - Nodal Interworking Function
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******** IP ********
* IPSP *----------* IPSP *
******** ********
+------+ +------+
|SCCP- | |SCCP- |
| User | | User |
+------+ +------+
| SCCP | | SCCP |
+------+ +------+
| M3UA | | M3UA |
+------+ +------+
| SCTP | | SCTP |
+------+ +------+
| IP | | IP |
+------+ +------+
It works using the client-server architecture. It is recommended
that the ISEP act as the client and initiate SCTP associations with
the SG. The port reserved by IANA is port number 2905. this is the
port upon which the SG should listen for client connections.
The assigned payload protocol identifier for the SCTP DATA chunks is
"3".
4.7 SUA (SS7 SCCP User Adaptation) Layer
This adaptation layer supports the transport of any SS7 SCCP-User
signalling such as MAP, INAP, SMS, BSSAP, RANAP over IP using the
services of SCTP.
For message relaying, SUA should have the same timing constraints as
SCCP . For the end-to-end approach, SUA applications may have
broader timing requirements (from 100 of milliseconds to hours)
which allows the applications to guard themselves.
Possible configurations showed in the pictures below:
- Interworking of SS7 and IP
- IP Node to IP Node communication
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******** 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 Signalling Transfer Point
******** IP ********
* *--------* *
* IPSP * * IPSP *
* * * *
******** ********
+------+ +------+
| SUAP | | SUAP |
+------+ +------+
| SUA | | SUA |
+------+ +------+
| SCTP | | SCTP |
+------+ +------+
| IP | | IP |
+------+ +------+
IANA has registered SCTP Port Number 14001 for SUA. It is
recommended that SGs use this SCTP port number for listening for new
connections. The payload protocol identifier for the SCTP DATA
chunks is "4".
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5 Security considerations
UALs are designated to carry signalling messages for telephony
services. As such, UALs must involve the security needs of several
parties: the end users of the services; the network providers and
the applications involved. Additional requirements may come from
local regulation. While having some overlapping security needs, any
security solution should fulfill all of the different parties'
needs. See specific Security considerations in each UAL technical
specification.
SCTP only tries to increase the availability of a network. SCTP does
not contain any protocol mechanisms which are directly related to
user message authentication, integrity and confidentiality
functions. For such features, it depends on the IPSEC protocols and
architecture and/or on security features of its user protocols.
Mechanisms for reducing the risk of blind denial-of-service attacks
and masquerade attacks are built into SCTP protocol. See RFC2960,
section 11 for detailed information.
Currently the IPSEC working group is investigating the support of
multihoming by IPSEC protocols. At the present time to use IPSEC,
one must use 2 * N * M security associations if one endpoint uses N
addresses and the other M addresses.
6 References and related work
[RFC2960] Stewart, R. R., Xie, Q., Morneault, K., Sharp, C. , ,
Schwarzbauer, H. J., Taylor, T., Rytina, I., Kalla, M., Zhang,
L. and Paxson, V, "Stream Control Transmission Protocol", RFC2960,
October 2000.
[RFccccc] Coene, L., Tuexen, M., Verwimp, G., Loughney, J., Stewart,
R. R., Xie, Q., Holdrege, M., Belinchon, M.C., and Jungmayer, A.,
"Stream Control Transmission Protocol Applicability statement",
RFCzzzz, April 2002.
[RFC2719] Ong, L., Rytina, I., Garcia, M., Schwarzbauer, H., Coene,
L., Lin, H., Juhasz, I., Holdrege, M., Sharp, C., "Framework
Architecture for Signalling Transport", RFC2719, October 1999.
[RFC3057] Morneault, K., Rengasami, S., Kalla, M., Sidebottom, G.,
"ISDN Q.921-User Adaptation Layer", RFC3057, February 2001.
[RFCxxxx] Morneault, K., Dantu, R., Sidebottom, G., George, T.,
Coene et al [Page 18]
Draft Telephony Signalling AS April 2002
Bidulock, B., Heitz , J., "Signaling System 7 (SS7) Message Transfer
Part (MTP) 2 - User Adaptation Layer", RFCxxxx, May 2002.
[RFCyyyy] Sidebottom, G., Pastor-Balbas, J., Rytina, I., Mousseau,
G., Ong, L., Schwarzbauer, H.J., Gradischnig, K., Morneault, K.,
Kalla, M., Glaude, N., Bidulock, B., Loughney, J., "SS7 MTP3-User
Adaptation Layer (M3UA)", RFCyyyy, May 2002.
[RFCzzzz] Loughney, J., Sidebottom, G., Mousseau, G., Lorusso, S.,
Coene, L., Verwimp, G., Keller, J., Escobar, F., Sully, W., Furniss,
S., Bidulock, B.,"SS7 SCCP-User Adaptation Layer (SUA)", RFCzzzz,
May 2002.
[RFCwwww] George, T., Dantu, R., Kalla, M., Schwarzbauer, H.J.,
Sidebottom, G., Morneault, K.,"SS7 MTP2-User Peer-to-Peer Adaptation
Layer", RFCwwww, June 2002.
[RFCqqqq] Weilandt, E., Khanchandani, N., Rao, S.,"V5.2-User
Adaptation Layer (V5UA)", RFCqqqq, June 2002
[RFCtttt] Vydyam, A., Mukundan, R., Mangalpally, N., Morneault,
K.,"DPNSS/DASS 2 extensions to the IUA protocol", RFCtttt, August
2002.
[ALLMAN99] Allman, M. and Paxson, V., "On Estimating End-to-End
Network Path Properties", Proc. SIGCOMM'99, 1999.
7 Acknowledgments
This document was initially developed by a design team consisting of
Lode Coene, John Loughney, Michel Tuexen, Randall R. Stewart,
Qiaobing Xie, Matt Holdrege, Maria-Carmen Belinchon, Andreas
Jungmaier, Gery Verwimp and Lyndon Ong.
The authors wish to thank Renee Revis, H.J. Schwarzbauer, T. Taylor,
G. Sidebottom, K. Morneault, T. George, M. Stillman and many others
for their invaluable comments.
8 Author's Address
Lode Coene Phone: +32-14-252081
Siemens Atea EMail: [email protected]
Coene et al [Page 19]
Draft Telephony Signalling AS April 2002
Atealaan 34
B-2200 Herentals
Belgium
Javier Pastor-Balbas Phone:
Ericsson Espana S.A. Email: [email protected]
C/ Ombu 3
28045 Madrid
Spain
Expires: August 2002
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