Signalling Transport Working group L. Coene Internet-Draft Siemens Expires: April 24, 2006 J. Loughney Nokia October 21, 2005 SUA Implementor's guide Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. 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 Internet-Draft will expire on April 24, 2006. Copyright Notice Copyright (C) The Internet Society (2005). Abstract This document contains a compilation of all defects found up until the publication date for SUA [RFC3868] [1]. These defects may be of an editorial or technical nature. This document may be thought of as a companion document to be used in the implementation of SUA to clarify errors in the original SUA document. This document updates RFC3868 and text within this document supersedes the text found in RFC3868. Coene & Loughney Expires April 24, 2006 [Page 1] Internet-Draft SUA implementor's Guide October 2005 Table of Contents 1. INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4 1.2. Conventions . . . . . . . . . . . . . . . . . . . . . . . 4 2. Correction to RFC3868 . . . . . . . . . . . . . . . . . . . . 5 2.1. Routing context list in connectionless and connectionoriented messages . . . . . . . . . . . . . . . 5 2.1.1. Description of the problem . . . . . . . . . . . . . . 5 2.1.2. Text changes to the document . . . . . . . . . . . . . 5 2.1.3. Solution description . . . . . . . . . . . . . . . . . 5 2.2. Congestion level parameter value . . . . . . . . . . . . . 5 2.2.1. Description of the problem . . . . . . . . . . . . . . 5 2.2.2. Text changes to the document . . . . . . . . . . . . . 6 2.2.3. Solution description . . . . . . . . . . . . . . . . . 7 2.3. Segmentation parameter value . . . . . . . . . . . . . . . 7 2.3.1. Description of the problem . . . . . . . . . . . . . . 7 2.3.2. Text changes to the document . . . . . . . . . . . . . 7 2.3.3. Solution description . . . . . . . . . . . . . . . . . 8 2.4. DAUD response message ordering . . . . . . . . . . . . . . 8 2.4.1. Description of the problem . . . . . . . . . . . . . . 8 2.4.2. Text changes to the document . . . . . . . . . . . . . 8 2.4.3. Solution description . . . . . . . . . . . . . . . . . 9 2.5. Host name parameter . . . . . . . . . . . . . . . . . . . 9 2.5.1. Description of the problem . . . . . . . . . . . . . . 9 2.5.2. Text changes to the document . . . . . . . . . . . . . 9 2.5.3. Solution description . . . . . . . . . . . . . . . . . 10 2.6. ASP routing context . . . . . . . . . . . . . . . . . . . 10 2.6.1. Description of the problem . . . . . . . . . . . . . . 10 2.6.2. Text changes to the document . . . . . . . . . . . . . 10 2.6.3. Solution description . . . . . . . . . . . . . . . . . 10 2.7. Parameters should only occur once in a message . . . . . . 11 2.7.1. Description of the problem . . . . . . . . . . . . . . 11 2.7.2. Text changes to the document . . . . . . . . . . . . . 11 2.7.3. Solution description . . . . . . . . . . . . . . . . . 11 2.8. TID label parameter . . . . . . . . . . . . . . . . . . . 11 2.8.1. Description of the problem . . . . . . . . . . . . . . 11 2.8.2. Text changes to the document . . . . . . . . . . . . . 12 2.8.3. Solution description . . . . . . . . . . . . . . . . . 13 2.9. DRM label parameter . . . . . . . . . . . . . . . . . . . 13 2.9.1. Description of the problem . . . . . . . . . . . . . . 13 2.9.2. Text changes to the document . . . . . . . . . . . . . 13 2.9.3. Solution description . . . . . . . . . . . . . . . . . 14 2.10. Usage of the TID and DRN label . . . . . . . . . . . . . . 14 2.10.1. Description of the problem . . . . . . . . . . . . . . 14 2.10.2. Text changes to the document . . . . . . . . . . . . . 15 2.10.3. Solution description . . . . . . . . . . . . . . . . . 17 2.11. Address Range paramete . . . . . . . . . . . . . . . . . . 18 Coene & Loughney Expires April 24, 2006 [Page 2] Internet-Draft SUA implementor's Guide October 2005 2.11.1. Description of the problem . . . . . . . . . . . . . . 18 2.11.2. Text changes to the document . . . . . . . . . . . . . 18 2.11.3. Solution description . . . . . . . . . . . . . . . . . 19 2.12. Interpretation of the mask parameter . . . . . . . . . . . 19 2.12.1. Description of the problem . . . . . . . . . . . . . . 19 2.12.2. Text changes to the document . . . . . . . . . . . . . 19 2.12.3. Solution description . . . . . . . . . . . . . . . . . 20 2.13. Reply on errors contained in a error message . . . . . . . 20 2.13.1. Description of the problem . . . . . . . . . . . . . . 20 2.13.2. Text changes to the document . . . . . . . . . . . . . 20 2.13.3. Solution description . . . . . . . . . . . . . . . . . 21 2.14. Use of stream 0 for SSNM messages . . . . . . . . . . . . 21 2.14.1. Description of the problem . . . . . . . . . . . . . . 21 2.14.2. Text changes to the document . . . . . . . . . . . . . 21 2.14.3. Solution description . . . . . . . . . . . . . . . . . 22 2.15. Timer Ta does not exist . . . . . . . . . . . . . . . . . 22 2.15.1. Description of the problem . . . . . . . . . . . . . . 22 2.15.2. Text changes to the document . . . . . . . . . . . . . 22 2.15.3. Solution description . . . . . . . . . . . . . . . . . 23 2.16. Error response on unsupported RKM messages . . . . . . . . 23 2.16.1. Description of the problem . . . . . . . . . . . . . . 23 2.16.2. Text changes to the document . . . . . . . . . . . . . 23 2.16.3. Solution description . . . . . . . . . . . . . . . . . 24 2.17. Filler/padding in Global title parameter . . . . . . . . . 24 2.17.1. Description of the problem . . . . . . . . . . . . . . 24 2.17.2. Text changes to the document . . . . . . . . . . . . . 24 2.17.3. Solution description . . . . . . . . . . . . . . . . . 25 2.18. Inclusion of routing context in the Routing key parameter . . . . . . . . . . . . . . . . . . . . . . . . 25 2.18.1. Description of the problem . . . . . . . . . . . . . . 25 2.18.2. Text changes to the document . . . . . . . . . . . . . 26 2.18.3. Solution description . . . . . . . . . . . . . . . . . 27 3. Security considerations . . . . . . . . . . . . . . . . . . . 28 4. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 29 5. References . . . . . . . . . . . . . . . . . . . . . . . . . . 29 Appendix A. Changes Control . . . . . . . . . . . . . . . . . . . 30 A.1. Changes from v00 to v01 . . . . . . . . . . . . . . . . . 30 A.2. Changes from v01 to v02 . . . . . . . . . . . . . . . . . 30 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 31 Intellectual Property and Copyright Statements . . . . . . . . . . 32 Coene & Loughney Expires April 24, 2006 [Page 3] Internet-Draft SUA implementor's Guide October 2005 1. INTRODUCTION This document contains a compilation of all defects found up until the publication date for the SCCP User Adaptation Layer (SUA) [RFC3868]. These defects may be of an editorial or technical nature. This document may be thought of as a companion document to be used in the implementation of SUA to clarify errors in the original SUA document. This document updates RFC3868 and text within this document, where noted, supersedes the text found in RFC3868. Each error will be detailed within this document in the form of: o The problem description, o The text quoted from RFC3868, o The replacement text, o A description of the solution. 1.1. Terminology The terms are commonly identified in related work SUA [RFC3868] [1]. 1.2. Conventions Coene & Loughney Expires April 24, 2006 [Page 4] Internet-Draft SUA implementor's Guide October 2005 2. Correction to RFC3868 2.1. Routing context list in connectionless and connectionoriented messages 2.1.1. Description of the problem The routing context parameter of a connectionless and connectionoriented message can contain a list of routing contexts. Normaly, the addressing info present in the message will yield only a single routing context. A list of routing contexts is valid only for SSNM, ASPTM and RKM messages 2.1.2. Text changes to the document --------- Old text: (Section 3.9.6) --------- 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. --------- New text: (Section 3.9.6) --------- 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. A list of routing contexts is only valid for SSNM, ASPTM and RKM messages. All other messages can contain only a single Routing Context. 2.1.3. Solution description Only 1 routing context value may be included in the routing context parameter of a connectionless and connectionoriented message. 2.2. Congestion level parameter value 2.2.1. Description of the problem The value of the congestion level is dependant on which info is present in the SCON message. If the SCON only contains the affected Coene & Loughney Expires April 24, 2006 [Page 5] Internet-Draft SUA implementor's Guide October 2005 pointcode, then the congestion level has values ranging between 0 and 3. If affected pointcode and subsystemnumber is included in the SCON message, then the value of the congestion level can be between 1 and 8. 2.2.2. Text changes to the document --------- Old text: (Section 3.10.24) --------- When the Congestion Level parameter is included in a SCON message that corresponds to an N-PCSTATE primitive, the Congestion Level field indicates the MTP congestion level experienced by the local or affected signalling point as indicated by the Affected Point Code(s) also in the SCON message. In this case, valid values for the Congestion Level field are as follows: 0 No Congestion or Undefined 1 Congestion Level 1 2 Congestion Level 2 3 Congestion Level 3 When the Congestion Level parameter is included in a SCON messagethat corresponds to an N-STATE primitive, the Congestion Level field indicates the SCCP restricted importance level experienced by the local or affected subsystem as indicated by the Affected Point Code and Subsystem Number also in the SCON message. In this case, valid values for the Congestion Level field range from 0 to 7, where 0 indicates the least congested and 7 indicates the most congested subsystem. --------- New text: (Section 3.10.24) --------- 2 different congestion levels ranges can be used accoring to ITU and ANSI congestion control algorithms. When the ANSI congestion control algorithm is used, the Congestion Level field indicates the MTP congestion level as experienced by the local or affected subsystem indicated by the Affected Point Code and Subsystem Number. In this case, valid values for the Congestion Level field range from 0 to 3, where 1 indicates the least congested and 3 indicates the most congested condition. Coene & Loughney Expires April 24, 2006 [Page 6] Internet-Draft SUA implementor's Guide October 2005 0 No Congestion or Undefined 1 Congestion Level 1 2 Congestion Level 2 3 Congestion Level 3 When the ITU congestion control algorithm is used, the Congestion Level field indicates the SCCP restricted importance level experienced by the local or affected subsystem as indicated by the Affected Point Code and Subsystem Number also in the SCON message. In this case, valid values for the Congestion Level field range from 1 to 8, where 1 indicates the least congested and 8 indicates the most congested condition. 2.2.3. Solution description The ITU SCCP congestion control procedures are described in SCCP procedures [Q.714] [4] paragraph 2.6. The ANSI SCCP congestion control procedures are described in SCCP procedures [T1.112.4] [5] paragraph 5.2.4. The SCC message in SCCP takes the value range 1..8, so the corresponding SCON should also be in that range. To indicate no congestion, it is sufficient to send only a DAVA. 2.3. Segmentation parameter value 2.3.1. Description of the problem The original sequence delivery option as original demanded(= before the segementing) by the SCCP application is not preserved after segmentation. The receiving SCCP application will always receive the message with sequenced delivery option set to 1. 2.3.2. Text changes to the document --------- Old text: (Section 3.10.23) --------- The first/remaining segments field is formatted as follows: o bit 8 (MSB) : indicates whether this is the first segment (1) or not (0) o bits 1-7: indicate the number of remaining segments, value between 0 and 15 Coene & Loughney Expires April 24, 2006 [Page 7] Internet-Draft SUA implementor's Guide October 2005 --------- New text: (Section 3.10.23) --------- The segmentation paramter consists of the following: o bit 0: first/remaing segment bit: first = 1, remaining = 0 o bit 1: sequence delivery option as original demanded(= before the segementing) by the SCCP application. class 0 = 0, class 1 = 1. o bit 2-3: spare o bit 4-7: number of remaining segments(4 bits, values 0 -15) o bit 8-31:segmentation reference(3 byte integer) 2.3.3. Solution description The segmentation parameter gets a extra bit(out of the spare bits present) indicating the original requested sequence delivery option as originally demanded by the sending SCCP application. 2.4. DAUD response message ordering 2.4.1. Description of the problem Should a SCON be send before the DAVA or DRST or after? The SCON is send first and DAVA/DRST after in M3UA. 2.4.2. Text changes to the document --------- Old text: (Section 4.5.3) --------- The SGP SHOULD respond to a DAUD message with the availability and congestion status of the subsystem. The status of each SS7 destination or subsystem requested is indicated in a DUNA message (if unavailable), a DAVA message (if available), or a DRST (if restricted and the SGP supports this feature). If the SS7 destination or subsystem is available and congested, the SGP responds with an SCON message in addition to the DAVA message. If the SS7 destination or subsystem is restricted and congested, the SGP responds with an SCON message in addition to the DRST. If the SGP has no information on the availability / congestion status of the SS7 destination or subsystem, the SGP responds with a DUNA message, as it has no routing information to allow it to route traffic to this destination or Coene & Loughney Expires April 24, 2006 [Page 8] Internet-Draft SUA implementor's Guide October 2005 subsystem. --------- New text: (Section 4.5.3) --------- The SGP SHOULD respond to a DAUD message with the availability and congestion status of the subsystem. The status of each SS7 destination or subsystem requested is indicated in a DUNA message (if unavailable), a DAVA message (if available), or a DRST (if restricted and the SGP supports this feature). If the SS7 destination or subsystem is available and congested, the SGP responds with an SCON message and a DAVA message. If the SS7 destination or subsystem is restricted and congested, the SGP responds with an SCON message and a DRST. If the SGP has no information on the availability / congestion status of the SS7 destination or subsystem, the SGP responds with a DUNA message, as it has no routing information to allow it to route traffic to this destination or subsystem. 2.4.3. Solution description The DAVA/DUNA/DRST/SCON messages may be send in random order. However if a SCON is send first and the destination is inaccessible, the SCON will be dropped. So it might be better to send the DAVA first followed by the SCON. 2.5. Host name parameter 2.5.1. Description of the problem The hostname is actually a Fully Qualified Domain Name(FQDN) as defined in RFC1983. The definition of the hostname(as found in RFC1983) would only allow for a part of the FQDN and that does not uniquely identify a endpoint. Also the encoding of the FQDN is not clear. 2.5.2. Text changes to the document --------- Old text: (Section 3.10.2.7) --------- This field contains a host name in "host name syntax" per RFC 1123 Section 2.1 [1123]. The method for resolving the host name is out of scope for this document. --------- New text: (Section 3.10.2.7) Coene & Loughney Expires April 24, 2006 [Page 9] Internet-Draft SUA implementor's Guide October 2005 --------- This field contains a host name in "Fully Qualified Domain Name syntax" per RFC 1035 section 3.1 [RFC1035] [3]. The method for resolving the host name is out of scope for this document. 2.5.3. Solution description The hostname is actually a Fully Qualified Domain Name(FQDN) which should be encoded following the RFC1035 section 3.1 coding rules. 2.6. ASP routing context 2.6.1. Description of the problem An ASP routes responses to the SGP that it received messages from; within the routing context which it is currently active and receiving traffic. 2.6.2. Text changes to the document --------- Old text: (Section 1.5.2) --------- An ASP routes responses to the SGP that it received messages from; within the routing context which it is currently active and receiving traffic. --------- New text: (Section 1.5.2) --------- An ASP routes responses to the SGP that it received messages from. The reponse will utilize the routing context from the received messages. 2.6.3. Solution description a. A routing context is an integer which is significant only for a given SGP-ASP pair. So it is circular logic to say that the ASP should use the RC to select the SGP - an RC value is meaningful only after the SGP has already assigned the RC for the the msg send to the ASP. b. An ASP can be active vis-a-vis an SGP for more than one RC - so it is not meaningful to say that the ASP uses "the" RC for which it is active. If the ASP response to a messages, it has to use the RC Coene & Loughney Expires April 24, 2006 [Page 10] Internet-Draft SUA implementor's Guide October 2005 of that received message in the reponse. 2.7. Parameters should only occur once in a message 2.7.1. Description of the problem Parameters in SUA messages can be repeated as many times as possible. This would lead to inconsistencies, such as 2 or more destination addresses. 2.7.2. Text changes to the document --------- Old text: (Section x.x) --------- --------- New text: (Section x.x) --------- 2.7.3. Solution description Unless explicitly stated or shown in a message format diagram, only one parameter of the same type is allowed in a message. 2.8. TID label parameter 2.8.1. Description of the problem The clarity of the definition of TID label parameters is unclear. Coene & Loughney Expires April 24, 2006 [Page 11] Internet-Draft SUA implementor's Guide October 2005 2.8.2. Text changes to the document --------- Old text: (Section 3.10.16) --------- 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 = 0x0110 | Length = 8 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | start | end | label value | +---------------+---------------+-------------------------------+ The Start parameter is the start position of label, between 0 (LSB) and 31 (MSB). The End parameter is the end position of label, between 0 (LSB) and 31 (MSB). Label value is a 16-bit integer, which is unique across an AS. --------- New text: (Section 3.10.16) --------- 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 = 0x0110 | Length = 8 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | start | end | label value | +---------------+---------------+-------------------------------+ The Start parameter is the start position of label, between 0 (LSB) and 31 (MSB). The End parameter is the end position of label, between 0 (LSB) and 31 (MSB). Label value is a 16-bit integer, which is unique across an AS. The label value has to match the TCAP transaction ID between the start and the end parameter(Logical AND operation). The rest of the TCAP transaction ID between 0 and the begin parameter(if begin parameter > 0) AND the end parameter(if end parameter value < 31) and 31 is wildcarded. An ASP that registers a label will be sent only those TID-bearing messages that match its label. An ASP that does not register a label may be sent any TID-bearing message. Coene & Loughney Expires April 24, 2006 [Page 12] Internet-Draft SUA implementor's Guide October 2005 2.8.3. Solution description The clarity of the definition of the TID and DRM label parameters is improved by adding what should be wildcarded in the TID/DRM and how to use the start and end field. It is assumed that these labels are simple values(at a certain location) that are logical ANDed(taking into account the start and end position where to apply) onto the received TID or DRN. If the result of the AND operation exactly matches the "Label" field, then the message is sent to the ASP that registered for this label via the ASPAC msg. If a another ASP sends a already used label then this ASPAC must be rejected. 2.9. DRM label parameter 2.9.1. Description of the problem See problem description TID label parameter 2.9.2. Text changes to the document --------- Old text: (Section 3.10.15) --------- 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 = 0x010F | Length = 8 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | start | end | label value | +---------------+---------------+-------------------------------+ The Start parameter is the start position of label, between 0 (LSB) and 23 (MSB). The End parameter is the end position of label, between 0 (LSB) and 23 (MSB). Label value is a 16-bit integer, which is unique across an AS. Coene & Loughney Expires April 24, 2006 [Page 13] Internet-Draft SUA implementor's Guide October 2005 --------- New text: (Section 3.10.15) --------- 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 = 0x010F | Length = 8 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | start | end | label value | +---------------+---------------+-------------------------------+ The Start parameter is the start position of label, between 0 (LSB) and 23 (MSB). The End parameter is the end position of label, between 0 (LSB) and 23 (MSB). Label value is a 16-bit integer, which is unique across an AS. The label value has to match the Destination Reference Number between the start and the end parameter(Logical AND operation). The rest of the DRN between 0 and the begin parameter(if begin parameter > 0) AND the end parameter(if end parameter value < 31) and 31 is wildcarded. An ASP that registers a label will be sent only those DRN-bearing messages that match its label. An ASP that does not register a label may be sent any DRN-bearing message. 2.9.3. Solution description See solution description of the TID label parameter. 2.10. Usage of the TID and DRN label 2.10.1. Description of the problem The use of the TID and DRM label parameters is unclear. Coene & Loughney Expires April 24, 2006 [Page 14] Internet-Draft SUA implementor's Guide October 2005 2.10.2. Text changes to the document --------- Old text: (Section 4.7.2.1) --------- After association setup and registration, an ASP normally goes active for each AS it registered for. In the ASPAC message, the ASP includes a TID and/or DRN Label Parameter, if applicable for the AS in question. All the ASPs within the AS must specify a unique label at a fixed position in the TID or DRN parameter. The same ASPAC message is sent to each SG used for interworking with the SS7 network. The SG builds, per RK, a list of ASPs that have registered for it. The SG can now build up and update a distribution table for a certain Routing Context, any time the association is (re-)established and the ASP goes active. The SG has to perform some trivial plausibility checks on the parameters: - Start and End parameters values are between 0 and 31 for TID. - Start and End parameters values are between 0 and 23 for DRN - ... - Start values are the same for each ASP within a RC - End values are the same for each ASP within a RC - TID and DRN Label values must be unique across the RC If any of these checks fail, the SG refuses the ASPAC request, with an error: Invalid loadsharing label . Coene & Loughney Expires April 24, 2006 [Page 15] Internet-Draft SUA implementor's Guide October 2005 --------- New text: (Section 4.7.2.1) --------- After association setup and registration, an ASP normally goes active for each AS it registered for. In the ASPAC message, the ASP can include a TID and/or DRN Label Parameter, if applicable for the AS in question. If at least one of the ASPs within an AS specifies a label, then all the ASPs within the AS must specify a unique label in the ASPAC's msg they send. Each of the ASPs within the AS must specify a unique label at a fixed position in the TID or DRN parameter. The ASP must send the same ASPAC to each SG it is attached to, for interworking with the SS7 network. The SG builds, per RC, a list of ASPs that have registered for it. The SG can now build up and update a distribution table for a certain Routing Context, any time the association is (re-)established and the ASP goes active. The SG has to perform some trivial plausibility checks on the parameters: - Start and End parameters values are between 0 and 31 for TID. - Start and End parameters values are between 0 and 23 for DRN - ... - Start values are the same for each ASP within a RC - End values are the same for each ASP within a RC - TID and/or DRN Label values must be unique across the RC If any of these checks fail, the SG refuses the ASPAC request, with an error, "Invalid loadsharing label." --------- Old text: (Section 4.7.3.1) --------- Messages not containing a destination (or "responding") TID, i.e., Query, Begin, Unidirectional, are loadshared among the available ASPs. Any scheme permitting a fair load distribution among the ASPs is allowed (e.g., round robin). When a destination TID is present, the SG extracts the label and selects the ASP that corresponds with it. If an ASP is not available, the SG may generate (X)UDTS "routing failure", if the return option is used. Coene & Loughney Expires April 24, 2006 [Page 16] Internet-Draft SUA implementor's Guide October 2005 --------- New text: (Section 4.7.3.1) --------- Messages not containing a destination (or "responding") TID, i.e., Query, Begin, Unidirectional, are loadshared among the available ASPs. Any scheme permitting a fair load distribution among the ASPs is allowed (e.g., round robin). When a destination TID is present, the SG extracts the label and if the result of the AND operation exactly matches the "Label" field, then the message is sent to the ASP that registered for this label via the ASPAC msg. An ASP that registers a label will be sent only those TID-bearing messages that match its label. An ASP that does not register a label may be sent any TID-bearing message. If an ASP is not available, the SG may generate (X)UDTS "routing failure", if the return option is used. 2.10.3. Solution description Improving the clarity of the use of the TID and DRM label parameters: If the result of the AND operation exactly matches the "Label" field, then the message is sent to the ASP that registered for this label via the ASPAC msg. An ASP that registers a label will be sent only those TID-bearing messages that match its label. An ASP that does not register a label may be sent any TID-bearing message. Redundancy - The label values are fixed length (16 bits). So why do we need both a "Start" and an "End" position for applying the mask? One or the other would seem to be enough. Simplicity - Why bother with a partial-sized mask at a specified "start" bit. Why not just specify a "full-sized" 32-bit (TID) or 23- bit (DRM) mask? Then we do not need a "start" and "end" position. Contradictions - Section 4.7.2.1 states that "All the ASPs within the AS _must_ specify a unique label at a fixed position in the TID or DRN parameter." The "must" here contradicts that fact the the TID and DRM parameters are listed as Optional in the ASPAC msg. Thus if Coene & Loughney Expires April 24, 2006 [Page 17] Internet-Draft SUA implementor's Guide October 2005 a label is present, then all ASP's belonging to that AS, must specifiy a label in the ASPAC msg. 2.11. Address Range paramete 2.11.1. Description of the problem It should explicitly state the order of the minimum and maximum addresses in this parameter. The most logical order would probably be first the min, followed by the max. 2.11.2. Text changes to the document --------- Old text: (Section 3.10.17) --------- Address field: The Address field the following parameters: Parameter Source Address Optional *1 Destination Address Optional *1 Note 1: The Address field must contain pairs of Source Addresses or pairs of Destination Addresses but MUST NOT mix Source Addresses with Destination Addresses in the same Address field. --------- New text: (Section 3.10.17) --------- Address field: The Address field the following parameters: Parameter Source Address Optional *1 Destination Address Optional *1 Note 1: The Address field must contain pairs of Source Addresses or pairs of Destination Addresses but MUST NOT mix Source Addresses with Destination Addresses in the same Address field. The minimum address must be first and the maximun Coene & Loughney Expires April 24, 2006 [Page 18] Internet-Draft SUA implementor's Guide October 2005 address must follow the minimum. 2.11.3. Solution description State the order of the minimum and maximum addresses in this parameter. The logical order is first the min, followed by the max. 2.12. Interpretation of the mask parameter 2.12.1. Description of the problem The mask paramater in the DAUD, DAVA and DUNA SUA messages can be in the range from 0 to 255 bits. This can go over the maximun pointcode range of 24 bits. Also if a ASP request via DAUD with a mask parameter of 24, the SG would need to return all pointcodes it know in his network to the ASP. (Which could be a lot). 2.12.2. Text changes to the document --------- Old text: (Section 3.9.18) --------- Mask: 8-bits 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 signalling 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 signalling that an ITU Region is unavailable. Coene & Loughney Expires April 24, 2006 [Page 19] Internet-Draft SUA implementor's Guide October 2005 --------- New text: (Section 3.9.18) --------- Mask: 8-bits 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 signalling 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". The range of mask parameter is limited to 0-24 for ANSI networks and is NOT used for ITU networks. 2.12.3. Solution description The parameter is limited to 14 bits for ANSI networks and is NOT USED in ITU networks. 2.13. Reply on errors contained in a error message 2.13.1. Description of the problem If a error message arrives with a error in it, what should be send out? Nothing in the RFC3868 describes this possibility. 2.13.2. Text changes to the document --------- Old text: (Section 3.7.1) --------- Coene & Loughney Expires April 24, 2006 [Page 20] Internet-Draft SUA implementor's Guide October 2005 --------- New text: (Section 3.7.1) --------- Error messages MUST NOT be generated in response to other Error messages. 2.13.3. Solution description No error msg must be send back in response on a received error message(containing a error). This would otherwise possibly lead to a storm of exchange error messages. 2.14. Use of stream 0 for SSNM messages 2.14.1. Description of the problem There seems to be some confusion in paragraph 4.5.1. First it is mentioned NOT to use stream 0 but a few lines later you MUST use stream 0 and that happen all in the same context of sending SSNM messages(DAUD, DUNA, DAVA..). It also contradicts statements made in paragraph 4.1.1. 2.14.2. Text changes to the document --------- Old text: (Section 4.5.1) --------- DUNA, DAVA, SCON, and DRST messages are sent sequentially and processed at the receiver in the order sent. SCTP stream 0 SHOULD NOT be used. The Unordered bit in the SCTP DATA chunk MAY be used for the SCON message. Sequencing is not required for the DUPU or DAUD messages, which MAY be sent unordered. SCTP stream 0 is used, with optional use of the Unordered bit in the SCTP DATA chunk. Coene & Loughney Expires April 24, 2006 [Page 21] Internet-Draft SUA implementor's Guide October 2005 --------- New text: (Section 4.5.1) --------- DUNA, DAVA, SCON, and DRST messages are sent sequentially and processed at the receiver in the order sent. The Unordered bit in the SCTP DATA chunk MAY be used for the SCON message. Sequencing is not required for the DUPU or DAUD messages, which MAY be sent unordered. SCTP stream 0 is used, with optional use of the Unordered bit in the SCTP DATA chunk. 2.14.3. Solution description The SSNM messages should be send on stream 0 of the association. 2.15. Timer Ta does not exist 2.15.1. Description of the problem Timer Ta is mentioned in paragraph 8 but nowhere specified. 2.15.2. Text changes to the document --------- Old text: (Section 8) --------- 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 Coene & Loughney Expires April 24, 2006 [Page 22] Internet-Draft SUA implementor's Guide October 2005 --------- New text: (Section 8) --------- 8. Timer Values 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 2.15.3. Solution description Timer Ta is removed. 2.16. Error response on unsupported RKM messages 2.16.1. Description of the problem If RKM messages are not supported by a implementation, a error message is send back with error cause "unsupported message Type". We should send back a error message with error cause "unsupported message class" . 2.16.2. Text changes to the document --------- Old text: (Section 4.4.1) --------- If the SGP does not support the registration procedure, the SGP returns an Error message to the ASP, with an error code of "Unsupported Message Type". --------- New text: (Section 4.4.1) --------- If the SGP does not support the registration procedure, the SGP returns an Error message to the ASP, with an error code of "Unsupported Message Class". Coene & Loughney Expires April 24, 2006 [Page 23] Internet-Draft SUA implementor's Guide October 2005 2.16.3. Solution description Send back a error message with "unsupported message class". If >RKM messages are not supported, the implementation actually rejects a whole class of messages, not just a single one. 2.17. Filler/padding in Global title parameter 2.17.1. Description of the problem The global title digits part of the global title parameter contains filler bytes. They should be called pading bytes so that they are not included in the calculation of the length of the global title parameter. 2.17.2. Text changes to the document --------- Old text: (Section 3.10.2.3) --------- Global Title: Octets contain a number of address signals and possibly filler as shown: 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 SHOULD be set to 0. Coene & Loughney Expires April 24, 2006 [Page 24] Internet-Draft SUA implementor's Guide October 2005 --------- New text: (Section 3.10.2.3) --------- Global Title: Octets contain a number of address signals and possibly filler and padding as shown: 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.| padding | | |if req | sig. | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ All filler and padding bits SHOULD be set to 0. 2.17.3. Solution description Insert padding into definition of the global title parameter. 2.18. Inclusion of routing context in the Routing key parameter 2.18.1. Description of the problem The Routing conext is missing from the Routing key parameter of the REG message, so leading to a inconsistency with section 4.4.1 where it is mentioned that the RC has to be present in order to change the registration data of a certain RC. If the RC is not present, then the registration data can not be identified and changed. Coene & Loughney Expires April 24, 2006 [Page 25] Internet-Draft SUA implementor's Guide October 2005 2.18.2. Text changes to the document --------- Old text: (Section 3.10.14) --------- The Key field contains the following parameters: Parameter Traffic Mode Type Optional Network Appearance Optional *1 Source Address Optional Destination Address Optional Address Range Optional Note 1: The Network Appearance parameter must be included in the Routing Key when the ASP is able to register in multiple SS7 Network contexts --------- New text: (Section 3.10.14) --------- The Key field contains the following parameters: Parameter Traffic Mode Type Optional Network Appearance Optional *1 Source Address Optional Destination Address Optional Address Range Optional Routing Context Optional *2 Note 1: The Network Appearance parameter must be included in the Routing Key when the ASP is able to register in multiple SS7 Network contexts. Note 2: The Routing Context parameter is included in the Routing Key when the ASP wishes to alter an existing Routing Key which corresponds to the indicated Routing Context. The Routing Context parameter MUST only occur once in the Key parameters. Coene & Loughney Expires April 24, 2006 [Page 26] Internet-Draft SUA implementor's Guide October 2005 2.18.3. Solution description Include the routing context parameter in the routing key parameter. And keep the text of section 4.4.1. Coene & Loughney Expires April 24, 2006 [Page 27] Internet-Draft SUA implementor's Guide October 2005 3. Security considerations No new treats have been identified besides the already known in SUA [RFC3868] [1]. Coene & Loughney Expires April 24, 2006 [Page 28] Internet-Draft SUA implementor's Guide October 2005 4. Acknowledgments The authors wish to thank B. Nagelberg, B. Bidulock, T. Asveren, S. Karl, K. Morneault and many others for their invaluable comments. 5. References [1] Loughney, J., Sidebottom, G., Verwimp, G., Coene, L., Keller, J., and B. Bidulock, "Signalling Connection Control Part User Adaptation Layer (SUA)", RFC 3868, October 2004. [2] Malkin, G., "Internet Users' Glossary", RFC 1983, August 1996. [3] Mockapetris, P., "Domain names - Implementation and Specification", RFC 1035, November 1987. [4] ITU, "Q.714 : SCCP procedures", Q. 714, July 1997. [5] ANSI, "T1.112.4 : SCCP procedures", T. 1.112.4, December 1993. Coene & Loughney Expires April 24, 2006 [Page 29] Internet-Draft SUA implementor's Guide October 2005 Appendix A. Changes Control A.1. Changes from v00 to v01 - Change of boilerplate - Typos. - Paragraph 2.6 ASP routing context: replacement text for section 1.5.2 - Paragraph 2.10 Usage of TID and DRM label parameter: text clarification for solution description - Paragraph 2.8 Use of ANSI intermediate signaling network identification (ISNI) parameter: Removed, no text proposed. A.2. Changes from v01 to v02 - Typos. - Paragraph 2.17 Filler/padding in Global title parameter: new - Paragraph 2.18 Inclusion of routing context in the Routing key parameter: new - Paragraph 2.8 TID label parameter:Changed: Another attempt at clarifying what a SG could be doing with TID label. - Paragraph 2.9 DRM label parameter:Changed: Another attempt at clarifying what a SG could be doing with DRM label. - Paragraph 2.10 Usage of TID and DRM label parameter:Changed: Another attempt at clarifying what a SG could be doing with TID and DRM labels. - Coene & Loughney Expires April 24, 2006 [Page 30] Internet-Draft SUA implementor's Guide October 2005 Authors' Addresses Lode Coene Siemens Atealaan 32 Herentals 2200 Belgium Phone: +32-14-252081 Email: lode.coene@siemens.com John Loughney Nokia Itdmerenkatu 11-13 Espoo 00180 Finland Phone: +358 50 483 6242 Email: john.loughney@nokia.com Coene & Loughney Expires April 24, 2006 [Page 31] Internet-Draft SUA implementor's Guide October 2005 Intellectual Property Statement The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. 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Disclaimer of Validity This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM 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. Copyright Statement Copyright (C) The Internet Society (2005). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Coene & Loughney Expires April 24, 2006 [Page 32]