Sigtran WG J. Bouwen Internet Draft Alcatel Document: K. Morneault Category: Informational Cisco February 2001 Layer 1 Activation Management for ISDN Q.931 User Adaptation Layer (IUA): ISDN Layer 1 Activation Adaptation Layer (IL1A) 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 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. 1. Abstract ISDN Basic Access terminations require an explicit activation/de- activation of layer 1. In a decomposed gateway architecture with an Access Gateway and a Media Gateway Controller, it is the Media Gateway Controller who controls the activation process. This draft describes the use of an SCTP adaptation layer for the exchange of the activation/de-activation messages. The defined messages can be considered as an extension for IUA [1] when layer 1 control of Basic Access interfaces is required. 2. Conventions used in this document The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC-2119 [1]. Bouwen & Morneault Expires August 2001 1 Internet Draft ISDN Layer 1 Activation Adaptation Layer February 2001 3. Introduction: layer 1 activation for ISDN In ISDN access gateway architectures, the layer 1 functionality for Basic Interfaces is split between the access gateway (access node) and the entity containing call control (the local exchange). When VoIP Access Gateways are deployed that support ISDN terminations, a similar functionality is required. Two sub-functions are necessary: 1. The Media Gateway Controller has to know if layer 1 of a particular ISDN Basic Access termination is permanently activated, or if activation/de-activation procedures are required. This information is a property of the ISDN termination, and is covered by a new Megaco termination property defined in [4] 2. The activation/de-activation procedure itself, which requires the exchange of a limited set of signalling messages between the Media Gateway Controller and the Access Gateway. The activation/deactivation procedure for Basic Interfaces is defined in ITU Recommendation I.430 [2]. Remark that the procedure is only valid for Basic Access interfaces, Primary Rate Interfaces are permanently activated. This document describes the use of an SCTP adaptation layer for the exchange of the activation/de-activation messages. The defined messages can be considered as an extension for IUA [1] when layer 1 control of Basic Access interfaces is required. Because IUA already contains layer 2 activation/de-activation messages, the use of IUA mechanisms for layer 1 activation/de- activation is preferred to implementing layer 1 functionality in Megaco events and signals. Co-ordination between layer 1 and layer 2 activation will be simplified. 4. Layer 1 Messages Table 1 shows the messages defined in G.964 [3] for layer 1 activation/de-activation, and the direction in which they are exchanged. Bouwen & Morneault Expires August 2001 2 Internet Draft ISDN Layer 1 Activation Adaptation Layer February 2001 +======================================================+ !Message ! MG û direction û MGC ! +======================================================+ ! Activation Initiated by User ! ----> ! +------------------------------------------------------+ ! DS Activated ! ----> ! +------------------------------------------------------+ ! Access Activated ! ----> ! +------------------------------------------------------+ ! Access Deactivated ! ----> ! +------------------------------------------------------+ ! Activate Access ! <---- ! +------------------------------------------------------+ ! Deactivate Access ! <---- ! +======================================================= Table 1 û G.964 Activation/de-activation Messages 5. ISDN Layer 1 Activation Adaptation Layer (IL1A) Messages) The ISDN Layer 1 Activation Adaptation Layer uses the message format as it is defined for IUA. The messages consist of the common header and the IUA message header defined for QPTM and TEI status messages. No additional variable-length parameters are required. Figure 1 shows the message format when integer based interface identifier are used, Figure 2 shows the format for text based interface identifiers. 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag (0x1) | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Interface Identifier (integer) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag (0x5) | Length=8 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | DLCI | Spare | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1 IL1A Message Format for integer I/F ids Bouwen & Morneault Expires August 2001 3 Internet Draft ISDN Layer 1 Activation Adaptation Layer February 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Version | Reserved | Message Class | Message Type | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Message Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag (0x3) | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Interface Identifier (text) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag (0x5) | Length=8 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | DLCI | Spare | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 2 IL1A Message Format for text I/F ids The fields have the following values: Version 1 : Release 1.0 Message Class 9 : IL1A messages Message types 0 : Reserved 1 : Activate Access 2 : Activation Initiated by User 3 : DS Activated 4 : Access Activated 5 : Deactivate Access 6 : Access Deactivated The values of the other fields are defined in the IUA specification 6. IL1A Support When one of the communicating parties (Access Gateway or Media Gateway Controller) does not support the IL1A message class, it will respond with the ôUnsupported Msg Classö error on receipt of an IL1A message. Error recovery procedures for this case are for further study. Bouwen & Morneault Expires August 2001 4 Internet Draft ISDN Layer 1 Activation Adaptation Layer February 2001 7. Security Considerations Security considerations for IUA apply. 8. IANA Considerations The IL1A Message Class has to be registered with IANA. 9. References [1] ISDN Q.921-User Adaptation Layer (IUA) RFC 3057, November 2000 [2] ITU-T Recommendation I.430 (1995), Basic user-network interface - layer 1 specification [3] ITU-T Recommendation G.964 (1994), V-interfaces at the digital local exchange (le) û V5.1-interface (based on 2048 kbit/s) for the support of access network (AN) [4] ISDN Package for Megaco draft-bouwen-megaco-isdn-pack-01.txt, February 2001 10. Author's Addresses Jan Bouwen Alcatel F. Wellesplein 1 B-2000 Antwerpen Belgium Email: jan.bouwen@alcatel.be Ken Morneault 13615 Dulles Technology Drive Herndon, VA 20171 USA Email: kmorneau@cisco.com Bouwen & Morneault Expires August 2001 5 Internet Draft ISDN Layer 1 Activation Adaptation Layer February 2001 Full Copyright Statement "Copyright (C) The Internet Society (date). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implmentation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into Bouwen & Morneault Expires August 2001 6