Sigtran Working Group J. Bouwen INTERNET-DRAFT Alcatel K. Morneault Cisco Systems Expires in six months Feb 2002 Layer 1 Activation Management for ISDN Q.921-User Adaptation Layer (IUA) ISDN Layer 1 Activation Adaptation Layer (IL1A) draft-bouwen-sigtran-il1a-01.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 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. Abstract This Internet Draft proposes an extension to the ISDN Q.921-User Adaptation (IUA) [1] layer for the exchange of layer 1 activation messages between a Media Gateway Controller and an ISDN Access Gateway. This extension is necessary to support ISDN Basic Rate Access (BRA). Bouwen-Morneault [Page 1] Internet Draft ISDN Layer 1 Activation Adaptation Layer Feb 2002 1. Introduction There is a need to extend the ISDN Q.921-User Adaptation (IUA) layer in order to fully support ISDN Basic Rate Access (BRA) devices. This draft provides support for the exchange of layer 1 activation messages between a Media Gateway Controller (MGC) and an ISDN Access Gateway. These layer 1 messages are not necessary for ISDN Primary Rate Access (PRA) because layer 1 is always active for ISDN PRA. Note: In this document, the term Q.921 user refers to an upper layer which uses the services of Q.921, not the user side of ISDN interface [2]. 2.0 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. Layer 1 Activation / De-Activation for ISDN In ISDN access gateway architectures, the layer 1 functionality for Basic Rate 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 Rate Access termination is permanently Bouwen-Morneault [Page 2] Internet Draft ISDN Layer 1 Activation Adaptation Layer Feb 2002 activated, or if activation/de-activation procedures are required. This information needs to be provisioned on the MGC and Access Gateway. It could be made a property of the ISDN termination that is made available via Megaco or MGCP, but that is out-of-scope of this draft. 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. This document only discusses sub-function (2) above. The activation/deactivation procedure for Basic Interfaces is defined in ITU Recommendation I.430 [2]. Note that the procedure is only valid for Basic Access interfaces, Primary Rate Interfaces are permanently activated. This document describes the use of the IUA 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. +======================================================+ !Message ! MG ¡ direction ¡ MGC ! +======================================================+ ! Activation Initiated by User ! ----> ! +------------------------------------------------------+ ! DS Activated ! ----> ! +------------------------------------------------------+ ! Access Activated ! ----> ! +------------------------------------------------------+ ! Access Deactivated ! ----> ! +------------------------------------------------------+ ! Activate Access ! <---- ! +------------------------------------------------------+ ! Deactivate Access ! <---- ! +======================================================= Bouwen-Morneault [Page 3] Internet Draft ISDN Layer 1 Activation Adaptation Layer Feb 2002 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 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=8 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Interface Identifier (integer) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag (0x5) | Length=8 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | DLCI | Spare | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1 IL1A Message Format for integer 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 (0x3) | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Interface Identifier (text) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag (0x5) | Length=8 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | DLCI | Spare | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 2 IL1A Message Format for text Interface Identifiers Bouwen-Morneault [Page 4] Internet Draft ISDN Layer 1 Activation Adaptation Layer Feb 2002 A new message class is necessary to support layer 1 activation / de- activation along with new message types in that message class. The new message class and message types are defined below: Message Class 12 IL1A messages Message types for IL1A messages 0 Reserved 1 Activate Access 2 Activation Initiated by User 3 DS Activated 4 Access Activated 5 Deactivate Access 6 Access Deactivated 7 to 127 Reserved by the IETF 128 to 255 Reserved for IETF-Defined MGMT extensions The values of the other fields are defined in the IUA specification 6. Security Considerations Security considerations for IUA apply. There are no additional security considerations. 7. References 7.1 Normative [1] ISDN Q.921-User Adaptation Layer (IUA), RFC3057, February 2001 [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) ¡ V5.1-interface (based on 2048 kbit/s) for the support of access network (AN) 8. Acknowledgments The authors would like to thank Eva Weilandt for reviewing this draft. 9. Author's Addresses Jan Bouwen Alcatel F. Wellesplein 1 B-2000 Antwerpen Belgium Email: jan.bouwen@alcatel.be Ken Mourneault Cisco Systems 13615 Dulles Technology Drive Herndon, VA 20171 USA Email: kmorneau@cisco.com Bouwen-Morneault [Page 5] Internet Draft ISDN Layer 1 Activation Adaptation Layer Feb 2002 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-Mournealt Expires August 2001 6