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Internet Engineering Task Force Sanjay Rao INTERNET DRAFT Neeraj Khanchandani Fahir Ergincan Nortel Networks Expires in six months July 2000 V5.2 extensions to the IUA protocol <draft-rao-sigtran-v5ua-00.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 document defines a mechanism for backhauling of V5.2 messages over IP by extending the ISDN User Adaptation Layer Protocol (<draft-ietf-sigtran-iua-03.txt>). The document aims to become an Appendix to IUA and to be the base for a V5.2 implementation. Rao,Khanchandani,Fahir [Page 1] Internet Draft V5.2 July, 2000 Table of Contents 1.Introduction ........................................ 3 1.1.Scope ............................................. 3 1.2.Terminology ....................................... 3 2.Overview ............................................ 4 2.1.Proposed V5.2 Backhaul Architecture ............... 5 2.2.IUA Message Header ................................ 6 2.3.New IUA Message Header for V5.2 implementations 2.4. References ....................................... 7 Rao,Khanchandani,Fahir [Page 2] Internet Draft V5.2 July, 2000 1. Introduction This document describes a method of implementing V5.2 back- haul messaging over IP using a modified version of the ISDN User Adapation Layer Protocol (IUAP). The document aims to become an Appendix to IUA and to be the base for the "appli- cation guide". 1.1. Scope There is a need for a V5.2 backhaul to meet the following access types: - Analog telephone access - ISDN Basic rate access - ISDN Primary Rate access (V5.2) - Other analog or digital accesses for semi- permanent connections without associated outband signaling information 1.2. Terminology Bearer Channel Connection (BCC) protocol - A protocol which allows the LE to instruct the AN to allocate bearer chan- nels, either singly or in multiples, on demand. Communication channel (C-channel) - A 64 kbit/s time slot on a V5.2 interface provisioned to carry communication paths. Communication path (C-path) - Any one of the following information types: - The layer 2 data link carrying the Control pro- tocol - The layer 2 data link carrying the Link Control protocol - The layer 2 data link carrying the PSTN signal- ling - Each of the layer 2 data links carrying the pro- tection protocol - The layer 2 data link carrying the BCC protocol - All the ISDN Ds-type data from one or more user ports - All the ISDN p-type data from one or more user ports - All the ISDN t-type data from one or more user ports Note: This definition includes the possibility that there is more than one C-path of the same information type, each allocated to a different logical C-channel. Logical Communication channel (Logical C-channel) - A group of one or more C-paths, all of different types, but exclud- ing the C-path for the protection protocol. Rao,Khanchandani,Fahir [Page 3] Internet Draft V5.2 July, 2000 Multi-link - A collection of more than one 2.048 kbit/s link which together make up a V5.2 interface. Multi-Slot - A group of more than one 64kbit/s channels pro- viding 8Khz and time slot sequence integrity, generally used together within an ISDN Primary Rate Access (ISDN-PRA) user port, in order to supply a higher bit-rate service. Physical Communication Channel (Physical C-channel) - A 64kbit/s time slot on a V5.2 interface which has been assigned for carrying logical C-channels. A physical C- channel may not be used for carrying bearer channels. Primary Link - A 2.048 kbit/s link in a multi-link V5.2 interface whose physical C-channel in time slot 16 carries a C-path for the protection protocol and, on V5.2 initializa- tion, also the C-path for the control protocol, link control protocol, and the BCC protocol. Other C-paths may also be carried in the time slot 16. Secondary Link - A 2.048 kbit/s link in a multi-link V5.2 interface whose time slot 16 carries a C-path for the pro- tection protocol, and, on V5.2 initialization, acts as the standby C-channel for the control protocol, link control protocol, and BCC protocol and any other C-paths initially carried in time slot 16 of the primary link. 2. V5.2 Overview V5.2 is an industry standard ETSI interface (reference ETS 300 347-1) defined between a Local Exchange (LE) and an Access Network (AN) providing access to the following types: - Analog telephone access - ISDN Basic rate access - ISDN Primary Rate access (V5.2) - Other analog or digital accesses for semi- permanent connections without associated outband signaling information The original V5 specification uses 2048 kbps links, V5.2 may use upto 16 such interface links. ---------- ---------- o--o | | E1 | |------- /\ | |--------------| | -- | LE | E1 | AN | | |--------------| | o--o | | | |------- /\ ---------- ---------- -- Rao,Khanchandani,Fahir [Page 4] Internet Draft V5.2 July, 2000 LE and AN are connected with up to 16 E1 (PCM30) links. Channels 16, 15 and 31 on any E1 link can be reserved for data communication between LE and AN. The channels reserved for data are called "Communication Channels" or "C- Channels." The C-Channels are the physical media to exchange data between the V5.2 protocol peer entities, as well as to transfer the ISDN BRI D-Ch messages between the terminals and the LE. A logical communication path between two peer entities is called a "C-path". The signaling information in V5.2 are defined as: - Analog signals are carried by means of the V5 PSTN protocol (L3) - ISDN/analog ports are controlled by the V5 Con- trol protocol (L3) - ISDN protocol messages are mapped to LAPD frames, which are carried by means of LAPV5-EF sublayer (L2) - V5 protocol messages are mapped to LAPV5-DL frames, which are carried by means of LAPV5-EF sublayer (L2) In order to support more traffic and dynamic allocation of links, the V5.2 protocol has several additions: - A bearer channel connection protocol establishes and de-establishes bearer connections required on demand, identified by the signalling information, under the control of the Local Exchange. - A link control protocol is defined for the multi-link management to control link identifica- tion, link blocking and link failure conditions. - A protection protocol, operated on two separate data links for security reasons, is defined to manage the protection switching of communication channels in case of link failures. The following protocols are defined for the various protocol layers: - LAPV5-EF - LAPV5-DL - V5-Link Control - V5-BCC - V5-PSTN - V5-Control - V5-Protection 2.1. Proposed V5.2 Backhaul Architecture Rao,Khanchandani,Fahir [Page 5] Internet Draft V5.2 July, 2000 ****** V5.2 ****** IP ******* * AN *---------------* SG *--------------* MGC * ****** ****** ******* +-----+ +-----+ |V5.2 | (NIF) |V5.2 | +-----+ +----------+ +-----+ | | | | IUA| | IUA | | | | +----+ +-----+ |LAPV5| |LAPV5|SCTP| |SCTP | | | | +----+ +-----+ | | | | IP + | IP | +-----+ +-----+----+ +-----+ NIF - Nodal Interworking function EP - End Point SCTP - Stream Control Transmission Protocol IUA - ISDN User Adap- tation Layer Protocol 2.2. IUA Message Header 0 1 2 3 0 2 4 6 8 0 2 4 6 8 0 2 4 6 8 0 2 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag (0x01) | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Interface Identifier | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | DLCI | Spare | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 2 IUA Message Header 2.3. New IUA Message Header for V5.2 implementations Spare field is now the Envelope Function Address (EFA) field. Rao,Khanchandani,Fahir [Page 6] Internet Draft V5.2 July, 2000 0 1 2 3 0 2 4 6 8 0 2 4 6 8 0 2 4 6 8 0 2 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag (0x01) | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Interface Identifier | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | DLCI |Spr| EFA | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 3 IUA Message Header for V5.2 The EFA identifies a C-path, which is a 13-bit number, ranging from 0 to 8191 (decimal). An EFA uniquely identifies one of the five V5.2 protocols, or an ISDN agent attached to an AN. The following list contains the possible values for the EFA Definition Value ---------- ------ ISDN_PROTOCOL 0 - 8175 PSTN_PROTOCOL 8176 CC_PROTOCOL 8177 BCC_PROTOCOL 8178 PROT_PROTOCOL 8179 LINK_CONTROL_PROTOCOL 8180 RESERVED 8181 - 8191 2.4. References  ISDN Q.921-User Adaptation Layer <draft-ietf-sigtran- iua-03.txt>  EN 300 347-1 (1999): V interfaces at the digital Local Exchange (LE); V5.2 interface for the support of Access Network (AN); Part 1: V5.2 interface specification.  EN 300 347-1 (1999): V interfaces at the digital Local Exchange (LE); V5.2 interface for the support of Access Network (AN); Part 1: V5.2 interface specification.  ETS 300 125 (1991) : DSS1 protocol; User-Network inter- face data link layer specification; (Standard is based on : ITU Q.920, Q.921).  ETS 300 166 (08/1993) : Transmission and Multiplexing; Physical and electrical characteristic of hierarchical digital interfaces (Standard is based on G.703).  ETS 300 167 (08/1993) : Transmission and Multiplexing; Rao,Khanchandani,Fahir [Page 7] Internet Draft V5.2 July, 2000 Functional characteristic of 2048 kbits/s interfaces (Standard is based on G.704, G.706). 2.5. Author's Addresses Sanjay Rao Tel +1-919-991-2251 Nortel Networks Email email@example.com 35 Davis Drive Research Triangle Park, NC 27709 USA Neeraj Khanchandani Tel +1-919-991-2274 Nortel Networks Email firstname.lastname@example.org 35 Davis Drive Research Triangle Park, NC 27709 USA Dr. Fahir Ergincan Tel +49 7545 96 8844 Nortel-Dasa Network Systems Email email@example.com 88039 Friedrichshafen Germany This Draft Expires in 6 months from July,2000 Rao,Khanchandani,Fahir [Page 8]
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