Network Working Group                                     R. R. Stewart
INTERNET-DRA                                                 S. Deering
                                                                  Cisco

expires in six months                                      June  1,2001



         IPv6 addressing and Stream Control Transmission Protocol 
                   <draft-stewart-tsvwg-sctpipv6-00>

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.

    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

    Stream Control Transmission Protocol [RFC2960] provides transparent
    multi-homing to its upper layer users. This multi-homing is
    accomplished through the passing of address parameters in the
    initial setup message used by SCTP. In an IPv4 network all addresses
    are passed with no consideration for their scope and routeablility.
    In a IPv6 network special considerations MUST be made to properly
    bring up associations between SCTP endpoints that have IPv6
    [RFC2460] addresses bound within their association.  This document
    defines those considerations and enumerates general rules
    that an SCTP endpoint MUST use in formulating both the INIT and
    INIT-ACK chunks.


Table Of Contents




1. Introduction


    Stream Control Transmission Protocol [RFC2960] provides transparent
    multi-homing to its upper layer users. This multi-homing is
    accomplished through the passing of address parameters in the
    initial setup message used by SCTP. In an IPv4 network all addresses
    are passed with no consideration for their scope and routeablility.
    In a IPv6 network special considerations MUST be made to properly
    bring up associations between SCTP endpoints that have IPv6
    [RFC2460] addresses bound within their association.  This document
    defines those considerations and enumerates general rules
    that an SCTP endpoint MUST use in formulating both the INIT and
    INIT-ACK chunks.

    The emphasis in the rules laid out in this document are to prevent
    an SCTP endpoint from listing an IPv6 address that is outside of its
    routeable scope to a peer endpoint. This will prevent black-hole
    conditions that may cause the unexpected failure of SCTP associations.

2. 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. Special rules for IPv6 address scoping

    When selecting IPv6 addresses to include as parameters in the INIT
    chunk the following rules MUST be applied:

    A1) The INIT chunk SHOULD NOT include any IPv6 Link Local
        address parameters unless the source or destination address
        in the IPv6 header is a Link Local address.

    A2) If IPv6 Link Local address parameters are included in the 
        INIT chunk, Link Local addresses that are NOT on the same 
	physical Link as that of the destination or source
        IPv6 address (found in the IPv6 header) MUST NOT be included.

    A3) The INIT chunk SHOULD NOT include any IPv6 Site Local
        address parameters unless the source or destination address
        in the IPv6 header is a Site Local address.

    A4) If IPv6 Site Local addresses are included in the INIT chunk,
        Site Local address that are NOT on the same site MUST NOT 
        be included.

    A5) If the destination and source address of the INIT is an 
        IPv6 Global address then the sender SHOULD NOT include any 
        Site Local or Link Local IPv6 address parameters in the 
        INIT chunk.

    When responding to an INIT chunk and selecting IPv6 address
    parameters to be included in the INIT-ACK chunk, the following rules
    MUST be applied:

    B1) The INIT-ACK chunk SHOULD NOT include any IPv6 Link Local
        address parameters unless the source or destination address
        in the IPv6 header of the INIT chunk is a Link Local address.

    B2) If IPv6 Link Local address parameters are included in the 
        INIT-ACK chunk, Link Local addresses that are NOT on the same 
	physical Link as the source or destination address in the
        IPv6 header of the INIT chunk MUST NOT be included.

    B3) The INIT-ACK chunk SHOULD NOT include any IPv6 Site Local
        address parameters unless the source or destination address
        in the IPv6 header of the INIT chunk is a Site Local address.

    B4) If IPv6 Site Local addresses are included in the INIT-ACK 
        chunk, Site Local address that are NOT on the same site 
        as the received INIT chunk MUST NOT be included.
 
    B5) If the destination and source address of the INIT is an 
        IPv6 Global address then the sender SHOULD NOT include any 
        Site Local or Link Local IPv6 address parameters in the 
        INIT-ACK chunk.

4. Authors addresses


   Randall R. Stewart
   24 Burning Bush Trail.
   Crystal Lake, IL 60012
   USA
   Phone: +1 815 477 2127
   EMail: rrs@cisco.com

   Stephen E. Deering
   Cisco Systems, Inc.
   170 West Tasman Drive
   San Jose, CA 95134-1706
   USA

   Phone: +1 408 527 8213
   Fax:   +1 408 527 8254
   EMail: deering@cisco.com


5. References

   [RFC2026]  Bradner, S., "The Internet Standards Process -- Revision
              3", BCP 9, RFC 2026, October 1996.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2460]  S. Deering, R. Hinden, "Internet Protocol, 
              Version 6 (IPv6) Specification." December 1998.

   [RFC2960]  R. R. Stewart, Q. Xie, K. Morneault, C. Sharp,
              H. J. Schwarzbauer, T. Taylor, I. Rytina, M. Kalla, L. Zhang,
              and, V. Paxson, "Stream Control Transmission Protocol," RFC
              2960, October 2000.
