Network Working Group R. R. Stewart INTERNET-DRAFT S. Deering Cisco expires in six months April 10,2002 IPv6 addressing and Stream Control Transmission Protocol 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 Stewart, Deering [Page 1] Internet Draft IPv6 addressing and SCTP April 2002 [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 the ULP requests establishment of an SCTP association to a IPv6 destination address, the following considerations apply: - the requested destination address will be accompanied by a locally-significant "zone identifier" [scoped-addr-arch]. - the source address in the initial IPv6 packet (the packet carrying the INIT) MUST be an address belonging to the specified destination zone. - the INIT chunk MUST include all of, and only, the initiator's bound addresses belonging to the destination zone and all larger, encompassing zones, with the optional exception of the source address. The receiver of an INIT will identify the relevant zone by the scope of the source address and the arrival interface. In choosing addresses to place in the INIT-ACK the following considerations apply: - the receiver of the INIT will use the locally-significant "zone identifier" [scoped-addr-arch] to scope the addresses listed in the INIT-ACK. - the source address in the initial IPv6 packet (the packet carrying the INIT-ACK) MUST be an address belonging to the destination zone. - the INIT-ACK chunk MUST include all of, and only, the initiator's bound addresses belonging to the destination zone and all larger, encompassing zones, with the optional exception of the source address. 4. Authors addresses Stewart, Deering [Page 2] Internet Draft IPv6 addressing and SCTP April 2002 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. [scoped-addr-arch] S. Deering, B. Haberman, T Jinmei, E Nordmark, A Onoe, B Zill, "IPv6 Scoped Address Architecture", Work In Progress, November 2001. Stewart, Deering [Page 3]