INTERNET DRAFT Jung-Soo Park Expires: May 2002 Myung-Ki Shin Yong-Jin Kim ETRI November 2001 Host-based IPv6 Multicast Addresses Allocation 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 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 obsolete by other documents at anytime. 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 specifies an extension to the multicast addressing architecture of the IPv6 protocol. The extension allows for sing interface-ID to allocate multicast addresses. When the link-local unicast address is configured at each interface of host, interface ID is uniquely determined. By delegating multicast addresses at the same time as interface ID, each host can identify their multicast addresses automatically at Layer 1 without needing to run an intra- or inter-domain allocation protocol in the serverless environments. Table of Contents: 1. Introduction 2. Terminology 3. Multicast Address Format 3.1 Link-local multicast address 3.2 Site-local multicast address 3.3 GLOP-based global multicast address Park, Shin, Kim Expires May 2002 [Page 1] INTERNET-DRAFT Host-based IPv6 Multicast Addresses Allocation Nov. 2001 4. Considerations 5. Security Considerations 6. References 1. Introduction This specification defines an extension to the multicast portion of the IPv6 addressing architecture [ADDRARCH]. The current architecture does not contain any built-in support for dynamic address allocation. The extension allows for using interface-ID to allocate mlticast addresses. When the link-local unicast address is configured at each interface of host, interface ID is uniquely determined. By delegating multicast addresses at the same time as interface ID, each host can identify their multicast addresses automatically without needing to run an intra- or inter-domain allocation protocol The current IPv4 multicast address allocation architecture [RFC 2908] is based on a multi-layered, multi-protocol system. The goal of this proposal is to reduce the number of protocols and servers that need to be deployed in order to get dynamic multicast address allocation. The use of interface ID-based multicast address allocation will, at a minimum, remove the need to run the Multicast Address Allocation Protocol (AAP) [AAP WORK][RFC 2909] and the Multicast Address Allocation servers [RFC 2908]. This document specifies encoded information in the multicast address to allow for dynamic allocation of IPv6 multicast addresses. 2. Terminology 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]. 3. Multicast Address Format Section 2.7 of [ADDRARCH] defines the following operational format of IPv6 multicast addresses: | 8 | 4 | 4 | 112 | +--------+----+----+---------------------------------------------+ |11111111|flgs|scop| group ID | +--------+----+----+---------------------------------------------+ Figure 1: Generic IPv6 Multicast Addresses Park, Shin, Kim Expires May 2002 [Page 2] INTERNET-DRAFT Host-based IPv6 Multicast Addresses Allocation Nov. 2001 This document introduces a new format that incorporates interface ID information in the multicast address. The idea delegating multicast addresses at the same time as interface ID, can be applicable to link local, site local, GLOP-based global scope. 3.1 Link-local multicast address Figure 2 illustrates the new format for link local scope. | 8 | 4 | 4 | 40 | 64 | 8 | +--------+----+----+-----------------------+------------+--------+ |11111111|flgs|scop| reserved |Interface ID|group ID| +--------+----+----+-----------------------+------------+--------+ Figure 2: Host-based link-local multicast addresses +-+-+-+-+ flgs is a set of 4 flags: |0|H|0|T| +-+-+-+-+ o H = 0 indicates a host-based multicast address that is not assigned based on the interface ID. This indicates a multicast address as defined in [ADDRARCH]. o H = 1 indicates a host-based multicast address that is assigned based on the Interface ID. o If H = 1, T MUST be set to 1, otherwise the setting of the T bit is defined in Section 2.7 of [ADDRARCH]. For example, if H=1 and T=0, H bit will be ignored. scop field is set to '2'. The scope of this multicast address MUST be independent of the scope of the unicast address, which derives the interface ID embedded in the multicast address. The reserved field MUST be zero. interface ID field is used to distinguish each host from others. And this value is obtained from EUI-64 based interface identifier of a unicast IPv6 address. group ID is generated randomly to indicate multicast application and is used to guarantee its uniqueness only in host. The lifetime of a host-based multicast addresses have no dependency to the Valid Lifetime field in the Prefix Information option, corresponding to the link-local unicast address being used, contained in the Router Advertisement message [RFC 2461]. Park, Shin, Kim Expires May 2002 [Page 3] INTERNET-DRAFT Host-based IPv6 Multicast Addresses Allocation Nov. 2001 3.2 Site-local multicast address Figure 3 illustrates the new format for site local scope. | 8 | 4 | 4 | 24 | 16 | 64 | 8 | +--------+----+----+------------+----------+------------+--------+ |11111111|flgs|scop| reserved | subnet ID|Interface ID|group ID| +--------+----+----+------------+----------+------------+--------+ Figure 3: Host-based site-local multicast addresses flgs is set to '0101'. The setting of the scop field follows the definition of RFC 2373. The reserved field MUST be zero. subnet ID field is used to distinguish the scope of site-local from others. And this value is obtained from the network prefix contained in the Router Advertisement message. But, all zero's subnet ID MUST be reserved to support link-local multicast addresses. interface ID is same as the link-local multicast address has. group ID is generated randomly in host. 3.3 GLOP-based global multicast address Figure 4 illustrates the new format for GLOP-based global multicast addresses. | 8 | 4 | 4 | 16 | 8 | 16 | 64 | 8 | +--------+----+----+-----+------+----------+------------+--------+ |11111111|flgs|scop| ASN |custID|subnet ID |Interface ID|group ID| +--------+----+----+-----+------+----------+------------+--------+ Figure 4: Host-based global IPv6 Multicast Addresses flgs is set to '0101'. The setting of the scop field follows the definition of RFC 2373. ASN indicates autonomous system number. ASN is assigned to the unique administrative authority. Therefore, the 16-bit ASN is a previously assigned AS, as registered by a network registry and listed in the RWhois database system[RFC 3180]. All zero's ASN MUST be reserved to support site-local multicast addresses. custID means a customer identifier and is managed by ASN authority. Customer site, which doesn't have an independent ASN, is allocated statically by the ASN owner. all zero's custID MUST be reserved to support site-local multicast addresses. Park, Shin, Kim Expires May 2002 [Page 4] INTERNET-DRAFT Host-based IPv6 Multicast Addresses Allocation Nov. 2001 subnet ID is same as the site-local multicast addresses have. interface ID is same as the link-local multicast addresses have. group ID is generated randomly in host. 4. Considerations The current approach to map IPv6 multicast addresses into IEEE 802 MAC addresses takes the low order 32 bits of the IPv6 multicast address and uses it to create a MAC address[RFC 2464]. So, the [RFC 2373] recommend to use the 32-bit group ID. The reason is that group ID's less than or equal to 32 bits will generate unique MAC addresses. Multicast addresses abided by our proposal should be assigned in host so that the group identifier is always in the low order 8 bits as shown in the figure 2 to 4. The prerequisite of our proposal is that 2^32 multicast applications don't need to execute simultaneously in a host. But, we need to verify that the prerequisite is true. This document proposes the second bit of flgs field to indicates a host-based multicast address. on the other hand, [UNIMULTI] proposed by Thaler uses the third bit to indicate unicast-prefix- based multicast addresses. If the second bit of flgs is set to '1', the third bit isn't care. Our proposal is also new method applicable to the zeroconf environment. 5. Security Considerations Using host-based multicast addresses can expose the interface ID globally. So, protection of interface ID is required. That is, the confidentiality service MUST be supported. 6. References [RFC 2373] R. Hinden and S. Deering, "IP Version 6 Addressing Architecture", RFC 2373, July 1998. [RFC 2460] S. Deering and R. Hinden, "Internet Protocol, Version 6 (IPv6) Specification", RFC 2460, December 1998. [RFC 2461] Narten, T., Nordmark, E., Simpson, W., "Neighbor Discovery for IP Version 6 (IPv6)", RFC 2461, December 1998. [RFC 2464] M. Crawford, "Transmission of IPv6 Packets over Ethernet Networks," RFC 2464, December 1998 [RFC 2908] D. Thaler, M. Handley and D. Estrin, "Th Internet Multicast Address Allocation Architecture," RFC 2908, September 2000. Park, Shin, Kim Expires May 2002 [Page 5] INTERNET-DRAFT Host-based IPv6 Multicast Addresses Allocation Nov. 2001 [RFC 2909] Radoslavov, P., Estrin, D., Govindan, R., Handley, M., Kumar, S. and D. Thaler, "The Multicast Address-Set Claim (MASC) Protocol", RFC 2909, September 2000. [RFC 3138] Meyer, D., "Extended Assignments in 233/8", RFC 3138, June 2001. [RFC 3180] Meyer, D. and P. Lothberg, "GLOP Addressing in 233/8", RFC 3180, September 2001. [AAP WORK] Handley, M. and S. Hanna, "Multicast Address Allocation Protocol (AAP)", Work in Progress. [ADDRARCH] R. Hinden and S. Deering, "IP Version 6 Addressing Architecture", Work In Progress, July 2001. [UNIMULTI] B. Haberman and D. Thaler, "Unicast-Prefix-based IPv6 Multicast Addresses," Work In Progress, December 2001. Authors Addresses Jung-Soo Park ETRI PEC 161 Kajong-Dong, Yusong-Gu, Taejon 305-600, Korea Tel : +82 42 860 6514 Fax : +82 42 861 5404 E-mail : jspark@pec.etri.re.kr Myung-Ki Shin ETRI PEC 161 Kajong-Dong, Yusong-Gu, Taejon 305-600, Korea Tel : +82 42 860 4847 Fax : +82 42 861 5404 E-mail : mkshin@pec.etri.re.kr Yong-Jin Kim ETRI PEC 161 Kajong-Dong, Yusong-Gu, Taejon 305-600, Korea Tel : +82 42 860 6564 Fax : +82 42 861 5404 E-mail : yjkim@pec.etri.re.kr Park, Shin, Kim Expires May 2002 [Page 6]