INTERNET DRAFT JUNHYUK SONG March 2002 SAMSUNG ELECTRONICS. MCI(Multicast Channel Identifier) DNS RR type for the support of SSM(Source Specific Multicast) draft-song-dnsext-mci-ssm-support-00.txt Status of This Memo Distribution of this memo is unlimited. 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 proposes the use of the new DNS RR type MCI (Multicast Channel Identifier), as it is specifying SSM (Source Specific Multicast) multicast channel [SSM] as a DNS Resource Record. It shall allow the advance multicast session advertisement by providing the dynamic mapping between SSM multicast channel and MCI. Song Expires September 2002 [Page 1] Internet Draft 25 March 2002 1. Introduction IP multicast is the efficient way of delivering IP packets from single source to multiple recipients or vice versa. It is especially beneficial for the limited bandwidth network such as Wireless network. However, one of the known challenge for the deployment of widely commercialized IP multicast is the address management. Unlike unicast IP address, Multicast IP addresses are not assigned to each of individual hosts. It rather statically or dynamically assigned to multicast group by service provider, and it often has its own address semantics. In order to expedite the the deployment of commercialized IP multicast service, the method of locating dynamically changed multicast group information may be beneficial. The purpose of this document is to propose the use of MCI (Multicast Channel Identifier) as a DNS RR so as to identify dynamically changed multicast source and SSM destination IP address for the SSM channel. The SSM (Source-Specific Multicast) is defined in [SSM] as below. "A datagram sent with source IP address S and destination IP address G in the SSM range is delivered to each host socket that has specifically requested delivery of datagrams sent by S to G, and only to those sockets." MCI shall provide the efficient way of identifying the SSM multicast group/channel information, that shall enable persistent mapping between multicast channel and dynamically changed Source IP address and SSM destination IP address. 2. Applicability Statement One of the challenge of the wide deployment of the multicast service is the address management. SSM(Source Specific Multicast) is one of the proposed the solutions, the delivery semantics for host specific addressing. IP address in the 232/8 (232.0.0.0 to 232.255.255.255) range are currently designated as source specific multicast (SSM) destination addresses and are reserved for use by source-specific applications and protocols [IANA-ALLOCATION]. The MCI RR defines the multicast channel. The channel is identified by (S,G), G for SSM address and S for source host address [SSM]. MCI (Multicast Channel Identifier) RR provides persistent way to identify the multicast channel information. Song Expires September 2002 [Page 2] Internet Draft 25 March 2002 There are two category of the multicast application that may make use of MCI, One-to-Many and Many-to-Many cases.[QA] One-to-Many case is a single source sending to one or more receivers The example of One-to-Many is Scheduled AV presentation, IP Push Service, File Distribution, White board, and etc. On the other hand, Many-to-Many case is multiple receivers also represent multiple senders. The example of Many-to-Many is multiple user network game, multi-user conference/chat and etc. In both cases, MCI can be beneficial because users can always locate the multicast group/channel by MCI, regardless of the dynamic allocation multicast IP address and source IP allocation. The multicast group subscribed user can access the service, since MCI shall always indicate unique SSM (S,G). Especially wireless mobile case, MS(Mobile Station) are more likely dynamically assigned to new Multicast IP address and source IP address. MS may be scattered over the visited networks, while having video conference. In that case, the potential members of the video conference group subscribe the group to the host of the the group by registering the home IP address or NAI [AM] by outband signaling. And then the host of the group can register MCI, assigned SSM destination IP address, source IP addresses or NAI of the members to DNS server. On scheduled time, the members of the group query the MCI to retrieve the SSM destination IP address, source IP addresses or NAI of other group members, and then send IGMPv3 report message [IGMPv3] to attached multicast router to join the conference call. With respect to session advertisement (Announcing information about the group), there are several approaches available, including WWW and SAP (Session Announcement Protocol) [QA]. However, it is outside the scope of this document. 3. MCI Resource Record MCI name space is resemble to Domain Name Space, except that it is a sequence of one or more labels, made of the Multicast Channel Identifier and domain name. MCI records cause no additional section processing The MCI record has the DNS RR type of "?", hence has the same QTYPE number. Note: MCI RR requires IANA number assignment. The class of MCI RR is defined in the IN class only. TTL should be configured to minimize the time of the RR being cached Song Expires September 2002 [Page 3] Internet Draft 25 March 2002 3.1 MCI RDATA format 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | SSM Destination Multicast IP address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |IP Addr Count | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Source Address [1] | +- -+ | Source Address [2] | +- . -+ . . . . . . +- -+ | Source Address [N] | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | NAI Count | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Network Access Identifier [1] | +- -+ | Network Access Identifier [2] | +- . -+ . . . . . . +- -+ | Network Access Identifier [N] | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ where: SSM Destination Multicast IP address is the IP address in the 232/8 (232.0.0.0 to 232.255.255.255) range. It also follows AS number scheme in RFC 1791 case 1 and RFC 3180(GLOP Addressing in 233/8)[ML], modified as follows: the high octet has the value of 232, identifying SSM scheme. There MUST be only one SSM Destination multicast IP address field. IP Addr Count is one octet long and indicating the number of Source IP addresses. Source address is the four octet long Source Host IP address, it always precede to NAI field. NAI Count is one octet long and indicating the number of NAI. Network Access Identifier is the four octet long Name Access Identifier and it always comes after Source address field. Song Expires September 2002 [Page 4] Internet Draft 25 March 2002 4. Examples Multicast Router that support GLOP addressing [ML] and SSM mechanism shall have the 16 bits AS(Autonomous System) number [ML] while allowed to use the IP addresses in the 232/8 (232.0.0.0 to 232.255.255.255) range [SSM]. If the host attached to the multicast router with AS number 5662 shall allow to use the subnet of 232.22.30.0 as a multicast IP address. The AS number 5662 is written in hexadecimal format as 161E. Separating out the two octets 16 and 1E results in 22 and 30 in decimal format. These values result in a subnet of 232.22.30.0 that would be uniquely reserved for the use of SSM capable AS 5662 domain. Resource Record for SSM MCI for starcraft.xbs.samsung.co.kr with two source IP address and one NAI will be like below: starcraft.xbs.samsung.co.kr 1440 IN MCI 232.22.30.4 165.213.114.7 165.213.114.1 santajun@lycos.co.kr 5. IPv6 support For IPv6, the address prefixes FF3x:: and FF2x:: are proposed for Source- Specific Multicast [SSMIPv6]. It shall be covered by another document 6. IANA Considerations It requires new RR type number from IANA. 7. Acknowledgements Special thanks to Professor of Murali Venkatesh of Syracuse University Song Expires September 2002 [Page 5] Internet Draft 25 March 2002 References [IANA] http://www.iana.org/numbers.html [AM] Bernard Aboba and Mark A. Beadles "The Network Access Identifier". RFC 2486. January 1999. [IGMPv3] B. Cain and S. Deering, I. Kouvelas and A. Thyagarajan. Internet Group Management Protocol, Version 3. Work in Progress. [IANA-ALLOCATION] Internet Assigned Numbers Authority, http://www.isi.edu/in-notes/iana/assignments/multicast-addresses. [ML] Meyer and Lothberg "GLOP Addressing in 233/8" RFC 3180 September 2001 [RFC1797] IANA, "Class A Subnet Experiment", RFC 1797, April 1995. [SSM] Brad Cain, Hugh Holbrook "Source-Specific Multicast for IP" Work in Progress. [SSMIPv6] Haberman, B. and Thaler, D. "Unicast-Prefix-based IPv6 Multicast Addresses." Work in Progress. [QA] Bob Quinn and Kevin Almeroth "IP Multicast Applications: Challenge and Solutions" RFC3170 September 2001 Author's Address Questions about this memo can be directed to the author: JUNHYUK SONG SAMSUNG ELECTRONICS. Packet Technology System Lab. Mobile Development Team Phone: +82-31-279-3639 Email: junhyuk@telecom.samsung.co.kr santajunman@yahoo.com Song Expires September 2002 [Page 6] Internet Draft 25 March 2002 Full Copyright Statement Copyright (C) The Internet Society (2002). 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 implementation 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 ore 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 languages other than English. The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns. This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Song Expires September 2002 [Page 7]