Network Working Group Chen Wumao Internet-Draft Huawei July 30, 2005 Expires: January 30, 2006 Extend IGMPv3 To Support Router Annoucing Information For Host Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. 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. This Internet-Draft will expire on January 2006. Copyright Notice Copyright (C) The Internet Society (2005). Abstract IGMP is used by IPv4 system to report their multicast group memberships to multicast routers. This document adds support for router annoucing information, that is, the ability for a multicast router to annouce information about a group to host. For example, some hosts may send reports to join a group that do not exist, so the router would send some message to inform the hosts. Chen Wumao Expires January 30,2006 [Page 1] INTERNET-DRAFT Extend IGMPv3 For Router Annoucing July 2005 1. Requirements notation 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 [RFC2119]. 2. Introduction The IGMP protocol (IGMPv1, IGMPv2, IGMPv3) is used by IPv4 hosts to report their IP multicast group memberships to its neighboring multicast routers. It specifies how an IPv4 host could join or leave multicast groups, and how an Multicast router use IGMP to learn which groups have members on each of its attached physical or logical networks. It is possible that an multicast router can not forward some groups to some of its attached networks. The reasons may be various. For example, the group is not exist, or the attached network does not have the right to access the group, or the bandwidth needed for the group is too high for the attached network to support. In these scenarios, the multicast router had better sends some messages to inform the reasons. This document specifies a new IGMP message that allows multicast routers annoucing information to hosts. 3. Meassage Formats The IGMP protocol (IGMPv1, IGMPv2, IGMPv3) has specified 5 types of IGMP messages, as following: Type Number (hex) Message Name ----------------- ------------ 0x11 Membership Query 0x12 Version 1 Membership Report 0x16 Version 2 Membership Report 0x22 Version 3 Membership Report 0x17 Version 2 Leave Group This document discribes a new type of message: YY Group Information (to be assigned by IANA) Similar to Membership Query Message, Group Informations are sent by multicast router, and have two sub-types: - General Information, used to annouce informations about the router to its attached network. Such informations are needed to learn by any member of any group. Chen Wumao Expires January 30,2006 [Page 2] INTERNET-DRAFT Extend IGMPv3 For Router Annoucing July 2005 - Group-Specific Information, used to annouce informations about a specific group to an attached network. Such informations are needed to learn by any member of the group. These two messages are differentiated by the Group Address, as described in section 3.3 . In this document Group Information messages are referred to simply as "Information". Informations have the following 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type = YY | Resv | Checksum | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Group Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Length | Notes | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ -+ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3.1. Resv (Reserved) The Resv field is set to zero on transmission, and ignored on reception. 3.2. Checksum The Checksum field is the 16-bit one's complement of the one's complement sum of the whole IGMP message (the entire IP payload). For computing the checksum, the Checksum field is set to zero. When receiving packets, the checksum MUST be verified before processing a packet. [RFC-1071] 3.3. Group Address The Group Address field is set to all zero when sending a General Information, and set to the IP multicast address being informing when sending a Group-Specific Information. 3.4. Length The Length field is the length of the Notes field, measured in octets. It MUST NOT be set to zero on transmission. Length with zero value indicates that the message MUST be silently discarded on reception. 3.5. Notes The Notes field is used to pass information, and text based. Chen Wumao Expires January 30,2006 [Page 3] INTERNET-DRAFT Extend IGMPv3 For Router Annoucing July 2005 3.6. Destination IP Addresses General Informations are sent with an IP destination address of 224.0.0.1, the all-systems multicast address. Group-Specific Informations are sent with an IP destination address equal to the multicast address of interest. 4. Requirement for Multicast Routers Only the Querier need to send Informations, the other multicast routers SHOULD keep silent. Routers SHOULD NOT forward Informations. 5. Security Considerations Information message will not change the status of Querier, so a forged Information will not creat any security concerns to multicast routers. A forged Informatin message sent to a group may pass some fake information to the hosts which are members of the group. This cause no protocol problems. 6. IANA Considerations This document introduces a new IGMP messages, this message requires a new IGMP Type value. This document requests IANA to assign a new IGMP Type values to IGMP Protocol: +-----------+-----------------+--------------------------------+ | IGMP Type | Section | Message Name | +-----------+-----------------+--------------------------------+ | YY | Section 3 | Group Information Message | +-----------+-----------------+--------------------------------+ 7. References [RFC-1112] Deering, S., "Host Extensions for IP Multicasting", STD 5, RFC 1112, August 1989. [RFC-2113] Katz, D., "IP Router Alert Option," RFC 2113, February, 1997. [RFC-2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC-2236] Fenner, W., "Internet Group Management Protocol, Version 2", RFC 2236, November 1997. [RFC-3376] Cain, B., Deering, S., Fenner, B., Kouvelas, I., and Thyagarajan, A., "Internet Group Management Protocol, Version 3," RFC3376, October 2002 Chen Wumao Expires January 30,2006 [Page 4] INTERNET-DRAFT Extend IGMPv3 For Router Annoucing July 2005 Author's Address Chen Wumao Huawei Industrial Base Bantian Longgang Shenzhen 518129 P.R.C EMail: Chenwm@huawei.com Intellectual Property Statement The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Copyright Statement Copyright (C) The Internet Society (2005). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. Disclaimer of Validity This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM 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. Chen Wumao Expires January 30,2006 [Page 5]