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bind9/doc/draft/draft-song-dnsext-mci-ssm-support-00.txt
Mark Andrews 828f5c0250 new draft
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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]
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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]
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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
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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.
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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
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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
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Full Copyright Statement
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