draft-ietf-ssm-overview-01.txt   draft-ietf-ssm-overview-02.txt 
INTERNET-DRAFT Supratik Bhattacharyya INTERNET-DRAFT Supratik Bhattacharyya
Expires 18 February 2002 Christophe Diot Expires 04 June 2002 Christophe Diot
Sprint ATL Sprint ATL
Leonard Giuliano Leonard Giuliano
Juniper Networks Juniper Networks
Rob Rockell Rob Rockell
Sprint E|Solutions Sprint E|Solutions
John Meylor John Meylor
Cisco Systems Cisco Systems
David Meyer David Meyer
Sprint E|Solutions Sprint E|Solutions
Greg Shepherd Greg Shepherd
Juniper Networks Juniper Networks
Brian Haberman Brian Haberman
Nortel Networks No Affiliation
18 August 2001 4 December 2001
An Overview of Source-Specific Multicast(SSM) Deployment An Overview of Source-Specific Multicast(SSM) Deployment
<draft-ietf-ssm-overview-01.txt> <draft-ietf-ssm-overview-02.txt>
Status of this Memo Status of this Memo
This document is an Internet-Draft and is in full conformance with This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026. all provisions of Section 10 of RFC2026.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet- other groups may also distribute working documents as Internet-
Drafts. Drafts.
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End-hosts may join and leave the group any time, and there is no End-hosts may join and leave the group any time, and there is no
restriction on their location or number. Moreover, any end-host may restriction on their location or number. Moreover, any end-host may
transmit to a host group, even if it is not a member of that group. transmit to a host group, even if it is not a member of that group.
Source-Specific Multicast (SSM) : This is the multicast service model Source-Specific Multicast (SSM) : This is the multicast service model
defined in [SSM-ARCH]. An IP datagram is transmitted by a source S to defined in [SSM-ARCH]. An IP datagram is transmitted by a source S to
an SSM destination address G, and receivers can receive this datagram an SSM destination address G, and receivers can receive this datagram
by subscribing to channel (S,G). SSM is derived from EXPRESS [EXPRESS] by subscribing to channel (S,G). SSM is derived from EXPRESS [EXPRESS]
and supports one-to-many multicast.The address range 232/8 has been and supports one-to-many multicast.The address range 232/8 has been
assigned by IANA [IANA-ALLOC] for SSM service in IPv4. For IPv6, the assigned by IANA [IANA-ALLOC] for SSM service in IPv4. For IPv6, the
range FF3x::/12 is defined for SSM services [SSM-IPV6]. range FF3x::/96 is defined for SSM services [SSM-IPv6].
Source-Filtered Multicast (SFM) : This is a variant of the multicast Source-Filtered Multicast (SFM) : This is a variant of the multicast
service model defined in RFC 1112. A source transmits IP datagrams to service model defined in RFC 1112. A source transmits IP datagrams to
a host group address in the range of 224.0.0.0 to 239.255.255.255. a host group address in the range of 224.0.0.0 to 239.255.255.255.
However, each "upper layer protocol module" can now request data sent However, each "upper layer protocol module" can now request data sent
to a host group G by only a specific set of sources, or can request to a host group G by only a specific set of sources, or can request
data sent to host group G from all BUT a specific set of sources. data sent to host group G from all BUT a specific set of sources.
Such support for source filtering is provided by version 3 of the Such support for source filtering is provided by version 3 of the
Internet Group Management Protocol (or IGMPv3) [IGMPv3] for IPv4, and Internet Group Management Protocol (or IGMPv3) [IGMPv3] for IPv4, and
version 2 of the Multicast Listener Discovery (or MLD) protocol for version 2 of the Multicast Listener Discovery (or MLD) protocol for
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5.1 Address Allocation 5.1 Address Allocation
For IPv4, the address range of 232/8 has been assigned by IANA for For IPv4, the address range of 232/8 has been assigned by IANA for
SSM. To ensure global SSM functionality in 232/8, including in SSM. To ensure global SSM functionality in 232/8, including in
networks where routers run non-SFM-capable protocols, operational networks where routers run non-SFM-capable protocols, operational
policies are being proposed [SSM-BCP] which prevent data sent to policies are being proposed [SSM-BCP] which prevent data sent to
232/8 from being delivered to parts of the network that do not have 232/8 from being delivered to parts of the network that do not have
channel subscribers. channel subscribers.
Note that IGMPv3/MLDv2 does not limit (S,G) joins to only the 232/8 Note that IGMPv3/MLDv2 does not limit (S,G) joins to only the 232/8
range. However, SSM service, as defined in [SSM-ARCH], is available range. However, SSM service, as defined in [SSM-ARCH], is guaranteed
only in this address range for IPv4. only in this address range for IPv4.
In case of IPv6, [HABE1] has defined an extension to the addressing In case of IPv6, [HABE1] has defined an extension to the addressing
architecture to allow for unicast prefix-based multicast addresses. architecture to allow for unicast prefix-based multicast addresses.
In this case, bytes 0-3 (starting from the least significant byte) of In this case, bytes 0-3 (starting from the least significant byte) of
the IP address is used to specify a multicast group id, bytes 4-11 is the IP address is used to specify a multicast group id, bytes 4-11 is
be used to specify a unicast address prefix (of up to 64 bits) that be used to specify a unicast address prefix (of up to 64 bits) that
owns this multicast group id, and byte 12 is used to specify the owns this multicast group id, and byte 12 is used to specify the
length of the prefix. A source-specific multicast address can be length of the prefix. A source-specific multicast address can be
specified by setting both the prefix length field and the prefix specified by setting both the prefix length field and the prefix
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{supratik,cdiot}@sprintlabs.com {supratik,cdiot}@sprintlabs.com
http://www.sprintlabs.com http://www.sprintlabs.com
Leonard Giuliano Leonard Giuliano
Greg Shepherd Greg Shepherd
Juniper Networks, Inc. Juniper Networks, Inc.
1194 North Mathilda Avenue 1194 North Mathilda Avenue
Sunnyvale, CA 94089 USA Sunnyvale, CA 94089 USA
{lenny,shep}@juniper.net {lenny,shep}@juniper.net
Robert Rockell Robert Rockell
David Mayer David Meyer
Sprint E|Solutions Sprint E|Solutions
Reston Virginia USA Reston Virginia USA
{rrockell,dmm}@sprint.net {rrockell,dmm}@sprint.net
John Meylor John Meylor
Cisco Systems Cisco Systems
San Jose CA USA San Jose CA USA
{jmeylor@cisco.com} jmeylor@cisco.com
Brian Haberman Brian Haberman
Nortel Networks No Affiliation
haberman@nortelnetworks.com haberman@innovationslab.net
 End of changes. 

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