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Configuring PIM PIM-SSM Support
OmniSwitch 6800/6850/9000 Advanced Routing Configuration Guide December 2007 page 7-31
PIM-SSM Support
Protocol-Independent Multicast Source-Specific Multicast (PIM-SSM) is a highly-efficient extension of
PIM. SSM, using an explicit channel subscription model, allows receivers to receive multicast traffic
directly from the source; an RP tree model is not used. In other words, a Shortest Path Tree (SPT) between
the receiver and the source is created without the use of a Rendezvous Point (RP).
By default, PIM software supports Source-Specific Multicast. No additional user configuration is required.
PIM-SSM is automatically enabled and operational as long as PIM is loaded (see page 7-6) and IGMPv3
source-specific joins are received within the SSM address range.
For detailed information on PIM-SSM and Source-Specific Multicast, refer to the IETF Internet Drafts
draft-ietf-pim-sm-v2-new-05.txt and draft-ietf-ssm-arch-04.txt, as well as RFC 3569, “An Overview of
Source-Specific Multicast (SSM).”
Note. For networks using IGMP proxy, be sure that the IGMP proxy version is set to Version 3.
Otherwise, PIM-SSM will not function. For information on configuring the IGMP version, refer to the ip
multicast version command.
Source-Specific Multicast Addresses
The multicast address range from 232.0.0.0 through 232.255.255.255 have been reserved by the Internet
Assigned Numbers Authority (IANA) as Source-Specific Multicast (SSM) destination addresses. The
PIM-Source-Specific Multicast (SSM) mode for the default SSM address range is not enabled automati-
cally and needs to be configured manually to support SSM. Addresses within this range are reserved for
use by source-specific applications and protocols (e.g., PIM-SSM). These addresses cannot be used for
any other functions or protocols. However, you can also map additional multicast address ranges for the
SSM group.
PIM-SSM Specifications
RFCs Supported 3569—An Overview of Source-Specific Multicast (SSM)
Internet Drafts Supported draft-ietf-pim-sm-v2-new-05.txt—Protocol Independent
Multicast – Sparse Mode (PIM-SM)
draft-ietf-ssm-arch-04.txt—An Overview of Source-
Specific Multicast (SSM)
Valid SSM Address Range 232.0.0.0 to 232.255.255.255