Brocade Communications Systems IPMC5000PEF manual Source-specific multicast

Source-specific multicast

TABLE 25 Output of show ip igmp settings (Continued)

This field	Displays
Last Member Query	The Last Member Query Interval is the Max Response Time used to calculate the Max
Interval	Resp Code inserted into Group-Specific Queries sent in response to Leave Group
	messages. It is also the Max Response Time used in calculating the Max Resp Code for
	Group-and-Source-Specific Query messages. Default: 10 (1 second)
Last Member Query	The Last Member Query Count is the number of Group-Specific Queries sent before the
Count	router assumes there are no local members. The Last Member Query Count is also the
	number of Group-and-Source-Specific Queries sent before the router assumes there are
	no listeners for a particular source. Default: the Robustness Variable.
Older Host Present	The Older Host Present Interval is the time-out for transitioning a group back to IGMPv3
Timer	mode when an older version report is sent for that group. When an older version report is
	received, routers set their Older Host Present Timer to Older Host Present Interval.
	This value must be ((the Robustness Variable) times (the Query Interval)) plus (one
	Query Response Interval).
Maximum Group	This value indicates the maximum number of group address that can be accepted by the
Address	router.

Source-specific multicast

Using the Any-Source Multicast (ASM) service model, sources and receivers register with a multicast address. The protocol uses regular messages to maintain a correctly configured broadcast network where all sources can send data to all receivers and all receivers get broadcasts from all sources.

With Source-specific multicast (SSM), the "channel" concept is introduced where a "channel" consists of a single source and multiple receivers who specifically register to get broadcasts from that source. Consequently, receivers are not burdened with receiving data they have no interest in, and network bandwidth requirements are reduced because the broadcast need only go to a sub-set of users. The address range 232/8 has been assigned by the Internet Assigned Numbers Authority (IANA) for use with SSM.

IGMP V3 and source specific multicast protocols

When IGMP V3 and PIM Sparse (PIM-SM) is enabled, the source specific multicast service (SSM) can be configured. SSM simplifies PIM-SM by eliminating the RP and all protocols related to the RP. IGMPv3 and PIM-SM must be enabled on any ports that you want SSM to operate.

Configuring PIM SSM group range

PIM Source Specific Multicast (SSM) is a subset of the PIM SM protocol. In PIM SSM mode, the shortest path tree (SPT) is created at the source. The SPT is created between the receiver and source, but the SPT is built without the help of the RP. The router closest to the interested receiver host is notified of the unicast IP address of the source for the multicast traffic. PIM SSM goes directly to the source-based distribution tree without the need of the RP connection. PIM SSM is different from PIM SM because it forms its own SPT, without forming a shared tree. The multicast address group range is 232.0.0.0/8.

158	FastIron Ethernet Switch IP Multicast Configuration Guide
	53-1003085-02