Brocade Communications Systems IPMC5000PEF Manuel D’Utilisation

Output of show ip igmp settings (Continued)

Last Member Query
Interval

The Last Member Query Interval is the Max Response Time used to calculate the Max
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
Count

The Last Member Query Count is the number of Group-Specific Queries sent before the
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
Timer

The Older Host Present Interval is the time-out for transitioning a group back to IGMPv3
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
Address

This value indicates the maximum number of group address that can be accepted by the
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.

Source-specific multicast