Brocade TurboIron 24X Series Configuration Guide - Manual (Page 889)

Brocade TurboIron 24X Series Configuration Guide 855
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IGMP V3
• Source-List-Change Record. If the interface wants to add or remove traffic sources from its
membership report, the membership report can have an ALLOW record, which contains a list
of new sources from which the interface wishes to receive traffic. It can also contains a BLOCK
record, which lists current traffic sources from which the interfaces wants to stop receiving
traffic.
In response to membership reports from the interfaces, the router sends a Group-Specific or a
Group-and-Source Specific query to the multicast interfaces. Each query is sent three times with a
one-second interval in between each transmission to ensure the interfaces receive the query. For
example, a router receives a membership report with a Source-List-Change record to block old
sources from an interface. The router sends Group-and-Source Specific Queries to the source and
group (S,G) identified in the record. If none of the interfaces is interested in the (S,G), it is removed
from (S,G) list for that interface on the router.
Each IGMP V3-enabled router maintains a record of the state of each group and each physical port
within a virtual routing interface. This record contains the group, group-timer, filter mode, and
source records information for the group or interface. Source records contain information on the
source address of the packet and source timer. If the source timer expires when the state of the
group or interface is in Include mode, the record is removed.
Default IGMP version
IGMP V3 is available on devices running software release 02.4.00 and later; however, devices are
shipped with IGMP V2 enabled. You must enable IGMP V3 globally or per interface.
Also, you must specify what version of IGMP you want to run on a device globally, on each interface
(physical port or virtual routing interface), and on each physical port within a virtual routing
interface. If you do not specify an IGMP version, IGMP V2 will be used.
Compatibility with IGMP V1 and V2
Different multicast groups, interfaces, and routers can run their own version of IGMP. Their version
of IGMP is reflected in the membership reports that the interfaces send to the router. Routers and
interfaces must be configured to recognized the version of IGMP you want them to process.
An interface or router sends the queries and reports that include its IGMP version specified on it. It
may recognize a query or report that has a different version, but it may not process them. For
example, an interface running IGMP V2 can recognize IGMP V3 packets, but cannot process them.
Also, a router running IGMP V3 can recognize and process IGMP V2 packet, but when that router
sends queries to an IGMP V2 interface, the host on that interface may not recognize the IGMP V3
queries. The interface or router does not automatically downgrade the IGMP version running on
them to avoid version deadlock.
If an interface continuously receives queries from routers that are running versions of IGMP that
are different from what is on the interface, the interface logs warning messages in the syslog every
five minutes. Reports sent by interfaces to routers that contain different versions of IGMP do not
trigger warning messages; however, you can see the versions of the packets using the show ip igmp
traffic command.
The version of IGMP can be specified globally, per interface (physical port or virtual routing
interface), and per physical port within a virtual routing interface. The IGMP version set on a
physical port within a virtual routing interface supersedes the version set on a physical or virtual
routing interface. Likewise, the version on a physical or virtual routing interface supersedes the
version set globally on the device. The sections below present how to set the version of IGMP.