Default Igmp Version; Compatibility With Igmp V1 And V2 - Dell PowerConnect B-RX Configuration Manual

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IGMP v3
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. 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 for BigIron RX Switches; however, these devices are shipped with IGMP
V2-enabled. You must enable IGMP V3 globally or per interface.
Also, you can 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. 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 downgraded version is supported, no the upgraded version.
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.
Globally enabling the IGMP version
To globally identify the IGMP version on a Brocade device, enter the following command.
BigIron RX(config)# ip igmp version 3
Syntax: ip igmp version <version-number>
Enter 1, 2, or 3 for <version-number>. Version 2 is the default version.
588 BigIron RX Series Configuration Guide
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