Users Guide

Table Of Contents
Version 2 leave group message
Version 3 provides support for source filtering. The system reports interest in receiving packets only from specific source
addresses, or from all the sources except some specific source addresses, sent to a particular multicast address.
Standards compliance
OS10 complies to the RFCs 1112, 2236, and 3376 for IGMP versions 1, 2, and 3, respectively.
OS10 uses version 3 as the default IGMP version. Version 3 is backwards compatible with versions 1 and 2.
Important notes
OS10 systems cannot serve as an IGMP host or an IGMP version 1 querier.
OS10 automatically enables IGMP on interfaces where you enable PIM sparse mode.
Supported IGMP versions
IGMP has three versions. Version 3 obsoletes and is backwards-compatible with version 2; version 2 obsoletes version 1.
OS10 supports the following IGMP versions:
RouterIGMP versions 2 and 3. The default is version 3.
HostIGMP versions 1, 2, and 3.
In IGMP version 2, the host expresses interest in a particular group membership (*, G). In IGMP version 3, the host expresses
interest in a particular group membership, and specifies the source from which it wants the multicast traffic (S, G).
Query interval
The IGMP querier periodically sends a general query to discover which multicast groups are active. A group must have at least
one host to be active. By default, the periodic query messages are sent every 60 seconds. You can configure this value using
the ip igmp query-interval command.
To configure a query interval:
OS10# configure terminal
OS10# interface vlan120
OS10(conf-if-vl-120)# ip igmp query-interval 60
Last member query interval
When the IGMP querier receives a leave message, it sends a group-specific query message to ensure if any other host in the
network is interested in the multicast flow. By default, the group-specific query messages are sent every 1000 milliseconds. You
can configure this value using the ip igmp last-member-query-interval command.
To configure last member query interval:
OS10# configure terminal
OS10# interface vlan120
OS10(conf-if-vl-120)# ip igmp last-member-query-interval 200
Maximum response time
The maximum response time is the amount of time that the querier waits for a response to a query before taking action.
1030
Multicast