Download complete user manual (PDF). - Brocade
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IGMP snooping overview 2<br />
connection to a PIM-enabled port, one of the devices must be configured as a querier. If multiple<br />
devices are configured as queriers, after these devices exchange queries, then all except the<br />
winner stop sending queries. The device with the lowest address becomes the querier. Although the<br />
system will work when multiple devices are configured as queriers, <strong>Brocade</strong> recommends that only<br />
one device (preferably the one with the traffic source) is configured as a querier.<br />
The non-queriers always forward multicast data traffic and IGMP messages to router ports which<br />
receive IGMP queries or PIM hellos. <strong>Brocade</strong> recommends that you configure the device with the<br />
data traffic source (server) as a querier. If a server is attached to a non-querier, the non-querier<br />
always forwards traffic to the querier regardless of whether there are any clients on the querier.<br />
NOTE<br />
In a topology of one or more connecting devices, at least one device must be running PIM configured<br />
as active. Otherwise, none of the devices can send out queries, and traffic cannot be forwarded to<br />
clients.<br />
VLAN-specific configuration<br />
IGMP snooping can be enabled on some VLANs or on all VLANs. Each VLAN can be independently<br />
configured to be a querier or non-querier and can be configured for IGMP V2 or IGMP V3. In<br />
general, the ip multicast commands apply globally to all VLANs except those configured with<br />
VLAN-specific multicast commands. The VLAN-specific multicast commands supersede the global<br />
ip multicast commands.<br />
IGMP snooping can be configured for IGMP V2 or IGMP V3 on individual ports of a VLAN. An<br />
interface or router sends the queries and reports that include its IGMP version specified on it. The<br />
version configuration only applies to sending queries. The snooping device recognizes and<br />
processes IGMP V2 and IGMP V3 packets regardless of the version configuration.<br />
To avoid version deadlock, an interface retains its version configuration even when it receives a<br />
report with a lower version.<br />
Tracking and fast leave<br />
<strong>Brocade</strong> devices support fast leave for IGMP V2, and tracking and fast leave for IGMP V3. Fast<br />
leave stops the traffic immediately when the port receives a leave message. Tracking traces all<br />
IGMP V3 clients. Refer to “Enabling IGMP V3 membership tracking and fast leave for the VLAN” on<br />
page 39 and “Enabling fast leave for IGMP V2” on page 40.<br />
Support for IGMP snooping and Layer 3 multicast routing<br />
together on the same device<br />
The <strong>Brocade</strong> device supports global Layer 2 IP multicast traffic reduction (IGMP snoopoing) and<br />
Layer 3 multicast routing (PIM-Sparse or PIM-Dense) together on the same device in the full Layer 3<br />
software image, as long as the Layer 2 feature configuration is at the VLAN level.<br />
FastIron Ethernet Switch IP Multicast Configuration Guide 29<br />
53-1002638-02