Configuration Guide User guide

FastIron Configuration Guide 1469
53-1002494-02
IGMP snooping configuration
Setting the maximum number of IGMP group addresses
When IGMP snooping is enabled, by default, FastIron X Series devices support up to 4096 of IGMP
group addresses, and the configurable range is from 256 through 8192. The configured number is
the upper limit of an expandable database. Client memberships exceeding the group limit are not
processed. Enter the system-max igmp-max-group-addr command to define the maximum number
of IGMP group addresses.
Brocade(config)# system-max igmp-max-group-addr 1600
Syntax: [no] system-max igmp-max-group-addr <num>
The <num> variable is a value ranging from 256 through 8192 and the default is 4096.
Enabling IGMP snooping globally on the device
When you globally enable IGMP snooping, you can specify IGMP V2 or IGMP V3. The ip multicast
version number command enables IGMP V3.
Brocade(config)# ip multicast version 3
Syntax: [no] ip multicast version 2 | 3
If you do not specify a version number, IGMP V2 is assumed.
Configuration notes for Layer 3 devices
• If Layer 3 multicast routing is enabled on your system, do not attempt to enable Layer 2 IGMP
snooping. Layer 2 IGMP snooping is automatically enabled with Layer 3 multicast routing.
• If the “route-only” feature is enabled on the Layer 3 Switch, then IP multicast traffic reduction
will not be supported.
• IGMP snooping is not supported on the default VLAN of Layer 3 Switches.
Configuring the IGMP mode
You can configure active or passive IGMP modes on the Brocade device. The default mode is
passive. If you specify an IGMP mode for a VLAN, it overrides the global setting.
• Active - When active IGMP mode is enabled, a Brocade device actively sends out IGMP queries
to identify multicast groups on the network, and makes entries in the IGMP table based on the
group membership reports it receives.
NOTE
Routers in the network generally handle this operation. Use the active IGMP mode only when
the device is in a stand-alone Layer 2 Switched network with no external IP multicast router
attachments. In this case, enable the active IGMP mode on only one of the devices and leave
the other devices configured for passive IGMP mode.
• Passive - When passive IGMP mode is enabled, it forwards reports to the router ports which
receive queries. IGMP snooping in the passive mode does not send queries. However, it
forwards queries to the entire VLAN.