User Guide

OmniAccess SafeGuard OS Administration Guide
164
Chapter 5: Setting Up SafeGuard Switches
Configuring IGMP Snooping
Internet Group Management Protocol (IGMP) is a multicast group membership
discovery protocol. In subnets where IGMP is configured, a host that wants to be a
multicast data receiver joins the group by sending a message to a multicast router on a
local interface. There are three versions of IGMP: IGMPv1, IGMPv2, and IGMPv3. All
three versions are supported by SafeGuard OS.
Even though multicast routing is more efficient than unicast routing, if the data receivers
are sparsely distributed, it can still be a waste of network resources. A more intelligent
method of forwarding multicast packets in a broadcast domain is called IGMP Snooping.
IGMP Snooping is a multicast traffic pruning technique on a LAN or VLAN.
The IGMP Snooping configuration tells the SafeGuard Switch which switch ports are
members of IGMP groups. By snooping IGMP registers information as it passes through
the switch, SafeGuard can determine which hosts are to receive packets with a specific
multicast address.
The following sections describe commands to configure IGMP Snooping:
■ Configuring Global IGMP Snooping
■ Configuring IGMP Snooping on a VLAN
■ Optional IGMP Snooping Configuration
■ Displaying IGMP Snooping Information
Configuring Global IGMP Snooping
IGMP Snooping is disabled by default. The only required configuration step is to enable
the feature. All other global IGMP Snooping configuration is optional. To enable IGMP
Snooping globally on the SafeGuard Switch, use the Igmpsnooping command in Global
Configuration mode. Use the no version of the command to disable IGMP Snooping.
Igmpsnooping
no Igmpsnooping
The commands have no parameters or variables.
The following example enables IPMP Snooping on the SafeGuard Switch:
(SafeGuardOS) #configure terminal
(SafeGuardOS) (config) #Igmpsnooping
(SafeGuardOS) (config) #exit
(SafeGuardOS) #
To verify the configuration, use the Privileged Exec show igmpsnooping command. This
command is described further in Showing the IGMP Snooping Configuration on page 172.