CANOGA PERKINS CanogaOS Configuration Guide - Manual (Page 168)

CanogaOS Configuration Guide
Proprietary & Confidential Canoga Perkins Metro Ethernet Switches Page 168 of 350
22 Configuring IGMP Snooping
22.1 IGMP Snooping Overview
Layer 2 switches can use IGMP snooping to constrain the flooding of multicast traffic by
dynamically configuring Layer 2 interfaces so that multicast traffic is forwarded only to those
interfaces associated with IP multicast devices. As the name implies, IGMP snooping requires
the LAN switch to snoop on the IGMP transmissions between the host and the router and to keep
track of multicast groups and member ports. When the switch receives an IGMP report from a
host for a particular multicast group, the switch adds the host port number to the forwarding table
entry; when it receives an IGMP Leave Group message from a host, it removes the host port
from the table entry. It also deletes entries periodically if it does not receive IGMP membership
reports from the multicast clients. The multicast router sends out periodic general queries to all
VLANs. All hosts interested in this multicast traffic send join
requests and are added to the forwarding table entry. The switch forwards only one join request
per IP multicast group to the multicast router. It creates one entry per VLAN in the Layer 2
forwarding table for each MAC group from which it receives an IGMP join request.
Layer 2 multicast groups learned through IGMP snooping are dynamic. However, you can
statically configure MAC multicast groups by using the ip igmp snooping vlan static global
configuration command. If you specify group membership for a multicast group address
statically, your setting supersedes any automatic manipulation by IGMP snooping. Multicast
group membership lists can consist of both user-defined and IGMP snooping-learned settings.
22.2 Configuring IGMP Snooping
22.2.1 Enable IGMP Snooping globally or per vlan
IGMP Snooping can be enabled globally or per vlan. If IGMP Snooping is disabled globally, it
can’t be active on any vlan even it’s enabled on the vlan. If IGMP snooping is enabled globally,
it can be disabled on a vlan. On the other hand, the global configuration can overwrite the per
vlan configuration. By default, IGMP snooping is enabled globally and per vlan.
DUT>enable Enter Privilege Exec mode
DUT#configure terminal Enter Configuration mode
DUT(config)# ip igmp snooping Enable igmp snooping globally
DUT(config)#ip igmp snooping vlan 1 Enable igmp snooping on vlan 1