In Layer-2 switches, multicast IP traffic is handled in the same manner as broadcast traffic and forwards frames received on one interface to all other interfaces. This creates excessive traffic on the network, and affects network performance. The Internet Group Management Protocol (IGMP) Snooping allows switches to monitor network traffic, and determine hosts to receive multicast traffic. Thus, at a time only an host’s membership report is relayed from a group instead of a report from each host in the group.

A Provider Bridge (PB) network is a virtual bridge Local Area Network (LAN) that comprises of Service provider bridges (SVLAN and PB) and attached LANs controlled under a single service provider administration. Provider bridges interconnect the MACs of the IEEE 802 LANs separately. This combined provider bridged network relay frames to all the connected LANs that provide customer interfaces for each service instance.

The existing IGMP Snooping extended to support in the Provider Bridged (PB) network. The PB connects customer LANs using the switched provider network consisting of SVLAN bridges and provider edge bridges. Each customer LAN is connected to a separate service VLAN inside the provider network. Current release supports the IGMPv1/IGMPv2/IGMPv3.

The following are supported:

This feature enables a Provider bridging network service provider to conserve bandwidth by efficiently switching the multicast packets.

IGMP snooping is available over a number of network underlays. In this chapter, it is assumed that Provider Bridge support is configured.