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Allied Telesis AT-8000S Switch
Web Browser Interface User’s Guide
Section 9. Configuring Multicast Forwarding
Multicast forwarding allows a single packet to be forwarded to multiple destinations. Layer 2 Multicast service is
based on a Layer 2 switch receiving a single packet addressed to a specific multicast address. Multicast
forwarding creates copies of the packet, and transmits the packets to the relevant ports. The Internet Group
Management Protocol (IGMP) allows hosts to notify their local switch or router that they want to receive
transmissions assigned to a specific multicast group.
This section describes the configuration of IGMP Snooping. When IGMP Snooping is enabled globally, all IGMP
packets are forwarded to the CPU. The CPU analyzes the incoming packets and determines:
•Which ports have Multicast routers generating IGMP queries
•Which ports want to join which Multicast groups
•Which routing protocols are forwarding packets and Multicast traffic.
Ports requesting to join a specific Multicast group issue an IGMP report, specifying that Multicast group is
accepting members. This results in the creation of the Multicast filtering database.
Multicast forwarding enables transmitting packets from either a specific multicast group to a source, or from a non-
specific source to a Multicast group.
This section contains the following topics:
•Configuring IGMP Snooping
•Defining Multicast Bridging Groups
•Defining Multicast Forward All Settings