TP-Link T1600G-28PS Jetstream Smart Switches User Guide - Page 234

Configuring Layer 2 Multicast 1 Layer 2 Multicast Layer 2 Multicast 1.1 Overview In a point-to-multipoint network, packets can be sent in three ways: unicast, broadcast and multicast. With unicast, many copies of the same information will be sent to all the receivers, occupying a large bandwidth. With broadcast, information will be sent to all users in the network no matter they need it or not, wasting network resources and impacting information security. Multicast, however, solves all the problems caused by unicast and broadcast. With multicast, the source only need to send one piece of information, and all and only the users who need the information will receive copies of the information. In a point-to-multipoint network, multicast technology not only transmits data with high efficiency, but also saves a large bandwidth and reduces network load. In practical applications, Internet information provider can provide value-added services such as Online Live, IPTV, Distance Education, Telemedicine, Internet Radio and Real-time Video Conferences more conveniently using multicast. Layer 2 Multicast allows Layer 2 switches to listen for IGMP (Internet Group Management Protocol) packets between IGMP Querier and user hosts to establish multicast forwarding table and to manage and control transmission of packets. Take IGMP Snooping as an example. When IGMP Snooping is disabled on the Layer 2 device, multicast packets will be broadcast in the Layer 2 network; when IGMP Snooping is enabled on the Layer 2 device, multicast data from a known multicast group will be transmitted to the designated receivers instead of being broadcast in the Layer 2 network. User Guide 209