Netgear GS516TP Software Administration Manual - Page 81

GS516TP Gigabit Smart Switches  To configure Auto-Video: 1. Select Switching > Multicast > Auto-Video Configuration. 2. Globally enable or disable the Auto-Video administrative mode for the switch by selecting Enable or Disable next to the Auto-Video Status radio button. The Auto-Video VLAN field shows the number of auto-configured IGMP snooping VLANs. 3. Click APPLY to send the updated configuration to the switch. Configuration changes take place immediately. IGMP Snooping Internet Group Management Protocol (IGMP) snooping is a feature that allows a switch to forward Multicast traffic intelligently on the switch. Multicast IP traffic is traffic that is destined to a host group. Class D IP addresses identify host groups, which range from 224.0.0.0 to 239.255.255.255. Based on the IGMP query and report messages, the switch forwards traffic only to the ports that request the multicast traffic. This action prevents the switch from broadcasting the traffic to all ports and possibly affecting network performance. A traditional ethernet network can be separated into different network segments to prevent placing too many devices onto the same shared media. Bridges and switches connect these segments. When a packet with a broadcast or Multicast destination address is received, the switch forwards a copy into each of the remaining network segments in accordance with the IEEE MAC Bridge standard. Eventually, the packet is made accessible to all nodes connected to the network. This approach works well for broadcast packets that are intended to be seen or processed by all connected nodes. In the case of multicast packets, however, this approach could lead to less efficient use of network bandwidth, particularly when the packet is intended for only a few nodes. Packets are flooded into network segments where no node has any interest in receiving the packet. While nodes rarely incur any processing overhead to filter packets addressed to unrequested group addresses, they are unable to transmit new packets onto the shared media for the period that the multicast packet is flooded. The problem of wasting bandwidth is even worse when the LAN segment is not shared, for example in full-duplex links. Allowing switches to snoop IGMP packets is a creative effort to solve this problem. The switch uses the information in the IGMP packets as they are being forwarded throughout the network to determine which segments should receive packets directed to the group address. From the IGMP Snooping link, you can access features described in the following sections: • IGMP Snooping Configuration • IGMP Snooping Table • IGMP Snooping VLAN Configuration IGMP Snooping Configuration Use the IGMP Snooping Configuration screen to configure the parameters for IGMP snooping. 81