3Com 3C16476A User Guide - Page 42

42 CHAPTER 4: CONFIGURING THE SWITCH After all the bridges on the network have determined the configuration of their ports, each bridge only forwards traffic between the Root Port and the ports that are the Designated Bridge Ports for each network segment. All other ports are blocked, which means that they are prevented from forwarding traffic. To use spanning tree, choose enabled from the drop State down menu, fill in the setup parameters, and click Apply. Figure 34 Spanning Tree Screen to receive the multicast service. This procedure is called multicast filtering. The purpose of IP multicast filtering is to optimize a switched network's performance, so multicast packets will only be forwarded to those ports containing multicast group hosts or multicast routers/switches, instead of flooding traffic to all ports in the subnet (VLAN). Choose enable or disable from the IGMP Snooping Mode drop down menu. Figure 35 IGMP Snooping Setup Screen IGMP Snooping This switch uses IGMP (Internet Group Management Protocol) to query for any attached hosts that want to receive a specific multicast service. It identifies the ports containing hosts requesting to join the service and sends data out to those ports only. It then propagates the service request up to any neighboring multicast switch/router to ensure that it will continue IGMP Query Choose enable or disable from the IGMP Query Mode drop down menu. Figure 36 IGMP Query Setup Screen