Dell PowerConnect 7048P User Manual - Page 705
What Is IGMP Snooping?, IGMP Snooping Querier
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What Is IGMP Snooping? IGMP Snooping is a layer 2 feature that allows the switch to dynamically add or remove ports from IP multicast groups by listening to IGMP join and leave requests. By "snooping" the IGMP packets transmitted between hosts and routers, the IGMP Snooping feature enables the switch to forward IP multicast traffic more intelligently and help conserve bandwidth. Based on the IGMP query and report messages, the switch forwards traffic only to the ports that request the multicast traffic. This prevents the switch from broadcasting the traffic to all ports and possibly affecting network performance. 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. IGMP Snooping Querier When PIM and IGMP are enabled in a network with IP multicast routing, the IP multicast router acts as the IGMP querier. However, if the IP-multicast traffic in a VLAN needs to be Layer 2 switched only, an IP-multicast router is not required. The IGMP Snooping Querier can perform the IGMP snooping functions on the VLAN. NOTE: Without an IP-multicast router on a VLAN, you must configure another switch as the IGMP querier so that it can send queries. When the IGMP snooping querier is enabled, the IGMP snooping querier sends out periodic IGMP queries that trigger IGMP report messages from the switch that wants to receive IP multicast traffic. The IGMP snooping feature listens to these IGMP reports to establish appropriate forwarding. What Is MLD Snooping? In IPv4, Layer 2 switches can use IGMP snooping to limit the flooding of multicast traffic by dynamically configuring L2 interfaces so that multicast traffic is forwarded to only those interfaces associated with an IP multicast address. In IPv6, MLD snooping performs a similar function. With MLD snooping, IPv6 multicast data is selectively forwarded to a list of ports that want to receive the data instead of being flooded to all ports in a VLAN. This list is constructed by snooping IPv6 multicast control packets. Configuring L2 Multicast Features 705
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1,189
-
1,190
-
1,191
-
1,192
-
1,193
-
1,194
-
1,195
-
1,196
-
1,197
-
1,198
-
1,199
-
1,200
-
1,201
-
1,202
-
1,203
-
1,204
-
1,205
-
1,206
-
1,207
-
1,208
-
1,209
-
1,210
-
1,211
-
1,212
-
1,213
-
1,214
-
1,215
-
1,216
-
1,217
-
1,218
-
1,219
-
1,220
-
1,221
-
1,222
-
1,223
-
1,224
-
1,225
-
1,226
-
1,227
-
1,228
-
1,229
-
1,230
-
1,231
-
1,232
-
1,233
-
1,234