Routing
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5
Multicast Routing
Multicasting is used to support real-time applications such as videoconferencing or
streaming audio. A multicast server does not have to establish a separate
connection with each client. It merely broadcasts its service to the network, and any
hosts that want to receive the multicast register with their local multicast router.
Although this approach reduces the network overhead required by a multicast
server, the broadcast traffic must be carefully pruned at every multicast network
device it passes through to ensure that traffic is only passed on to the hosts that
have subscribed to the service.
This device uses IGMP (Internet Group Management Protocol) Snooping to monitor
IGMP service requests passing between multicast clients and servers, and
dynamically configure the ports that need to forward multicast traffic.
Figure 5-48. Multicast Route (Router mode)
IGMP Snooping — The wireless AP/Router can passively snoop on IGMP Query
and Report packets transferred between IP multicast routers and IP multicast host
groups to identify the IP multicast group members. It simply monitors the IGMP
packets passing through it, picks out the group registration information, and
configures the multicast filters accordingly.
• Enable – Enables IGMP snooping on the wireless AP/Router.
IGMP Proxy — Collects and sends multicast group membership information onto
the upstream interface based on IGMP messages monitored on downstream
interfaces, and forwards multicast traffic based on that information.
• IGMP Proxy – Enables IGMP proxy on the wireless AP/Router.
• Quick Leave – The wireless AP/Router can immediately delete a member port of
a multicast service if a leave packet is received at that port.
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