Technical information

Cuda 12000 IP Access Switch CudaView Administration Guide
About IP Multicast 461
■ IGMP Host Role — The Cuda 12000 IP Access Switch, through the IP
interface thus configured, receives the queries and replies to the querier
with information on each multicast group that needs to receive traffic.
IGMP Proxy
The Cuda 12000 IP Access Switch uses IGMP Proxy to inform a multicast
router about members of multicast groups to which the router must forward
multicast traffic. These members are directly connected to the Cuda 12000
IP Access Switch on one or more interfaces, but are not directly connected to
the multicast router.
Example
For example, in Figure 17-1, each Cuda 12000 IP interface except the one
connected to the remote multicast router is configured to perform the IGMP
querier role. The Cuda 12000 sends out IGMP queries on each interface on
which it performs the querier role. Each IGMP host that receives these
queries replies to the Cuda 12000 with IGMP reports for each multicast
group to which the host belongs. The reports tell the Cuda 12000 about the
multicast groups to which group members PC4, PC3, PC2, and PC1 belong.
To transmit multicast traffic to PC4, PC3, PC2 and PC1, the Cuda 12000
informs the remote multicast router that these multicast group members are
requesting to receive traffic for the groups to which they belong.
If IGMP proxy is enabled on the Cuda 12000, the Cuda 12000 joins these
multicast groups for the Ethernet interface that connects the Cuda to the
remote multicast router (this interface is called the proxy interface). When
the remote multicast router sends an IGMP query to the Cuda 12000, the
Cuda 12000 replies with IGMP reports on behalf of these multicast groups.
The remote multicast router can then route multicast traffic destined for
these groups onto the Ethernet that connects it to the Cuda 12000, and the
Cuda 12000, in turn, can route the multicast traffic to the appropriate
destinations.
For example, in the figure, if the remote multicast router receives a multicast
packet addressed to 224.17.1.5, the router forwards the packet to the Cuda
12000 across their common Ethernet connection. The Cuda 12000 then
receives the packet and forwards it to interface 1/2/1 and 1/5/3. PC3 and
PC2 receive the multicast packet.