Igmp Proxy; Example - Allied Telesis AR400 Series How To Configure

IGMP proxy

In very simple tree-design networks, IGMP Proxy is a useful simple alternative to a multicast
routing protocol for multicasting between VLANs.
An IGMP Proxy sends IGMP Membership Report and Leave group messages to an upstream
subnetwork on behalf of downstream devices, and sends Queries downstream. In other
words, an IGMP Proxy effectively ferries IGMP messages from one VLAN to another. The
IGMP Proxy looks like an IGMP Querier to the downstream VLAN, and like a client to the
upstream VLAN. Note that the Proxy can only have one configured upstream VLAN.
IGMP Proxy is available on all Allied Telesis routers and managed layer 3 switches except
AT-9800 and SwitchBlade series. For AT-8948, AT-9900 and x900-48 series switches, it
requires software version 2.8.1 or later.
If you use IGMP Proxy on a switch, multicast data packets are processed by the CPU so are
not forwarded at wirespeed.

Example

IGMP Proxy only works in tree networks, so for this example we convert the network from
a loop into a tree by disabling port 50 on the AT-8948 switch.
Switch 3 is the IGMP Proxy. Switch 1 is upstream of the Proxy. Switch 2 is downstream of the
Proxy on vlan100. Therefore, the multicast server and client 1 are now in different VLANs
and switch 3 sits on the boundary between the two VLANs. This network is shown in the
following figure.
Page 21 | AlliedWare™ OS How To Note: IGMP
Multicast Server
Rapier 24i
Switch 2:
Snooper
port 2
Client 1
AT-8948
port 1
vlan200
port 49
downstream
port 25
vlan100
IGMP proxy > Example
Switch 1:
Querier
upstream
vlan200
port 26
Rapier 24i
port 25
Switch 3:
Proxy
igmp-proxy.eps