Allied Telesis AT-WA7500 - Manual (Page 120)

5 - Configuring the Spanning Tree
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If you enable IGMP on the root access point, the root access point uses a
Class D IP multicast address to send IP hello messages through IP routers
to access points on other subnets. If you enable IGMP on remote IP
subnets, intermediate IP routers will forward the IP hello messages to
those subnets. Normally, you should enable IGMP and configure the IP
multicast address in at least one access point on each remote IP subnet.
(Some routers can provide proxy IGMP services for IP hosts.)
To create a multicast IP tunnel
1. Make sure that end devices that will roam between the root IP subnet
and the remote IP subnet have IP addresses from the root IP subnet
and their default router is set the same as the root access point. There
are no address restrictions for non-IP end devices.
2. Make sure that your routers are configured to pass multicast frames.
3. Make sure that the root access point and the access point at the
endpoint of the IP tunnel have the same LAN ID.
4. On the root access point, set the Mode parameter to Originate if
Root. For help configuring a root access point, see About the
Primary LAN and the Root Access Point on page 109.
5. On the access point at the endpoint of the IP tunnel, set the Mode
parameter to Listen.
6. On the root access point, select IP Tunnels then IP Addresses. Enter
the multicast address 224.0.1.65.
7. On the access point at the end of the IP tunnel, check the Enable
IGMP box.
8. Select Submit Changes to save your changes. To activate your
changes, select Save/Discard Changes from the menu bar then Save
Changes and Reboot. For help, see Saving Configuration Changes
on page 41.