Allied Telesis AT-WA7500, AT-WA7501 manual About the Access Point Spanning Tree

Chapter 5: Configuring the Spanning Tree

About the Access Point Spanning Tree

AT-WA7500 and AT-WA7501 access points with the same LAN ID arrange themselves into a self-organized network using a spanning tree topology. The spanning tree provides efficient, loop-free forwarding of frames through the network and allows efficient roaming of wireless end devices. It contains at least a primary LAN and a root access point, but it may also contain secondary LANs, designated bridges, and other access points.

This spanning tree contains a root access point on the primary LAN and a designated bridge on the secondary LAN.

Host

Root

Primary LAN (root IP subnet)

Designated bridge

Secondary LAN (remote IP subnet)

Within the spanning tree, access points use IAPP (Inter Access Point Protocol) or secure IAPP to communicate with each other across the Ethernet network, over wireless secondary LANs, and through IP tunnels to remote IP subnets. IAPP also enables fast roaming in an 802.11g, 802.11b or 802.11a network using 802.1x security. Secure IAPP prevents unauthorized access products from joining the spanning tree.

For example, when an end device roams to a new access point, the new access point informs the old access points via the root access point that any traffic for the end device needs to be routed to the new access point. As end devices are added to or removed from the network, access points are automatically updated so they can maintain reliable operation and communication.

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