Allied Telesis AT-WL2411 - Manual (Page 82)

Configuring the Spanning Tree
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By default, wireless traffic is not bridged to a remote IP subnet. Any
access point on a remote subnet that can receive IP hello messages can
establish an IP tunnel; therefore, multiple IP tunnels can exist between
the root access point and a single remote IP subnet.
If bridging is disabled, all traffic for end devices is forwarded between
access points using data link encapsulation, which means that the MAC
source/destination addresses correspond to the access points
originating/receiving the traffic for the end devices. By using data link
encapsulation, you prevent network monitoring tools and other
network components from detecting end device MAC/IP addresses that
belong to the remote subnet. It is strongly recommended that you use
the default setting when you are using IP tunnels to provide mobility of
other routable protocols, such as IPX. In some network installations,
detecting these addresses may generate alarms or cause switches to
behave erroneously. There is no additional forwarding overhead for
disabling bridging in this situation.
If you enable bridging on a remote subnet, a single access point
functions as the designated bridge for the secondary LAN. In this case,
only the designated bridge can establish an IP tunnel. Any other access
point on the remote subnet must attach to the network through the
designated bridge. End device MAC/IP addresses are fully visible on the
remote subnet. If you are using IP tunnels to provide mobility for IP and
other non-routable protocols, you can enable bridging on remote IP
subnets, because IP has built-in safeguards and filters for protecting the
operation of IP routers and other network components.
Also, you should enable bridging if the root access point and the
gateway that supports the NNL devices are on different IP subnets. You
may also need to enable bridging if your wireless end devices use
terminal emulation running the NNL protocol or if you use wireless end
devices that are running both IP and NNL.