Allied Telesis AT-WL2411 - Manual (Page 96)

Configuring the Spanning Tree
96
Frame
Forwarding
Any data packet sent through an IP tunnel is addressed to the unicast IP
address of the access point at the other end of the tunnel. An access
point at the remote end of the tunnel learns the unicast IP address of the
root access point by listening to IP hello packets. The root access point
learns the unicast IP address of a remote access point when the access
point attaches to the network.
Usually, ARP requests (which are multicast packets) that originate on the
home IP subnet are forwarded outbound to all devices on the network,
including through IP tunnels to remote IP subnets. If you configure the
access point as an ARP server, ARP packets are only sent through the IP
tunnel to the destination end device.
Unicast frames are only forwarded outbound through an IP tunnel if the
destination address identifies an end device that has roamed to a
remote IP subnet. Usually, wireless traffic is not bridged to remote IP
subnets and traffic from a remote IP subnet is never forwarded inbound
through an IP tunnel.
MAC frames originating on the home IP subnet are encapsulated in the
root access point, forwarded through the IP network, unencapsulated by
the access point at the remote end of the IP tunnel, and forwarded to the
appropriate access point (if necessary) for delivery to the destination
end device. For inbound frames, the same process is used in reverse
between the access point at the remote end of an IP tunnel and the root
access point.
Certain frame types are never forwarded through tunnels. Frame types
that are never forwarded include IP frames used for coordinating routers
and MAC frames used for coordinating bridges. Frame types that are
never forwarded include:
❑ 802.1D bridge frames
❑ Proprietary VLAN switch frames
❑ IP frames with a broadcast or multicast Ethernet address
❑ IP frames with the following router protocol types and decimal
values:
— DGP (86) (Dissimilar Gateway Protocol)
— EGP (8) (Exterior Gateway Protocol)
— IDPR (35) (Inter-Domain Policy Routing Protocol)
— IDRP (45) (Inter-Domain Routing Protocol)
— IGP (9) (Interior Gateway Protocol)