Intermec MobileLAN access WA21 System Manual page 130

Chapter 5 — Configuring the Spanning Tree
116
Root
Primary LAN
(root IP subnet)
IP router
IP network
Designated
bridge
IP router
Secondary LAN
(remote IP subnet)
Only one IP tunnel can exist between the root access point and an access point (usually
the designated bridge) on a remote IP subnet. The root access point has a one-to-one
relationship with each wireless network. All roaming end devices must have an IP
address from the root IP subnet.
IP tunnels use encapsulation to establish a virtual LAN segment through
IP routers. The virtual LAN segment includes the root IP subnet and
logically extends to include end devices attached to access points on remote
IP subnets. IP tunnels are branches in the spanning tree topology.
Any access point on a secondary LAN that can receive IP hello messages
can be the endpoint of an IP tunnel. Usually, the access point that is the
endpoint of an IP tunnel is also the designated bridge. After an IP tunnel is
formed between the root access point and an access point on a remote IP
subnet, end devices can roam to the remote IP subnet. End devices must
have an IP address from the root IP subnet. However, there are no address
restrictions for non-IP end devices. When end devices roam to the remote
IP subnet, their data is IP tunneled back to the root IP subnet (where it
belongs) and everything works properly.
If you have a DHCP server in your network, it must be on the root IP
subnet. All access points on secondary LANs must have permanent IP
addresses. On the root access point, you must allow IP multicast frames to
pass.
Host
AP2
AP4
AP5
21XXT073.eps
MobileLAN access System Manual