Wireless/Redundant Edge Services xl Module Management and Configuration Guide WS.02.xx and greater

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Introduction
Layer 2 and Layer 3 Roaming Between RPs and Modules
Figure 1-26. Network Requiring Layer 3 Roaming
Note It is important that the difference in subnetwork be reflected in different VLAN
IDs because Layer 3 roaming relies on a changing VLAN ID to detect a Layer
3 roam. In other words, the two modules in Figure 1-26, which are in different
subnetworks, correctly place WLAN A traffic on different VLANs. If both used
the same VLAN ID, the modules would treat roaming between their RPs as
Layer 2 roaming and the roaming would not be seamless.
To implement Layer 3 roaming, Wireless Edge Services xl Modules perform
these functions:
■ Establish a Layer 3 mobility domain—A domain can include up to 12
modules, or peers, each of which can support up to 500 stations. Every
station has a home module (HM) and a current module (CM). The HM is
on the same VLAN as the station, and the station is currently associated
to the CM; the two modules might be the same device.