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Understanding Roams in Converged Access
Since roams in Cisco Unified Wireless Network are explained earlier, this section explains the roams as they occur
in converged access mode. It will be clear that the roams in converged access deployment are no different than
those that occur in an existing Cisco Unified Wireless Network. In converged access deployment, QoS policies are
applied at the foreign or PoA switch, and ACL policies are applied at the anchor or PoP switch.
In converged access mode, there are two methods of supporting roams: tunneled (sticky) mode and nontunneled
(nonsticky) mode.
Tunneled mode is the default method of supporting L2 roams and the only method of supporting L3 roams in
converged access deployment. This means that even for L2 roams, by default, only the PoA moves with the user
mobility, and PoP is maintained at the anchor switch for stateful policy application.
Figure 19 shows the switches are trunked to the distribution VSS, and the client wireless VLAN 500 is spanned
across the access switches. The initial client join occurs on the MA1 switch. The initial client traffic profile is
CAPWAP encapsulated to the switch. The switch terminates the wireless traffic and sends out a converted
Ethernet frame. Hence PoP and PoA both are on MA1 for the initial client join. After clients roam to MA2, the PoP
stays at MA1, and the PoA moves to MA2, as seen earlier. Hence, the roamed traffic is CAPWAP encapsulated to
the new mobility agent. The new mobility agent encapsulates this traffic on the full mesh SPG1 tunnel to PoP
switch. After arriving on the PoP switch, the traffic is terminated and converted and shipped off into the wired world
by MA1. Since the client roams within the SPG, the roamed traffic does not need to traverse the mobility controller
switch. Typically the SPG will be formed around switches within a distribution block inside a building, or a floor:
areas to which most users roam.
Figure 19. L2 Roam in Tunneled Mode in Converged Access