Примечания к выпуску для Cisco Cisco 2000 Series Wireless LAN Controller

This section describes important information about the controllers and access points.

The Catalyst 6500 Series Switch chassis can support up to five Cisco WiSMs without any other service 
module installed. If one or more service modules are installed, the chassis can support up to a maximum 
of four service modules (WiSMs included).

When the network path between access points and the controller is configured for an MTU size less than 
1500, the controller does not receive join requests from access points in local mode. (MTU settings less 
than 1500 are common when you use tunneling protocols such as IPsec VPN, GRE, and MPLS.) The 
access point join request is larger than 1500 bytes, so the request is fragmented. The size of the first 
fragment is 1500 bytes (including IP and UDP header) and the second fragment is 54 bytes (including 
IP and UDP header). 

Access points in REAP mode are not affected by this limitation, and the problem is resolved in the 4.0 
release train because the LWAPP tunnel can reassemble up to 4 fragments. The problem occurs when all 
four of these conditions exist on your network: 

Your controller runs release 3.2 or earlier

Your controller is configured for Layer 3 LWAPP

The network path MTU between the access point and the controller is less than 1500 bytes

The access point is in local access point (LAP) mode (not REAP mode)

Use one of these workarounds to resolve the problem on your network:

Upgrade to controller software release 4.0 if the controller platform supports it.

Use 1030 series access points in REAP mode for locations reachable through low-MTU paths.

Increase the network path MTU to 1500 bytes.