Important Notes
Important Notes
This section describes important information about the controllers and access points.
Service Modules Supported in the Catalyst 6500 Series Switch
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).
Access Points Fail to Join Controllers If MTU Setting Is Less Than 1500
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)
Workarounds
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
•Increase the network path MTU to 1500 bytes.
Release Notes for Cisco Wireless LAN Controllers and Lightweight Access Points for Release 3.2.171.6
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