Примечания к выпуску для Cisco Cisco 4404 Wireless LAN Controller
7
Release Notes for Cisco Wireless LAN Controllers and Lightweight Access Points for Release 3.2.195.13
OL-14249-01
Important Notes
RADIUS Server Failover Behavior
If you enter the config radius aggressive-failover enable command, the RADIUS server switches over
to the backup server if it fails to answer one RADIUS request after five retransmissions. This is the
default behavior. If you enter the config radius aggressive-failover disable command, the RADIUS
server switches over to the backup server only if it fails to answer three consecutive RADIUS requests
(where each RADIUS request is retransmitted five times).
to the backup server if it fails to answer one RADIUS request after five retransmissions. This is the
default behavior. If you enter the config radius aggressive-failover disable command, the RADIUS
server switches over to the backup server only if it fails to answer three consecutive RADIUS requests
(where each RADIUS request is retransmitted five times).
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).
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
software release because the LWAPP tunnel can reassemble up to four fragments. The problem occurs
when all four of these conditions exist on your network:
software release because the LWAPP tunnel can reassemble up to four fragments. The problem occurs
when all four of these conditions exist on your network:
•
Your controller runs software 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 low-MTU paths.
•
Increase the network path MTU to 1500 bytes.
Note
New out-of-the-box access points default to local mode and run a special image that helps them join the
controller but does not contain this fix. If you use these access points in hybrid-REAP mode across a
WAN, have them first join the controller to resolve this issue before deploying them across the WAN in
the remote office.
controller but does not contain this fix. If you use these access points in hybrid-REAP mode across a
WAN, have them first join the controller to resolve this issue before deploying them across the WAN in
the remote office.