Date: Tue, 31 Jan 2012 08:29:57 -0500
From: Dan Brisson<[email protected]>
Subject: Cisco APs losing CAPWAP session
I'm curious if any Cisco users out there are experiencing or have
experienced what we're seeing on our campus. This past summer we
installed 3502i's in all of our residence halls - approximately 500
total. Ever since the students have moved in, we will get messages from
WCS stating that "AP XYZ" is down and disassociated from the
controller. When I check out the AP, the uptime is fine, but the
"CAPWAP join time" is for like 30 seconds, or however long it took me to
check.
We've tracked this and it is totally random as to what AP will drop,
which makes troubleshooting this very tough. The log on the AP isn't
helpful. I'm working with TAC who suggests that keepalives are getting
missed. I'm not sure why that would be the case since we have another
500 or so APs on the admin side that very rarely drop. Adding to that,
when the students left for break, the AP drops stopped. They came back,
and sure enough, the drops start up again.
I will say that the AP always joins back immediately, but for the time
that it does drop A) I'm sure connectivity is affected in that area and
B) we get an email.
Anyone experiencing this?
Wow, Deja vu! I had almost exactly the same problem a few years ago
and it nearly drove me nuts.
It turned out to be unrelated to the wireless. The wired network
switches in the dorms were configured for dynamic vlan steering based
upon a response from a radius server. The radius server would randomly
glitch and return the "wrong" vlan for one or more of the ports that
the wireless access points were plugged into, which would sever the
connection between the AP and controller.
I pulled most of my hair out before finally figuring it out by sniffing
the radius queries and responses and meticulously matching them up and
"Aha!!".
You really remember the problems that leave skid marks across your
backside! :-)
--
Earl Barfield -- Academic & Research Tech / Information Technology
Georgia Institute of Technology, Atlanta Georgia, 30332
Internet: [email protected] [email protected]
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