If DAI, I'd expect your switch logs would show the AP ports being disabled
(and assume you must have auto-recovery enabled)

Perhaps somehow hitting DAI's ARP default inbound pps limit?

If so, question may be why the switch would see more than (default) 15 pps
of ARP traffic inbound from lightweight APs.

 

If no DAI entries on the switch, then might be source guard more silently
dropping packets for some reason.

You might try configuring one/or the other feature to help determine which
it is.

 

While working without issue now, is DHCP snooping (alone) still configured
on the AP ports?

 

 

From: The EDUCAUSE Wireless Issues Constituent Group Listserv
[mailto:[email protected]] On Behalf Of Dan Brisson
Sent: Monday, February 06, 2012 9:47 AM
To: [email protected]
Subject: Re: [WIRELESS-LAN] Cisco APs losing CAPWAP session

 

For those following this thread, while we still haven't determined the exact
cause of this problem, we also have not had a drop from an AP where we
turned off DAI and IP source verify.  Seems logical that one (or both) of
those could be causing problems, although what is not entirely logical is
how that would be related to load/activity, since the APs never drop when
the students are gone on break.

TAC has been very responsive and at this point I've asked if we can get
someone from the Switching side to look at the possibility that DAI and/or
IP Source verify could be the cause.

-dan





Dan Brisson
Network Engineer
University of Vermont
(Ph) 802.656.8111
[email protected]


On 2/1/2012 2:38 PM, Dan Brisson wrote: 

Ah right, yes, 'mls qos' is NOT configured on any of the 3560X switches.

We used DAI and DHCP snooping b/c the majority of APs are actually in
student rooms due to, well, no other place really to put them.  :)  Now that
you've brought that up, though, we had to go in the ceiling in one of our
newer, bigger complexes.  I'm going to turn off DAI and IP Source verify
there and see if the drops stop.

Will let folks know what I find.

Thanks!
-dan





Dan Brisson
Network Engineer
University of Vermont
(Ph) 802.656.8111
[email protected]


On 2/1/2012 12:41 PM, Garry Peirce wrote: 

Dan,

A small but important point to verify re: QoS.

By 'no QoS in place', does that mean the global  'mls qos' is NOT configured
on the resHall switches or that no specific QoS config has been configured?


Ex. if the global 'mls qos' is enabled, all ports (including APs) would be
untrusted by default with all packet markings remarked as 0.

Also, any QoS/service policies on the relevant router's interfaces?

 

Given the L2 functions you mention are unique to the ResHall side, I'd
disable them on the ports used by the APs.

I wouldn't expect these L2 security functions to be needed on known AP ports
and removing them might provide further insight on the issue.

DAI disabling AP ports due to ARP pps threshold (odd)? Is errdisable
auto-recovery of DAI enabled?

Any log data from the switch of an affected AP?

 

 

 

From: The EDUCAUSE Wireless Issues Constituent Group Listserv
[mailto:[email protected]] On Behalf Of Dan Brisson
Sent: Wednesday, February 01, 2012 11:35 AM
To: [email protected]
Subject: Re: [WIRELESS-LAN] Cisco APs losing CAPWAP session

 

Ok, thanks for validating.  It also seemed a bit strange to me and yes, I
checked a bunch APs that haven't dropped recently and they all showed
10-12ms.

One thing that occurred to me is we are doing DHCP snooping and Dynamic Arp
Inspection on the 3560Xs.  That is unique to this part of campus as we
haven't yet rolled that out to the entire admin side.

Thanks,
-dan






Dan Brisson
Network Engineer
University of Vermont
(Ph) 802.656.8111
[email protected]


On 2/1/2012 10:23 AM, Mike King wrote: 

 

On Wed, Feb 1, 2012 at 10:03 AM, Dan Brisson <[email protected]> wrote: 




 

It's been awhile since I've read these, but If I interpret this correctly,
It took 1m 15s for the AP to associate to the controller.  That's a very
long time.   Mine usually have association in the 10-20 second range.

 

Not sure what that indicates, but it's an anomaly from my point of view.

 

I don't think it's a rouge herring.  (See Backhoe joke from earlier in the
thread)

 

Mike

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