We've had the same issues regardless of Mac or Windows clients. We tracked it down with TAC on our controllers (running either 7.6.122.9 or 7.6.130.0) as an issue with both WPA&WPA2 enabled along side client band select/load balancing. Band select and load balancing are obviously big ones, but disabling WPA and leaving only WPA2-AES layer 2 security has remediated the problem for us.
-Britton Britton Anderson <[email protected]> | Senior Network Communications Specialist | University of Alaska <http://www.alaska.edu/oit> | 907.450.8250 On Wed, Oct 1, 2014 at 3:10 PM, Ashfield, Matt (NBCC) <[email protected] > wrote: > Hello > > We are seeing some intermittent issues with some of our student computers > (a lot of HPs, but some others) whereby they will be working away, well > connected, and suddenly get the yellow exclamation mark in on their wifi > connection in the taskbar and lose connectivity. Sometimes they can get > back on, sometimes they have to reboot. We have tried updating drivers and > that has not fixed the problem, although in one case we forced the client > to 2.4ghz range thru settings in the adapter and that seemed to fix the > probem in some cases. > > The issue is very odd. It appears almost to be location or AP specific > although reports are hard to nail down. Anecdotal reports suggest more > difficulty with non-3702i APs (we have some 3500's and 3600's APs as well) > The network is an EAP-TLS network with client side certs. > > As with most student wifi issues, it’s nearly impossible to get real > debugging results, but one thing we have noticed is when the student is > having issues, we’ve seen where the controller is showing them as > associated and authenticated, but the client machine seems to show that it > has an IP gateway and mask but for some reason there’s no gateway entry in > the ARP table of the client. Release/Renew does nothing. Ping from the > gateway does nothing. Very odd issue. DHCP is provisioned by a central > Microsoft DHCP server (ie, not the cisco device) and we’re using 1 hour > lease times. Some students we've seen it happen to are a result of their > laptop going asleep. > > I personally tend to lean towards this being a client driver issue. > Problem is, it's nearly impossible to have every student with up to date > drivers in this BYOD type world we operate in. At the end of the day, we > have students who need wifi access and cannot get on and blaming IT. This > is a small subset of users, but an issue nonetheless. > > I have heard rumblings of various wlc options/settings that may be > causing issues and we do have the following list below. Turning one off at > a time is an option I suppose, but hoping that someone may have some better > recommendations here. > - Client Band Select enabled > - Client Load Balancing enabled > - User Idle Timeout set to 5400 Seconds (this is under Controller/General) > - CCKM enabled > - Session Timeout 36000 (this is under WLAN/Advanced) > - DHCP Address Assignment Required is checked > > Any advice/info is appreciated. > > Thanks > > Matt > > ********** > Participation and subscription information for this EDUCAUSE Constituent > Group discussion list can be found at http://www.educause.edu/groups/. > ********** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/.
