Clients on Guest WLAN Losing Layer 3 Connectivity

Configuring Wireless Cisco Networks and Wireless Controllers.
Guest

Clients on Guest WLAN Losing Layer 3 Connectivity

Post by Guest » Sun Sep 12, 2010 2:23 am


Hello NetPro gurus!I am currently troubleshooting an issue we are having with our Guest (completely open) WLAN in which it seems certain clients are losing their layer 3 connectivity while staying 'connected' to the LWAP(s). These certain clients lose their layer 3 configuration and are not able to access internal or external resources until they disable/enable their wireless connection. I specifically have this problem, and it's only on the Guest WLAN that this occurs. I am using a Lenovo T61 with an Intel 4965AG internal wireless chipset. I know this chipset is relatively new and I have tried multiple drivers, all with the same result. Not all machines have this issue. MacPro laptops do not seem to have this issue nor do machines with Intel Pro 2200BG chipsets. I tested with a Netgear PCMCIA card and did not have this issue either.Here's some more background information:We have 5 WLCs (2 WiSM blades each in a Catalyst 6509 and 1 WLC 4402) and 7 WLANs. The 4 WiSM controllers have each WLAN configured on it, and the 4402 WLC only knows about one Guest wireless network (it is a completely open WLAN i.e. no security). This is the particular network we see this issue with. We have approximately 200 LWAP 1131AG's (47 in one building, 154 in another) all broadcasting the Guest SSID. Our server core Catalyst 6509's each have seperate VLANs (with Port-channels in them) for the WiSM blades. The Guest WLC 4402 is in the DMZ in its own VLAN. Each WLC is providing DHCP for each of the WLANs. The issue that seems to be occuring is the fact that during our troubleshooting I lose all layer 3 connectivity. I continue to stay "connected" to the AP and signal strength is excellent however my continuous pings to the Guest WLC (192.168.0.x network) time out and I cannot get out to the Web. I noticed the following error on my laptop (Lenovo T61 w/ an Intel 4965AG wireless chipset) in the system event viewer:Description:The system detected that network adapter Intel(R)...Link 4965AG - Packet Scheduler Miniport was disconnected from the network, and the adapter's network configuration has been released. If the network adapter was not disconnected, this may indicate that it has malfunctioned. Please contact your vendor for updated drivers.This occured at the exact time I lost my layer 3 connectivity. A co-worker and I did some research and determined that this was exactly one half of the way through my 1-hour DHCP lease from the Guest WLC (the 4402). The DHCP leases are set to expire at 1 hour as we have a lot of clients on the Guest WLAN that come and go and only have one network configured for the Guest WLAN w/ 229 available IP's to be handed out. We were wondering if it was an issue with the DHCP renewal process from the WLC. This does not occur on the Internal WLANs configured with strict authentication security. We tested with a few machines, such as an Apple laptop, an older laptop with an Intel Pro 2200BG chipset, and even my same laptop with a Netgear PCMCIA WiFi card none of which exhibited this problem. Connectivity at layer 3 was not interrupted. I have tried multiple drivers as well, all with the same result.Now, we are not sure if it is an issue with the WLC itself or a chipset issue. The Intel 4965AG chipset is rather new but we have a lot of WLAN clients with this chipset on the network. That also doesn't explain why this issue ONLY occurs on the Guest WLAN. We were thinking of placing a small DHCP server on the network to take over DHCP responsibilities from the Guest WLC to see if that makes a difference. Another idea we had was to increase the DHCP scope to two Class B networks (191.168.0.0 - 191.168.1.255 /23 to give us 510 hosts so we can extend the DHCP lease time). I plan on doing further testing today by placing a few more machines on the Guest WLAN with multiple chipsets and taking note of which ones exhibit the problem.Any and all help is MUCH appreciated. Thanks!Shane

Guest

Re:Clients on Guest WLAN Losing Layer 3 Connectivity

Post by Guest » Sun Sep 12, 2010 3:03 am


I have seen this issues also with various other Intel cards.  The fix was to change around the drivers or if you are using a 3rd party utility like Access Connections on your IBM.  I had to upgrade my driver a couple of times and also the utility.  Since you narrowed it down to certain wireless cards, its not your wlan.  Make sure you use the driver that the laptop manaufacture recommends and not the latest Intel.  I have had issues using the latest Intel from their website.  I use Access Conections now and no problems at all.  The fix before was to remove the 3rd party utility and just use windows to configure the wifi.

Guest

Re:Clients on Guest WLAN Losing Layer 3 Connectivity

Post by Guest » Sun Sep 12, 2010 4:03 am


Thanks for the information. Doesn't it seem a little odd that this only happens on our guest WLAN? I would think that if it indeed was a driver issue, I/we would see this on any of the WLANs that exist. For reasons I have yet to determine, I think it has something to do with the WLC controlling the guest WLAN, WLC 4402 running software version 4.2.130.0. Our WiSM blades are running 4.2.130.0 as well and the WCS is on version 5.0.56.2. I can paste any relevant configuration of the Guest WLAN if that might help.

Guest

Re:Clients on Guest WLAN Losing Layer 3 Connectivity

Post by Guest » Sun Sep 12, 2010 5:34 am


Do you notice if it occurs only on certain ap's or on a certain wlc on the WiSM?  Post your show run-config on the dmz and on your wlc.  This way we can eliminate issues with configuration.

Guest

Re:Clients on Guest WLAN Losing Layer 3 Connectivity

Post by Guest » Sun Sep 12, 2010 6:43 am


It seems to occur when associated to any access point broadcasting the Guest SSID. I want to test my theory of the DHCP issue(s) before submitting all of the configs, just to see if my theory is correct. I think it's doing something funky though debugs on the WLC didn't show anything interesting. I noticed that when the problem occured just a little while ago (while testing) I could release my IP but it would not renew.

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