Clients disconnecting

[Steve Wood]

I am having an issue where clients dis-connect and re-connect anywhere between 2-6 times an hour. This can be a short outage (seen by citrix dis-connecting and re-connecting) or a drop out with task bar reporting limited access (infrequent)

Observations:

WLC on 7.4.100 has been stable since install in Feb and has started displaying the issue for nearly a month

Clients obtain DHCP from an ASA at address 192.168.0.1 pool has 250 available leases which has never gone above 140 leases. Lease time is 12 hours

Concentrated on one machine which was displaying the error. Had a continuous ping to 192.168.0.1 running. Saw that when the disconnect occurs 2-3 pings are dropped. Never managed to see the limited access failure

Not OS specific as ipads and windows suffer

InSSIDer shows signal never drops

Unchecked session timeout (was 1800) and Aironet IE for the SSID. No change

I see the following entry in the message log

ARP_CLIENT_IP_DUPLICATED: dtl_arp.c:1847 ARP entry overwrite, conflict detected via ARP Request from client with MAC-ID  c4:85:08:8d:f5:54 and IP Address  192.168.0.83, Old client MAC-ID was d8:9e:3f:06:be:34

*Dot1x_NW_MsgTask_4: Jun 27 15:04:44.507

ARP_CLIENT_IP_DUPLICATED: dtl_arp.c:1847 ARP entry overwrite, conflict detected via ARP Request from client with MAC-ID  c4:85:08:8d:f5:54 and IP Address  192.168.0.83, Old client MAC-ID was d8:9e:3f:06:be:34

*Dot1x_NW_MsgTask_4: Jun 27 15:04:44.507

Attached are the debug client and show client detail. Thanks in advance

[Amjad Abdullah]

Hi Steve,

the messages indicate duplicate IP.
Possibly some clients use static IPs?
What is the ARP timeout and user idle timeout values?

Try force DHCP on the WLAN and monitor.

Regards,

Amjad

Sent from Cisco Technical Support iPad App

[Steve Wood]

Thanks for the reply Amjad. Could I ask what is meant by the term " Try force DHCP on the WLAN and monitor". Does this mean try using the DHCP server on the WLC. One thing I was going to see if I can change the scope on the ASA away from 192.168.0 net as I wondered if there was a rogue DHCP server on the net

[Amjad Abdullah · Accepted solution]

Hello Steve,

I meant to enable DHCP required under the WLAN config under advanced tab.

HTH

Amjad

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[Shaoqin Li]

can you make arp timeout at least 1/2 timeout of lease time?

also try to use microsoft sever for stable performance.

Sent from Cisco Technical Support iPad App

[Steve Wood]

Disabling the DHCP server on the ASA and enabling the DHCP server on the WLC seems to have resolved the issue. Still cannot explain the logic why the errors started occurring after 6 months stability though