Duplicated IP error on some clients

[valeriy.nebogin]

Hello,  Dear All.

We have typical deployment with WLC550x (7.0.116.0) and 16 APs (AIR-LAP1242G-E-K9) placed on same site. WLC connected to 3560 (with LAG , and dhcp relay)  , and all wireless clients( Motorolla MC3100 handled PC ) work with same WPA2-PSK SSID. All APs configured as HREAP group and SSID has local switching and auth settings. DHCP server for clients work on Windows 2008r2 failover cluster, APs give addresses from WLC builtin server.

Almost all works great.  But sometimes some clients go insane . After wake up,  they show duplicate IP error and wont connect to nework.  On DHCP server  this IP shown as leased to client mac(without any errors and so).

Client reboot wont resolve this issue.

After reboot client try another dhcp address (after marking dchp decline message) but also without luck, with same error and another IP.

All this looks like client side problem . But when i try debug arp on root switch 3560  i get following situation.

After client wake-up

*Apr 10 18:44:32.773: IP ARP: rcvd req src 10.116.51.59 0023.68cb.a8fc, dst 10.116.51.59 Vlan51

*Apr 10 18:44:32.782: IP ARP: rcvd req src 10.116.51.59 0023.68cb.a812, dst 10.116.51.59 Vlan51

After reboot

*Apr 10 19:16:40.123: IP ARP: rcvd req src 10.116.51.24 0023.68cb.a8fc, dst 10.116.51.24 Vlan51

*Apr 10 19:16:40.131: IP ARP: rcvd req src 10.116.51.24 0023.68c9.a29b, dst 10.116.51.24 Vlan51

*Apr 10 19:16:40.459: IP ARP: rcvd req src 10.116.51.27 0023.68cb.a8fc, dst 10.116.51.27 Vlan51

*Apr 10 19:16:40.467: IP ARP: rcvd req src 10.116.51.27 0023.68cb.a9b6, dst 10.116.51.27 Vlan51

Where  0023.68cb.a8fc problem clent mac and   0023.68cb.a812,

0023.68cb.a9b6, 0023.68c9.a29b    - another full working clients  MACs(with another ip address).

Looks like another client (or ??  ap or controller) send ARP reqest with same IP right after problem client. How this possible ?

I'll be

appreciate for any opinions

and comments!

[Scott Fella]

Never mind I did see you had the dhcp lease set for 8 hours and the idle timeout set for 300 seconds. Just ran I to a similar issue and the idle timeout was causing issues when set high. It was keeping the devices information but dhcp was handing out address to cause a duplicate error on the WLC.

Sent from Cisco Technical Support iPhone App

[valeriy.nebogin]

After disabling local switching and auth for WLAN,  WLC work without %APF-4-EGISTER_IPADD_ON_MSCB_FAILED error more than 24 hours and client didnt receive duplicated address errors . This  wont prove anything but usually error occure earlier. I will wait additionaly   for 48 hours  or more before any conclusions.

But some client notice  connection freezes (they work with rdp) and even connection losts. This can be releated also with  wireless network our neibghours deploying now.

I will try disable and re-enable WLAN after experiment with disabling HREAP.

[valeriy.nebogin]

Definitely this problem related with HREAP.  Proved that disabling local switching for WLAN  resolve problem.

I think  this is may be  design error ,because WLC interfaces and  APs placed  in same  broadcasts domains. That  definitely is not typicall hreap deployment.

But why it work flawlessly  for day or two?

[valeriy.nebogin]

Problem resolved by correcting design. I'd remove wlc interfaces from wlans . And now system work almost flawlessly

Sent from Cisco Technical Support iPhone App