WLC and mobility anchor- dhcp

[Neil Haswell]

Hi,

The setup I have an issue with is one where a suboffice has a WLC. The head office has another WLC as the anchor for mobility groups. We are using a main corportate SSID with certificate authentication although the mobility group is for the guest wireless.

Just the other day after a router swap out the office clients could no longer get an IP address from the headoffice WLC where the internal DHCP service is kept on the WLC.

I understand that DHCP requests are made from WLC to WLC over eoip. Is there anything in the router config that might prevent this. (ACL etc..)

The headoffice can ping the DHCP default gateway for this guest network but the suboffice WLC cannot ping the default gateway. However running a ping from the suboffice WLC GUI to the HO mobility anchor works fine and visa versa?

If there any any troubleshooting commands that may help they would be gratefully appreciated.

Many thanks,

[Scott Fella]

Is your mobility up? Are you able to eping or mping from the CLI of one wlc to the other.

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[wireless wlc]

Hi Neil,

  "but the suboffice WLC cannot ping the default gateway "  :  if you cannot ping gateway, i suspect a routing issue, maybe few routes are missing in the newly installed router ? do a sh ip route for the suboffice and headoffice networks and see if you have the routes.

If routing is proper and if it still doesnt work, you should check mping and eping from suboffice to headoffice to see if the mobility tunnels are up (show mobility summary on the wlc's) .  You need to open up UDP ports 16666  (if there are any ACL's on your WAN gateway/firewall etc blocking this ) and also IP protocol 97 should be allowed all the way from your suboffice wlc to headoffice. 

hope this helps

Joe

[Neil Haswell]

HI,

I have checked the eping and mping from the suboffice WLC and visa versa and that checks out ok.

I suspect the new router is the issue but I need to try and find a way of proving it.

Is there any command I can use on the suboffice WLC to test that all the required ports are open a sort of telnet 16666?

Trying a ping from the router or switch to the DHCP server doesnt work even in the HO as I suspect the traffic has to originate from the WLC that is creating the eoip tunnel.

Thanks for your help

[wireless wlc]

Do a 'debug ip packet ' on the router and 'debug dhcp messages enable' on the wlc's and see what the logs say.

regards

Joe

[George Stefanick]

Neil,

6.x and 7.0.98.0 have issues with the DHCP scope on the WLC. In fact, Cisco released 7.0.98.4 to fix the known issue(s). May not be related to your issue, but wanted to mention it ...

[wireless wlc]

George, did you mean 6.0.199.4 ? Cos i dont find 7.0.98.4 on CCO ?

regards

Joe

[Surendra BG]

Hi,

Yes 6.0.199.4 and 7.0.98 is affected!! you need to raise a TAC case to get the 7.0.98.4 or 6.0.200.6

Regards

Surendra

[wireless wlc]

Thanks for the info Surendra. Does the fix allow you to also clear the dhcp leases on the WLC ? it was not possible earlier and was quite annoying .to reboot to clear DHCP lease. (and sometimes even reboot didnt clear the leases ! )

regards

Joe

[Surendra BG]

Hi,

Thanks for the response!!

if you are running 7.0 and above then its possible.. just now checked the same on my WLC.. the command is..

(WiSM-slot2-2) >config dhcp clear-lease ?

   Enter the IP address.
all            Clear all Leases.

lemme know if this answered your question..Regards
Surendra
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[George Stefanick]

If i could offer any device when it comes to DHCP on the WLC, dont do it ... 

This has been a thorn in a lot of peoples side for a lond time.

[wireless wlc]

Agree with George !, put that dhcp scope anywhere else other than on the WLC ! If there is a dhcp malfunction, you will have to reboot your wireless network to get things running again, not to mention the many instances where your clients dont get an ip address and related 'side effects' of putting dhcp scope on the WLC !

regards

Joe

[Scott Fella]

Okay so the wlc must be able to ping it's default gateways and the gateway of the other wlc. Have you checked the configurations on the router? Nothing has changed in the wireless side correct? Here is a good link regarding mobility. It's guest anchoring, but it's the same what you are trying to do.

http://www.cisco.com/en/US/products/ps6366/products_tech_note09186a0080b1a506.shtml

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