DHCP clients having problem on WLC 5520

[pavel.mr4]

Hi, 

We have two WLC on HA, and 3 SSID broadcasting in different interfaces, but some clients does not receive any IP from DHCP, the client policy manager state is DHCP_REQD or 8021X_REQD regardless is not an 802.1x SSID. we are running code version 8.2.141.0 with AP 3802i. Any clue?

Kind regards!

[Rasika Nayanajith]

Have you narrow down what type of clients mostly having this issue ? windows/mac ? which chipsets those client got ?

Also does this happen on both bands (2.4GHz and 5GHz) ?

If it is 5GHz only, pls post "show advanced 802.11a channel" output to see how you configure your WLC.

HTH

Rasika

**** Pls rate all useful responses ****

[pavel.mr4]

Hi Rasika,

It seems to be randomly since there are android phones, iphones and some windows PCs that can't receive DHCP, this happens on both bands, I checked one by one on both 2.4 and 5 Ghz.

Regards!

[tbvc.network]

Hi,

just an idea: one item to check is also on your switches if ip helper address is pointing to your DHCP server.

If the SSID are mapped to a VLAN, then check on your switches the vlan config for ip helper address.

Regards

[pavel.mr4]

Hi tbvc.network

The switches have ip helper pointing the DHCP, however there are some clients who get DHCP seamlessly, and other clients just dont and keep stuck on client policy manager state: DHCP_REQD.

So I dont know what else to do

[tbvc.network]

Might be this link is helpful:

http://www.cisco.com/c/en/us/support/docs/wireless/aironet-1200-series/100260-wlc-debug-client.html

DHCP_REQD—Controller needs to learn the L3 address from client, which is done either by ARP request, DHCP request or renew, or by information learned from other controller in the mobility group. If DHCP Required is marked on the WLAN, only DHCP or mobility information are used.

If windows clients are stuck as well, I would also check the communication with wireshark to check DHCP packets.

Regards

[Rasika Nayanajith]

If it is across many client types & both radio bands, this is more likely be a software issue of the code you running.

It is worth reach TAC & see any known issues with this code and any fix (there are many issues listed with 3800/2800 series AP related). There is an upcoming 8.2MR5  & worth exploring that early if your issues are too problamatic to clients

https://supportforums.cisco.com/discussion/13205296/82mr5-interim-availability

HTH

Rasika

[Vivian Dutch]

To anyone still having this issue:

It is a software issue with the 8.2.x.x WLC software and the 2800/3800 series APs.  The APs randomly stop forwarding DHCP requests.  Power cycling the AP fixes it for an unknown amount of time, as it can happen anywhere from 4 hours to 60 days, from my experience. I contacted Cisco TAC and they didn't have a confirmed fix for the issue, but they gave me links (for 5508 and 5520) to software version 8.2.167.6 (not available on the download site), in hopes that the other fixes they had implemented for the 2800/3800 series APs would also fix my issue.  So far, so good.  We're at 25 days without an issue so far.