topic Re: DHCP server override on 4402 WLC in Wireless

DHCP server override on 4402 WLC

grabonlee — Sun, 04 Jul 2021 05:01:25 GMT

I have successfully implemented wireless guest access using 4402 WLC as the Anchor and 5508 as Foreign. The Anchor controller also provides dhcp services to guest clients. The 5508 is LAGged and there is no issue with the guests traffic separated from corporate. At a remote site, there is a 4402 WLC using LAG and also acting as a Foreign controller. But when a client connects to the guest WLAN, it obtains a corporate dhcp address instead of the dhcp address assigned from the Anchor controller. The guest WLAN setting is the same as with the 5508 controller i.e. DHCP server override is ticked and the management IP address of the Anchor controller is specfied. Also DHCP Addr required is ticked. Could anyone explain why the 4400 controller is not forwarding dhcp requests to the anchor controller and instead sending to the corporate dhcp server.

Re: DHCP server override on 4402 WLC

Scott Fella — Wed, 18 Apr 2012 23:05:15 GMT

Well it could be a few things. First, is your mobility anchor defined on the SSID on the remote wlc? The APs are in local mode not in h-reap or FlexConnect. Even though you have the dhcp override, if the traffic isn't getting tunneled, you won't get a dhcp from the anchor.

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Re: DHCP server override on 4402 WLC

Stephen Rodriguez — Wed, 18 Apr 2012 23:56:58 GMT

For anchoring to work, the WLAN config must match.

If you are anchoring the WLAN to a DMZ WLC, you don't need to set the tho override parameter, as the DGCP will come from the DMZ WLC by default.

Now if you have that setting on the inside, you must have the same settings on the DMZ as well

Steve

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Re: DHCP server override on 4402 WLC

grabonlee — Thu, 19 Apr 2012 06:04:23 GMT

Thanks for you responses. However, I mentioned that APs connected to the 5508 WLC are working as expected. That means the guest WLAN config on the 5508 is the same as the 4400 and DMZ WLC. The guest WLAN is centrally switched.

Re: DHCP server override on 4402 WLC

Stephen Rodriguez — Thu, 19 Apr 2012 06:50:56 GMT

Are you able to eping and mping between them? If you run debug client and debug mobility handoff. You should see messages on the anchor of its not able to create the tunnel for the user.

Steve

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Re: DHCP server override on 4402 WLC

grabonlee — Thu, 19 Apr 2012 13:58:38 GMT

The mobility data and control path (eping/mping) is up. I will run a debug later.

Re: DHCP server override on 4402 WLC

grabonlee — Fri, 20 Apr 2012 12:59:50 GMT

Looked at the mobility stats on the controller and discovered that there is no Client handoff as Foreign. Compared the config between 5500 and 4400 Foreign WLCs and found no error. My config is as follows:

1. LAG is enabled

2. Guest wlan mapped to management interface

3. Anchor WLC is 4400

4. Both Foreign and Anchor controllers have DHCP server override with the management IP add of the Anchor specified

5. Both Foreign and Anchor controllers management interfaces have no DHCP server IP specified

6. There is no guest vlan interface or subnet.

7. DHCP proxy is only enabled on Anchor controller

8. 5500 WLCs have been supporting guest access properly since 2011

This is really frustrating. I wish Cisco would could maintain some consistency

Re: DHCP server override on 4402 WLC

Scott Fella — Fri, 20 Apr 2012 13:05:19 GMT

On your foreign wlc, you have the SSID anchored to the 4400 and of course the 4400 guest WLAN is anchored to itself.

Thanks,

Scott Fella

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Re: DHCP server override on 4402 WLC

Scott Fella — Fri, 20 Apr 2012 13:06:48 GMT

I have the same setup using a 4400 (repurpose) as an anchor for a couple of my clients and no issues with 5508's as the foreign.

Thanks,

Scott Fella

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Re: DHCP server override on 4402 WLC

grabonlee — Fri, 20 Apr 2012 16:47:35 GMT

Scott,

Please read my comments. I never said I had issues with 5508 as Foreign WLC. My problem is with the Foreign 4402 WLCs. Anyway, l have planned to remove LAG from the Anchor 4400 and create a separate interface for the guest WLAN.

Re: DHCP server override on 4402 WLC

Scott Fella — Fri, 20 Apr 2012 17:15:40 GMT

Never said it was an issue with the 5508. But if you don't see anything anchored to your anchor WLC, then your 5508 is not anchoring the traffic for that WLAN. There is nothing different per say config wise from a 4400 and 5508 running the same code except for the ap manager interface on the 4400. Why not post your show run-config on your 4400 and 5508 which is the issue.

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Re: DHCP server override on 4402 WLC

grabonlee — Fri, 20 Apr 2012 19:00:58 GMT

My 5508 has no issues handing off to the 4400 Anchor. The problem is a foreign 4400 handing off to the 4400 Anchor despite the fact the config being the same as the 5508.

Re: DHCP server override on 4402 WLC

Scott Fella — Fri, 20 Apr 2012 21:06:49 GMT

Well that should be simpler since its the same hardware, you eliminate hardware compatibility issue. You need to post your config for us to be able to see if it's setup correctly.

Thanks,

Scott Fella

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Re: DHCP server override on 4402 WLC

George Stefanick — Sat, 21 Apr 2012 17:11:28 GMT

You should never map the GUEST interface to managment even if its doesnt do DHCP, just bad pratices. If the tunnel breaks your guest will get dropped on the side of your network. You should create dummy interface.

What code revs are all these devices on ?

Re: DHCP server override on 4402 WLC

grabonlee — Sat, 21 Apr 2012 19:19:13 GMT

My Anchor controller is on a DMZ. The corporate 4400s are not using etherchannel, hence there is a Guest interface that is not mapped to management. I only used LAG when the anchoring was not working between the Anchor 4400 and the Foreign 4400. The Anchor uses etherchannel, hence no separate guest interface. I have decided to create a separate guest interface on the Anchor controller to see if that solves the issue. This I will do on Monday. The 4400s are on 7.0.230.

Re: DHCP server override on 4402 WLC

George Stefanick — Sat, 21 Apr 2012 19:45:54 GMT

It sounds very confusing, you mentioned above

2. Guest wlan mapped to management interface

Not sure what etherchannel has to do with your guest interface.

Its pretty simple...

Foreign controller -- DUMMY GUEST WIRED INTERFACE regarless of LAG or not. Your foreign controller will act as the relay point to your anchor. If configured right.

Anchor -- you need a guest interface to dump the guest traffic. Its good pratice.

Re: DHCP server override on 4402 WLC

grabonlee — Sat, 21 Apr 2012 21:04:15 GMT

George,

In my opinion, whether the guest wlan on the Anchor controller is mapped to the management interface or not doesn't matter as it is behind the FW and there is no external DHCP server. When the I first configured the 5508 to relay guest traffic, it worked. But because of increasing demand for guest access in some sites with 4400s, I had to integrate the 4400. The config on the 4400 Foreign controllers were made similar to the 5508:

1. Created guest wlan and dhcp server override with IP address of the anchor

2. Created mobility group

From the debug, the Foreign 4400 actually contacted the Anchor, but there was no handoff. That is why I earlier said that the only change I intend to make is to create a guest interface on the Anchor and see if it solves the problem. But it is strange that the 5508 could hand off to the 4400 Anchor but the 4400 Foreign can't.

Re: DHCP server override on 4402 WLC

George Stefanick — Sat, 21 Apr 2012 21:20:37 GMT

I agree, i was thinking intrenal, my bad. But if you map it on the mangement interface your guest clients are sitting on and can access the mangament . But regardless, they can anyway becuase its connected route in the wlc.. but anyway

What is your code revs on all these controllers?

Re: DHCP server override on 4402 WLC

grabonlee — Sun, 22 Apr 2012 13:08:20 GMT

The 4400s are on code 7.0.230. The 5500s are on 7.2.

Re: DHCP server override on 4402 WLC

George Stefanick — Sun, 22 Apr 2012 13:56:30 GMT

Normally when anchoring cisco recommends staying on the same 7.x code. But I understand, 4400 cant support 7.2.

I know I've had anchoring issues when my anchors were on 5.x and my foreign controllers were on 6.x