FlexConnect and WLC5508

buo2200
buo2200 used Ask the Experts™
on
Hello!
I'm trying to configure FlexConnect on my wlc 5508 and I'm having some troubles. The clients connected to the SSID with FlexConnect don't receive an IP from our DHCP (Windows 2008 R2).

Configuration on port connected to the AP running on FlexConnect. (switch 2960)

interface GigabitEthernet3/0/45
 description to_AP_2B_Iberia_Port164Pannel
 switchport trunk native vlan 100
 switchport trunk allowed vlan 20,22,100
 switchport mode trunk
 spanning-tree portfast

WLAN VLAN Mapping on WLC:

WLAN ID: 1
VLAN ID: 22
Native VLAN: 1

Of course.. helper-address is well configured pointing to the dhcp server.

Any thoughts? Thanks!
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Top Expert 2014

Commented:
Can the DHCP server ping the router IP on VLAN 22?

Author

Commented:
Yes! It's reachable.

The thing is that I have another SSID (but without flexconnect) working on the same VLAN22, and it's working well. The problem is the SSID with flexconnect, the clients connected on it, don't receive any IP from dhcp. I checked the logs on the dhcp server and didn't found any trace.
Top Expert 2014

Commented:
OK, can you give a client a static IP while connected to the FlexConnect SSID and try to ping the IP of the router?

The port config looks good for the AP.  Is the WLC connected to the same switch as the AP?  If not, could you show the show vlan brief output please from the switch where the AP connects, and the trunk link config?
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Author

Commented:
I gave an static IP while I connected to the flex SSID and the ping to the IP router was not working.
I don't think that the problem is on the trunk or swtich configuration... I believe is 100% flexconnect configuration.

If I connect to the same flexconnect SSID but through an AP where flexconnect is not configured, the SSID is working fine, it assigns me a valid IP (Vlan22).

I attach images showing my flexconnect configuration on the WLC,
WLAN_Config.png
Wireless_Config.png
wificontroller_ES.png
wificontroller_ES_2.png
Top Expert 2014

Commented:
I don't think that the problem is on the trunk or swtich configuration... I believe is 100% flexconnect configuration.
This is why I asked whether the AP is on the same switch as the WLC or not.

When you don't use FlexConnect all the traffic from the AP tunnels back to the WLC, so if the VLAN isn't on the switch where the AP connects it doesn't matter, if the WLC and AP are on different switches.

I need to know whether the AP and WLC are on different switches or not as the config you have at the WLC looks good to me.  The only thing I'm curious about really is why you're telling the AP to use AP-specific FlexConnect config, instead of simply using the Group config?

Author

Commented:
The AP is in a different switch as the wlc.

WLC is connected on a layer 3 cisco catalyst 4500 model.
AP is connected on a layer 2 cisco 2960 model.

I'm assuming that the AP takes the flexconnect config from the Group config. Where did you see that? I've checked again and everything seems to be correct.

Any thoughts? Do they have to be on the same switch?
Top Expert 2014

Commented:
They don't have to be on the same switch.

Can I ask, why are you using FlexConnect?

Author

Commented:
Sure!
I just have one WLC working in the office and wanted to avoid that all AP stop working if the WLC crashes someday.

And the second intention is to implement flexconnect in remote offices where there is no WLC present.
Top Expert 2014
Commented:
Thanks.

FlexConnect is only really meant to be used to allow you to deploy APs over WAN links, to minimize the amount of traffic that has to traverse the WAN.  It's not really used for surviving a WLC failure... that's more of a N+1 or HA feature.  Yes, you'll be able to survive a WLC failure to a certain extent, but there are lots of caveats and some things just won't work while the WLC is unreachable...

http://www.cisco.com/c/en/us/td/docs/wireless/controller/7-2/configuration/guide/cg/cg_flexconnect.html#wp1241304

When using FlexConnect at an AP, the VLAN that you're mapping to the WLAN must exist on the switch where the AP connects.  If it doesn't, the traffic will either go nowhere or onto an undesired VLAN.  It's not as simple as trying it with a local-mode AP and getting an IP address.  As I explained earlier, all the traffic in that case is tunnelled from the AP to the WLC in local-mode, even if the WLAN is configured to use FlexConnect.

So, can you please provide switch config for both switches and tell me which ports join the switches together?  Also I'll need to see the show vlan brief output from each switch and I'll need to know which ports the AP and WLC are connected to.  I'll be able to tell you what the issue is from that if it is a switch issue :-)

Author

Commented:
Solved!! :)
The problem was that the command 'vlan 22' was not present on the switch L2.

Thank you for your support!!

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