Workstation pulling from incorrect subnet

[DARRELL MILAM]

We have a test lab setup using

DHCP server = windows 2008

WLC = 5508,

AP=lap1142n

switch = cisco sg300

vlan1= 10.10.10.0

vlan128=10.10.128.0

vlan160=10.10.160.0

The server is in vlan 1 with dhcp scopes setup for vlan 1, 128 and 160

The wlc is connect to the switch on a untagged vlan1 and tagged vlan 128 and 160

One AP is on a untagged vlan128 the other on a untagged vlan160

when connecting a workstation through wireless we always get a vlan1 ip address. We have tested the vlan and dhcp config by connecting a workstation to the indiviual vlans and we recieve the correct ip address.

Any Ideas?

[DARRELL MILAM]

I ran a sniffer on the server and found that the dhcp request does not show a relay agent when connecting through the AP

but when directly connected tot he switch it does.

any thought of why the wlc is not passing or acting like a dhcp relay?

[pcroak · Accepted solution]

Hello Darrell,

One thing to remember here is that when using APs with controllers, all client traffic by default will be tunneled back to the WLC. The client traffic will then be placed in the interface that you defined under the WLAN configuration on the WLC.

If you want your users in a different vlan, you will need to create a dynamic interface for the desired VLAN (controller > interfaces) and then bind the specified WLAN to that interface.

Thanks,

-Pat

[pcroak]

Hi Darrell,

The WLC can operate in 2 ways with regards to DHCP:

DHCP Proxy enabled: The WLC will act as a proxy and unicast the client's DHCP discover broadcast to the configured DHCP servers on your WLC interfaces.

DHCP Proxy disabled: The WLC will simply bridge client DHCP discover broadcast onto your wired network, and you can use ip helper-addresses to get the broadcasts to your DHCP server.

This setting is found under Controller > Advanced > DHCP.

-Pat

[daviwatk]

The WLC will act as a relay when DHCP Proxy is enabled. From the WLC GUI: CONTROLLER> Advanced > DHCP > "Enable DHCP Proxy"

Now, your original problem is that you have 3 VLANs configured, however your wireless clients are always ending up on VLAN 1. (10.10.10.0)

Are these for "local" mode APs, or are you configuring these as H-REAP APs (central or local switching)?

If these are local mode APs, what interface is your WLAN associated with; and what is the network information for this interface? IP: Netmask: Default-Gateway, etc?

Assuming these are local mode APs, your switchport for the AP only needs to be configured as an access port for your desired VLAN.  Your wireless client will connect to whichever WLAN you choose and egress its traffic out of the WLC from that interface.

Provide the following and we can help you out.

1. Please specify the WLAN interface being used, and it's current configuration

2. Please provide the show run for the switchport interface where the controller is configured.

3. Please provide the show run for the l3 interfaces of your other VLANs: 128 and 160 (ie, are there helper addresses configured for your DHCP server?)

It sounds like you may have mapped your WLANs to the WLCs management interface, so all clients connecting to those respective WLAN wind up on the same network (VLAN 1)

[DARRELL MILAM]

Thanks for the quick reply

The WLC DHCP is configured with the Proxy Disabled.

The AP are configured local mode

WLAN associated to management interface , I have only one wlan configured

       management interface  10.10.10.20 / 255.255.255.0    g/w 10.10.10.10 

Switch ports for AP are access

Switch port for WLC is trunk

your last statement is correct I'm only using the management interface. But I thought the wlc would pass or relay the

dhcp helper to the server,  If set to bridge.  Does this mean I have to configure seperate vlan interfaces?

[daviwatk · Accepted solution]

That is correct.  As Pat mentioned, you must create dynamic interfaces on your WLC for the respective VLANs you want to communicate on.

You will then map your WLAN to the desired interface (for the respective VLAN you want).

This is the 7.0.116.0 config guide linked to Dynamic Interface creation

http://www.cisco.com/en/US/docs/wireless/controller/7.0MR1/configuration/guide/cg_ports_interfaces.html#wp1114099

[DARRELL MILAM]

Thank you Pat and David that seems to have fixed out problem. 

At present we only have one port active on the wlc and all 3 vlans mapped to that one port.  We are planning to add more ports to the wlc. What would be best pratice know we have multiple vlans but only one wlan.

1. configure LAG and map all wlans

2. configure each port on a seperate vlan and then map to single wlan

[George Stefanick]

Darrell,

I thought I would chime in as I have a few minutes free.

LAG is always the recommended option. LAG is etherchannel and as such you benefit from link redundancy. So shoudl you lose a SFP or fiber and you have more than 1 uplink you keep on ticking!

Keep in mind, your switch uplinking to the WLC needs to support etherchannel. And you can not straddle LAG ports between 2 difference switches.

ALSO very important. On the switch you configure portchannel in the ON position. As the WLC can not negotiate port-channel.

I hope this helps!

If so you can show you appreciation by rate ALL post that are helpful!

Thanks!

[DARRELL MILAM]

A Big thanks to all that posted

I think we are on the right track now, Just need to a little more testing and try out

the LAG settings.