Guest WLAN making other WLAN stop working

[Tiziana Cassar]

Hi,

I have a WLC 2500 WLC.  I have a WLAN for internal use which is working fine. This is using the management interface.  When I add a second WLAN for guest users on a dynamic interface (called guest) on VLAN 20, the internal WLAN stops functioning properly.  When I enable the guest WLAN, anyone trying to connect to the internal WLAN doesn't get an IP address.  I want the users on the guest WLAN to get an IP from a router connected to the guest network which will also provide internet access.

This is a summary of my setup:

Internal WLAN:

management interface, DHCP server on the network, no VLAN tagging, subnet 192.168.6.x

Guest WLAN:

dynamic interface, DHCP server on the guest network, VLAN 20, subnet 192.168.0.x

On the switches, I have set up the port connected to the WLAN as a trunk, while the port connected to the router for the guest network as static access on port 20.

Any ideas what may be the problem?

Tiziana

[Sandeep Choudhary]

Hi,

Can you paste the config of the swicth port where wLC is connected??

Normally this should be the config:

interface f0/xx

Description Connected to the WLC

switchport trunk encapsulation dot1q

switchport trunk native vlan

switchport trunk allowed vlan ,20

switchport mode trunk

also check this docs:

http://www.cisco.com/en/US/tech/tk722/tk809/technologies_configuration_example09186a008070ba8f.shtml

Regards

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[Tiziana Cassar]

Hi,

Thanks for the prompt reply.  I had seen the document before...what is strange is that I had done this configuration at two other sites with no problems.

Here is the config for the switch port where WLC is connected:

interface GigabitEthernet0/21

switchport access vlan 20

switchport trunk encapsulation dot1q

switchport trunk allowed vlan 1,20

switchport mode trunk

This is copied from the running config.

Tiziana

[Sandeep Choudhary · Accepted solution]

HI Tiziana,

Dont use swicthport access vlan 20 command.

Use this config:

interface GigabitEthernet0/21

switchport trunk encapsulation dot1q

swicthport access vlan 20

switchport trunk native vlan 1-------

switchport trunk allowed vlan 1,20

switchport mode trunk

Try this and let me know the result

Regards

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[Tiziana Cassar]

HI Sandeep,

Yes, vlan 1 is my management VLAn.

I will try this tomorrow as I am currently offsite and will let you know.

Thank you,

Tiziana

[Tiziana Cassar]

One more question, what about the port connected to the router on guest network (this will only see traffic from the guest network).

Right now it is set up as:

interface GigabitEthernet0/20

switchport access vlan 20

switchport mode access

Is this correct?

Thanks,

Tiziana

[Sandeep Choudhary]

Can you please posts the topology disgramm then I can say about this above problem.

Regards

[Tiziana Cassar]

Hi Sandeep,

Attached is the diagram.  VLANs are configured on the core switch.

Tiziana

[Sandeep Choudhary]

Hi,

For the port where your router is connected :

interface GigabitEthernet0/20

switchport access vlan 20

switchport mode access

this is the right config, dont need to change anything.

just change the port config where WLC is connected.(As per my last posts)

Regards

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[Tiziana Cassar]

Thanks Sandeep.

Will try tomorrow and update accordingly.

Tiziana

[Tiziana Cassar]

Hi,

When I changed the VLAN on the switch as per Sandpeep instructions, the problem of having either production or guest VLAN working was solved.

However, I still could not get IP addresses for the guest WLAN from the external router (192.160.0.1).  I had to go with a workaround and set the WLC as the DHCP server for the guest WLAN.  This solved the issue immediately and guests were placed on a seperate VLAN & subnet with guest internet access only.

Thanks for the help,

Tiziana

[Sandeep Choudhary]

Glad that my post work for you and thanks for rating.

Reagrd

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