AP joins WLC and broadcasts SSID but clients don't get IP address from DHCP server

[Tanyi]

Hello guys,

I am taking on a wireless deployment, but I'm not a pro in the domain. The attached image gives the topology being deployed using WLC2504 and AP1572. All interfaces/networks are routed using OSPF. As shown, both APs are provisioned with static configurations and both point to the WLC successfully.

I have created 2 SSIDs: (WiFi-VLAN130 and WiFi-VLAN126) on the WLC and both are being broadcasted by AP-1.

WiFi-VLAN130

- dynamic interface: 10.201.30.3/24

- gateway: 10.201.30.1

- DHCP server: 10.201.61.51

WiFi-VLAN126

- dynamic interface: 10.201.26.3/24

- gateway: 10.201.26.1

- DHCP server: 10.201.61.51

ISSUES:

1. wireless clients can view both SSIDs from AP-1 but can't pick up IP addresses from the Linux DHCP server. When static IP addresses are used on the wireless clients, they successfully connect on the network. What could I be doing wrong?

2. how do I get AP-2 to broadcast the SSIDs because SW2 is the default gateway for that network area, and I am not too sure about the settings for WiFi-VLAN126!

Below is the configuration of the switches:

!********* SW1 config **********
vlan 999 name NATIVE VLAN
vlan 130
vlan 161
vlan 162

interface vlan 130
ip address 10.201.30.1 255.255.255.0
ip helper-address 10.201.61.51

interface vlan 161
ip address 10.201.61.1 255.255.255.0

interface vlan 162
ip address 10.201.62.1 255.255.255.0

interface Gi1/0/8
description TRUNK LINK TO WLC
switchport mode trunk
switchport nonegotiate

interface Gi1/0/23
description LINK TO AP-1
switchport mode access
switchport acess vlan 130

!********* SW2 config ***********
vlan 999 name NATIVE VLAN
vlan 126

interface vlan 126
ip address 10.201.26.1 255.255.255.0
ip helper-address 10.201.61.51

vlan 126
interface Gi1/0/23
description LINK TO AP-2
switchport mode access
switchport acess vlan 126

Any help for my problems will be much appreciated.

[Flavio Miranda]

Hello,

1. wireless clients can view both SSIDs from AP-1 but can't pick up IP addresses from the Linux DHCP server. When static IP addresses are used on the wireless clients, they successfully connect on the network. What could I be doing wrong?

 Does the WLC have connectivity to DHCP ?

- dynamic interface: 10.201.30.3/24

- gateway: 10.201.30.1

- DHCP server: 10.201.61.51

Your DHCP server is not on the same network as the WLC dynamic interface. Make sure this communication is ok.

Also, make sure DHCP server is working properly.

Take a look on the "CONTROLLER" tab and under "Advanced", confirm it "Enable DHCP Proxy" is enable.

2. how do I get AP-2 to broadcast the SSIDs because SW2 is the default gateway for that network area, and I am not too sure about the settings for WiFi-VLAN126!

What did you mean ? Does the AP-2 is not broadcasting any SSID?

[Tanyi]

Hello Flavio,

1. The WLC management interface communicates with the DHCP server through OSPF routing. The DHCP server has all the pools required as per the attached graphic topology.

Are you suggesting I try a "ping test" from the DHCP server IP address to the dynamic interfaces (e.g. 10.201.30.3 and 10.201.26.3) and vise versa?

On the other hand, I did not do ["CONTROLLER" tab and under "Advanced", confirm it "Enable DHCP Proxy" is enable.] which I will enable and verify.

2. I confirm AP-2 does not broadcast any SSID.

[Flavio Miranda]

For AP2 make sure you have it on the correct group, if you are using AP group. This could be problem to not advertising SSID.

 About DHCP keep in mind the Broadcast nature of DHCP transactions. Ping is the first step in the process but more then reachability, you need DHCP packets going back and forth. 

[Tanyi]

Hello Flavio,

I see enabling DHCP Proxy is suited if I want to use the WLC which is not the case. I would like to use the external DHCP server to assign IP addresses to the clients.

[Flavio Miranda]

Dhcp proxy is not for dhcp server on the wlc.

 This is for wlc act as dhcp client. The wlc receive clients dhcp request and instead toward this request to the dhcp server, it create a new dhcp request using its virtual IP as source. Then, when the dhcp reply, wlc forward the dhcp to client.

 From the client point of view, wlc is the server but it is not in fact. This is useful for security reason and when client can't reach dhcp server directly due network limitation.

Only enable it if you are sure about what is the better fit for you.

[Tanyi]

Hello Flavio,

I have not had access to the equipment in a while, but been doing a lot of reading and research.

If I were to "untagged" the management VLAN on the WLC, does the switch trunk port need the native vlan command?

example:

Management interface (0 = untagged): 0

Management IP: 10.201.62.3/25

Management GW: 10.201.62.1

interface Gi1/0/1

 description TRUNK TO WLC

 switchport mode trunk

 switchport trunk native vlan 162

On such a configuration, will I be able to access the WLC web interface from a PC on another VLAN? (considering routing is enabled) say VLAN 110 [10.201.110.1/24] 

[Flavio Miranda · Accepted solution]

Hi,

Providing that you had enable LAG on the WLC yes. 

You can let WLC as '0' Zero and put Native Vlan on the switch trank port or you can put the Management interface on VLAN 162 and do not use Native VLAN.

[ppure]

My case is little different ... please refer the diagram 

My AP is getting EIGRP routes injected for two gateways (Guest interfaces on two firewalls) to public internet for Guest SSID

AP is authenticating the clients but not issuing ip address i.e. DHCP lease to Guest SSID clients

There are other SSIDs on the AP which are working fine except Guest

When i shutdown the Guest WiFi interface on either firewall ... Guest SSID starts working fine

Any suggestion would be greatly appreciated 

Thank you