Cisco WLAN Controller not pushing out DHCP addresses, what else could it be?

[nLinked]

On our Cisco WLAN Controller web interfaces, in Controller > Interfaces, I have made a new interface with these settings:

VLAN Identifier 202
IP Address 172.16.202.1
Netmask 255.255.255.0
Gateway 172.16.202.254
Primary DHCP Server 172.16.100.3
Secondary DHCP Server 172.16.100.2
Port: LAG

I've also made a new WLAN and assigned it to the above interface. I have saved changes. But our wireless devices, although they seem to authenticate with the WLAN fine, they always get stuck on "obtaining DHCP address", so it seems the WLAN Controller isn't pushing out DHCP addresses to our devices.

We do have a DHCP scope for the above in Windows Server 2008 R2 and everything there seems fine.

If I connect a device with a static address (e.g. 172.16.202.10), it will connect. Stuck on what to do

[paulfinlay]

you will need to add an ip-helper address to VLAN202 on whichever devices is doing the routing in your network. As it stands VLAN202 has no way of sending the DHCP requests to a server in the other VLAN.

[nLinked]

Thanks for your reply. We do seem to have that in our config below:

interface Vlan202
description WIRELESS_TABLETS
ip address 172.16.202.253 255.255.255.0
ip helper-address 172.16.100.1
ip helper-address 172.16.100.2
ip helper-address 172.16.100.3
ip helper-address 172.16.100.40
ip helper-address 172.16.100.44
ip pim dense-mode
standby priority 110
standby name WIRELESS_TABLETS
standby 202 ip 172.16.202.254
standby 202 priority 105
standby 202 preempt




We also have:

interface GigabitEthernet11/5
description ***WiSM_1_WLC1***
switchport
switchport trunk encapsulation dot1q
switchport mode trunk
no ip address
no snmp trap link-status
no cdp enable
channel-group 202 mode on
!
interface GigabitEthernet11/6
description ***WiSM_1_WLC1***
switchport
switchport trunk encapsulation dot1q
switchport mode trunk
no ip address
no snmp trap link-status
no cdp enable
channel-group 202 mode on
!
interface GigabitEthernet11/7
description ***WiSM_1_WLC1***
switchport
switchport trunk encapsulation dot1q
switchport mode trunk
no ip address
no snmp trap link-status
no cdp enable
channel-group 202 mode on
!
interface GigabitEthernet11/8
description ***WiSM_1_WLC1***
switchport
switchport trunk encapsulation dot1q
switchport mode trunk
no ip address
no snmp trap link-status
no cdp enable
channel-group 202 mode on




That all looks right to me unless I'm mistaken?

I have noticed we have the following for another VLAN but not for VLAN 202. Do you think we'll need it for 202 too?:

interface GigabitEthernet11/9
switchport
switchport access vlan 201
switchport mode access
no ip address
no snmp trap link-status
no cdp enable

[glennda]

I have a feeling with Cisco controller there is two places to set the DHCP server, with one being a global setting which affects all of the ssid's, I may be wrong.

[paulfinlay]

from the wireless device with the static IP can you ping the DHCP server?

[nLinked]

from the wireless device with the static IP can you ping the DHCP server?

OK just tried this and although it connects to wifi fine with the static IP, pings are failing to the DHCP server (the DHCP server does accept pings normally and I can ping it from a wired workstation fine).

[paulfinlay]

sounds like VLAN202 isn't fully connected across the network. You need to try and trace where it's failing, i'd start by pinging 172.16.202.254 from the DHCP server to ensure routing is working, then try pinging the controller interface 172.16.202.1 from both the DHCP server and then the static client.

[nLinked]

Thanks, you're right, none of those pings are successful! None.

[nLinked]

On the Cisco switch if I do show ip route, I can immediately see all the VLANs in a list but not the 202 one. This must be the problem so it's probably a routing issue as you say. But I thought we did add the VLAN. Going to have to look at commands for getting our 202 vlan into there...

[nLinked]

Thanks all for your replies. We've managed to fix it, it was related to the VLAN not appearing when doing show ip route.

The solution was to create the VLAN in this way:

switch# configure terminal
switch(config)# vlan 202
switch(config-vlan)# name wirelesstablets
switch(config-vlan)# state active
switch(config-vlan)# no shutdown
show ip route (to confirm)