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Unable to get clients to pull DHCP addresses when using VLANs

chris.tenley
Level 1
Level 1

I am unable to get some of my clients to pull DHCP addresses when associated to my APs when I have VLANs configured on the APs. Once I delete the VLANs my clients can pull IPs, but when I put the VLANs back on they can not pull DHCP addresses. I an going to attach the AP configs in order to see if anyone out there can figure out what is going on. I can not seem to resolve this issue. Thanks for all you help!

1 Reply 1

s.vautour
Level 1
Level 1

Hello,

I had a quick glance and everything looks OK to me. Did you remember to setup the Native VLAN on your uplink switch to match the Native VLAN on the AP? Can you reach the AP over your mgmt VLAN? Remember that DHCP won't work until after your clients are properly associated. Are your clients showing up in the AP log or under "show dot as"? What is their associated state? Where is the DHCP server and do you you have the proper helper commands setup to forward your requests on? You can also try to setup a DHCP on the AP to see if it helps.

Here's a VLAN config I use on my APs that works for me. Some parts have been snipped out.

---------------------------------

interface Dot11Radio0

no ip address

no ip route-cache

!

encryption vlan 35 mode ciphers tkip

!

broadcast-key vlan 35 change 360

!

ssid SSIDNAME

vlan 35

authentication open eap eap_methods

authentication key-management wpa

guest-mode

!

interface Dot11Radio0.35

encapsulation dot1Q 35

no ip route-cache

bridge-group 2

bridge-group 2 subscriber-loop-control

bridge-group 2 block-unknown-source

no bridge-group 2 source-learning

no bridge-group 2 unicast-flooding

bridge-group 2 spanning-disabled

!

interface Dot11Radio0.1000

description mgmt VLAN

encapsulation dot1Q 1000 native

no ip route-cache

bridge-group 1

bridge-group 1 subscriber-loop-control

bridge-group 1 block-unknown-source

no bridge-group 1 source-learning

no bridge-group 1 unicast-flooding

bridge-group 1 spanning-disabled

!

interface FastEthernet0.35

description User VLAN

encapsulation dot1Q 35

no ip route-cache

bridge-group 2

no bridge-group 2 source-learning

bridge-group 2 spanning-disabled

!

interface FastEthernet0.1000

description MGMT VLAN

encapsulation dot1Q 1000 native

no ip route-cache

bridge-group 1

no bridge-group 1 source-learning

bridge-group 1 spanning-disabled

!

interface BVI1

description Mgmt interface

ip address x.x.x.98 255.255.255.224

no ip route-cache

!

ip default-gateway x.x.x.126

---------------------------------

I hope this helps.

Serge

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