cisco wireless controller having dhcp problems across vlans. 1

[jm9776]

I have job of setting up a cisco 4400 wireless controller on our network. The network consist of cisco 3750 gig switches performing the layer 3 routing. I have a dl320 as the DC giving out dns and dhcp for two networks( w/dns entry for controller). the data network is x.x.10.0 and the wireless network is x.x.20.0.

The switches have the vlan interfaces setup (and are pingable) The wireless controller is on the .20 net and the dhcp server is on the .10 network. The problem is the AP's will not get a dhcp address for the .20 net. The server switch port is setup for the two vlans and is a trunk port along with the controller. The ap port's are set for vlan access for .20 net. It seems like i am having a vlan issue.

If i set all of it up on one network all work fine. Somewhere i am missing step and could use some help.

 

[ADB100]

There are 2 things that need to be setup:

1. IP Helpers need adding to the VLAN interfaces that don't have a DHCP connected directly to point to the DHCP Servers (you can add multiple helpers for resilience):

interface Vlan 20
 description Wireless VLAN
 ip address 10.10.20.254 255.255.255.0
 ip helper-address 10.10.10.1

2. DHCP Server needs to provide Option 43 to the AP's to inform them where the Wireless Controller is.

http://www.cisco.com/en/US/products...stallation_guide_chapter09186a0080799c21.html

Appendix A on the following link shows how to configure Windows DHCP with the correct Vendor Classes to support the LWAPP AP's. The previous link shows the correct Vendor Class Identifiers sent by each different AP type.

http://www.cisco.com/en/US/products/hw/wireless/ps430/prod_technical_reference09186a00804fc3dc.html

I would also restrict the UDP broadcast forwarding to only allow BOOTP/DHCP as by default unnecessary broadcasts are also forwarded; add this global configuration:

no ip forward-protocol udp tftp
no ip forward-protocol udp nameserver
no ip forward-protocol udp domain
no ip forward-protocol udp time
no ip forward-protocol udp netbios-ns
no ip forward-protocol udp netbios-dgm
no ip forward-protocol udp tacacs

HTH

Andy