WLC 2504, APs in local mode, DHCP proxy required ?

[Clem58]

Hello,

We have a WLC 2504 with APs in local mode, on management interface we have a DHCP server indicated, and on WLAN interfaces we have also a DHCP server indicated, but not the same than for management interface. There is also one virtual interface with only 1.1.1.1 IP.

The APs trunk switch ports are configured as Trunk and native vlan same than the WLC management interface one.

The core switch has VLANs defined, and there is a dhcp-helper configured already.

My question : do we need to indicate DHCP servers (proxy) in WLC interfaces level, while we have already dhcp-helper indicated on the VLAN config at the Core switch level ?

Thanks by advance for your help, it's a bit confused for me.

[Scott Fella · Accepted solution]

If you are using ip helpers, then do not configure dhcp proxy. Dhcp proxy is really if you don’t have ip helpers or no way for clients to discover the dhcp server and or override exiting dhcp servers for testing.

[Clem58]

Many thanks for your answer Scott, so do I just need to remove the DHCP IPs on interfaces, or do I also need to disable DHCP Proxy feature ?

[Scott Fella]

If you have ip helpers on your infrastructure, then disable dhcp proxy and also get rid of the dhcp server ip address on the interface.

[Scott Fella]

Here is a good read: http://what-when-how.com/deploying-and-troubleshooting-cisco-wireless-lan-controllers/dhcp-proxy-vs-dhcp-bridging-cisco-wireless-lan-controllers/

[Clem58]

Thanks Scott for your help.

[Clem58]

Disabling DHCP proxy has solved a lot of issue with our scanners disconnections, + a conflict with a scope and WLAN interface IP.

We have also another controller, that is in Flexconnect mode with local switching for LWAPP, on this controller we have around 300 APs, and DHCP Proxy is activated. In Flexconnect mode is DHCP proxy enabled also impacting DHCP IP addresses assignment ? I mean, on every sites we have DHCP helpers defined on Core switch level, and we certainly don't need the DHCP Proxy. But as we don't have WLAN interfaces on flexconnect mode but only a management one, is the DHCP Proxy really used ?

[Scott Fella]

It is not. You shouldn’t use dhcp proxy unless you want the wlc to issue dhcp. That is the only reason I would have that enabled. Anytime you have an external dhcp server with up helpers, never turn that on.

[Clem58]

Thanks Scott !