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New Member

Can not use external DHCP Service for Guest-WLAN at remote WLC


i have a common scenario

Location-Branch-WLC1-------------WAN/EoIP----------Location Headquarter-WLC2(Anchor in DMZ)----Internet

Software on WLC is 7.0.230

WLC is Model 2504 or 5508 in branch offices and 4404 in Headquarter.

Access Points are AIR-CAP3502i.


All WLAN Guests should get ClientIP from an external Microsoft DHCP Server that is in the Headquarter (where WLC2 is implemented), no matter in which location the wlan guest is associated to the guest SSID.

What works:

Access Points that are connected to WLC2 directly, CAN provide IPs to wlan guest clients from external DHCP (DHCP Relay on WLC 2 is enabled).

Guests in the branch office only get DHCP IP-address in guest wlan when the dhcp service and scope is configured directly on the WLC2 (anchor controller).

What does not work:

Access Points that are connected to WLC1 in the branch office can NOT deliver IPs to wlan guest clients from the external DHCP, but only from DHCP Service that is configured locally on WLC2 (Anchor Controller).

Is it possible - and if yes, HOW, that ALL WLAN Guests get IPs from the same IP Network, and from an external DHCP?

The reasons for this..1. the dhcp on WLC sometimes crashes and have to reboot the WLC 2. i want to manage the guest IP scope on one dhcp and not split the client ip pool onto several wlan controller dhcp services

Everyone's tags (5)
VIP Purple

Re: Can not use external DHCP Service for Guest-WLAN at remote W

Yes, this is possible & one of the common way of deploying it.

Have you enabled DHCP proxy on your controllers (in GUI Controllers -> Advanced -> DHCP -> DHCP Proxy) ?

Also SSID configuration should be identical in your foreign controllers & anchor controller except the interface it is mapped to.

You can take a "debug client " output of your anchor controller to see what's happening with client DHCP request. Below post (based on code) may help you as well



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New Member

Re: Can not use external DHCP Service for Guest-WLAN at remote W

Hello bro,

yeah dhcp relay on wlc is functional.
The ssid settings are also 100% same. EoIP Tunnel is up and funtional.

The remote wlan guests GET an IP from the anchor controller local dhcp service successfully - but the anchor controller will not pass dhcp discovers from wlan guests which are associated to access points which are connected to remote wlan controllers to an external dhcp.That means - remote wlan guest dhcp discover packets REACH the anchor controller via the EoIP connection, but for some reson the anchor controller wont relay these dhcp discover packets to the external dhcp server. Thats the question - why the anchor controller wont relay dhcp requests from wlan guests from branch offices.

The anchor controller only relays dhcp discover packets from wlan guests who are associated to access points which are connected directly to anchor controller, not remote wlan controllers in branch offices.

Will check debug output. Thanks for your support...