Do you mean that you're trying to get your linux server to be the DHCP server for your VSCs, without the controller?
For the linux server to be the DHCP server for all VSCs, bypass the controller's DHCP altogether. Each VSC goes into its own VLAN, like this:
Controller:
- Set the Controller to Controller >> Network >> Address allocation >> DHCP Services: None.
- Define a VLAN for each VSC (Controller >> Network >> Network profiles)
- Bind each VSC to its VLAN profile as an egress network (Controlled APs >> Default Group >> VSC bindings).
Wired network:
- For every AP, put the AP switch port into all the VSC VLANs.
- For every VLAN, add an ip-helper address in the VLAN's IP interface pointing to your linux DHCP server.
- Make sure the routing between the VLAN IP interface and the DHCP server works.
- Make sure your Linux server has a DHCP scope defined for each VSC subnet.
The AP will tag DHCP Discover frames from each VSCs' wireless clients with the VLAN ID for that VSC. The IP interface for that VLAN will convert the broadcast into unicast with its own source address, then will forward the DHCP Discover to the DHCP server. Then the rest of the DHCP relay process (discover, offer, request, ack) proceeds.
So in this scenario, DHCP for VSCs is handled entirely by the wired network, and not at all by the Controller. (However, I can't get this to work with access-controlled VSCs -- that is, it works TOO well, since traffic bypasses the controller, and for HTML-based authentication I can't get the splash page to come up.) But if that's what you want, that's how!
thanks,
noemi