Cisco WLC9800 DHCP Configuration Needed

[King_1988]

We have newly deployed WLC-9800-L but now we are getting DHCP ip from WLC. But clients want DHCP should be thrown from router. What configuration is needed to make this happen in WLC? Should we configure relay?  

[jagan.chowdam]

Refer the following config guide

https://www.cisco.com/c/en/us/td/docs/wireless/controller/9800/config-guide/b_wl_16_10_cg/dhcp-for-wlans.html

External DHCP Servers

The operating system is designed to appear as a DHCP relay to the network and as a DHCP server to clients with industry-standard external DHCP servers that support DHCP Relay, which means that each controller appears as a DHCP relay agent to the DHCP server, and as a DHCP server in the virtual IP address to wireless clients.

Because the controller captures the client IP address that is obtained from a DHCP server, it maintains the same IP address for that client during intra controller, inter controller, and inter-subnet client roaming.

CJ

[Rasika Nayanajith]

It looks like you have configure SVI for client vlan on 9800. You only required WLC management SVI on 9800 and no other SVI for client vlan. (like L2 switch, you only need L2 vlans define on 9800 for client vlans).

In that way you always point to upstream switch for gateway, So DHCP broadcast will not responded by 9800

HTH
Rasika
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[King_1988]

Thanks. Yes, I have actually configured SVI for all vlans. I have made trunk with upstream L3 switch and passed all vlan via trunk port. So, no SVI is needed for service vlans, right? Is there any more configuration rather than removing the SVI? It would be better if you can provide any sample config.

[Flavio Miranda]

Hi @King_1988 

   If the WLC have a interface vlan configured for those clients. you need to add relay.  If only layer2 then you need to make sure that the DHCP will get to the router by using the vlan. 

[King_1988]

Can you have any sample configuration?

[Rich R]

There is no configuration required on the WLC.  You simply use whatever config you would normally use on the router or switch - same as you would for LAN connected users.  The WLC simply forwards the packets onto the VLAN at layer 2 - all layer 3 functions (including the DHCP are handled by your next hop device (eg router) in the normal way.