DHCP off router, do you still need helper?

[Joe Lentine]

                   Hello all,

I have setup a 4500 series core/router.. the customer decided to run dhcp off the router for whatever reason... I have 20 different scopes handing out to their vlans... Does each vlan interface need an helper address?

vlan 1 on router is 10.85.0.1

i used the ip dhcp-server command pointed to 10.85.0.1

and then for ex.

int vlan 20

ip add 10.85.20.1 255.255.248.0   

ip helper-address 10.85.0.1

i am now getting a loopback error on the router, and i believe this is the cause...

any help would be great..

thanks!

[Raju Sekharan · Accepted solution]

Hi

If this router is acting as DHCP server, then there is no need of "IP helper-address" command

Thanks

Raju

[Nagendra Kumar Nainar]

Joe,

From your configuration, it appears that you have "ip dhcp-server <>" which is not your local box. In this case, you need "ip helper-address <>" under the respective interface (where dhcp clients are connected).

Basically, you need this command to have the router act as a kind of relay router to unicast the dhcp req to server and relay the address to client.

-Nagendra