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New Member

External DHCP

I have a 2610 with a NM-16-AM module and I have a external DHCP server, what I have to do in order the remote user gets it´s own address and configuration from the external DHCP (server)?

If you can help with a configuration sample!

New Member

Re: External DHCP


if your DHCP server is not in the same segment with clients, you have to put "ip helper-address a.b.c.d" command under your ethernet interface (which is the default gateway for clients). a.b.c.d is DHCP server address, so router can forward DHCP requests to DHCP server. Otherwise DHCP request stays in the clients' segment. because that's a broadcast packet.and routers don't forward broadcasts through itself.

hope this helps..

for example;

interface Fa0/1 ---> the clients gateway-interface

ip address

ip helper-address ---> DHCP server address

New Member

Re: External DHCP

So if I configure the router only for access via ppp (remote users) they will get it´s configuration with the external DHCP Server using the ip-helper address?

I mean IP address, wins´ server ip address, dns ip address!


New Member

Re: External DHCP


ip-helper is used to change the DHCP broadcast to a unicast to the DHCP server. So clients on a separate subnet can reach the DHCP server.

For using DHCP with PPP you have to configure your PPP setup in such way the router will retrieve the ip adresses for the ppp clients from the DHCP server. To do this setup the DHCP server in global config mode:

router(config)#ip dhcp-server

And define it on the interface:

router(config-if)#peer default ip address pool dhcp