DHCP FORWARD

gcocchi · ‎07-14-2004

Hi.

My CAT4006 connect many remote offices with pair of 26xx router and serials point-to-point line.

How can i permit remote offices pc clients to receive dhcp address form servers on CAT4006 LAN?

I tried to exec ip forward-protocol udp bootpc on each router but nothing.

Any hints?

Thx.

Georg Pauwen · ‎07-14-2004

Hello,

in addition to the 'ip forward-protocol udp bootpc' command, you also need the command:

ip helper-address X.X.X.X

where X.X.X.X is the IP address of the DHCP server.

HTH,

GP

gcocchi · ‎07-14-2004

I need to issue this command on remote 26xx, or on 2 routers and switch?

ymj · ‎07-15-2004

You need to issue this command on every (Layer3) interface behind which your DHCP clients are connected.

Example:

So if you want DHCP clients in subnet 10.1.1.0/24 to be able to use a remote DHCP server you have to do like this

interface vlan xx

ip address 10.1.1.1 255.255.255.0

ip helper-address

You dont have to issue

ip forward-protocol udp bootpc

because it's on by default.

BUT, many other protocol are on by default (such as NetBIOS over TCP/IP UDP/137 UDP/138 ...)

They'll be forwarded if related packets are broadcast.

and you may want to prevent such broadcast from being forwarded, possibly loading the path between the local router and the DHCP server.

So disable them with

no ip forward-protocol udp xxx