DHCP Forwarding

[raceman3]

I have two ethernet interfaces and a HSSI configured as follows:

int gig0/0
ip address 10.28.3.1
ip helper-address 10.30.1.2

int gig0/1
ip address 10.28.4.1
ip helper-address 10.30.1.2

int hssi1/0
ip address 10.30.1.2
ip helper-address 10.30.1.1 (other side of the wan)

Am I missing anything or is that all I need to forward dhcp requests from the Ethernet segments out across the WAN?

What show command will display the stats for dhcp forwarding?

 

[ADB100]

You only need to apply the IP Helper on the interface where the DHCP Clients are. You should configure the IP Helper to be your DHCP servers IP address (you can have multiple IP Helpers configured) or an IP Network Broadcast address such as 192.168.100.255.
It is not needed on the Interface where the DHCP Server is.
It is normally only used on WAN's for Auto-Install.

HTH

Andy

 

[raceman3]

The DHCP clients are on the Ethernet segments but the DHCP servers are on the other side of the WAN and not on the same subnet as the WAN router. I didn't think the WAN would forward the broadcast without using IP Helper command to process it the whole way through?

 

[ADB100]

The router effectively converts the Broadcast packet into a Unicast packet and adds in the IP address of the interface it was received on. Once it is a Unicast packet the WAN routers will just forward it like any other unicast packet.

http://www.ciscopress.com/articles/article.asp?p=330807&seqNum=9&rl=1

HTH

Andy

 

[raceman3]

Thanks for the clarification