I have two routers (routerA and routeurB)
RouterA has one LAN interface, one serial link towards routerB.
The latter (routerB) has, apart the serial link with routerA, two LAN interfaces : fa0/0 fa0/1.
A DHCP server is on the subnet of fa0/1
My question is about how to use the ip helper command to help people on routerA's LAN interface to go the DHCP server via its serial link.
on routerA's fa0/0 : ip-helper DHCP_IP_ADDRESS.
but before reaching the DHCP server, the UDP broadcasting packet must pass through the serial link.
Does routerB needs no to advertise its serial interface with the ip-helper command also ?
Or routerA encapsulated directly the packet to reach the DHCP server ?
Here's what i think the packet should look like (in my opinion, it won't be a new broadcasting causing routerB use ip helper on its serial int)
IP sender : routerA's IP
IP destination : DHCP'IP
MAC sender : routerA's
MAC destination : routerB's
and the DATA will inform the DHCP server the host which is trying to get an IP by putting it's MAC associated with the IP 0.0.0.0