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Here is the sceneiro:

PC --- 827 --- DSLAM --- 3660

If the 3660 serves as the ip pool, the PC can initialize a PPPoE session to it and get an ip address, using the command 'peer default ip pool pool-name'. However, if the 3660 was configured to direct the DHCP request to a W2K DHCP server, using 'peer default ip dhcp' and 'ip dhcp-server', the PC cannot get an ip. Running debug on 3660 shows that it doesn't send any packet to the DHCP server.

Should I use the command 'ip helper-address' on 827 for the PC to get an ip from the DHCP server?

What's the difference between the mechanism of getting ip address using 'ip helper-address' and 'peer default ip dhcp'?

Cisco Employee

Re: DHCP over PPPoE

You need to use the "ip helper-address x.x.x.x" command under the interface on 3660 over which it can reach the dhcp server with ip x.x.x.x...By default router will not forward broadcast on its interfaces..The ip helper address command enables BOOTP broadcast forwarding for to a dhcp server's ip address...

Pl. make sure that you can ping the dhcp server from 3660 and enter the "ip helper-address x.x.x.x" command under that interface over which dhcp server is reachable..To know whats wrong during session..We need to to get the following debug for a session

debug ppp negotiation

debug dhcp

debug dhcp detail

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