DHCP over PPPoE

Glenn Satchell Glenn.Satchell at uniq.com.au
Thu Apr 27 12:42:21 UTC 2006


>From: JOBY THAMPAN <JOBYTHAMPAN at nestec.net>
>To: "'dhcp-users at isc.org'" <dhcp-users at isc.org>
>Cc: "'Glenn.Satchell at uniq.com.au'" <Glenn.Satchell at uniq.com.au>
>Subject: DHCP over PPPoE
>Date: Thu, 27 Apr 2006 14:19:35 +0530
>
>> Hi all ,
>> 
>> 	I have a setup like this
>> 	
>> 	Linux Machine 1
>> 	Eth0	-	DHCP Server
>> 
>> 
>> 	Linux Machine 2
>> 	Eth1	-	Got IP from DHCP Server
>> 	Eth0	-	PPPoE Server 
>> 	ppp0 Interface formed
>> 
>> 
>> 	Linux Machine 3
>> 	Eth0	-	PPPoE Client
>> 	Eth1	-	IP is 192.168.40.1
>> 	ppp0 Interface formed
>> 	Dhcp Relay is running on Linux Machine 3
>> 
>> 
>> 	Windows Machine 4
>> 	Expecting an IP of 192.168.40. after renewing the ip address of
>> windows machine
>> 
>> 	But there is no result
>> 	
>> 	Without PPPoE interfaces the windows machine is getting an ip in the
>> range 192.168.40.
>> 	
>> 	Wouldn't DHCP Protocol work over PPP Interface?
>> 
>> 	If any one knows, please reply.
>> 
>> Rgds
>> Joby

So the dhcrelay is forwarding the requests across the PPPOE link. That
should work, but maybe it isn't hearing the responses from the dhcp
server because the dhcrelay isn't listening on the ppp0 interface?

When you start dhcrelay which interfaces does it say it is listening
on? I bet ppp0 is not on that list. Listening on eth0 is no good as
dhcrelay doesn't know how to unencapsulate the ppp packets.

Perhaps running a packet sniffer on the ppp0 interface might show you
what traffic is there?

An alternative might be to run dhcrelay on a different linux box on the
192.168.40 subnet (if there is one). It doesn't have to run on the
gateway device.

regards,
-glenn



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