eth1 goes to sleep when tired

[Rashkae]

Dave Stevens wrote:
> Hi,
> 
> I have a little 2P server with 2 ports, eth0 and eth1. eth1 is  
> connected to a router and dsl service it shares with other computers.  
> It works fine. I need a faster dsl service so I have a different ISP's  
> dsl modem connected to eth1. eth1 is connected to a ubuntu 10.04.1  
> instance running apache2 to serve pages for a custon on-line service.  
> Everything works fine for a while and whenever we are using the eth1  
> service, but when we stop using it, the eth1 port somehow shuts down,  
> no outside access is possible through ssh or the web. But if I tunnel  
> in through the other port (eth0) and ping the outside world, or do a  
> traceroute, then all of a sudden the access from outside is restored.
> 

Is eth1 connected directly to a modem, or one of these pervasive 
'modem/router' combos?  In particular, did you have to configure PPPoE 
on the server to achieve that connection? (In ubuntu, I believe, you 
would use pppoeconf.)  Since this is a server connection, you don't want 
it managed to network manager, which is only meant to be used as client 
connections, and I have no idea how it would mangle a PPP connection.