pppoe and ethernet connections

[adc_raptor]

Hello,

I'm having a problem with keeping up and functional a pppoe connection and an ethernet one at the same time. I'm in a private network and I use pppoe to access the internet. At first I used Network Manager to manage my connections but when I connected to the pppoe one the ethernet connection was automaticly closed. Even though my internet connection was working fine I couldn't access the private network anymore.
Next I tried to bypass the Network Manager and decided to manually start and manage the two connections. They seem to be working fine up to a point when the pppoe connection stops working. The connection is still up but I cannot access the internet anymore. After I manually close and and restart the pppoe connection it works fine. Untill the same thing happens.
At the moment I am using Ubuntu 8.10 but I had this problem in Fedora Core 9 too.

Does anybody have an idea why this is happening? I'm preety sure that this problem is related to the way pppoe connection works in general, but I haven't found an answer till now. Maybe I'm just google-ing the wrong thing.

Edit: I forgot to mention that the computers that have Windows do not have this problem and a friend of mine that also had Fedora Core had this problem too.

[D-cat]

Is this computer connected directly to the Internet or do you have a router? I'm just curious. PPPoE is supposed to work OVER an established Ethernet connection, so to have it interfere with the connection to me makes no sense, and further this is a common problem? Sounds like something's broken on a fundamental level.

Anyway, my less than ideal solution is to put a cheap router that supports PPPoE natively (most do) between your computer and your ISP connection.

[adc_raptor]

My computer is one of the many from the network. It does not connect dirrectly to the internet but connects through a main server using NAT. PPPoE should work over an Ethernet connection. It's just that when Network manager activates the PPPoE connection(ppp0) the previous connection(eth0) is automaticly closed.

[D-cat]

Is the NAT server serving remote (as in ISDN, DSL or Dial-in) connections, as in it answers the phone? I can think of no other reason you would set up a client to use PPPoE served via NAT. In fact, if you're tunneling through a NAT, any of your other clients could be responsible for disconnecting you even after you get one working.

Typically in a home or small office, you'd only have the server dealing with the PPPoE and you'd gateway (not tunnel) through the server. It might also give you an opportunity to serve a cache proxy as well for attempted network performance upgrade (just an idea). The only thing any client should see is an ethernet connection to an Internet gateway.

[adc_raptor]

I'm not entirely sure about this but I think it's serving DSL connections.

[D-cat]

I'm going to guess then that you are not a server admin. Is this server physically located in your building (not that I have a solution, but that might have some effect on if a solution is possible)?

If you're trapped using the current method, I really don't know what to tell you. PPPoE is in my opinion the wrong way to do authentication over a LAN, it's really just a workaround solution for remote ISP authentication where an intermittent connection is present at the end point and therefore you may not have the luxury of an IP address at first. This is ideal for wired severable remote connections like DSL, but adds a layer of complexity for LAN. The server's setup also plays a role in this (as in allowing multiple logins or not; if it doesn't, any connection you make will get booted as soon as another client makes a connection with the same account).

Resolving this one may require a discussion with whoever administers the server. I don't know if they will be willing to help you or not, but I'm pretty much at the end of my knowledge of this subject.

[adc_raptor]

No I am not the server admin. If I would have been I wouldn't have chosen pppoe eiher. The network is on the university campus and the server isn't in my building.
There isn't a problem with multiple logins since we each have an username and a password.
Thank you very much for your help. I have already contacted the admins but I'm not entirely sure about their capabilities.

[D-cat]

I still think a cheap router with a built-in PPPoE client would work, a Linksys wired only one isn't too expensive (you'd want to go wired on a campus anyway, most have a "no wireless" clause in their TAC).