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EviLBoX 10-16-2006 01:18 PM

Losing Connectivity
I have a server running Fedora Core 4 and have assigned it a static IP address. I have placed the server in two different networks and made the necessary IP address changes for each of the networks. On one of the networks I have no problem with the server whatsoever, but on the other I'm having an issue. If I ping the server using its external IP address I get a lot of packet loss, up to 23%. After a while I'll get "Request Timed Out" for about 10-15 seconds then the server comes back and works fine. Whenever I ssh into the server as well, I lose connection after 5-10 minutes of being in the server, then after 10-15 seconds I am able to reconnect. I have a network admin who has done several ping tests and he said the problem appears to be with the server, but I don't see how it could be since the server works fine on the other network. Anyone have any idea what could be causing this?


kvedaa 10-16-2006 01:56 PM

Well, there are several possible problems, but my past experience has told me that the physical layer is one of the most likely culprits. I would first check to make sure that the Ethernet cable connected to the server (on the interface that you are pinging) is firmly connected both to the server, as well as to the switch (or other network device that it may be connected to).

If the problem persist I would suggest trying another known good cable. And finally I would consider trying to make use of another network card.

Only if you clear all of these steps, would I suggest delving into the software side of the equation.

Happy Hunting!

EviLBoX 10-16-2006 02:05 PM

We have tried 2 different cables, but have had the same results. As for the network card, it's built into the motherboard so I haven't tried a new one, but how could that be the issue if it works on one of the networks, but not the other?

kvedaa 10-16-2006 02:10 PM

My apologizes for not reading close enough to your description.

But please allow me to back step a moment and ask for clarification. When you say that you are on two separate networks, do you mean that you have multi-homed the interface and are talking to both networks at once? Or are you manually moving the system from one network to another and changing the configuration as the system is moved?

EviLBoX 10-16-2006 02:18 PM

I'm manually moving the system from one network to another.

kvedaa 10-16-2006 02:38 PM

OK, we are moving from one network to another, follow up question, does this change envolve connecting to a diffrent hub/switch/etc or is this simply a change of network settings with both networks running over the same hardware?

If possible (and assuming that you are running in private address space, so that you will not be giving up much useful netowrk information, if real address, feel free to replace the last two octets with *s) could you run a traceroute from your workstation to this server from both the 'good' network and the 'bad' network, so that we can get a better feel for how the bits are heading down the wire.

Happy Hunting!

prasanta 10-17-2006 01:28 AM


Originally Posted by EviLBoX
As for the network card, it's built into the motherboard so

Cables might not be the problem. I faced the same problem with an onboard network card, which I later found out to be faulty. Just check that with another network card.


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