I administer a small network for a cab company, and have lately been battling an internal connectivity problem for the last several days. It seems that 2 of the 5 computers on the LAN intermittently “drop” connection without losing their IP addresses. If I disable the network connection on the “dropped” machine, and then immediately re-enable it, it seems to work for anywhere from 5 minutes to a couple of hours, then “drops” again. All LAN IP addresses are configured manually. I’ve posted an image of the network map at http://www.geekcavecreations.com/images/network_map.gif to illustrate how the LAN is arranged.
The local network has 2 computers that connect to the internet through the DSL router, one for ICS, and the other has an external web server (neither one has connectivity problems).
One computer on the LAN has an internal web server that handles our dispatch program. All computers on the network need to be able to access this box.
The dispatch client has to access the dispatch server, but can’t have internet access. It’s blocked from the internet through the simple expedient of not having an external DNS server assignment.
Now, for the meat of the problem. I’ve checked and re-checked the configurations for both the dispatch server and the dispatch client, and find no problems. Both have the most recent drivers for the network cards, and both have new cables. I’ve swapped out a known good hub for the LAN, and have made sure that there are no mis-configured hosts files. As outlined previously, disabling and enabling the NIC on the offending machine will restore connectivity for a while. I’ve checked each machine for an overheating problem, just in case, and find no trouble there. All machines are running XP Pro.
I can’t shake the feeling that I’m missing something basic and simple, but I’m at a loss as to what that might be. Any suggestions?