Hi everyone.
We have 5 servers here, linked to 5 buildings across the site. Each building has a network switch which uplinks back to the main network switch in the server room. All of a sudden, all PCs in one of the buildings cannot access our file server, which also runs MS Exchange. These PCs can however access the resources on the other 5 servers. The strange thing is there is only one uplink cable (fibre) between this building and the server room, so the cable uplink IS working because if it wasn't, the PCs wouldn't be able to access the resources on the other 4 servers. I have made no changes that could have made this happen, so I really do not know why this is occurring. The server they can't connect to is a Windows Server 2003 R2 server. We have another 2 servers with the same OS on which are fine, and the other 2 servers run Windows Server 2008. The PCs are running Windows XP. This was all working a week ago, so I do not know why this has suddenly happened.
This is what I have tried so far, none of which has changed the situation.
1. Changed the switch in the problem building for another.
2. Tried a different port on the new and old switch for the fibre patch cables.
3. Changed the port the server uses on the main network switch.
4. Re-started all switches by turning the power off and back on.
5. Re-started all the servers.
6. Took a machine from a part of the site that is fine, plugged it into the switch in the problem building. But then this machine has the same problem. Back in it's normal "home" it is fine again.
7. On one of the problem machines I released the IP settings using ipconfig, deleted it's DHCP lease in DHCP and then restarted the machine. Same problem again.
For all the world it appears to be a configuration or software issue on the "problem" server, because the uplink cable back to the main network switch is clearing working. But what the problem is I don't know.
Here is a link to a "crude" network diagram showing the setup - http://www.ldbsa.co.uk/images/net_setup.png
The computers in the building on the left in the picture are able to access 4 of the 5 servers in the server room, but not the fifth. The other 4 buildings on the site are able to connect to everything without any problems at all.
Does anybody have any suggestions?