Connection problem

[Hightower]

We have a Jana Proxy server here which has been working fine, but have just been told by music that they can't connect to the internet.

 

Logged on, can ping every server BUT the proxy server from music. Can ping EVERY server from other machines on the network.

 

What is so special about music that it can't see the proxy, but can see other servers?

[jamesb]

What does an NSLookup give you on the proxy from music, and from other stations in the school?

[Hightower]

NSLookup seems fine.

 

When trying to ping from music machines to proxy it successfully does the lookup (obviously gets this from the DNS server) but it can't talk to the proxy server once it has resolved the name.

 

The proxy server can ping every other machine but when trying to ping a music machine it can't talk to it either.

 

Music is at the far end of the school, running from its own little switch. I'm starting to think a switch problem but can't see how/why?

[jamesb]

NSLookup seems fine.

 

When trying to ping from music machines to proxy it successfully does the lookup (obviously gets this from the DNS server) but it can't talk to the proxy server once it has resolved the name.

 

The proxy server can ping every other machine but when trying to ping a music machine it can't talk to it either.

 

Music is at the far end of the school, running from its own little switch. I'm starting to think a switch problem but can't see how/why?

 

Try a tracert to the server.

 

Its actually sounding like a problem I hit while in a private school. We had fibre-optic connecting each building, with the art department passing through four buildings on the way to the server room. This was passing straight through, rather than going through switches, and couldn't communicate with servers in the server room, although it could with other computers on the network.

 

Eventually we worked out that the dB loss was increasing with each pass through it made. When talking to the servers the switch was trying to be smart and route directly to the server room. When talking to other stations it was routing through its second fibre connection, to a switch in the next building.

 

The dB loss to the server room was killing any packets going through to there. Eventually it was fixed by just taking out the direct link and resetting the switches.

 

May or may not be relevant to your case. How is the music room connected to everything else?

[Hightower]

I don't think this is the same, as the machines can talk to the servers which are plugged into the same swicth as the proxy.

 

I've attached a (very cruddy) diagram of how things are linked.

[jamesb]

For a bit of troubleshooting, can you get one of the machines either plugged into a different switch, or bypass the switch entirely and see if it makes a difference? That should at least eliminate the switch as the problem, or confirm it.

 

Alternatively see if a laptop plugged into the switch has the same problem.

 

Edit: Any error logs on the clients, or the server?

Edited February 2, 2009 by jamesb

[Hightower]

Going to do that now - will get back to you soon.

[Hightower]

Laptop can't connect to proxy server from down music, but can from anywhere else.

[jamesb]

Laptop can't connect to proxy server from down music, but can from anywhere else.

 

Looks like its the switch then.

 

You could try resetting it, which I suspect you've already done, or replacing it if you've got a spare.

 

Is it a managed switch at all? Could it be preventing traffic from reaching that particular IP address?

 

As a random thought, are the clients, the proxy server and the switch using the same subnet mask, and if so are they all on the same net per that mask?

[Newton]

Is it a switch you log into and ping the proxy from the switch?