clients lose network connection at random times

[jheyrman]

We have a strange network problem on our LAN.

At certain times (randomly) our network clients seem to lose their network connection to a server, when this occurs they can't connect to one server but are still able to connect to other servers.
This results in many strange things and errors.

"Disk or network error" (MS-Access)
"Cannot save document you must select another file name" (MS-Word en MS-Excell)
"The file is in use by another user… " (MS-Excell)

We have the impression that the problem exists more when network traffic is low.
As a result of this we started pinging the servers every second from a client PC connected to the same switch as the servers. And we discovered that when this error occurs the server in question gives no replies on the ping command. (Sometimes for more than 15 seconds and this happens about 20 times a day)

We discovered now that when we open PcAnywhere sessions to the servers the problem disappears.
The server consoles need to be unlocked and the CPU monitor needs to be visible (to send more data over the PcAnywhere session).
When the sessions are open the servers can respond to the ping command at all times and the clients don't lose their network connections to the servers anymore. When we keep the servers very busy (CPU and LAN) then the clients also seem to keep their connections alive.

Does anyone know of this phenomena or knows a solution?


Here are some specs of the things we have.

Servers:
Poweredge 1300 WinNT 4.0 SP6a (with Intel pro 10/100 LAN card)
Poweredge 4200 WinNT 4.0 SP6a (with 3com 3c980 server LAN card)
Poweredge 2500 WinNT 4.0 SP6a (with Intel 8255xx-based 10/100 LAN card)

Network:
Cisco Ethernet switch model 3524
All servers are connected to this switch and they negotiate 100Mbit Full Duplex.

Things we already tested but didn't help:
We tested with other switches (baystack, 3com) and hubs (Intel)
We changed the cabling.
Forced the auto-negotiation to 100/full 100/half 10/full 10/half
Other network cards (in clients and servers)
Checked out the temp directories on clients (MS KB: Q150943)
We disabled all the power saving on clients (NT4 Server has no power saving)


Best regards
Johan

 

[TheLad]

I have found that you can set the Cisco switch to auto-negotiate then have to force the server to whatever speed you want.

Personally, I would force your ports on your Cisco router to 100Mb Half-Duplex (as a start), then force your servers to the same.

Do your clients connect at Half-Duplex or Full-Duplex? -----------------------------------------------------
"It's true, its damn true!"
-----------------------------------------------------

 

[jheyrman]

Thanks for the quick reply:

This was my first impression about this fault to.
As i mentioned im my post

>Things we already tested but didn't help:
>Forced the auto-negotiation to 100/full 100/half 10/full 10/half

We did this on the servers, switches and clients but this didn't solve our problem.

Best regards
Johan