Network loses connection

[dmarquesdrc]

Hi,

I have a small network in my office with 1 server, 1 nas and 12 pc's.
I made up a gb network with 2 smc switches, but I've got a big problem.
I normally copy to nas and server big quantities of data and I usually leave it copying during the night, but a lot of times the connection falls for some moments and the copying stops. This is very often as I can see it happening sometimes during the day.
Does someone has an idea of where's the problem of this and how can I try to solve it.

Thanks in advance.

 

[LawnBoy]

That's a tough situation to troubleshoot.

Are the server and NAS on the same switch? Are you on the same switch with them?

With the sympoms you describe, it could be:
Your NIC
The cabling between your NIC and the switch
An intermittent port on a switch
An intermittent switch
speed/duplex mismatch anywhere in the chain


If you could describe your topology a little more we can derive a good starting point to test from.

"We must fall back upon the old axiom that when all other contingencies fail, whatever remains, however improbable, must be the truth." - Sherlock Holmes

 

[dmarquesdrc]

Well, problem with pc's or their cards is not an option as I checked when this happens, it happens on all pc's.
So it can be a problem of 1 of the switches.
I'll check cabling again to see where are the server and nas connected, if they are in the same switch.
How can I check if there's any intermitent switch?

Server has 2 network gigabit cards. If I connect 2 cables to it, do I again anything with it?

Thanks.

 

[LawnBoy]

It's not the server, as it happens on the NAS too.


"We must fall back upon the old axiom that when all other contingencies fail, whatever remains, however improbable, must be the truth." - Sherlock Holmes

 

[technome]

Aside from the above...

Order of faults on a network..
NIC speed/duplex setting, cabling issue, IRQ contention, buggy NIC driver,power issues, bad NIC, bad switch port. Bad NIC or switch ports are rare.(this after ruling out malware/viruses)

Are all cables CAT certified ?..testing with anything but an expensive CAT tester is basically useless; testers from Radio Shack will not do it. Mis-wired or poorly terminated wires can pass on a cheap tester but affect an entire network. Lint and corrosion on termination contacts,other slim possibilities.

IRQ contention.. If the NIC is sharing with another device (particularly disk controllers), and the two (or more) devices do not play well together, you could get intermittent losses.

Are your switches on a UPS ? Power supplies on switches/routers generally do not have large capacitors to maintain power during power fluctuations.

If you have managed switches, you have the option of checking the entire switch or individual ports for errors, a worthwhile investment, as a managed switch can direct you to a cable or NIC fault. If you have an unmanaged switch, it is impractical to test it, as any issue could be the cables or any NIC on the LAN; cheaper to buy a managed switch. Switch ports generally shut down from faults or die completely, they can produce intermittent disconnect symptoms due to error buildup from cable/NIC faults.



........................................
Chernobyl disaster..a must see pictorial

http://www.kiddofspeed.com/default.htm