have you ever heared of network voodoo. well if you haven`t you will now

i have a router(slackware 10.1) the internet connection is on eth0
the connection to the clients is eth1(from eth1 to a switch to 8 clients)
it worked fine for a month and a half and then suddenly problems appeared


the clients behind the switch are complaining that the internet has aleator intreruptions it works 10 min and half an hour it doesn`t(they lose connection with the server`s eth1, that is in the same class with them)
the net works aleatory for 2 or 5 clients or all the clients

i have connection from the internet on eth0 it works great without intreruptions
the cable has been tested with a tester(it`s ok)
the ip-s are statical, and i don`t have any nat
the firewall is also down


i thought of seweral sollutions that didn`t gave any result
- i recrimped the jacks on the ends of the cable betwen the router and the switch
- i replaced the switch
- i reinstalled linux on the box

NOTHING can you come with some logical sollutions, because i am starting to belive in voodoo

Run ifconfig and see if there are any errors on your interfaces under RX/TX packets

i`ve runned ifconfig.. nope no errors

eth1 Link encap:Ethernet HWaddr 00:10:5A:4B:80:88
inet addr:xx.xxx.xxx.xxx Bcast:xx.xxx.xxx.xxx Mask:255.255.255.240
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:1501489 errors:1 dropped:0 overruns:0 frame:1
TX packets:993553 errors:0 dropped:0 overruns:0 carrier:0
collisions:1386 txqueuelen:1000
RX bytes:810878058 (773.3 Mb) TX bytes:135580961 (129.3 Mb)
Interrupt:10 Base address:0x1400


one error....

Hmm, interesting you've got collissions.. but not an excessive amount for the amount of data you're running. You said there's no firewalling or nat or anything like that? Do all the clients get the same error message? What message are they getting? I wonder if it is a service like DNS that is failing..

the client does not get any error message
it cannot ping the server(on NIC eth1)and there is no internet connection ,like there is no link between the router and client

i don`t have dns on my linux box. i use the dns of my provider

i can`t find any sollutions
i`m going nutz

Something else that is cheap that you can try to replace is the NIC. Or swap w/ a spare one somewhere. Instead of re-crimping, replace the wire. Is the switch a smart switch? You don't have it into the WAN port or have the button pushed that would represent that, do you?

When they have trouble can you ping from the router? Can it reach the outside?

have you tried connecting a single client to the server via crossover? takes all other machines, plus the switch out of the loop. 'tcpdump' would also be helpful, run it up on the server as 'tcpdump -n -i eth1' and send some pings from a client without connectivity. You might see some interesting stuff going on, or nothing at all maybe also check the router and switch or switch and clients aren't trying to autonegotiate a link speed - see if you can set them all to 100Mbps full duplex.

just some ideas.

i`ve tryed replacing the NIC`s...

afther all i`ll try replacing the wire... it`s not the best thing to do because it`s a 80 m long wire....

anything else?

You probably have, but check behing the wallplates as well to make sure that the wires aren't crossed.

Since the run is that long you'll also need to look at what it is running next to. Maybe it is sitting to close to a florescent light? Maybe it is running right next to a 110V or 220V power line? Too close to an AC duct fan? Next to a hot water pipe and melted a little? Just check for the possibility of electonic interference. It almost sounds like that could be a culprit. It could be a coffee pot turning on and off..... I work at a place where they had that kind of trouble before I was around and they had to re-run AND re-route the wire. Try thinking of something powerful that could be turning on and off to cause that.

Yes, I've had a problem with fluorescent lights. They can cause bad interference. It is best to stay away from them and your 110v lines. If you have to run by power (I know it usually can't be avoided) it is best to cross the lines perpendicular, not run parallel next to them.