Switch Question?

I recently ran into a problem in a peer-to-peer network (about 16 PC's) where one PC had completely stopped all network traffic including internet access (not one PC could see any thing). After unplugging the "bad" PC from the switch everything returned to normal. I checked out the "bad"PC and found it to have an HDD issue (sounds like a box of rocks and cant get past the windows boot screen, also BIOS wont recognize it most the time). The question I am getting to is this, arent switches supposed to stop these type network problems? Do they not provide a single path to another device for that session? Help understanding this would be appreciated. The switch is a CNET Power switch (CNSH-1600).
Thanks!

 

Hi Stik62
That's not very reassuring to hear. I'm of the same opinion, that "switches" are usually advertised as being capable of isolating the port which is causing trouble. Try to duplicate the problem on a different switch-port. By swapping the port and duplicating the problem you are trying to prove that the original port has hardware integrity.(not broken). If the port's not broken, then the Techs at Cnet woulf love to hear the details. It'll help them build better boxes.

 

Thanks for the response prometheos. Unfortunately I dont think it would be a good idea to reconnect the "bad machine" and run the risk of stopping network traffic again. So im a little limited as to troubleshooting at the moment.

 

thats a wierd problem. i hope you get a chance to find out more about it. im thinking about takeing switch and hook a few comps up to it and have a bad HDD in one to see what happens.

 

might be a good idea to test the nic also.

 

Im going to try and duplicate when i have the chance. Its a customer sight so I dont have free reign.

 

Ok, what has a bad HDD got to do with anything? This is a network problem!

Here are some things to check out:
1. are you using DHCP? If so, all PCs should be getting their IPs automatically! No exceptions!
2. Are all the network cables connected up correctly? Are you sure you're not creating a loop when the machines is turned on?
3. Can you ensure that the cable you connect is not faulty?
4. Can sure ensure that the NIC isn't faulty?

That should get you pointing in the right direction ....

 

Im not sure the HDD created the problem those are just the symptoms that occured. Found that machine locked (web page open no keyboard or mouse function) and the port it was connected to on the switch was constantly Tx & Rx along with the port connection to the router (fractional T1) no other port activity on the switch. As soon as I unplugged the that machine from the port it opened up the network. All static IP's. Cables are fine. I allready know the machine is bad. The whole point is that because of one bad device connected to the switch it pulled down the whole network and I thought switches provided port isolation to prevent that?

 

sounds like a broadcast storm. switches dont stop broadcasts.

 

If the computer does not boot it is be a deeper problem then Networking.

Could be power related, I would strongly recommend to keep this computer Off the Network and fixed it first on its own.

 

I doubt its a broadcast storm. I'd wager the NIC in that machine has something to do with it.

An "easy" way to check is to isolate the machine on the switch by itself, disconnected from the network. If it still locks, its not a broadcast storm, as you put it.

 

why wouldn't it be a broadcast storm?

http://www.webopedia.com/TERM/B/broadcast_storm.html

a faulty nic could have sent a bad packet which could have caused a broadcast storm.

 

A bad packet won't take an entire network down.

Also, the machine is freezing, and if the OS cannot send or receive data due to it being...dead...

But, its all theory at this point anyway. Either way, its points to a bad NIC.

 

Ironman,
This is the first ive heard the term "broadcast storm". Is it a virus, malware or somthing else?

Adrynalyne,
It would be nice to isolate the machine and switch but there are 15 or so other machines connected to this switch. So I would need a test bed (which I dont have right now) for your suggestion.

BTW. Thanks for everyones input!

 

heres a definition for boradcast storm.

http://www.webopedia.com/TERM/B/broadcast_storm.html

if you need anymore definitions for it just go to http://google.com and search for broadcast storm.

a broadcast storm can be caused by a virus as well as a bad nic constantly sending out bad packets congesting the network.

 

Thanks dude