Can a misbehaving NIC cause a network to crash?

I have a cable that when put into a switch seems to cause the entire network to crash -- however, only when put into a specific PC. When I'm trying the cable on another PC, I can't reproduce this. the cable is run through the wall, so replacing the cable is a hassle at this point unless I know it's the cable.

Is it possible for a misbehaving NIC or glitchy NIC to cause this issue? How can I diagnose this?

It actually crashes when the PC is OFF, when it's ON everything is okay..

Vaughan Hilts

Posted 2014-01-21T17:10:06.937

Reputation: 67

Yes, it theoretically could, especially if your switch sucks. :) If you want to try a different cable with the suspect computer, it's probably easiest to move the suspect computer closer to the switch to try different cables. – Ƭᴇcʜιᴇ007 – 2014-01-21T17:13:07.297

@techie007 Moving the PC is a bit troublesome, but it'll defintely be easier than moving the cable. :) – Vaughan Hilts – 2014-01-21T17:15:35.333

When you say (in other comments) that's it's only doing it while it's OFF, do you mean Soft-off, or does it also do it when the computer is REALLY off (like unplugged from mains power). Have you ensured the RJ-45 jack/pins on the NIC aren't physically damaged? – Ƭᴇcʜιᴇ007 – 2014-01-21T17:57:01.983

@techie007 This is soft off presumably (powered down by Windows). I haven't verified the NIC isn't damaged, but if I knew how to check, I would. I'll do a hard off and see. – Vaughan Hilts – 2014-01-21T17:58:52.950

It's easy to start, just use your eyes! :) Look into the jack -- are the pins touching, bent, full of crud, etc? Also, can you confirm the problem goes away if power is completely removed from the system (hard off)? – Ƭᴇcʜιᴇ007 – 2014-01-21T18:01:08.280

Looks like everything is okay here if I directly pull the power plug... BIOS doing something whacky? – Vaughan Hilts – 2014-01-21T18:02:02.937

1@techie007 Updating the BIOS worked. Funny, huh? – Vaughan Hilts – 2014-01-21T18:52:21.157

Weird for sure. Glad to know you got it figured out! – Ƭᴇcʜιᴇ007 – 2014-01-21T19:24:11.477

Could not only be the NIC, could also be services running on that NIC. What exactly is crashing? Are there any error-signs on the other computers? I'd guess it could be something like a dhcp broadcast storm or something. – Vanadis – 2014-01-21T17:31:39.043

It actually crashes when the PC is OFF, when it's ON everything is okay... weird. Is the BIOS swapping on some kind of service? – Vaughan Hilts – 2014-01-21T17:37:58.413

@VaughanHilts Well... leaving the PC On should fix the problem. – Vanadis – 2014-01-21T17:43:41.913

That would be logical... but it's a waste of power and does not solve the root cause. :) – Vaughan Hilts – 2014-01-21T18:05:43.333

@techie007 After a little bit more diagnosis, it turns out the real suspect was the Wake On LAN setting, see this thread for information: http://forums.anandtech.com/showthread.php?t=2334881 (Enabling ERP turns off WOL forcefully, why would WOL crash it.. oh well.)

– Vaughan Hilts – 2014-01-23T17:34:49.853

Answers

Based on :

It actually crashes when the PC is OFF, when it's ON everything is okay.

I would suspect Wake on LAN ( WOL ) feature of some NICs. Basically, it allows the PC to be powered up remotely by sending specific commands to the NIC which stays in stand-by mode even when the PC is "shut down".

I am only familiar with the general working principle, but the wikipedia article hits that this capability does not always work as expected :

This is because it requires appropriate BIOS, network card and, sometimes, operating system and router support to function reliably.

It is highly probable that either your switch / router or NIC is not properly configured / designed to work in your setup.

user1190

Posted 2014-01-21T17:10:06.937

Reputation: 569

You were entirely correct. I forgot to post back. :) I never figured out WHY WoL was causing the crash, though – Vaughan Hilts – 2015-11-28T07:32:39.413

If you are having frequent crashing, the easiest way to test this would be to remove the NIC from the network for awhile, after noting the frequency of the crashing. Then, if you go substantially longer than normal without a crash, you know that it did, in fact, cause the issue.

Also, you can get a standard NIC for 12 bucks. You could swap it out and see if it fixes it. Worst case scenario, you are out 12 bucks.

WreithKassan

Posted 2014-01-21T17:10:06.937

Reputation: 406

It actually crashes when the PC is OFF, when it's ON everything is okay... weird. – Vaughan Hilts – 2014-01-21T17:37:25.457

So, when this NIC specifically is turned on, the network is fine? But the network does not work when the PC is turned off? Do you have the PC set up as a piece of your network, and not just a client? If so, that is obviously a bad idea. – WreithKassan – 2014-01-21T17:44:30.430

1@VaughanHilts "It actually crashes when the PC is OFF, when it's ON everything is okay..." That's a valuable piece of info, you should edit it into your original question. – Ƭᴇcʜιᴇ007 – 2014-01-21T17:55:31.663

Sure can!

In my case, the PC with a soft power done was causing my entire network to crash. When it was unplugged physically from the wall, everything was fine. As it turns out, the motherboard must have been doing something weird. After updating the BIOS, everything was working as expected.

For future visitors, the PC in question has a GIGABYTE GA-Z77-DS3H

Vaughan Hilts

Posted 2014-01-21T17:10:06.937

Reputation: 67