Students and Network Cables

[ninjabeaver]

Here's a sort of tip for anyone who's Network suddenly goes really slow then dies.

This is the second time this has happened to our network here, and it's such a simple mistake the students can do.

Anyways, today at about 09:30 the school network decided to take a nose dive in performance. I hate it when this happens. Panic starts and alarm bells ring.

I ran some packet watching software that monitors all network movement and it was through the roof. Luckily, as I've said, I'd seen this before.

Bascially, one of the students noticed a network cable unplugged and being the helpful sort decided to plug it back into an RJ45 wall socket. Very sweet. The only problem being that the other end was also plugged into the RJ45 wall socket next to it.

This then sent the network crazy and a million phone calls came in telling me the network was not working, or did I know it was not working etc. Then my radio goes off telling me the same.

I then had to keep running the packet watching software and unplug one fibre link at a time to wittle down the rooms until I found where the problem was. Took about 20 mins to re-set the system which I thought was quite good for me as the first time was nearly two days. ops:

So if you have the same remember the above.

[ChrisH]

Wow that seems a lot of disruption for something like that 8O

[ninjabeaver]

Yeah, that's what I thought as well. It brought the whole school network to its knees. I'm just hoping the students don't start doing it for a laugh.

I'm wondering if anyone knows of a way to stop this?

[russdev]

yes heard of this not seen it here but as soon as kids find out they do it for alughs so just keep an eye on it just do the proccess work from outside of network comeing in a switch until you find it

Russ

[Geoff]

Most managed switches have a feature called Spanning Tree Protocol. Enable it and it wont matter if kids (or you!) make network loops.

[ninjabeaver]

yes heard of this not seen it here but as soon as kids find out they do it for alughs so just keep an eye on it just do the proccess work from outside of network comeing in a switch until you find it

Russ

Thanks Russ, thats what I'm doing. First time round I had to pull network switches all down and then fire them up one at a time until we found the room. This time was alot easier thanks to the new fibre backbone.

I was just worried that my network was configured incorrectly and this was a stupid problem of my own making.

Thanks.

[ninjabeaver]

Most managed switches have a feature called Spanning Tree Protocol. Enable it and it wont matter if kids (or you!) make network loops.

Ah ha, I thought there must be something to help combat this. Thanks Geoff.

[tarquel]

I ran some packet watching software that monitors all network movement and it was through the roof. Luckily, as I've said, I'd seen this before.

lol didnt even notice this thread *ahem* before I created my topic in this board regarding this sort of monitoring type tool.

Please post there with ome info on what you use if ya cud for me

Cheers
Nath

[Geoff]

Ethereal comes to mind.

http://www.ethereal.com/

[ninjabeaver]

Ethereal comes to mind.

http://www.ethereal.com/

That's the one. Using Ethereal I just watched the count jump in 10's of thousands over a matter of seconds.

[mark]

Our tech department - run by the head of technology and nothing to do with me [until december that is]. Funny - he complained like it was my fault :P

Visiting his area I noticed one port lit up two port lights when I unplugged it. He took me to the wall socket and there was a cable looped into two sockets! Funny you should mention it here - two days later!

[tarquel]

lol I can't remember that ever happening - mainly as theres no spare lead or ports for them to mess about with and there isn't any they can unplug both ends of

Interesting stuff tho

N.

[KeithFermor]

He He! Yes... this has happened here as well. The cable though was hidden behind a filing cabinet and it was only because of some pretty tight documentation on switch ports vs room ports that had just been completed... that it was found.

Our school is a Jarvis school and uses large numbers of EtherWan switches. No documentation, no management and no control! I spotted it by a lengthy process of switch/port elimination.

[Ric_]

Apparantly it happened here not long before I started - it drove my predecessor crazy for days.

I don't patch in unused ports - reduced the chance of this and people randomly plugging rogue equipment in

[andy]

Happened to me before - just as the Slammer virus was going round!

Nowadays there aren't many spare ports on switches - so if a port isn't connected to a computer (or similar) it probably isn't connected to the switch either!

Andy.