Oh crap!

[leonfagan71]

12 minutes ago, jagdtigger said:

Most likely the school uses enterprise grade switches so a loop back wont be enough to take down the network....

Even enterprise switches aren't always configured correctly.

I've been to a school years 3-6 (junior school) this network was susceptible.

I've been to a secondary school (academy/Comprehensive) this was susceptible.

I've been to a upper school (dropped out of secondary) also susceptible.

 

Very simple stuff that knocks down an entire network.

[ultimatemythbuster]

OP needs to give us an update on what happened.  Unless of course the school burned to the ground and nobody got out alive.

[baconbuilder99]

there was lag

[thendawg]

On 11/27/2016 at 11:47 AM, leonfagan71 said:

Even enterprise switches aren't always configured correctly.

I've been to a school years 3-6 (junior school) this network was susceptible.

I've been to a secondary school (academy/Comprehensive) this was susceptible.

I've been to a upper school (dropped out of secondary) also susceptible.

 

Very simple stuff that knocks down an entire network.

Any decent network should have STP or one of its varients (typically RSTP) enabled. Hell I have it enabled on my home network that Im 100% sure will never have a loop lol. As long as spanning tree is enabled, it might cause a bit of insanity on the switch for a second or two, but the ports will go to blocked mode pretty quickly and everything will return to normal.

[leonfagan71]

8 hours ago, thendawg said:

Any decent network should have STP or one of its varients (typically RSTP) enabled. Hell I have it enabled on my home network that Im 100% sure will never have a loop lol. As long as spanning tree is enabled, it might cause a bit of insanity on the switch for a second or two, but the ports will go to blocked mode pretty quickly and everything will return to normal.

The IT department would unplug every switch and plug each one in until they found the switch causing the issue.

Then hunt for the cable in the room.

Not always simple.

 

I'm sure they could enable these features but they have things like WDS (Windows Deployment Services) that send lots of traffic through the switches so sometimes the switch will block packets and cause failed Windows installations.

[leadeater]

46 minutes ago, leonfagan71 said:

The IT department would unplug every switch and plug each one in until they found the switch causing the issue.

Then hunt for the cable in the room.

Not always simple.

 

I'm sure they could enable these features but they have things like WDS (Windows Deployment Services) that send lots of traffic through the switches so sometimes the switch will block packets and cause failed Windows installations.

Yep I've found things like STP and broadcast storm control on low end switches like D-Link DGS to be buggy and crap and block things like PXE booting, pain in the ass. It also doesn't help when you have to support rubbish consumer desktop motherboards that have extremely bad PXE implementations and use all FF's as the mac address when PXE'ing, omg so stupid.

 

Edit:

Good network design can be hindered by bad equipment purchasing decisions by someone else.