Volkswagen Mark IV Forum banner

1 - 20 of 24 Posts

·
Registered
Joined
·
1,560 Posts
Discussion Starter · #1 ·
I just created a loop on our network that left 2500 people unable to work [:$]. It only lasted 5 minutes and I knew what I had done pretty quickly.

Major school boy error.

How to bring a network down in one easy step. DOH!!!!!!!!!!!!!!!
 

·
Registered
Joined
·
4,528 Posts
I have done something similar except I shut down an exchange server by
hitting the power button, it took 3 hours to check the message store,
after I hit the power on it thinking it was the file server I was
rebuilding. easy but silly mistake, left the company with no exchange
or messaging for 3 hours
 

·
Registered
Joined
·
139 Posts
you should return your iPaq immediately for the inconvenience [:D]

been there done all the above, luckily our domain only has a max of 50 accounts
 

·
Registered
Joined
·
1,560 Posts
Discussion Starter · #7 ·
was it STP ?
I take it you mean Shielded Twisted Pair eg Cat5 etc.

If so yes it was, we are in the middle of refurbing/moving our server room and I plugged a switch into another switch using some old cabling that was still live and shouldn't have been. I should have checked it first but I'm gonna blame whoever left the old (unlabeled) cabling in place.

I've held my hands up to stop an investigation taking place. There wont be any repercussions thankfully
 

·
Registered
Joined
·
139 Posts
talking of cat5, we just upgraded to a managed gig switch in our server room because a large percentage of our Dell machines are also gigabit ready, a couple of client machines refuse to run at full speed in certain locations [auto negotiating at 100 full duplex] so was wondering, if older cat5 cable was used would it be the cause, or do all cat5 cables allow gigabit speeds ?

most of the wiring was installed behind partition walls when the factory was built 12 years ago, so signal path is :-

Server > Gig Switch > Patch Box[cables run from patch box thru wall to wall sockets] > Wall Socket > Client PC
 

·
Registered
Joined
·
182 Posts
I took down an entire hospital system once and then buggered off to
lunch for an hour!! Didn't realise what I'd done 'till I came
back - surprisingly I don't work in computers anymore!!
 

·
Registered
Joined
·
1,560 Posts
Discussion Starter · #11 ·
It should run at gig no problem. Have you tried setting the ports manually to 1000 on both the switch and the client pc or server.

Auto negotiation is the bain of my life. it seems to work differently for different equipment. So I usually hard code it between server and switch or switch and switch and leave auto switch to client. We don't have any clients running gig so don't know how it works there but I would probably hard code it.
 

·
Registered
Joined
·
6,626 Posts
talking of cat5, we just upgraded to a managed gig switch in our server room because a large percentage of our Dell machines are also gigabit ready, a couple of client machines refuse to run at full speed in certain locations [auto negotiating at 100 full duplex] so was wondering, if older cat5 cable was used would it be the cause, or do all cat5 cables allow gigabit speeds ?

most of the wiring was installed behind partition walls when the factory was built 12 years ago, so signal path is :-

Server > Gig Switch > Patch Box[cables run from patch box thru wall to wall sockets] > Wall Socket > Client PC
Depends. I use Cat 5e and try to use Cat 6 where possible on Gigabit installations. Also bear in mind that out of the box, Gigabit is "only" about 5x faster than 100Base. To get closer to the real theoretical 1000Base you need to enable Jumbo Frames, which is not supported on all adapters (Intel seem pretty good in this respect). It's a similar concept to tweaking MTU, or, the difference between two trains travelling at 100 mph but one of them with all carriages full while the other is only half-occupied. Same line speed, different throughput.
 

·
Registered
Joined
·
1,560 Posts
Discussion Starter · #14 ·
was it STP ?
I take it you mean Shielded Twisted Pair eg Cat5 etc.
Or Spanning Tree Protocol. If configured on supported hardware, allows multiple redundant uplinks between switches, without causing loops.
Oh yeah forgot about that, bloody acronyms, anyway we don't run spanning tree, but one of my objectives for the year is to produce a report on how we could implememt it. At the moment we have about 180 switches in a flat network config. Spanning tree could be a PITA to implement. Usually loops happen at the fringe of the network (in my experience) apart from today [:$]. So have been thinking about implementing spanning tree on the edge switches and then bringing it into the core eventually.

Do you have experience with spanning tree. I have never really used it but know it is relatively easy to switch on. Would you leave it to sort itself out on a network this size or would you force a root bridge and then let it sort it out.
 

·
Registered
Joined
·
794 Posts
hahahaha

Yes STP meaning spanning tree protocol.

You can bring switches down if messed configured and I was guessing thats what you did. Read up about it ....great fun with core switches like cisco 6500
 

·
Registered
Joined
·
139 Posts
Rule #1 in IT - abbreviate everything and tell end users the problem was due to moon phases affecting the earths polarity

Rule #2 in IT - never use rule #1 on someone with as much knowledge as you
 

·
Registered
Joined
·
1,120 Posts
On this gigabit negotiation thing-

Are you SURE you want your clients able to hit the servers at gigabit speed? You run the risk of having the servers LAN interface struggling to keep up with the demands from all the clients.

Unless there's a strong reason to, I would tend to stick at 100Mb for clients, leaving gigabit speeds for the server room.
 
1 - 20 of 24 Posts
Top