Home Network Question: Collision detected on my Hub.

[dxkj]

I have two computers plugged into a hub, that hub is plugged into my cable modem which is plugged into the wall. Normally everything works fine, but today when I was trying to do something on both computers the hub started flashing "Collission" and neither computers could browse/do anything with the internet.


Is there something Im doing wrong that I should change? Why would collision happen just at random like that?


Thanks

 

[skyking]

spidey or cmetz or one of the real experts will come by with a detailed explanation, but it sounds like a broadcast storm of some sort. Think of getting a microphone too close to the speaker; nasty feedback gets going, howling like crazy. The two computers and the hub got to repeating the same bunch of data till it turned into a giant traffic jam.
I would go back to business as usual, and see if it happens again. My guess is it was a random thing.

 

[dxkj]

hrm i just opened up my computer case today and it was interfering with the TV reception (which is right next to the hub...) but im wondering why it cleared up after i unplugged the second computer from the lan

 

[kt]

Network collision occurs when two computers try to send packets at the same time. When that happens both computers would wait for a random amount of time and try to resend the same packet again. I am not sure, but I think the fact you have your cable modem directly connected to the hub has something to do with it. You should maybe invest in a router/switch, they are fairly cheap now a day.

As for your interference problem, it's normal. If you look at the back of most of your computer components.. especially your network card, you'll see there's a FCC regulation sticker on it. It will disclaim something along the line that the card will most likely cause interference with radio/communication signal. So, if you have your computer close enough to your TV set, it will more than likely cause snowy picture.

 

[spidey07]

Collisions are a normal operation of Ethernet. Like others have said it is when more than one station transmits at the same time. As long as there aren't too many performance will be fine.

It is when there is a lot of traffic or cabling problems that you'll see a high collision rate. And that can cause performance problems. What is most likely happening in your case is because the cable modem attaches directly to a hub all the "crap" traffic on your cable segment is broadcasting onto your hub so when you do anything network related you get a lot of collisions.

I've taken a look at the traffic on my cable segment and there is a tremendous amount of "crap" traffic. I let a little SOHO router block all that stuff for me so it doesn't affect my local LAN.

 

[Macro2]

Hubs extend collision domains and they don't support full duplex, only half duplex. Collisions are the result. On ethernet, when a collision occurs, the sender is instructed to wait a period of time and send again.
All this slows down your throughput.

A router or switch is what you need. A switch for instance increases the number collision domains and gives full bandwidth on each port unlike a hub that divides up the bandwidth.
Routers segment the network as well. That may be your best bet.