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Old 08-09-2004, 10:28 AM   #1
tricky_linux
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10BaseT Hub, Collision???


I have a 10BaseT Hub from DYNA-NET.
this hub is pretty old, i never used it to do anything.
now, i got many files to transfer. it works but how come everything i transfer something from port a to port b. the Collision light blinks!
i just wondering does that means bad or ???
 
Old 08-09-2004, 12:09 PM   #2
Dark_Helmet
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It's nothing to worry about unless the light stays on constantly (no blinking, just solid).

A collision occurs in networking when two computers/items try to talk at the same time. The connection between them can only allow one individual to talk at once. So each individual has the ability to detect if someone else is trying to talk at the same time. When that happens, each network machine trying to talk will "back off" and wait a random amount of time before trying again. It's normal to see the collision light blink every so often.
 
Old 08-09-2004, 12:14 PM   #3
tricky_linux
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thanx
 
Old 08-10-2004, 03:04 AM   #4
theYinYeti
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And when it constantly blinks?

I have a switch, and whenever I sftp a file between my two PCs (only 2 on the switch), the collision light blinks madly without interruption until the file-transfer is done.

Yves.
 
Old 08-10-2004, 07:27 AM   #5
fredgt
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When you're using a 10BaseT Hub it's normal that you have all these collisions.
10BaseT means that you"re using an 10Mbit hub when you are probably using 10/100 Mbit network adapters so the hub will slow down traffic to 1.25 MB/s, when you use an 100Mbit hub it would be 12.5MB/s.
The second problem is that you're using a hub and not a switch. A hub sends all the traffic to every port of the hub so when you send data from computer A to computer B, it will also be send to all other computers on that hub with will cause all these collisions. A switch is a little more intelligent and will send it only to the computer that the data is supposed to go to.
So if you have a lot of traffic trough the hub it might be a good idea to replace that with a 10/100BaseT switch.
 
Old 08-10-2004, 10:58 AM   #6
Dark_Helmet
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The more the collision light blinks, the slower your transfer will be (because it's riddled with retries). If the transfer succeeds, then it's not a fatal problem. However, if you're trying to transfer a 1MB file and it takes 10 minutes, then that's not good. Collisions can occur for any number of reasons: bad cables, bad hardware, different settings between devices. I wouldn't worry about it too much if the transfers happen in a reasonable amount of time.

You can always time the transfer (using the time command or a stopwatch) for a large file. Then calculate what the actual transfer rate is. You'll never actually achieve the ideal speed of 10Mbit or 100Mbit depending on what devices are involved. I would say 75% or better is probably acceptable. 50% - 75% is cause for some concern and might be worth investigating. Anything below 50% is the point I would start swapping components if possible.
 
Old 08-10-2004, 01:32 PM   #7
J.W.
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I agree 100% with Dark_Helmet's comments. The only thing I'd add is that if you do observe unsatisfactory transfer speeds, make sure you are using a quality brand of cable. We encountered a situation like this a while back, and simply replacing the generic, no-name cable with a brand name made all the difference in the world. Obviously there can be other causes, but don't overlook the cables. -- J.W.
 
Old 08-10-2004, 04:40 PM   #8
tricky_linux
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thanx to fredgt and Dark_Helmet

from the start i know hub is a little dumb and switch is smarter.
but i am just not clear what the difference is.
now i understood.
thanx you ya's help

also, i have a question regarding hubs.
you(fredgt) said that hub sends all signals to other port. so does that mean switches are secure?
since it's not a 1 to all action, but 1 to 1 transfer action
and does switch do one tasks at a time or can do mutiple tasks unlike hubs?
 
Old 08-10-2004, 05:29 PM   #9
fredgt
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"and does switch do one tasks at a time or can do multiple tasks unlike hubs?"
well the problem with for example a 5 port hub would be that if you send information from port1 to port2 it will also occupate the other ports while with a switch will only use port1 and port2 so the other ports have the full bandwidth available because there is no other data beng transmitted.

When you go from dumb to smart the order would be something like this:
HUB -> unmanaged SWITCH -> managed SWITCH -> ROUTER
HUB : sends data to all ports
unmanaged SWITCH : normal cheap switch you can buy at you local computer store.
ideal for home networks and small company networks
managed SWITCH : the same as the other switch but has some extra options you can configure. This is for big networks with high capacities.
ROUTER : Does the same as a switch but it acts like a computer, it has an IP address, it has a build in DHCP server to supply the connected computers of a dynamic IP,... This is used to share internet connections,...

If it is just to replace the hub a small unmanaged SWITCH should do the trick.
a 5 port hub cost about 30 ( or $ 37 ) this price can be different depending on where you live.
 
Old 08-10-2004, 07:34 PM   #10
MS3FGX
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Quote:
I have a switch, and whenever I sftp a file between my two PCs (only 2 on the switch), the collision light blinks madly without interruption until the file-transfer is done.
Switches don't have "Collision" lights (at least, I have never seen a switch with one). What you are probably seeing is the "Activity" light, which should light up when traffic is going through the switch.
 
  


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