Suddenly high network traffic

[Chris Yuen]

Our company's network infrastructure makes use of 3Com SuperStack 3300 Switches.

Recently, my officer bought a H3C LS5100 48P Gigabit Switch for a room.

All the connections inside this room are currently using Cat 6 cabling and all the computers inside this room install with Gigabit NIC.

I connected a Cat 5e cable from the 3Com SuperStack 3300 Switch to that switch (100Mb/s).

I turned on one computer only.

At first, it seemed everything was alright.

However, when I pinged our web server, etc, it got one timeout result out of eight pings.

I connected one more Cat 5e cable from the 3Com SuperStack 3300 Switch to that switch to achieve higher speed (perhaps 200Mb/s).

I found the traffic light for the 3Com SuperStack 3300 Switches had been freezed.

All the "pings" returned the timeout results.

I removed one of the Cat 5e cables and it seemed getting alright again (with little timeout result).

If I turned on all the computers inside this room, more and more timeout results will be occurred even connected with one Cat 5e cable only.

Should we use any switch with 100Mb/s for solving this problem?

Can anyone tell me how to solve this problem?

Thank you very much!

[homecomputeraid]

Hello Chris,

It sounds like you may have created a switching loop. Loops on switches occur when traffic has more than one path between two switches. Spanning Tree Protocol (STP) should stop a loop from occurring if it is enabled. If it is not enabled, or if it not working, and a loop occurs, a broadcast storm will instantly take down the switches.

You can't just plug another cable in. You have to enter the switch configuration, if the switch allows this, and trunk or bundle the ports such that they will appear as one connection between switches.

I'm not sure why you chose gigabit switches in one room, or what the users on that switch expect to connect to, or what kind of throughput you're looking for.