Network storm between 2 switches

[harryting]

At one of the sites, the local techs swapped out two older network switches to two new switches made by N-Tron (524TX-A). After the update they run into network issues once a while and noticed all the ports became solid green , which indicates to me a broadcast storm.

Disconnecting the connection (copper, RJ45) between these two switches then reconnect would solve the issue for a while.

Yes, I know the one question people would ask, is there a network loop? At this point we are quite confident that there is no network loop.

What I'm struggling with is that from what I know, this shouldn't be happening. While these switches don't support Spanning-Tree, there is no loop to cause an issue.

Any ideas?

 

[rupej]

Is it possible that some device on the network is going bonkers and sending a continuous stream of broadcasts?

 

[sparkie]

Do you have any way to set up logging for the switches?

 

[Maxkling]

You really need a packet sniffer like Wireshark and make a tap to monitor traffic between the two and figure out the issue.

 

[damica1]

I would drop back to the basics.

Was this NETWORK working BEFORE the 2 new switches were installed? OR did you have network problems and that is why the 2 switches got replaced?

Was any new cables built to replace old? Did any cables get replaced?

If this was a very old install and all the cables had to be moved or re-routed I would suspect cable problems.

If everything was working and the only thing was to replace a 2 switches, I would suspect something more with cables/ends/routes.

 

[harryting]

These switches are so called "monitored" switch, capable of doing VLAN but are not full fledged managed switch. I'll have the local guys install NTron's monitoring software and also see if they can do a packet capture.

- Yes, these were working before the new switches were installed.

- Doens't appear to be a problem with a device. I say this because I had them unplug one device at a time and it's not until they disconnected the one that goes between the two switches that the "storm" goes away.

NTron support did write me a very detailed response on what to look for next and I'll update this once I have implemented some of their suggestions.

 

[rdrast]

Were the older switches connected set up with Spanning Tree or a Ring Network?
What you describe sounds like either connecting the switches together in a Ring without being configured for it, or connecting the switches together twice. The latter is the same thing as taking a taking a patch cord and jumpering two ports on the same hub/unmanaged switch if STP is not configured.