Troubleshoot network with fiber connections

[Isegrimm24]

Hi, I'm troubleshooting a network consisting of 6 switches connected with fiber in a ring topology.

Some users in the network experience temporary lock-ups on their pc's, but they are al located in the same area of the building. Users in other parts of the company do not experience problems. Or they simply don't complain, but for now I assume the former.

To narrow things down, I'd like to rule out physical connections. Right now I have my doubts about the fibers they use. Those connections are about 10 years old. Switches and gbics are new, they were completely replaced last year.

Is there any way to make sure the fiber is not at fault here? I have seen troublesome connections in the past that were caused by a bad fiber, but no errors showed up on the interfaces where the gbics on both ends were connected.

Unfortunately I don't have spare connections to test.

[Fred_Mancen_1]

Even considering that maybe the fibers are the root cause of your problem, we have to consider some items before:

1. What are the running STP settings?

2. Do you know if the switches supports RRPP?

Maybe, for some reason, a STP loop was created and it's forcing a convergence in the topology, that causes these breaks in the network. The RRPP is the best protocol to be enabled in a ring topology, because it's much faster that STP in topology convergency.

Make sure that there is no problem concerning the items above before proceed any changes in the fiber cables.

Regards

[Isegrimm24]

Hi Fred,

I have considered STP issues. It is running fine and without unexpected convergences.

[LucianoCarvalho]

Hello,

As you think that the fiber can be the problem, I think that it would be a good idea to use a tester to test the fibers and find out if it is ok or not.


Regards