Finding network topology issues

Tom L.

3/27/24, 9:11 AM

I am trying to check a network with redundant links for possible issues with switching (STP?) and/or routing. I have a feeling that the issues are intermittent but I'm struggling to find a method how to detect these. What I am trying to do is to throw some server names into a list and try to check the link via trace route. Yet, I was unable to detect any issues as of now. I do not have access to the configuration interface of any of the switches.

Is there a tool or method which allows me to detect such errors?

0 + 5

routing

switch

redundancy

vidarlo

3/27/24, 9:39 AM

Get access to the configuration interface and configure logging. Switches logs L2 changes and Spanning Tree reconfigurations.

Zac67

3/27/24, 5:25 PM

`tracert`/`traceroute` can only display L3 hops, not L2 ones - there's no way to get the latter in a similar fashion. You can analyze the physical, VLAN and STP topologies or run test traffic (iperf3) and watch interface utilization.

fission

3/28/24, 1:01 AM

Hi Tom, it might help to mention here what specific issues you’re seeing. Then someone could propose a better solution to assist you.

Tom L.

3/28/24, 4:18 AM

It's pretty hard to pinpoint the issue. Sometimes users cannot load random websites, 2 seconds later it works. There are issues with SIP telephony (calls are dropping or not created, UDP-related?). Sometimes connectivity issues with various databases (although they can be reached a second later). I know that there is a redundant path between two server rooms which may not work as expected but I have no idea how to check that and somehow I get the idea that maybe there is an intermittent MTU issue. Unfortunately that network was not built by me (in fact that's a good thing) and the main admin

Tom L.

3/28/24, 4:19 AM

is confident that everything works as is (which it does 99% of the time). I have a feeling that there is a misconfiguration going on here and I'd like to point it out without really guessing.

Elon Musk

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EN: Finding network topology issues

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