Troubleshooting made easy, well easier..

[m.x]

As a starting network engineer is sometimes do not see the switches through the cabling... So my colleague advice's me to draw myself a map. Sadly he never has the time to explain me properly how. So I'm hoping you, as my fellow network engineers, could share some tips to help me out...

This what i got thus far. When trying to ping 172.16.25.21 (a server in our network) I get no answer. When I trace the route, Im going i the worn direction. So how should I draw this, to help me analyse the problem? Do I draw the correct network or do I follow the route?

Does anyone know a way to learn this? Perhaps some material about this or a youtuber that explains this?

Any help is welcome!

Thanks

Marnix

[Georg Pauwen]

Hello,

you could use a (free) network mapping tool such as the one linked below, which will automatically generate a map of your topology and let's you visualize how everything is connected...

https://www.paessler.com/network-mapping

[m.x]

Thank you for your suggestion.

Unfortunatly that is not going to work as I work for a small ISP. We dont have monitoring on all routers we have put in the field. So I'm tryig to teach my self where the packets need to go and where they originate. And put this proces on paper. I just get stuck when it comes to the path the packet needs to take.. or takes. 

This is the proces i looking for help with. Troubleshooting a routing problem mostly..

Gr.

Marnix

[Jon Marshall]

You need to draw out both paths, the one the packets should be taking and the one they are actually taking to work out where it is not working. 

Traceroute is a very useful tool for this because it will show you the L3 path hop by hop and if you know the path the packets should take you can then see at which hop the packets take a different path and that hop is where you should start looking at the routing. 

Bear in mind routing is a two way thing ie. just because there is a path one way in the routing tables does not mean there is a path back. 

Jon

[Georg Pauwen]

Hello,

the idea was to use one of these tools to automatically discover your network and draw out a topology map for you. You usually don't have to install anything on the routers itself...

https://www.whatsupgold.com/network-discovery/