Routing Analysis Approach

[Rchaoua12]

I have recently been appointed to upgrade our lab infrastructure and topology. While I have used routing protocols previously, this is a new enviornment and I am unsure how to properly assess the network's current routing scheme. Does anyone have any thoughts on how to gain an understanding of how the LAN routes. I would like to use this information to configure my own routing scheme, thereby unfying the routing in this LAN. Right now there is a mixture of static routes, OSPF, EIGRP and RIPv1.

Thanks!

[Jon Marshall]

You need to draw out your LAN topology with every L3 device, showing all it's connections and include in this any WAN connections.

Then you need to go onto every L3 device and print off the routing table for that device. Then overlay that with the topology drawing you have done.

It can be a laborious process but there are no real shortcuts because you need to understand exactly which protocol is responsible for which routes. If you have a mixture of OSPF/EIGRP/RIP ans statics then it sounds as though the LAN has evolved rather than been designed.

I would choose either EIGRP or OSPF to standardise on. Obviously if you have multi-vendor equipment then OSPF would be a better choice but if it is all Cisco then i would also consider EIGRP which in my opinion is very easy to configure and very fast reconvergence if you have redundant links.

Jon

[Rchaoua12]

Thanks, Jon, for the input. Your suggestions were what I had planned but I was hoping there was a smoother way of doing it.

I do plan to use OSPF. You are right this network has been pieced together over time and I recently started and am trying to clean things up.

Thanks, again!

[Jon Marshall]

Your suggestions were what I had planned but I was hoping there was a smoother way of doing it.

Bear in mind there are tools that can map your network layout eg. Solarwinds do a network mapping tool. If you google network mapping you'll see the available options. So it can be automated to an extent but i would still want to check the actual routing tables etc. myself.

Jon

[Alexander Maroukian]

Hi,

If you are going to redesign the network alot of considerations should be taken into account. I usually use top-down approach which is to find out the goals to be achieved and then the more technical part for the L3/L2 logical topology, protocols and physical topology.

As Jon said the better is to do manual mapping and checking so that you will understand and know what logic is behind the current network and its pros and cons. This will make the new design better.

Best regards,

Alex