Plotting a network map or topology

[firesec]

What information to look for in a firewall, router, switch device Configuration to plot a network map or topology?

Interfaces,

Zones,

VLan,

Route tables ?

[Mark Malone]

Hi

turn on CDP and LLDP everywhere while your building it , follow the physical connections and design it at layer 1 first get the actual layout , turn it off especially on edge devices when finished
first you do the HLD high level , how it fits together etc , then when happy with that create and LLD of how it all works , IPs , models protocols etc

This is what HLD would look like , network laid out easy to see whats where , different coloured lines can be different types of speed fibre etc

[firesec]

Thank you Mark for your reply. Perhaps I didn't frame the question well. Let me rephrase it. Will it be possible to plot out a network map using the extracted configuration files of firewall, router, switch ? What are the parameters or attributes could help in connecting the dots - Interfaces, Zones, VLan, Route Tables ? Lets assume here that one may not have access to these devices, but just the configuration dump.

[Mark Malone]

Hi
you could try its going be very difficult unless its a small basic network as a lot of it will be logical so really you need to build the physical layer 1 layout first then you use the current configs routing tables interfaces etc to build the logical overlay , same as troubleshooting you start at layer 1 work up to layer 3 etc , use same method for building a network topology , your going to be relying on descriptions too that could be wrong or were not updated

so if someone asked me to do it , id say no not unless i can plot the physical setup first to understand the layout then id go for understsaanding teh logical design that fits on the physical