Standards and Tools for Computer Network Diagrams?

_kabel asks: "Recently I've been asked to draw a map of my company's computer network. Gathering the data to do this isn't the problem though - it's drawing it all. This is no easy task, as it contains hundreds of hosts in many locations around the world, linked together with quite a variety of methods (modem, ISDN, ADSL, VPN over Internet and more.) So I have two questions: (1) Are there any standards on computer network diagrams (i.e. the symbols used for the various devices and connections) and (2) are there any tools already available to assist in this?" I know Visio has the capabilities and the symbols to do this, but what about the free-software diagramming tools?

Comments

Standard Symbols 2

[Cmdr. Marille]

Well,
just found this http://www.cisco.com/warp/public/503/2.html>
standard networking symbols from cisco, in a whole slew of formats, with a reference pdf

Why graphical mapping is important...

[Cmdr. Marille]

First of all, yes spreadsheets can be very important for network documentation, but i think a spreadsheet alone is insufficient(at least once the network reaches a certain size)
Think about it, what if something happens to you?
You (and your admin colleagues) may have everything in their minds. Where is which router, what does it connect, what vlans are configured on that switch, what uplinks, stp configuration, redundant interfaces/links.
Now what if sonmething happens to you and your colleagues.
Suddenly someone else has to administer the network, and if the network has a certain size, it will be a taunting task to find out how exactly the topology(physical as well as logical) is structured.

Also a graphical map prevents misunterstandings and generally speeds up the process of making topological changes to your network.
If you have a consultant or external support at your site, it helps. Show them the diagram instead of explaining for half an hour.
For me it also is very nice to have such a diagram, from time to time it's very helpfull to take a step back and look at such a map when troubleshooting.
It helps when you work with other admins, because you can draw and comment on a printed out version of the map.

I think the mistake a lot of people are making(especially with visio VNE) is to win graphic design awards when drawing network maps, that's not the purpose of it.
Keep them simple, with only a limited set of stencils(but then again comment them well).

At last drawing the network maps helps to understand the network, if you for example have a junior admin at your site, let him draw a map, he will understand the network much better(if you build the network yourself, drawing a map obviously very seldom helps your undertsanding ;-) )

Also drawing network maps is important when proposing network designs to customers or suggesting network changes to executives(see, this is very the firewall is going, protecting your precious e-mail server).