Complex Network Design Tools?

I'm-Not-A-BOFH asks: "How do you do your large scale network design? I am currently designing a large enterprise network - and there is a ton of information to track and think about. I use AutoCAD, Visio and Cisco Configmaker (which sucks) and many other applications. I am looking for software specifically designed to help you design a network. What tools do you use - and what tools are out there that maybe are little known? How do you begin to manage network documentation when your hosts get into the thousands and your routers and routes into the hundreds? I am really just interested in the tools used to accomplish this - as all the tools I have been finding are just not adequate or well thought out. Please let me know what you think is invaluable to you when you design your systems."

Comments

Some useful tools.

[Mordant]

http://www.research.att.com/sw/tools/graphviz/

http://www.lumeta.com/ipsonar.html

The whiteboard.

A good knowledge of networking protocols, etc.

The hardcore network engineer doesn't need diagrams - sh ip route, sh ip bgp, sh ip ospf, sh cdp neigh, sh arp, sh cam dyn, etc. (in Cisco-speak; there are equivalents for other vendors) are enough to visualize/plan/troubleshoot, quite frankly.

opnet

[austad]

Opnet

I've been looking at this recently to see how different things will affect my network, since I can't really test them on the live network without making a lot of people and clients really mad. I have not used it yet though.

I prefer to design the network simply using Visio to get a good logical design, and then once that is down, I create another map with the physical layout. Worry about your routing protocols after you have figured out the best logical design (redundancy, required link speeds, etc.). Most network admins have a favorite routing protocol, which for most seems to be EIGRP with cisco equipment. I personally like OSPF because it offers enormous flexibility, and it works with equipment from vendors other than Cisco.

There's a fine line between an ingeniously designed network and something that is overly complex. It takes experience to figure out where that line is. If it seems like you are doing something screwed up, you probably are.