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."

Netviz

[ryanmoffett]

We use Netviz. It is data-driven and all the data for the diagrams can be stored in a database. Create one instance of a router, and that instance can appear in any of your diagrams with all of the properties, links and any number of user-defined attributes. Diagrams can be constructed in a hierarchy with drill-down-to-detail capability. Obviously, this is only one component of many you will need in the design process. It doesn't contain all the device specific config-checking tools that some other vendor-specifc tools have, but who needs those anyway?

Also, another set of tools that you might find useful is Opnet IT guru. If you need to model a proof of concept involving a complex network and application interaction, this can do it.

If you run a very Cisco-centric network (or totally Cisco) you can use IPAT Plus from WANDL. It takes Cisco router configs and builds a network model that can be used for reachability proof and various what-if scenarios.

Re:Some useful tools.

[Mordant]

I do just that, every day - on a VERY large enterprise network. Before that, for an ISP hosting one of the busiest Web sites in the world.

Our network changes so much (because it's so large, and there are many people doing things to it 24/7 worldwide) that any sort of diagrams are pretty much obsolete the moment they're drawn. The pretty pictures are useful props for talking to management, etc., but they are of zero value in troubleshooting the network.

I don't need to visualize thousands (we went into five figures years ago) of devices simultaneously - nobody does. But since we adhere to sound architectural principles, and know what we're doing, I can troubleshoot any portion of said network without any diagrams other than the ones in my head as I poke around and a few quick sketches I might draw 'live' on a pad as I make inferences from my observations.