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.

Cisco Network Designer

[dago]

If you want to make design, why head to cisco configmaker instead of cisco network designer ?

Use your HEAD

[noah_fense]

First, use visio to design your CORE network. This would include all your high bandwidth, long haul fibre links. Choose a routing protocol (ISIS and OSPF are what most carriers use). If you want to implement newer protocols like MPLS, you still need OSPF or ISIS to run underneath it. Your core network should be layer three only. Avoid using ATM links becuase they add an extra "layer 2.5".

Then, off of each core router, drop gig-e links off to your layer 2/3 routers. If redundancy is a huge issue (which is probabally is), you will probabally have two core layer 3 routers (probably cicso, juniper) with a small number of ports, and two layer 2/3 routers (riverstone, foundry, extreme) with a large number of layer two ports at each major location with gig-e multimode links btween them to provide extra redundancy. Before you go and buy everything, spend time testing this four router configuration (see how long it takes to reroute traffic when links go down). This is especially important if you ever intend on implementing VoIP on your new network.

All critical systems (DNS servers, domain controllers, application servers, VoIP gateways, database servers) should be on the layer 2/3 routers, not on the smaller routers underneath that most "end users" will be connected to throughout each location. Essentially the layer 3 routers are just for core routing, and the layer 2/3 routers will provide most of your functionality.

Once you have everything up and running, use SNMP to monitor your links (most SNMP management software draws your network for you, and it will draw nice broken links when links go down). Good SNMP software will map every network device on you network, as long as you configure SNMP on all your new nodes. Also, make sure you have a really cool NOC (Network Operations Center) with lots of LCD projectors and linux/unix workstations. Make sure you have a good naming convention for all your network links and routers.

Don't deploy at 100% capactiy immediately, run at 10% capacity then work your way up.Many unforseen problems WILL come up (Routers have more bugs than you can imagine). In the end, you will probably have a nice buildingwide, statewide, nationwide, or worldwide modern next-generation (VoIP etc) capapable network.

-n