How to document unknown network

Unanswered Question
May 17th, 2007

Darn. Imagine you have a network with hubs all over the place. Topology diagrams and labels on cables connected to the hubs are unreliable.

How would you go about documenting and creating a diagram in this case?

I have been trying to trace cable by cable but that's cumbersome like hell. Please suggest how folks handle this.

I have this problem too.
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chris.lepa Thu, 05/17/2007 - 14:39

Ususally people use a software network discovery tool to do the work for them. I think solarwinds has one built in to its suite. SNMP programs can build a decent map for you.

ariela Thu, 05/17/2007 - 15:06

Hi,

design expert di netformx is a good choise. For a free discovery, try 'nedi'.

HTH

Andrea

milan.kulik Fri, 05/18/2007 - 03:28

I'm afraid if there are cheap hubs used (i.e., no SNMP nor Telnet available) there is no other way but tracing cables :-(

BR,

Milan

patrickvanham Fri, 05/18/2007 - 08:22

If it's hubs as you say, I'm afraid the only way is the hard way following cables.

You can try solarwinds (30 day trial) to make a discovery, but hubs won't generally be discovered.

clausonna Fri, 05/18/2007 - 10:19

A few thoughts:

1) if you have at least some switches in your mix, and are trying to figure out what ports have hubs vs. single users, you can use the "show mac-address dynamic" commands to see which switchports have multiple MAC addresses, and thus have hubs attached. Also use 'show ip arp' and 'trace mac ip' for host port investigation.

2) buy a good physical cable tracer / tone generator and go in on a weekend. Disconnect a cable from the hub and attach the tone generator on that end. Now walk around with the 'wand' piece of the cable tracer "pen" and touch it to where you think the cables are connected (i.e. run the tracer across the patch panel) The tone generator sends a singal down the ethernet cable, and the pen will make a 'woo-woo-woo' sound when its touches the exact cable. A good tracer will run you under $100. (I'm not talking about a cable-pair tester here, which shows whether or not an ethernet cable is good, is a cross-over, has bad pairs, etc.)

You're going to want two people with walkie-talkies for this, depending on how big the office is, # of floors, how crazy/bad your cabling is, etc.

I'd also suggest investing in a good cable labeller that does wire-wrap labels (Brady makes a few good ones.) wire-wrap labels are SO much better than standard flat labels like you'd use on a file folder.

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