Network diagram software

(nanog) Brian Battle nanog at
Thu Feb 19 22:02:20 UTC 2009

Graphviz will do this. (

The basic (dot) syntax for what you describe below is:

digraph G {
	R1 -> VLAN100;
	R2 -> R1;
	SW1 -> VLAN100;
	SW2 -> R2;
	H1 -> SW1;
	H2 -> SW1;
	H3 -> SW2;
	H4 -> SW2;

It'll output a GIF flowchart-style diagram with the nodes connected as
described above.
It's also good for visualizing BGP AS paths .

-----Original Message-----
From: Ross Vandegrift [mailto:ross at] 
Sent: Wednesday, February 11, 2009 9:42 AM
To: Mathias Wolkert
Cc: nanog at
Subject: Re: Network diagram software

On Wed, Feb 11, 2009 at 02:06:09PM +0100, Mathias Wolkert wrote:
> I'd like to know what software people are using to document networks.
> Visio is obvious but feels like a straight jacket to me.
> I liked netviz but it seems owned by CA and unsupported nowadays.
> What do you use?

I'd like to put a second request.  I often want to very quickly
mock-up a diagram that I'm going to use for myself or for internal

Is there any application that takes some kind of *simple* description
and produces a (possibly not so beautiful) picture?  For example, I
might say something like:

	Router(rtr1) connects to vlan 100
	Router(rtr2) connects to Router(rtr1) via T1
	switch(sw1) connects to vlan100
	switch(sw2) connects to Router(rtr2)
	A few hosts connect to Switch(sw1)
	A few hosts connect to Switch(sw2)

Ross Vandegrift
ross at

"If the fight gets hot, the songs get hotter.  If the going gets tough,
the songs get tougher."
	--Woody Guthrie

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