Slightly-Offtopic - Networking audit question

[Brian]

On Tue, 2004-08-17 at 16:44, Travis Roy wrote:
> My company is doing an audit to find out what customers are connected to 
>   what switch ports.
> This is our current procedure:
> 
> 1.  Determine one of the IP addresses that the customer is using.

What if they have 3 machines in a subnet?  Does every customer get
exactly one ethernet feed, and then they supply their own switch/hub for
multiple machines?


> 3.  At the prompt, type "show arp | include [IP ADDRESS]":
> 4.  The output will look like the following:
> 
> Internet  xxx.xxx.xxx.xxx          59   yyyy.yyyy.yyyy  ARPA 
> FastEthernet0/0/0
> 

> 16.  We look up port 17 and see that it is otherwise unallocated, so it 
> must be the port of our customer.

FWIW, it's handy to label the switch ports with the customer name as
they are assigned.  Maybe you already know this and are doing it for new
customers, but I just thought I would mention it.

> Okay, so basically what I'm looking for, is there an easier way to do 
> this? What would be good options to automate this? I have our IP ranges, 
> it would be nice to just feed them in then get a list of what IPs are 
> connect to whatever switch port.

At my last job, I wrote a collection of perl scripts that basically
managed customer data, IP subnet, and could configure Cisco equipment
with SNMP.  All of what you are doing could probably be handled with a
handful of perl and a little bit of seed information (Like customer
name, subnet, etc).  However, you probably don't want to go learning
SNMP and all that just for this little project.  I would suggest you
look at the Net::Telnet::Cisco perl module (I'm pretty sure that is/was
the name of it).  

If all your gear is already setup with SNMP communities and stuff (I
assume it is for basic monitoring), you could download a 30-day trial of
WhatsUp Gold, which will walk your network and pretty much map it all
out for you.