[mrtg] Re: Number of Ips

[Jay Hennigan]

On Tue, 18 Mar 2003, michael smith wrote:

> I am searching for OID for cisco routers , thats give me number of used
> IPs per interface or per router and also the available IPs that can be
> used per interface or also per router .

Per interface, you'll want to calculate it from the network mask applied
to the interface for available IPs directly connected.  However, the total
amount of IPs that can be routed to an interface is a whole different
animal, and can be either static or dynamic.  For the number of directly
connected IPs, take the ones' complement of the netmask in binary, subtract
three*, and that's the number of hosts.  As to how many of them are actually
in use, that's a bit tougher.  The OID for IP subnet mask or network mask
is what you want.  Unnumbered interfaces, NAT, etc. can give unreliable or
wrong results.

Per router?  That's a whole different animal, and if you have a default
route it could be, well...  rather large.

I don't see how MRTG would come in to play here.

> If anyone know that pls advice

Tell us what the problem is that you're trying to solve with this question
and there is a good chance someone here has done it, though I suspect maybe
not using MRTG.  Netmask changes on router interfaces aren't normally the
type of thing one needs to graph every five minutes.  :-)

* one for the network all-zeros address, one for the broadcast all-ones,
  and one for the interface itself = three.

-- 
Jay Hennigan - CCIE #7880 - Network Administration - jay at west.net
NetLojix Communications, Inc.  -  http://www.netlojix.com/
WestNet:  Connecting you to the planet.  805 884-6323

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