[mrtg] Re: MIB -> OID

[Grendel]

Hello Roy,
	You need to learn how to read backwards.
	Once you've found the name of the node you want in the MIB file, you
should see a set a of brackets with the name of the parent node followed
by the number of your desired node within that parent node. Write down
that number on the right hand side of a piece of paper with a dot
immediately to the left of it. Then take the name of that parent node
and go hunting for its parent and number. Write that new number just to
the left of the dot, and then another dot to the left of that number.
Continue that process upwards until you've built a full OID you can use
as a target. Generally you only need to go upwards until you reach
familiar territory. For example, all Cisco-proprietary OIDs begin with
1.3.6.1.4.1.9. Once you find something like "cisco { enterprises 9 }"
then you've gone as far back up as you need to go.
	Just as a warning, once you've reached the top of one file you may find
you need to jump to another file to continue the search.
	As another warning, if the OID you dig up is not part of a table of
some kind, then you generally need to stick a .0 on the end.

	Trying the search here. Writing out names as well as numbers helps
serve as a reminder of where I am:

local.lenv.envTestPt1Measure
1.79

At the top of the file
ftp://ftp.cisco.com/pub/mibs/v1/OLD-CISCO-ENV-MIB.my I see "local FROM
CISCO-SMI" so I need to continue in that file:

cisco.local.lenv.envTestPt1Measure
2.1.79

In CISCO-SMI is where I find the familiar cisco, as far as I need to go.
The target in MRTG would look something like this:

Target[blort_temp]:
1.3.6.1.4.1.9.2.1.79.0&1.3.6.1.4.1.9.2.1.79.0:public at router

Mind you this is all theory as far as your router is concerned. I have
no way of testing it myself. But this is how I have successfully built
OIDs to measure strange things like channel usage of individual T1
interfaces on Lucent MAXes. Try it with snmpwalk first to see if you're
close to something useful:

snmpwalk router public .1.3.6.1.4.1.9.2.1.79


Best regards,
James

Roy Rapoport wrote:
> 
> So I want to get the temperature of my c3620.
> 
> http://www.cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml
> claims that the C3620 supports OLD-CISCO-ENV-MIB, which contains
> envTestPt1Measure, which _looks_ like what I want.
> 
> But how do I query for it? snmpwalk'ing the entire tree on this router
> netted me nothing that looked appropriate.
> 
> Having read the FAQs, I feel like this -- the ability to understand how to
> translate what I'm reading in a MIB to an actual quaryable OID -- is the
> one critical piece I'm missing.
> 
> -roy
> 
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