[mrtg] ISDN up/down status - was Re: SNMP based monitoring of

Tim_Cahoon at fmo.com Tim_Cahoon at fmo.com
Thu Dec 13 15:54:24 MET 2001

I don't know that this discussion belongs here, but I do have something to
share.  So I am sending this once.  Anyone who wants to talk about it
further can email at my address below.

I have been trying to do the same thing, monitor the ISDN ports and make
sure layer 1 is up.  The ISDN line bills are paid by the local site and
they have a tendency to stop paying them and losing the line.  So I wanted
a way to verify all 100+ sites that their ISDN is working.

There are 2 Cisco ISDN MIBs.  One is for IOS under 12.0 and one is 12.0 and
higher (I think I got that right).


On our 2600 series routers it's a piece of cake.   The new MIB is made for
this sort of thing and reports the layer 1 status of the Interface.

The 2500's running 11.2 or 11.3 use the older MIB.  The problem there is
that you can't see the Interface itself, you can only see sub-BRI's  (BRI0
0  and BRI0 1).  The problem is that status appears on  .1 or .2 or .3 of
the mib call.  I need a way to query and find out what interface nbr they
are and then do the call.  Technically there are 2 status checks you need
to do for each BRI (one for each spid)

 I wrote a hack in PHP (which uses the ucd-SNMP programs). This tries to
create a web page of the current status of the ISDN interfaces.

What this program needs is a way to check the model number of the router so
I can eliminate the drop down logic.   I also haven't worked on our 3600
series routers with multiple BRI interfaces yet.

What the program does is:
1)  Reads IP address of the router to call from database and see if it
should check the ISDN status (looks for "Y" in record).
2) Makes a call using new mib.  If it gets a valid response (I'm only
looking for 3 of the values) then it stops.
3) If it doesn't get a valid response I do a call from the older MIB
(assuming a 2500 here with older IOS) on the .1 interface.  If not valid do
.2 then .3
4) If I don't get a response then mark it UNKNOWN.

The IP addresses are all in a MYSQL database, with a code to tell if I
should check it ( "Y"), not check it ("N"), or if it is a router using
analog dial backup ("A").  The idea for this came from a TECH REPUBLIC
article (www.techrepublic.com) called "Build your own Ping Server" by Ed
Carp.  I modified the idea to use for this project.  When done, I want a
script to run daily or weekly to load the status into the database where I
can look at it anytime.

Tim Cahoon
Technical Systems Engineer
Federal-Mogul Corporation
Southfield MI, USA
tim_cahoon at fmo.com

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