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New Member

Combining several MIB files into a single MIB file

Hi,

I have a Cisco CUCM, and it comes with several MIB files and dependency MIB files.

Unfortunately the 3rd SNMP server has a limitation that it can't compile the MIB files and also can't upload more then 1 MIB file per device.

I was wondering is it possible to create my own MIB file which consist of all the CUCM MIB files and it's dependency MIB files.

This case i'll only need to provide a single file to the 3rd SNMP server for it to monitor CUCM.

Thanks.

  • Network Management
10 REPLIES
New Member

Combining several MIB files into a single MIB file

If the 3rd SNMP server allows you to put the OID (Example 1.3.6.1.4.1.9.9.27) instead of object (Example ciscoCallHistoryMib), you do not need to add MIBs to the 3rd SNMP server. You will be able to monitor the individual OIDs.

The only problem will be that you will see numbers instead of leters.

New Member

Combining several MIB files into a single MIB file

We tried using OID directly and it work, show letters (we need to choose the OID type, which has Char/Int whichever is

Appropriate).

But then, for CUCM each time a phone unregisters / register, the OID for the phone changes.

So we can't monitor the phone based on OID.

New Member

Re: Combining several MIB files into a single MIB file

If you see letters instead of numbers this means that mib is already compiled by default on that 3rd party snmp server. Some snmp applications are comming with a lot of precompiled mibs inside by default.

No, oid does not change, OID will be the same, only the MagicNumber of the phone will change.

You will have to take mac of the phone, convert to hex, and there is another OID where you input the mac and you get the MagicNumber. Afther that you take the magic number and ask different values from CUCM. You should have all the macs in an asset database somewhere.

OID will be something similar to: OID.10.11.12.13.14.15 = MagicNumber where 10.11.... is the mac of the phone in hex.

I did not tested this by myself on CUCM, I answered only from snmp experience.

New Member

Re: Combining several MIB files into a single MIB file

Hi Simionov,

Great to know that the last digit of the OID is not just some random number.

I believe what you meant by Magic Number is the last digit of the OID for the phone right.

But if it depending on the Mac Address, shoudn't the same phone remiain with the same OID.

This is a discussion i created awhile ago:

https://supportforums.cisco.com/message/3506543#3506543

As you can see here, the same user's phone has differrent OID values on different dates.

New Member

Re: Combining several MIB files into a single MIB file

From my tests I can say that this magic number association will take some time to change. The phone has to be off for a long period of time, try to see this as a dhcp lease expire. And it always change, do not use it in scripts, always calculate this number.

In my case the expire was 24 hours of downtime.

Maybe you did not knew, but also when you monitor traffic on an interface on a router, you are reffering to an index of the interface. If for example you will add or remove cards on the router, that index will change, and the full oid for a specific port will also change. This is why there is a command on the router to preserve this index, which most poeple are not using.

I made a small mistake, I just checked some old documentations, you enter with mac in decimal cause mac is already in hex format.

Try to make a snmpwalk on .1.3.6.1.4.1.9.9.156.1.2 and see maybe you find something. Try to look for an longer oid, should be +6 more numbers.

New Member

Re: Combining several MIB files into a single MIB file

Ya, i believe there is an intervel too before the change, i notice this too.

And ya, Cisco IOS has the snmp ifindex persistence feature to pervent any OID change.

How do i get the other OID,  "there is another OID where you input the mac and you get the MagicNumber."

Where/what is this OID.

Did you mean to try a snmpwalk on .1.3.6.1.4.1.9.9.156.1.2, to search for this other OID which would be a 6 or more numbers OID

New Member

Re: Combining several MIB files into a single MIB file

Try a walk on:

1.3.6.1.4.1.9.9.156.1.2.5.1.1

Description:

"An arbitrary integer, selected by the local CUCM,

which uniquely identifies a Phone Extension within the

CallManager."

AND

1.3.6.1.4.1.9.9.156.1.2.1.1.1

Description:

"An arbitrary integer, selected by the local CUCM,

which uniquely identifies a Phone within the CallManager."

What you can do also is:

Make a full snmpwalk on the CUCM in a file.

Now you take one magic number (pointer), and parse the text file for that number:

#cat DUMP_FILE | grep MagicNumber

Hopelly you will see only some lines, most of them with the pointer left of = sign and one reply with pointer on right of = sign. Actually now you need an oid which you will create with something you know (mac in our case) which will have as a reply the pointer of the phone, which you do not know and is always changing.

New Member

Re: Combining several MIB files into a single MIB file

Hi Simionov,

I'll give it a try tomorrow, once i go onsite.

Will update my findings

Thanks.

New Member

Re: Combining several MIB files into a single MIB file

Hi Simionov,

I have tried yesterday but couldn't find any for both the OID mention. It seem it is just and index with no value.

I tried for ccmIndex, ccmPhoneIndex and ccmPhoneExtnIndex.

All got the same result. Attached is a screen shot of what i got.

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