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HP 1920 SNMP monitoring

 
Lars_nijhuis32
Occasional Visitor

HP 1920 SNMP monitoring

Hello everybody,

I have a question regarding monitoring an hp switch using SNMP, i am quiet new to SNMP.
I have read up the basic principles for SNMP monitoring and i have some questions:

I have downloaded the MIB list for the switch and have enabled the SNMP on the switch.
But how can i get the OID out of the MIB list/files i have downloaded?

also is there an guide for snmp monitoring for hp switches?

1 REPLY
Matti_Kurkela
Honored Contributor

Re: HP 1920 SNMP monitoring

MIB files are basically text files with some strict formatting rules to enable them to be processed automatically.

If you want to look up numerical OIDs from MIB files, you will need a "MIB Browser" utility program.

In theory, you could look up a small number of OIDs manually by just reading the appropriate MIB files, but that's going to be a very tedious job.

Most MIB files have an IMPORTS clause at the beginning, referring to other MIB files (usually very standard ones, like RFC1155-SMI, RFC-1212 or RFC1213-MIB). Then, they define their UID space starting from a particular base UID.

For example, HP-UNIX MIB imports the "enterprises" keyword from RFC1155-SMI. That keyword refers to UID .1.3.6.1.4.1, or "iso.org.dod.internet.private.enterprises" in text form. Then, the first few definitions in the file are:

hp              OBJECT IDENTIFIER ::= { enterprises 11 }
nm OBJECT IDENTIFIER ::= { hp 2 }
system OBJECT IDENTIFIER ::= { nm 3 }
interface OBJECT IDENTIFIER ::= { nm 4 }

That means, it defines UID .1.3.6.1.4.1.11.2 as "iso.org.dod.internet.private.enterprises.hp.nm", adding some new levels to the UID tree structure. After that, there is a branch in the structure: ...enterprises.hp.nm.system and ...enterprises.hp.nm.interface will be .1.3.6.1.4.1.11.2.3 and .1.3.6.1.4.1.11.2.4, respectively.

The actual data is typically held in the leaf nodes of the UID tree, which will have a more elaborate definition in the MIB file:

computerSystemUpTime OBJECT-TYPE
        SYNTAX  TimeTicks
        ACCESS  read-only
        STATUS  mandatory
        DESCRIPTION
                "Time since the last boot."
        ::= { computerSystem 1 }

That's the definition for .1.3.6.1.4.1.11.2.3.1.1.1, or ...enterprises.hp.nm.system.general.computerSystem.computerSystemUpTime. It is a read-only value of standard type TimeTicks, i.e. hundredths of a second. It is a non-negative number between 0 and (2e32-1), inclusive.

Usually, your SNMP monitoring application should be reading the MIB files and using them to translate the UIDs and their values into human-readable strings and meaningful display formats. Some SNMP utilities can also walk through the SNMP information available from a particular network device and present the available information as a list.

Some parts of the UID trees are defined as containing tables of information, e.g. a some types of information for each port of a switch. To present such a SNMP table in a meaningful way, you'll usually need an application to do it for you: picking the data you want manually from a list-form SNMP walk output is extremely tedious.

In short, you'll need a MIB browser utility to visualize the structure of the SNMP information for you. Such an utility might be integrated in your monitoring software, or it might be a separate utility you'd use to identify the right OIDs you would then plug into the actual monitoring software.

The next question will inevitably be, which operating system are you running, on your monitoring system, and/or on your workstation that you would use for visualizing the UID structure and looking up the UID numbers as necessary?

On Linux, I use the Net-SNMP command-line tools (snmpwalk, snmptable) for verifying that SNMP connectivity exists and the desired information is actually available from a given device. I also use mbrowse ( https://sourceforge.net/projects/mbrowse/ ) mainly to visualize the UID tree, but it can also send SNMP queries and do some of the things the command-line tools can do.

Network switches are usually fairly easy to monitor with SNMP, as they are likely to have much of their interesting information in the standard iso.org.dod.internet.mgmt.mib-2 sub-tree, or .1.3.6.1.2.1.*.

MK