Life, the Universe, and Everything...

or the Hitchhiker's Guide to SNMP...

These days, I have been reading - or re-reading, Douglas Adams' Hitchhiker's Guide to the Galaxy. Funny enough, this will be the subject of my SNMP blog today...

As a side-story, the Hitchhiker's Guide to the galaxy recount how a supra intelligent pan-galactic race - whose name I won't disclose to preserve those readers who might not yet be acquainted with that novel - have built themselves a gigantic monstrous computer to resolve the great enigma of Life, the Universe, and Everything. After seven and a half million years of computation, the monstrous computer, named Deep Thought, has finally arrived at the answer. And it ascertains that without any doubt, the answer to the question of Life, the Universe, and Everything... is forty two.

As shocked politicians and showbiz representatives wonder how they are going to announce the dismaying answer to the crowds who have gathered in great numbers to hear the ultimate answer to the question of Life, the Universe, and Everything, the super computer elaborate on how to understand the answer of forty two, you would have to formulate the exact ultimate question which would make the ultimate answer obviously clear.
Although it declares itself unable to provide the ultimate question to the ultimate answer to Life, the Universe, and Everything - Deep Thought says he can design and build a yet greater and even more monstrous computer which will be able to compute the ultimate question to the ultimate answer...

Funny enough, my blog today will also lead us to the Ultimate answer to Life, the Universe, and Everything...

In a previous entry, Simple Is Not Easy, I have briefly talked about SNMP itself. Today I am going to introduce the concept of OBJECT-IDENTIFIERS, which are at the root of the Structure of Management Information (SMI) used to describe SNMP data.
To make it brief, an OBJECT-IDENTIFIER or OID identifies a node in a global tree whose arcs (segments between parent and child nodes) are identified by numbers.
All SNMP definitions - MIBs, objects, etc... are identified by their OID in this global tree. The root of the OID tree is defined by the ASN.1 standard, and has three nodes at its first level iso, ccitt, and joint-iso-ccitt. More of interest to us are two sub-branches of this global tree:

mgmt OBJECT IDENTIFIER ::= { iso(1) org(3) dod(6) internet(1) 2 }

is the sub-branch that is used by standard SNMP MIBs, like for instance those defined by RFC2011, RFC2012 and RFC2013.

enterprises OBJECT IDENTIFIER 
            ::= { iso(1) org(3) dod(6) internet(1) private(4) 1 }

is the sub-branch where each company can obtain a subnode in order to register its own MIBs. The IANA (Internet Assigned Numbers Authority) is responsible for the allocation of these subnodes. And the subnode owned by Sun Microsystems is precisely... forty two, leading to the OID:

sun OBJECT IDENTIFIER ::= 
           { iso(1) org(3) dod(6) internet(1) private(4) enterprises(1) 42 }

Usually, such an OID would be written - in what we call the dot notation, as:

1.3.6.1.4.1.42

As a further example, the root OID of the JVM-MANAGEMENT-MIB that we will be examining later has been defined as:

sun 2 jmgt(145) standard(3) jsr163(163) 1

In fact, Sun Microsystems is responsible for the allocation of any node that falls under the branch:

sun OBJECT IDENTIFIER ::= 
           { iso(1) org(3) dod(6) internet(1) private(4) enterprises(1) 42 }

So does this means that Sun is also the answer to Life, the Universe, an Everything? Well - only the future will tell, but my next entry is going to take you further down the SNMP global OID tree, in the bowels of the Structure of Management Information and the JVM-MANAGEMENT-MIB.

Until such a time, have a nice trip to the root of the SNMP universe!

Note: The next post in the SNMP Series is Understanding the Structure of Management Information (SMI)... or the Hitchhiker's Guide to SNMP, Part-II.

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Daniel Fuchs blogs on Scene Builder, JMX, SNMP, Java, etc...

The views expressed on this blog are those of the author and do not necessarily reflect the views of Oracle.

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