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Re: Writable SNMP
From: Leo Bicknell <bicknell () ufp org>
Date: Tue, 6 Dec 2011 12:13:38 -0800

In a message written on Tue, Dec 06, 2011 at 11:16:02AM -0500, Jared Mauch wrote:
Anyone that has spent any quantity of time with ASN.1 generally would agree.

SNMP has two fatal flaws for large scale write based configuration.

ASN.1 was basically obsolete before it was written.  It was designed
to be a compact data transfer format in the days of 56k lines, and
is nothing but annoying in practice.  Hard to write, hard to debug,
hard to understand to save a little bandwidth which no longer
matters.

(Note, there is apparently an XML version of ASN.1 which may or may
not make things better, but I have never seen a single bit of gear
anywhere that implemented it.)

But then on top of ASN.1, the transaction model is all wrong.  No
way to group writes together (e.g. commit a series of changes at
once).  One RTT incurred for each write/read-back (for verification,
since it's UDP).  If you try and configure a device with SNMP over
a 500ms link it might take longer than the lifespan of the gear!  :)

Jared also makes a good point about the device not reading SNMP on
boot, it reads a text file, and being able to alter that directly
makes more sense.

Lastly, let's not forget that at most vendors SNMP seems to be a
low priority item.  How many years was it after we had IPv6 BGP
before there was an IPv6 BGP MIB actually implemented?

I actually would submit SNMP was never the right tool for the job,
just the tool we had.  Even today where it's most popular use is
to poll interfaces for statistics it would be easier on the device,
programmer, and operator to make one tcp connection, send a list
of things to poll, and get back a blob of text.  I hesitate to say
XML + Restful, becuse I think it need not be that specific solution,
but that is a solution that meets the criteria.  The only thing SNMP has
going for it at this point in time is inertia.

-- 
       Leo Bicknell - bicknell () ufp org - CCIE 3440
        PGP keys at http://www.ufp.org/~bicknell/

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