Re: [Agentx] Some confusion, while watching AgentX-Register-PDU in net-snmp 5.4

["Randy Presuhn" <randy_presuhn at mindspring.com>]

Hi -

> From: "Mark Atwood" <me at mark.atwood.name>
> To: "Randy Presuhn" <randy_presuhn at mindspring.com>
> Cc: <agentx at ietf.org>
> Sent: Friday, July 06, 2007 6:37 PM
> Subject: Re: [Agentx] Some confusion, while watching AgentX-Register-PDU in net-snmp 5.4


...
> > I'd have expected 9, based on the text on page 24 of RFC 2257,
> > as well as the example on page 25, since it's using the prefix kludge.
> > It might be worth looking at the actual byte stream, rather than
> > a pretty-printed version; it's possible that the pretty-printer is
> > obscuring what's really happening.
> 
> I think the RFC is reasonably clear here.
> 
> | Note that r.range_subid indicates the (1-based) index of
> | this sub-identifier within the OID represented by r.subtree,
> | regardless of whether or not r.subtree is encoded using a
> | prefix. (See the example below.)
> 
> "within the OID represented by r.subtree" tells me that the index is
> into the *actual* complete OID.  r.subtree is just a representation of
> the complete OID.

The example shows an r.range_subid value of 5.  For the example
to make sense, this is the fifth word in the encoding (with a value of 1),
not the fifth subidentifier of the object identifier it represents.  For your
interpretation to be correct, r.range_subid in the example would
be 10.

Note that the text says "r.subtree", *not* "r.region", and thus is not
in terms of the complete object identifier that r.region encodes.
At least that's how I read it. 

Either the example is incorrect, or the explanatory text is unclear, or both.  :-)

> I supposed it could be more clear.  The proof of the pudding would be
> an interop-fest, I supposed.

There was one, long long ago.  Perhaps someone who hasn't been away
from this stuff as long as I have should comment.

Randy