Re: SMIv2 Doubt

["David T. Perkins" <dperkins@dsperkins.com>]

HI,

In the below, C.M. Heard is teasing you! If you do not specify an
INDEX or AUGMENTS clause, then you have an illegal set of definitions
in a MIB module. You DO NOT have "a related collection of scalars".
Again - the only thing you have is illegal definitions!

At 09:02 AM 7/15/2003 -0700, C. M. Heard wrote:
>On Mon, 15 Jul 2002, Sharninder Singh-662 wrote:
>> i have written an MIB in SMIv2. I have a table in it and am not
>> using the INDEX clause in it. the snmptranslate utility in
>> net-snmp package shows the tree to be fine. is the INDEX clause
>> necessary .. what is its use ? the definition in the rfc was a
>> bit vague ?
>
>RFC 2578 (which is the RFC in question) is not vague.  You just need
>to read it more carefully.
>
>The INDEX (or AUGMENTS) clause is used to identify instances of the
>columnar objects in a conceptual table.  See the second paragraph of
>RFC 2578 Section 7, "Mapping of the OBJECT-TYPE macro", and then
>read the elaboration in Section 7.7, "Mapping of the INDEX clause".
>
>It is not legal to have a conceptual row definition without an INDEX
>or AUGMENTS clause.  This is unambiguously stated in the first
>sentence of RFC 2578 Section 7.7.  A strict MIB module syntax
>checker should have complained.  Evidently snmptranslate does only
>as much syntax checking as it needs to do the translation, and is OK
>with a missing INDEX or AUGMENTS clause.
>
>So, the question is, what does snmptranslate do with your
>definition?
>
>Well, if you don't have an INDEX or AUGMENTS clause, then each
>column in the table can only be interpreted as a scalar, and would
>be identified by appending a sub-identifier of zero to the OID value
>assigned to the OBJECT-TYPE invocation (as stated in the second
>paragraph of RFC 2578 Section 7).  So you wouldn't really have a
>table at all, but only a related collection of scalars.  The OID
>tree would look OK, but the the result would probably not do what
>you want.
>
>//cmh
Regards,
/david t. perkins