Re: [Fwd: Re: [RMONMIB] I-D ACTION:draft-ietf-rmonmib-raqmon-pdu- 08.txt]

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

HI,


On Thu, 13 Jan 2005, Randy Presuhn wrote:
 ...
> > This discussion goes back to why "accessible-for-notify" was added
> > in the first place. It was added after an interim meeting near
> > the DFW airport in the early 1990's.
> >
> > I believe it's meaning and use has changed.
> 
> I was there.  I don't see how the meaning has changed.
> I don't see how the use has changed.
> 
 ...

Before the meeting (and before the v2Proto Ops), the concensus
view was that only "table" and "row" object types could have
the access value of "not-accessible". There were a few instances
of MIB designers creating definitions of objects with access
of "not-accessible" to be used for TRAP-TYPE definitions.
And there were others creating definitions with access type
of "write-only". However, these MIB designers were writing
broken propretary MIB modules. They just didn't know they
were not following the rules. 

With the v2Proto Ops, the "trap" operation was replaced
by "v2Trap" and "inform" operations that had the same
structure as the other operations. (Remember that v1Trap
messages were "sligthly different" than GET/SET/GETNEXT/RESPONSE.)
However, with inform and v2trap ops, there was some "extra"
info that was needed to be included that could not be
stuck in other fields like was done for the extra info
needed for GETBULK. The approach was to include objects
sysUpTime.0 [RFC3418] and snmpTrapOID.0 [RFC3418]
as the first two entries in varBindList for a notification.
(And for proxy from v1Traps to include snmpTrapEnterprise.0 [RFC3418]
as the last entry of the varBindList.) Object sysUpTime
already existed as an assessible object. RFC 1450 contains
the definitions of objects snmpTrapOID and snmpTrapEnterprise
with access of "not-accessible". These were special
objects for use only for notifications (so v2Trap
and inform ops could have the same structure as other
v2 ops).

Because only table and row objects could have access
of not-accessible, unless MIB compilers special cased
these two objects and any other special objects
created for new operations, then MIB compilers
would generate an error message. To eliminate
this problem, the new max-access value of
"accessible-for-notify" was added. It was not
added so that MIB designers could create
definitions of objects whose existance was
only at the time a notification was reported.

However, after the change was added, MIB designers
saw it as a way to create definitions of object
types whose existance was only present when
a notification was being reported, and include
them in the OBJECTS clause for a NOTIFICATION-TYPE
construct (and thus in the varBindList of a
v2Trap or inform).

Some people would say this is a good thing.

I just say that many people have found it
useful, and that the SMI should be updated
to reflex current use.

How does your memory differ?

Regards,
/david t. perkins