Re: Challenges for the BGP MIBv2

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

Hi -

> From: "Jeffrey Haas" <jhaas@nexthop.com>
> To: <ietfmibs@ops.ietf.org>
> Sent: Tuesday, September 28, 2004 9:56 AM
> Subject: Re: Challenges for the BGP MIBv2
...
> Would you recommend having both forms - the human readable form
> and also the machine readable form?

I'd be wary of doing so, unless there was very clear language about
which took precedence if the two forms didn't agree, both for reads and
for writes.

...
> To ask a related question, when working on a standards track MIB,
> is the inclusion of an object that is longer than 400 octests
> an immediate red flag?

As a reviewer, I'd want to know more about the motivation and
expected usage, and would be strongly inclined to request a more
robust alternative.

...
> I believe that the primary effect of this is that a walk of
> the PathAttrTable subtree will *not* show the community table since
> that is "elsewhere".

This is not a problem.
This is the way, for example, all the media-specific stuff works
with respect to the interfaces table.

> Is there an accepted practice that allows one to extend an existing
> table without have to issue a new document that revises the entire
> table?

According to RFC 2578 (page 38), one of the things that may be done is:
(7)  A conceptual row may be augmented by adding new columnar objects at
     the end of the row, and making the corresponding update to the
     SEQUENCE definition.

Other options include creating a new table using common indexes or AUGMENTS.

> I really expect the answer to the above question is "no, that's not
> the way SMI works".  This would be a pity since allowing something like
> this allows for cleanly extending table contents for extensions.
...

For applications (or scripts) doing MIB walks, there's really no difference in
code size or complexitity between doing
     get-next(T1.a.i, T1.b.i, T1.c.i, T1.x.i)
and
     get-next(T1.a.i, T1.b.i, T1.c.i, T2.x.i)

It boils down to a tradeoff between document tidiness and whether
cycling back to proposed standard would be a problem.

Randy