Subject: Re: [netmod] yang 1.1 webex on wednesday october 29th

From: Randy Presuhn <[email-masked]>
Date: Wed, 29 Oct 2014 19:29:33 -0700 (GMT-07:00)

Hi -

>From: Andy Bierman <[email-masked]>
>Sent: Oct 29, 2014 5:04 PM
>To: Juergen Schoenwaelder <[email-masked]>, Andy Bierman <[email-masked]>, "[email-masked]" <[email-masked]>
>Subject: Re: [netmod] yang 1.1 webex on wednesday october 29th
...
>None of the SNMP server code I worked on supported multiple revisions
>of any module in the agent.  There was 1 module loaded for each module name.
>SMIv2 has no way to import a specific revision of a definition.

FWIW, though, it's really easy to support this in systems using
subagent technology, in part due to the SMI's restrictive rules
for revising modules.  It's not terribly likely in single vendor
single processor boxes where all the firmware is kept in synch.
In "open" systems, and ones in which subagent soft/firmware
resides on more-or-less independently updated line cards or similar
modules, it can very easily happen.  Coping with this gracefully
is one of the big plusses of subagent technologies.

Randy

---

From: Martin Bjorklund <[email-masked]>
Date: Thu, 30 Oct 2014 09:14:00 +0100 (CET)

> is one of the big plusses of subagent technologies.

I don't think the subagent mechanism solves the problem.  Suppose you
have a column in some table in v1 of a MIB.  In v2 this column's
syntax has an expanded range.  Now, suppose subagent A implements v1
of the MIB, and registers for one row in the table, and subagent B
implements v2 of the MIB and registers for another row.  How does the
SNMP manager know which instances of column C support the new values
introduced in v2, and which don't?

/martin