[j-nsp] SNMP interface index change after upgrade to 9.2

[sthaug at nethelp.no]

> Even though current JUNOS behaviour can be considered spec-compliant I
> would still like to see the ifIndexes being kept static - it would be a
> great feature enhanchement for those of us that (unwittingly) chose SNMP
> software that doesn't handle ifIndexes changing.  As I pointed out in my
> first message, it can't be that hard - just reserve some space for the
> private ifIndexes and start the public ones from, say, 1000.  (This is
> what my Extreme switches does.)

Our experience is that the ifIndexes *are* kept across upgrades. I think
we have had them change *once* on one of our Juniper routers.

> Speaking of Extreme, by the way...  Juniper is the first vendor whose
> gear has changed ifIndexes on me, ever.

Then I'm afraid you haven't been in the field for very long. (Hint: Look
up the documentation for the Cisco command "snmp-server ifindex persist"
and try to figure out how long Cisco had been selling boxes with SNMP
before that command showed up...)

> I assume most of the people on this list are not application developers,
> but network administrators - at least I am not.  So I/we are stuck with
> whatever pieces of software is available, and changing an already-
> established setup is probably going to be a big project in most cases.
> Considering that not even the ubiquitous MRTG handles changing ifIndexes
> by default I think static ifIndexes would be a worthwhile feature for
> Juniper to implement in an upcoming JUNOS release.

As already mentioned - in most cases it *is* static.

Steinar Haug, Nethelp consulting, sthaug at nethelp.no