DECnet MIB question

"John A. Shriver" <> Tue, 11 August 1992 15:19 UTC

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Date: Tue, 11 Aug 92 10:11:45 EDT
From: "John A. Shriver" <>
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In-Reply-To: Debasis Dalapati's message of Mon, 10 Aug 92 18:57:49 EDT <>
Subject: DECnet MIB question

   Date: Mon, 10 Aug 92 18:57:49 EDT
   From: (Debasis Dalapati)


   I am looking at the document "DECnet Digital Network Architecture
   Phase IV, Routing layer Functional Specification, December 1983"
   and not sure how the following management information is modeled in
   the Phase IV mib specification.

   1) page 38-39, adjacency database.  Adjacencies are for broadcast
   circuits, neighbors on non-broadcast circuits, all router
   adjacencies on the ethernets and endnodes in the home-area.

      In the RFC1289, page 50 for Adjacency group, PhivAdjEntry is
      INDEXed by phivAdjCircuitIndex. The DESCRIPTION for
      phivAdjCircuitIndex is "A unique index value for each known

I suspect that the wording is a little off here.  I suspect that the
index is unique for each adjacency.  Each adjacency on a line can be
viewed as a circuit.  The wording of the RFC probably needs to be
fixed here.

      This is fine if only the broadcast circuit adjacencies are of
      management interest.  Are the broadcast router adjacencies and
      endnode adjacencies are of no management interest? Why? Is it
      because they are of transient nature based on the hello timer?
      If all kind of adjacencies at a given point of time are of
      management interest, should not the INDEXing be through
      phivAdjNodeAddr with some way of identifying the multiple
      broadcast circuit adjacencies?

You don't want to use the node address because you'd need to double
index, because you can have multiple adjacencies with the same node.
Double indexed tables are a bitch.

   2) In the RFC1289, page 53-59 talks about line table and
   non-broadcast line table.  In the UNIX environment, these tables
   may be initialized from the kernel.  In the non-UNIX environment,
   at least for my target environment, it is other way; the drivers (
   at least the non-broadcast ones) start by reading these table. In
   other words, these tables are populated at initialization.

      Would it be appropriate to define a new ACCESS type that brings
      out the
      fact that some objects are writable at initialization only and
      then they are read-only?

SNMP has never given a clear mapping of what an SNMP write does.  Eg.,
is an SNMP write the same as an NCP SET or qan NCP DEFINE?  To the
best of my knowledge, the typical mapping is "SET", eg. only affect
volatile database.

   3) IfIndex is so specific to UNIX environment and it is used to
   describe few objects in the MIB spec! A non-UNIX person just asked
   me the question after looking at the MIB spec?

Huh?  IfIndex was derived in the router environment, which was, after
all, the first SNMP target.  It corresponds quite closely with the
interface numbers in our router.