Re: DECnet MIB question (3) -- adjacency index

saperia@tcpjon.ogo.dec.com Fri, 21 August 1992 18:20 UTC

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To: art@opal.acc.com
Cc: deb@tci.bell-atl.com, phiv-mib@pa.dec.com, saperia@tcpjon.ogo.dec.com
Subject: Re: DECnet MIB question (3) -- adjacency index
Date: Fri, 21 Aug 92 14:02:13 -0400
From: saperia@tcpjon.ogo.dec.com
X-Mts: smtp

Hi,  This has gotten a bit confusing for me, so I have extracted form the mib,
entered changes - Please comment on this directly. 

Is this what John/Art are suggesting:


       phivAdjTable OBJECT-TYPE
           SYNTAX SEQUENCE OF PhivAdjEntry
           ACCESS not-accessible
           STATUS mandatory
           DESCRIPTION
               "The Adjacency Table."
           ::= { adjacency 1 }

       phivAdjEntry OBJECT-TYPE
           SYNTAX PhivAdjEntry
           ACCESS not-accessible
           STATUS mandatory
           DESCRIPTION
               "There is one entry in the table for each adjacency."
----->     INDEX  { phivAdjCircuitIndex, phivAdjNodeAddr }
           ::= { phivAdjTable 1 }

       PhivAdjEntry ::=
           SEQUENCE {
               phivAdjCircuitIndex
                   INTEGER,
               phivAdjNodeAddr
                   PhivAddr
:
:lines deleted
:
      phivAdjCircuitIndex OBJECT-TYPE
           SYNTAX INTEGER
           ACCESS read-only
           STATUS mandatory
           DESCRIPTION
------>        "A unique index value for each known adjacency."
           ::= { phivAdjEntry 1 }

       phivAdjNodeAddr OBJECT-TYPE
           SYNTAX PhivAddr -- OCTET STRING (SIZE (2))
           ACCESS read-only
           STATUS mandatory
           DESCRIPTION
               "The address of the adjacent node."
           ::= { phivAdjEntry 2 }

This still leaves us with no connection to the circuit over which the
adjacency occurs.  We can either add circuit (as I noted yesturday)  or we can
redefine phivAdjCircuitIndex to be something else (e.g., the Circuit Table
index).  If we do the latter are we certain that we have under all
circumstances created unique indicies to the table?

/jon
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Date: Fri, 21 Aug 92 10:36:48 PDT
From: art@opal.acc.com (Art Berggreen)
Message-Id: <9208211736.AA17463@opal.acc.com>
To: deb@tci.bell-atl.com, phiv-mib@Pa.dec.com, saperia
Subject: Re: DECnet MIB question (3)

>
>I am in agreement with Art regarding the concept. But, I am not sure if any
>new object is needed. Just modification of the INDEX specification to use
>the tuple ( phivAdjCircuitIndex, phivAdjNodeAddr ) should be sufficient.
>I am not clear about how the simple, single index of phivAdjCircuitIndex 
>allows for unique identification.
>(John@proteon.comcom: I didn't meant double indexing through both
>phivAdjCircuitIndex and phivAdjNodeAddr in my original question.) 
>My comment is, why keep the unique identification mechanism implementation
>dependent when it could be done through the use of existing objects in the
>table entry. Also, ( phivAdjCircuitIndex, phivAdjNodeAddr ) tuple would be
>more appropriate than ( phivAdjNodeAddr, phivAdjCircuitIndex ) tuple as
>multiple adjacencies to same node through more than one circuit would be
>relatively rare. 

debasis,

I believe that the two part instance that the tuple (phivAdjCircuitIndex,
phivAdjNodeAddr) implies is what John is trying to avoid.  I'd accept the
single, unique local identifier easier if the values are not required to
be consecutive and the size can be up to 32 bits.  This would allow me to
form my unique identifiers as ( (circuit_index * 65536) + adj_addr ).
Since this a local identifier, someone else's box could use whatever they
prefer.

Art


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