Subject: snmpconf Pointers from Policy MIB -> implementation-specific MIB

From: David Partain <[email-masked]>
Date: Thu, 29 Jun 2000 09:31:06 +0200

Greetings,

While speaking with Jon and Harrie, we talked about the need
to have a way to "debug" policies.  Basically, there needs to
be something showing the relationship between a policy in the
policy MIB and its instantiation "lower" down.

We want this so that there is a way of correlating policies
with things that are broken.  If you don't who's implementing
a policy or the parameters that cause the change you want
(or the change you _didn't_ want), you cannot debug it.

Different strategies are possible.  Three are:

 - pointers from the "lower" MIBs (implementation-specific)
   into the policy MIB

 - shared indices between the policy MIB and the
   implementation-specific MIBs

 - pointers from the policy MIB into the implementation-specific
   MIBs

This was discussed at the last interim meeting, and the best
approach appears to be the last of them.  It allows the most
flexibility with respect to how many places to point to (which #2
doesn't), while avoiding the problems that are associated with
#1.

So, we propose that something along the lines of the objects
below be added to the policyMgt MIB in
draft-ietf-snmpconf-pm-??.txt.  The arguments for this are:

  1) If we don't put the relationship pointers in a central
     place we have to spread them all over (if we're going to
     have the information available). Thus, putting them in
     the POLICY-MANAGEMENT-MIB avoids defining them in each
     implementation-specific MIB.

  2) From an implementation-specific MIB module it is not
     possible to know all relationships of applied policies. The
     other way around is that when a policy is applied, the
     management station should already select which
     implementation-specific or instance-specific objects
     are applicable.

  3) Having the relationships in a central place makes them
     useful for debugging policies. For instance, if multiple
     pointers from everywhere pointing to a policy in the Policy
     MIB module you could have well overlooked 1 relationship.

We're obviously not attached to any names.  If someone has a
better way of solving this problem, those ideas are greatly
appreciated.

pmPolicyMechanismTable OBJECT-TYPE
    SYNTAX       SEQUENCE OF PmPolicyMechanismEntry
    STATUS       current
    DESCRIPTION
        "This table is used to show the relationships
        from policies to mechanism specific policy definitions."
    ::= { policyMgt xx }

-- uses a shared index with the pmPolicyTable
pmPolicyMechanismEntry OBJECT-TYPE
    SYNTAX       PmPolicyMechanismEntry
    STATUS       current
    DESCRIPTION
        "An row of the pmPolicyMechanismTable."
    INDEX { pmPolicyIndex, pmPolicyMechanismIndex }
    ::= { pmPolicyMechanismTable 1 }

PmPolicyMechanismEntry SEQUENCE ::= {
    pmPolicyMechanismIndex      Unsigned32,
    pmPolicyMechanismPointer    RowPointer
    }

pmPolicyMechanismIndex OBJECT-TYPE
    SYNTAX       INTEGER (1..2147483647)
    STATUS       current
    DESCRIPTION
        "A unique index for the mechanism pointers."
    ::= { pmPolicyMechanismEntry 1 }

pmPolicyMechanismPointer OBJECT-TYPE
    SYNTAX       RowPointer
    STATUS       current
    DESCRIPTION
        "A row pointer that connects a policy instantiated at
        'pmPolicyIndex' to mechanism specific."
   ::= { pmPolicyMechanismEntry 1 }

Your comments are welcome.

With kind regards,

--
David Partain                  [email-masked]
Ericsson Radio Systems AB      Tel: +46 13 28 41 44
Research and Innovation        Fax: +46 13 28 75 67
P.O. Box 1248
SE-581 12  Linköping, Sweden

---

From: Jon Saperia <[email-masked]>
Date: Thu, 29 Jun 2000 06:55:09 -0400

> from policies to mechanism specific policy definitions."
Excellent points David. Whatever we call this table, it should reflect the
fact that this is really a Mechanism and Implementation MIB Module pointer
table. That is, some vendors will have a 'standard' mechanism specific MIB
Module and a technology specific MIB Module that contains additions or
modifications to those items found in the mechanism specific table.

This table then would support multiple entries for a single policy which is
exactly what we want.

Steve W. Can we add this along with the other items I posted?
 
/jon