One document matched: draft-ronc-domain-phb-set-ldap-rep-00.txt

Internet Draft                                      R. Cohen
Expires: September 2000                             Y. Snir
draft-ronc-domain-phb-set-ldap-rep-00.txt           J. Strassner
                                                    Cisco Systems
                                                    March, 2000

       LDAP schema for Domain Per Hop Behavior Set



Abstract

This memo provides an LDAP representation for Domain PHB sets.
A Domain PHB set allows the network administrator to control and
tune PHB parameters within its DS domain in an abstract form.

1. Status of this Memo

This document is an Internet-Draft and is in full conformance with
all provisions of section 10 of RFC2026.  Internet-Drafts are
working documents of the Internet Engineering Task Force (IETF),
its areas, and its working groups.  Note that other groups may also
distribute working documents as Internet-Drafts.

Internet-Drafts are draft documents valid for a maximum of six
months and may be updated, replaced, or obsoleted by other
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ftp.isi.edu (US West Coast).


2. Introduction

Domain PHB Sets are defined in [PHBSET]. A Domain PHB set allows
the network administrator to control and tune PHB parameters within
its DS domain in an abstract form. This memo defines the mapping
of the [PHBSET] information model classes to a directory that
uses LDAPv3 as its access protocol. This memo fits into the overall
framework for representing, deploying, and managing QoS policies
being developed by the Policy Framework Working Group. The memo
complements the framework built by the core policy schema [PCORE]
and the QoS policy schema [PQoS].


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Implementations that use an LDAP directory as their policy
repository SHOULD use the LDAP policy schema defined in this
document.
This memo refers to [PHBSET] for details and examples of PHB Sets
and their mapping to actual device configuration parameters.

3. General discussion on the Directory representation

This section discuss the class definitions, specified in the next
section, the DIT containment recommended and restriction on the
implementation of a set of valid PHBs.


3.1 Naming Conventions

Domain PHB sets are part of the QoS extensions to the core schema.
The naming conventions for classes and attributes follow the rules
and recommendations in [PCORE] and [PQoS]. All class names start
with qosPolicy prefix, while attribute names start with qp prefix.
Auxiliary classes names end with AuxClass suffix.

3.2 Classes and DIT structure

Two classes are used to represent a Domain PHB set. An auxiliary
class qosPolicyPHBSetAuxClass that carries global parameters of
the PHB set, and a series of qosPolicyPHBClass structural classes,
each representing a single PHB in the set. All qosPolicyPHB
classes of the set must be located in the Data Information Tree
(DIT) directly under the class the qosPolicyPHBSetAuxClass
is attached to.

PHB sets can be kept in a repository. A repository, modeled in
[PCORE] using the structural class policyRepository is a
container for reusable objects. A set of reusable PHB Sets
can be used as a pre-prepared library of standard and non-
standard PHB Sets a network administrator can choose from. A
PHB Set can be reused in different QoS Domains. In order to
put a PHB Set in a repository qosPolicyPHBSetAuxClass must
be attached to the structural class policyInstance. The
policy instance carries the name of the reusable PHB set and
allows the instantiation of the PHB set object by providing a
structural class for attachment. The reason for defining a PHB
set class as auxiliary class lies in the general requirement
of efficient representation of the policies in an LDAP server.

A QoS Domain deploying differential services must include a Domain
PHB set that specifies the set of PHBs provisioned in the domain.
QoS domain is modeled in [PQoS] by the structural class
qosPolicyDomain. There are two possible methods for associating a
PHB set with a domain. The qpPHBset attribute of the

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qosPolicyDomain may hold a DN pointer to a PHB set in the
repository. The PHB Set can be directly attached to the Domain if
there is no need for reusability.

In order to be able to build end to end QoS services, the same
set of PHBs should be enforced on the entire domain. Nevertheless,
in some circumstances a need to fine tune some of the PHB parameters
on a smaller scope may be required. For example, modifying the
reserved bandwidth on high speed interfaces for a given PHB.
To allow overriding the domain PHB set parameters on a smaller
scope, PHB sets can either be referenced from the
qosPolicyNamedContainers qpPHBSet attribute, or attached to the
named containers. Note that the consistency of end to end PHBs
is not enforced by the schema, and the applications managing
the schema should make sure that overriding does not break end
to end behavior.

3.3 Inheritance Hierarchy

The following diagram illustrates the class hierarchy of the PHB
Set classes relative to the LDAP Core Policy Schema classes and
QoS Policy schema classes.

     top
      |
      +--policy (abstract)
          |
          +--qosPolicyPHB (abstract)
          |      |
          |      +--qosPolicyPHBClass(structural)
          |
          +--qosPolicyPHBSet (auxiliary)
	         |
                 +--qosPolicyPHBSetAuxClass (auxiliary)


qosPolicyPHB and qosPolicyPHBSet are defined in the QoS Policy
Schema [PQoS].


4. Class Definitions

The formal language for specifying the classes, attributes, DIT
structure and containment rules is defined in reference [ATTR].
Note: all attribute, object class, and name form OIDs,
and all structure rule integers, are place holders, and syntax
OIDs in definitions have been replaced by names for clarity.




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4.1 The Auxiliary class qosPolicyPHBSetAuxClass

This class carries global parameters relevant to the entire PHB
set and can be attached either to policyInstance when placed in
a repository, to a qosPolicyDomain or to a qosPolicyNamedContainer.

Class definition:

     ( <oid-oc1> NAME 'qosPolicyPHBSetAuxClass'

            DESC 'The central class for representing a PHB Set
                  enforced on a domain'
            SUP Policy, qosPolicyPHBSet
            MAY (qpTotalBufferSize $ qpTotalPacketNum)
     )


The attributes are defined as follows:

     ( <oid-at1> NAME 'qpTotalBufferSize'
            DESC 'The total buffer size in bytes available in each
                  network node scheduling interface for queuing
                  packets. This buffer space is shared between the
                  PHBs.'
            SYNTAX INTEGER
            EQUALITY integerMatch
            SINGLE-VALUE
     )

     ( <oid-at2> NAME 'qpTotalPacketNum'
            DESC 'The total number of packets that can be queued
                  on each network interface.'
            SYNTAX INTEGER
            EQUALITY integerMatch
            SINGLE-VALUE
     )

One of this attribute is needed whenever the network administrator
chooses to allocate percentage of the buffer space to each PHB and
there is a need to get to definite number of queue and threshold
sizes derived from the PHB Set.

4.1 The class qosPolicyPHBClass

The qosPolicyPHBClass class represents a single PHB in the PHB Set. The
qosPolicyPHBClass is a structural class, that has a single superior
in the DIT containment definition, the Structural class
qosPolicyPHBSetAuxClass is attached to. The defined scope of the
qosPolicyPHBClass is the qosPolicyPHBSetAuxClass namespace.

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The qosPolicyPHBClass inherit the cn (common name) attribute from the
abstract Policy class. The cn is used to provide a human friendly
name for the PHB. Examples include 'EF', 'Mission Critical', etc.

The attribute qpDSCP is used as the RDN for the qosPolicyPHBClass class,
in order to enforce uniqueness of DSCP value per PHB. There is
no requirement to define qosPolicyPHBClass object for every possible
value of DSCP.

The classes PolicyElementAuxClass [PCORE] and qosPolicyElementAuxClass
[PQoS] can be attached to qosPolicyPHBClass entries to mark these
entries as Policy elements and QoS policy elements respectively.
This provides an easy selection criteria for efficient retrieval.


Class definition:

     ( <oid-oc2> NAME 'qosPolicyPHBClass'

            DESC 'A class representing a single PHB within a PHB
            Set.'
            SUP policy, qosPolicyPHB
            MUST (qpDSCP)
            MAY (qpSchedulingClass $ qpDefaultClass $
                 qpImmediateFwrd $ qpReservedBW $ qpFwrdFctr $
                 qpResrvedPckts $ qpBufferFctr $ qpTrafficType $
                 qpPcktSize $ qpMaxPerHopDelay)
     )


For further discussion and examples of the use of each attribute
refer to [PHBSET]. The attributes are defined as follows:

     ( <oid-at3> NAME 'qpDSCP'
            DESC 'A PHB selector. Each PHB must have a distinct DSCP
                 value. DSCP values range between 0..63'
            SYNTAX INTEGER
            EQUALITY integerMatch
            SINGLE-VALUE
     )

     ( <oid-at4> NAME 'qpSchedulingClass'
            DESC 'A number identifying all PHBs that belong to the
                  same scheduling class. Order of packets must be
                  preserved for all PHB with the same scheduling
                  class.'
            SYNTAX INTEGER
            EQUALITY integerMatch
            SINGLE-VALUE
     )

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     ( <oid-at5> NAME 'qpDefaultClass'
            DESC 'A Boolean flag that must be set on one and only one
                  of the PHBs in the set. This specifies the default
                  PHB provided to flows with an unspecified PHB
                  selector.'
            SYNTAX Boolean
            EQUALITY booleanMatch
            SINGLE-VALUE
     )

     ( <oid-at6> NAME 'qpImmediateFwrd'
            DESC 'A Boolean flag that specifies whether immediate
                  forwarding of packets belonging to this PHB is
                  required.'
            SYNTAX Boolean
            EQUALITY booleanMatch
            SINGLE-VALUE
     )

     ( <oid-at7> NAME 'qpReservedBW'
            DESC 'Bandwidth in Kb/sec reserved for the behavior
                  aggregate. For PHBs that do not require immediate
                  forwarding, the reserved bandwidth value
                  determines the minimal bandwidth reserved for this
                  service. In immediate forwarding PHBs, the reserved
                  bandwidth indicates the Maximal bandwidth allowed
                  for this behavior aggregate.'
            SYNTAX INTEGER
            EQUALITY integerMatch
            SINGLE-VALUE
     )

     ( <oid-at8> NAME 'qpFwrdFctr'
            DESC 'A percentage of the scheduling resources consumed
                  by the behavior aggregate. This is an alternative
                  representation of the reserved bandwidth field.
                  Within a domain PHB set, a mixed assignment of
                  forwarding factors to some scheduling classes and
                  reserved bandwidth to others classes is allowed.
			qoFwrdFctr value must be between 0-100'
            SYNTAX INTEGER
            EQUALITY integerMatch
            SINGLE-VALUE
     )






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     ( <oid-at9> NAME 'qpReservedPckts'
            DESC 'Number of packets reserved in queue prior to
                  discard. Large values allows sustain of bursts.
                  Within a scheduling class, this parameter
                  specifies the relative drop precedence of PHBs.'
            SYNTAX INTEGER
            EQUALITY integerMatch
            SINGLE-VALUE
     )

     ( <oid-at10> NAME 'qpBufferFctr'
            DESC 'A percentage of the buffer resources kept for
                  this behavior aggregate. This is an alternative
                  representation of the Reserved Packets field.
                  The sum of buffer factors assigned to the
                  scheduling classes is 100%. Within each
                  scheduling class, the buffer factor specifies
                  the relative drop precedence of the PHBs.
			qpBufferFctr value must be between 0-100'
            SYNTAX INTEGER
            EQUALITY integerMatch
            SINGLE-VALUE
     )

     ( <oid-at11> NAME 'qpTrafficType'
            DESC 'An enumeration indicating the traffic responsiveness
                  to loss. The defined values for this attribute are
                  elastic (1) and in-elastic (2).
            SYNTAX INTEGER
            EQUALITY integerMatch
            SINGLE-VALUE
     )

     ( <oid-at12> NAME 'qpPcktSize'
            DESC 'Typical packet size in bytes of traffic of this
                  behavior aggregate. This parameter is used for
                  example when there is a need to arrive at a byte
                  count representation of reserved packets field.'
            SYNTAX INTEGER
            EQUALITY integerMatch
            SINGLE-VALUE
     )

     ( <oid-at13> NAME 'qpMaxPerHopDelay'
            DESC 'The maximal delay in msecs before a packet of this
            behavior aggregate is forwarded. This parameter is relevant
            mostly to immediate forwarding PHBs.'
            SYNTAX INTEGER
            EQUALITY integerMatch
            SINGLE-VALUE
     )
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5. Acknowledgments

This document is based on the work done by Arthur Zavalkovsky and
Nitsan Elffasy in [PHBSET].

6. Security Considerations

Management of PHBs within a DS Domain requires adequate security measures.
These measures are outside the scope of this memo and should be covered
in the appropriate protocols used for provisioning the network.

7. Intellectual Property Considerations

Cisco may have IPR on material contained in this draft. Upon approval
by the IESG of the relevant Internet standards track specification and
if any patents issue to Cisco or its subsidiaries with claims that are
necessary for practicing this standard, any party will be able to
obtain the right to implement, use and distribute the technology or
works when implementing, using or distributing technology based upon
the specific specification(s) under openly specified, reasonable, non
-discriminatory terms.


8. Reference

[PCORE] J. Strassner, E. Ellesson, B. Moore, Ryan Moats, "Policy
      Framework LDAP Core Schema",
      draft-ietf-policy-core-schema-06.txt, November 04

[PHBSET] R. Cohen, A. Zavalkovsky, N. Elffasy, " Domain PHB Set
      Specification", draft-ronc-domain-phb-set-specification-00.txt,
      February 2000.

[DSARCH] S. Blake, D. Black, M. Carlson, E. Davies, Z. Wang, W. Weiss,
     "An Architecture for Differentiated Services", RFC2475, December
      1998

[NEWTERMS] D. Grossman, "New Terminology for Diffserv",
     draft-ietf-diffserv-new-terms-00.txt, October 1999

[ATTR] Wahl, M., and A. Coulbeck, T. Howes, S. Kille, "Lightweight
       Directory Access Protocol (v3):  Attribute Syntax Definitions",
       RFC 2252, December 1997.

[PQoS] Y. Snir, Y. Ramberg, J. Strassner, R. Cohen "QoS Policy Schema",
       draft-ietf-policy-qos-schema-00.txt, March 2000.


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9. Authors' Address

Ron Cohen                           Cisco Systems, Inc.
Phone: +972-9-9700064               4 Maskit St.
Email: ronc@cisco.com               Herzeliya Pituach,
                                    Israel 46766

Yoram Snir                          Cisco Systems, Inc.
Phone: +972-9-9700085               4 Maskit St.
Email: ysnir@cisco.com              Herzeliya Pituach,
                                    Israel 46766

John Strassner                      Cisco Systems, Inc
Phone: +1 408-527-1069              170 West Tasman Drive
Email: johns@cisco.com              San Jose, CA 95134


































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