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I2RS working group                                              S. Hares
Internet-Draft                                                     Q. Wu
Intended status: Standards Track                                  Huawei
Expires: April 30, 2015                                 October 27, 2014


             An Information Model for Basic Network Policy
                   draft-hares-i2rs-bnp-info-model-01

Abstract

   This document contains the Basic Network Policy (BNP IM) Information
   Model which an instantiation and extension of the PCIM work (RFC3060,
   RFC 3460, RFC 3644) that supports both the configuration models and
   the I2RS ephemeral models.  The PCIM work contains a Policy Core
   Information Model (PCIM) (RFC3060) and the Quality of Service (QoS)
   Policy Information Model (QPIM)(RFC3644) and policy based routing.
   The PCIM work provided a framework to incorporate ACL filters, prefix
   filters, and more complex filters.  This extension to PCIM model
   incorporate ACLs, Prefix-filtering, and complex policy (match, set,
   modify, set) into the PCIM framework.  Complex policy is need by I2RS
   programmatic interface to BGP, flow specification filtering, Policy
   Based Routing (PBR), MPLS topology management, and flow specification
   filtering.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on April 30, 2015.

Copyright Notice

   Copyright (c) 2014 IETF Trust and the persons identified as the
   document authors.  All rights reserved.





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   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Definitions and Acronyms  . . . . . . . . . . . . . . . . . .   3
   3.  PCIM Overview . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Top-Down yang Diagram for PCIM  . . . . . . . . . . . . . . .   5
     4.1.  Policy Set Structures . . . . . . . . . . . . . . . . . .   5
     4.2.  Policy Group Expansion for Basic Network Policy (BNP) . .   6
   5.  Example of use in BGP . . . . . . . . . . . . . . . . . . . .   9
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  10
   8.  Informative References  . . . . . . . . . . . . . . . . . . .  10
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  11

1.  Introduction

   The Interface to the Routing System (I2RS) provides read and write
   access to the information and state within the routing process within
   routing elements.  The I2RS client interacts with one or more I2RS
   agents to collect information from network routing systems.  The
   processing of collecting information at the I2RS agent may require
   the I2RS Agent to filter certain information, group pieces of
   information, or perform actions on the I2RS collected information
   based on specific I2RS policies.

   The generic policy work done in PCIM WG has been has been recast into
   I2RS work.  The PCIM work contains a Policy Core Information Model
   (PCIM) [RFC3060], Policy Core Informational Model Extensions
   [RFC3460] and the Quality of Service (QoS) Policy Information Model
   (QPIM) ([RFC3644]) The basic concept of PCIM is that there are policy
   rules which are combined into policy groups.  If nesting and
   aggregation of policy groups is necessary, the PCIM work defines a
   policy set that operates under specific rules.  Policy Groups can be
   used without using policy sets.  This concept of a policy group as an
   entity that contains a set of policy rules is also reference utilized
   by the OpenDaylight group policy project.





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   In initial work for I2RS or netmod, the policy group that simply
   combines and orders policies rules will be sufficient.

   Policy rules may include specific filters such as ACL or prefix
   filters by simple reference.  The following drafts provide these more
   specific filters;

   o  ACL policy [I-D.bogdanovic-netmod-acl-model]

   o  BGP Prefix filter policy [I-D.zhdankin-netmod-bgp-cfg]

2.  Definitions and Acronyms

      BGP: Border Gateway Protocol

      CLI: Command Line Interface

      IGP: Interior Gateway Protocol

      Information Model: An abstract model of a conceptual domain,
      independent of a specific implementations or data representation

      INSTANCE: Routing Code often has the ability to spin up multiple
      copies of itself into virtual machines.  Each Routing code
      instance or each protocol instance is denoted as Foo_INSTANCE in
      the text below.

      NETCONF: The Network Configuration Protocol

      PCIM - Policy Core Information Model

      RESTconf - http programmatic protocol to access yang modules

3.  PCIM Overview

   The PCIM work created the concepts of Policy Set, Policy Group, and
   Policy Rule.  This section reviews these concepts as background for
   the application of these concepts to current configuration and I2RS
   policy.  In addition, this section suggests placement of policy rule
   concepts.

   The basic PCIM concepts are:

   Policy Set

      is a class which derived from Policy, and it is inserted into the
      inheritance hierarchy above both PolicyGroup and PolicyRule (as
      figure 1 shows).  The Policy set is a coherent set of rules that



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      has two properties of PolicyDecisionStrategy and PolicyRoles, and
      supports PolicySetComponent subclass.  The PolicySetComponent is
      an aggregation class that allows aggregation of policy groups and
      under policy groups the a set of rules.  The PolicySet contains
      rules for nesting policies that include matching strategies (all-
      matching or first-match), priorities between rules, and roles.
      One of the roles that must be conditionally matched is the models
      denotation of "read-only" or "read-write".

   Policy Group

      Policy is described by a set of policy rules that may be grouped
      into subsets.  [RFC3060] defines policy groups as either a group
      of policy rules or group of policy groups - but not both.  A
      policy group is used to provide a hierarchical policy definition
      that provides the model context or scope for sub-rule actions.
      The policy group is identified by a policy group name, and
      contains policy rules.  Policy groups can be nested within other
      policy rules only within Policy sets.

   Policy Rule

      A Policy Rule is represented by the semantics "If Condition then
      Action".  A Policy Rule may have a priority assigned to it.



























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                     | "nests and aggregates policy-group"
         +-----------^-------------+
         |       Policy Set        |
         +--+-------------------+--+
             ^                  ^
            /|\                /|\
       +------------+   +--------------+
       |Policy Group|   | Policy Group |
       +------------+   +--------------+
            ^                  ^                +------------------+
            |                  |             ---| ACL Policy-Rule  |
            |                  |             |  |   Additions      |
            |                  |             |  +------------------+
            |                  |             |  +------------------+
   +--------^-------+   +-------^-------+    |--|Prefix Policy-Rule|
   | Policy Rule   |   | Policy Rule   |<----|  Additions       |
   +----------------+   +---------------+    |  +------------------+
                          :          :       |      . . .
                          :          :       |  +------------------+
                    ......:          :.....  ---|Other Policy-Rule |
                    :                     :     | Additions        |
                    :                     :     +------------------+
                    :                     :
          +---------V---------+         +-V-------------+
          |  Policy Condition |         | Policy Action |
          +-------------------+         +---------------+
              :     :    :                 :     :    :
         .....:     .    :.....       .....:     .    :.....
         :          :         :       :          :         :
    +----V---+  +---V----+ +--V---+ +-V------++--V-----++--V---+
    |  Match |  |Policy  | |Policy| |  Set   || Policy ||Policy|
    |Operator|  |Variable| |Value | |Operator||Variable|| Value|
    +--------+  +--------+ +------+ +--------++--------++------+

              Figure 1: Overall model BNP IM structure

4.  Top-Down yang Diagram for PCIM

   The top down architecture has policy sets, policy groups, and policy
   rules.  It is not necessary to have policy sets to have policy rules.

4.1.  Policy Set Structures

   Per PCIM, the PolicySet contains rules for nesting policies that
   include matching strategies (all-matching or first-match), priorities
   between rules, and roles.  The Yang diagram is below.





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            Figure 2 - Policy Set Yang

       module: ietf-pcim
         +--rw policy-set [policy-set-name]
         |  +--rw policy-set-name string
         |  +--rw matching-strategy enumeration
         |  +--rw policy-roles enumeration
         |  +--rw default-rule-priority uint16
         |  +--rw policy-group* [policy-group-name]

            Figure 2 - PSET Yang level

4.2.  Policy Group Expansion for Basic Network Policy (BNP)

   Policy groups within the PCIM work have a name that identifies the
   grouping of policy rules.  In PCIM, the policy rule has a name,
   status, priority, match condition with an action.  The status for the
   policy rule is enabled or disabled.  The priority is the priority
   within the policy rule order.  This expansion of the PCIM policy rule
   adds a policy-rule order field, a reference count (pr-refcnt).  It
   expands the PCIM match/condition methods to include a reference to
   other match-action fields.

   I2RS which requires that a read/write scope be tied to a particular
   portion of the ephemeral tree.  This requirement is instantiated as
   the I2RS-role at the policy group level.  However, it is anticipated
   this will be replaced by an expansion of [I-D.ietf-netconf-restconf]
   functionality surrounding the xpath feature.  This element is left in
   this model to until these restconf xpath additions have been
   finalized.

   The logical structure is below in figure 3 with an expansion of the
   pcim match-action-operation in figure 4.


















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                     Figure 3 - Policy Group
        +-------------------------------------+ (optional)
        |             Policy Group            |....
        +--------------------------------------+   :
          *      *                   *        ^    :
          |                          |        :....:
          |      |                   |         |
          |      |                   |         |
          |      |                   |         |
     +------+ +----+    +-----------------------+
     | Name | |I2RS|    |  Policy Rule          |
     |      | |Role|    |                       |
     +------+ +----+    +-----------------------+
               *   *      *
               |   |      |
            +--+   |      | +----------+
            |      |      |-|   Name   |
            |      |      | +----------+
       +----+---+ ++----+ | +----------+
       |        | |I2RS | | + Policy   |
       |Resource| |Scope| | +rule order|
       +--------+ +-----+ |-+----------+
                   *   *  | +----------+
         +------+  |   |  |-| Status   |
         |read  |--|   |  | +----------+
         |scope |  |   |  | +----------+
         +------+  |   |  |-| priority |
         +------+      |  | +----------+
         |write |------|  | +----------+
         |scope |         |-| refcnt   |
         +------+         | +----------+
                          | +--------------+
                          |-|    PCIM      |
                          | | match/action |
                          | +--------------+
                          | +--------------+
                          |-|   ACL        |
                          | | match/action |
                          | +--------------+
                          |-+--------------+
                            | Prefix-list  |
                            | match/action |
                            +--------------+








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             Figure 5 - Policy Rule's match-condition

               +----------------+
               |    PCIM        |
               | Policy Rule    |
               +----------------+
                 *           *
                 |           |
                 |           |
        +---------+        +--------+
    ...>|Condition|<.......| Action |<...
    :   +---------+<.......+--------+   :
    :    :   *                *    :    :
    :.....   |                :    :... :
             |                :
        +--------+...........:
        |Operator|
        +--------+

   The basic yang high-level structure for the policy group is included
   below in figure 6.

          Figure 6

         module: ietf-pcim
         +--rw policy-set [policy-set-name]
         |  ....
         |  +--rw policy-group* [policy-group-name]
         |  |  +--rw policy-group-name
         |  |  +--rw i2rs-scope
         |  |  |  +--tree-xpath
         |  |  |  +--access  enumeration
         |  |  +--rw policy-rule*  [policy-rule-name]
         |  |  |  +--rw pr-name string
         |  |  |  +--rw pr-order unit16
         |  |  |  +--rw pr-status enumeration
         |  |  |  +--rw pr-priority unit16
         |  |  |  +--rw pr-refcnt unit16
         |  |  |  +--rw pr-match-act
         |  |  |  |   +--rw pr-match-act-type
         |  |  |  |   +case: pcim match-act ref-cnt
         |  |  |  |   +case: acl acl-ref
         |  |  |  |   +case: Prefix-list prefix-list-ref
         |  |  |  +   +case: pbr-pcim-match-act  pbr-pcim-match-act-ref







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5.  Example of use in BGP

   The PCIM suggests a patch structure of match-field, operator for
   match, action (send packet), and set value.  The following is an
   example is an example structure for the pcim of the match-condition
   applied to BGP.

       figure 7

         +--rw bnp-match-act
         |  +--rw bnp-match-act-bgp-i2rs
         |  |  +--rw bgp-match-field
         |  |  |  +--rw bgp-afi
         |  |  |  +--rw bgp-local-rib
         |  |  |  +--rw bgp-peer
         |  |  |  +--rw bgp-rib-in
         |  |  |  |  +--bgp-rib-in-policy-type
         |  |  |  |  +--bgp-rib-in-policy
         |  |  |  |  +--case: policy-set pcim-policy-set-name
         |  |  |  |  +--case: policy-group pcim-policy-group-name
         |  |  |  +--rw bgp-rib-out
         |  |  |  |  +--bgp-rib-out-policy-type
         |  |  |  |  +--bgp-rib-out-policy
         |  |  |  |  +--case: policy-set pcim-policy-set-name
         |  |  |  |  +--case: policy-group pcim-policy-group-name
         |  |  |  +--rw bgp-route-prefix
         |  |  |  | .. prefix or prefix-range
         |  |  |  +--rw bgp-attribute-list
         |  |  |  |  ... bgp attributes
         |  |  |  +--rw bgp-state-info
         |  |  |  |  ... bgp state
         |  |  +--rw bgp-match-operator
         |  |  |  +--rw operator-type enumeration
         |  |  |  +--rw bgp-prefix-range-operator
         |  |  |  +--rw bgp-attribute-operator
         |  |  |  +--rw bgp-state-operator
         |  |  +--rw bgp-action
         |  |  |  +--bgp-act enumeration
         |  |  |  +--bgp-act value
         |  |  +--rw bgp-set
         |  |  |  +--bgp-set enumeration
         |  |  |  +--bgp-set value

6.  IANA Considerations

   This draft includes no request to IANA.





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7.  Security Considerations

   TBD

8.  Informative References

   [I-D.bogdanovic-netmod-acl-model]
              Bogdanovic, D., Sreenivasa, K., Huang, L., and D. Blair,
              "Network Access Control List (ACL) YANG Data Model",
              draft-bogdanovic-netmod-acl-model-02 (work in progress),
              October 2014.

   [I-D.hares-i2rs-bgp-im]
              Hares, S., Wang, L., and S. Zhuang, "An I2RS BGP
              Information Model", draft-hares-i2rs-bgp-im-01 (work in
              progress), October 2014.

   [I-D.hares-i2rs-usecase-reqs-summary]
              Hares, S., "Summary of I2RS Use Case Requirements", draft-
              hares-i2rs-usecase-reqs-summary-00 (work in progress),
              July 2014.

   [I-D.ietf-i2rs-architecture]
              Atlas, A., Halpern, J., Hares, S., Ward, D., and T.
              Nadeau, "An Architecture for the Interface to the Routing
              System", draft-ietf-i2rs-architecture-05 (work in
              progress), July 2014.

   [I-D.ietf-i2rs-rib-info-model]
              Bahadur, N., Folkes, R., Kini, S., and J. Medved, "Routing
              Information Base Info Model", draft-ietf-i2rs-rib-info-
              model-03 (work in progress), May 2014.

   [I-D.ietf-netconf-restconf]
              Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
              Protocol", draft-ietf-netconf-restconf-02 (work in
              progress), October 2014.

   [I-D.zhdankin-netmod-bgp-cfg]
              Alex, A., Patel, K., and A. Clemm, "Yang Data Model for
              BGP Protocol", draft-zhdankin-netmod-bgp-cfg-01 (work in
              progress), October 2014.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.






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   [RFC3060]  Moore, B., Ellesson, E., Strassner, J., and A. Westerinen,
              "Policy Core Information Model -- Version 1
              Specification", RFC 3060, February 2001.

   [RFC3460]  Moore, B., "Policy Core Information Model (PCIM)
              Extensions", RFC 3460, January 2003.

   [RFC3644]  Snir, Y., Ramberg, Y., Strassner, J., Cohen, R., and B.
              Moore, "Policy Quality of Service (QoS) Information
              Model", RFC 3644, November 2003.

   [RFC5511]  Farrel, A., "Routing Backus-Naur Form (RBNF): A Syntax
              Used to Form Encoding Rules in Various Routing Protocol
              Specifications", RFC 5511, April 2009.

Authors' Addresses

   Susan Hares
   Huawei
   7453 Hickory Hill
   Saline, MI  48176
   USA

   Email: shares@ndzh.com


   Qin Wu
   Huawei
   101 Software Avenue, Yuhua District
   Nanjing, Jiangsu  210012
   China

   Email: bill.wu@huawei.com


















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