    Network Working Group                                            K. Chan
    Request for Comments: 3084                                   J. Seligson
    Category: Standards Track                                Nortel Networks
                                                                   D. Durham
                                                                       Intel
                                                                      S. Gai
                                                               K. McCloghrie
                                                                       Cisco
                                                                   S. Herzog
                                                                   IPHighway
                                                               F. Reichmeyer
                                                                         PFN
                                                                 R. Yavatkar
                                                                       Intel
                                                                    A. Smith
                                                            Allegro Networks
                                                                  March 2001

                 COPS Usage for Policy Provisioning (COPS-PR)

    Status of this Memo

       This document specifies an Internet standards track protocol for the
       Internet community, and requests discussion and suggestions for
       improvements.  Please refer to the current edition of the "Internet
       Official Protocol Standards" (STD 1) for the standardization state
       and status of this protocol.  Distribution of this memo is unlimited.

    Copyright Notice

       Copyright (C) The Internet Society (2001).  All Rights Reserved.

    Abstract

       This document describes the use of the Common Open Policy Service
       (COPS) protocol for support of policy provisioning (COPS-PR).  This
       specification is independent of the type of policy being provisioned
       (QoS, Security, etc.) but focuses on the mechanisms and conventions
       used to communicate provisioned information between PDPs and PEPs.
       The protocol extensions described in this document do not make any
       assumptions about the policy data model being communicated, but
       describe the message formats and objects that carry the modeled
       policy data.

    Chan, et al.                Standards Track                     [Page 1]

    RFC 3084                        COPS-PR                       March 2001

    Conventions used in this document

       The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
       "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
       document are to be interpreted as described in [RFC-2119].

    Table of Contents

       Glossary........................................................... 3
       1. Introduction.................................................... 3
       1.1. Why COPS for Provisioning?.................................... 5
       1.2. Interaction between the PEP and PDP........................... 5
       2. Policy Information Base (PIB)................................... 6
       2.1. Rules for Modifying and Extending PIBs........................ 7
       2.2. Adding PRCs to, or deprecating from, a PIB.................... 7
       2.2.1. Adding or Deprecating Attributes of a BER Encoded PRC....... 8
       2.3. COPS Operations Supported for a Provisioning Instance......... 8
       3. Message Content................................................. 9
       3.1. Request (REQ)  PEP -> PDP..................................... 9
       3.2. Decision (DEC)  PDP -> PEP....................................10
       3.3. Report State (RPT)  PEP -> PDP................................12
       4. COPS-PR Protocol Objects........................................13
       4.1. Complete Provisioning Instance Identifier (PRID)..............14
       4.2. Prefix PRID (PPRID)...........................................15
       4.3. Encoded Provisioning Instance Data (EPD)......................16
       4.4. Global Provisioning Error Object (GPERR)......................21
       4.5. PRC Class Provisioning Error Object (CPERR)...................22
       4.6. Error PRID Object (ErrorPRID).................................23
       5. COPS-PR Client-Specific Data Formats............................23
       5.1. Named Decision Data...........................................23
       5.2. ClientSI Request Data.........................................24
       5.3. Policy Provisioning Report Data...............................24
       5.3.1. Success and Failure Report-Type Data Format.................24
       5.3.2. Accounting Report-Type Data Format..........................25
       6. Common Operation................................................26
       7. Fault Tolerance.................................................28
       8. Security Considerations.........................................29
       9. IANA Considerations.............................................29
       10. Acknowledgements...............................................30
       11. References.....................................................30
       12. Authors' Addresses.............................................32
       13. Full Copyright Statement.......................................34

    Chan, et al.                Standards Track                     [Page 2]

    RFC 3084                        COPS-PR                       March 2001

    Glossary

          PRC     Provisioning Class.  A type of policy data.
          PRI     Provisioning Instance.  An instance of a PRC.
          PIB     Policy Information Base.  The database of policy
                  information.
          PDP     Policy Decision Point.  See [RAP].
          PEP     Policy Enforcement Point.  See [RAP].
          PRID    Provisioning Instance Identifier.  Uniquely identifies an
                  instance of a PRC.

    1. Introduction

       The IETF Resource Allocation Protocol (RAP) WG has defined the COPS
       (Common Open Policy Service) protocol [COPS] as a scalable protocol
       that allows policy servers (PDPs) to communicate policy decisions to
       network devices (PEPs).  COPS was designed to support multiple types
       of policy clients.

       COPS is a query/response protocol that supports two common models for
       policy control: Outsourcing and Configuration.

       The Outsourcing model addresses the kind of events at the PEP that
       require an instantaneous policy decision (authorization).  In the
       outsourcing scenario, the PEP delegates responsibility to an external
       policy server (PDP) to make decisions on its behalf.  For example, in
       COPS Usage for RSVP [COPRSVP] when a RSVP reservation message
       arrives, the PEP must decide whether to admit or reject the request.
       It can outsource this decision by sending a specific query to its
       PDP, waiting for its decision before admitting the outstanding
       reservation.

       The COPS Configuration model (herein described as the Provisioning
       model), on the other hand, makes no assumptions of such direct 1:1
       correlation between PEP events and PDP decisions.  The PDP may
       proactively provision the PEP reacting to external events (such as
       user input), PEP events, and any combination thereof (N:M
       correlation).  Provisioning may be performed in bulk (e.g., entire
       router QoS configuration) or in portions (e.g., updating a DiffServ
       marking filter).

       Network resources are often provisioned based on relatively static
       SLAs (Service Level Agreements) at network boundaries.  While the
       Outsourcing model is dynamically paced by the PEP in real-time, the
       Provisioning model is paced by the PDP in somewhat flexible timing
       over a wide range of configurable aspects of the PEP.

    Chan, et al.                Standards Track                     [Page 3]

    RFC 3084                        COPS-PR                       March 2001

           Edge Device               Policy Server
           +--------------+          +-----------+     +-----------+
           |              |          |           |     | External  |
           |              |  COPS    |           |     | Events    |
           |   +-----+    |  REQ()   |  +-----+  |     +---+-------+
           |   |     |----|----------|->|     |  |         |
           |   | PEP |    |          |  | PDP |<-|---------+
           |   |     |<---|----------|--|     |  |
           |   +-----+    |   COPS   |  +-----+  |
           |              |   DEC()  |           |
           +--------------+          +-----------+

                        Figure 1: COPS Provisioning Model

       In COPS-PR, policy requests describe the PEP and its configurable
       parameters (rather than an operational event).  If a change occurs
       in these basic parameters, an updated request is sent.  Hence,
       requests are issued quite infrequently.  Decisions are not
       necessarily mapped directly to requests, and are issued mostly
       when the PDP responds to external events or PDP events (policy/SLA
       updates).

       This document describes the use of the COPS protocol [COPS] for
       support of policy provisioning.  This specification is independent
       of the type of policy being provisioned (QoS, Security, etc.).
       Rather, it focuses on the mechanisms and conventions used to
       communicate provisioned information between PDPs and PEPs.  The
       data model assumed in this document is based on the concept of
       Policy Information Bases (PIBs) that define the policy data.  There
       may be one or more PIBs for given area of policy and different
       areas of policy may have different sets of PIBs.

       In order to support a model that includes multiple PDPs
       controlling non-overlapping areas of policy on a single PEP, the
       client-type specified by the PEP to the PDP is unique for the area
       of policy being managed.  A single client-type for a given area of
       policy (e.g., QoS) will be used for all PIBs that exist in that
       area.  The client should treat all the COPS-PR client-types it
       supports as non-overlapping and independent namespaces where
       instances MUST NOT be shared.

       The examples used in this document are biased toward QoS Policy
       Provisioning in a Differentiated Services (DiffServ) environment.
       However, COPS-PR can be used for other types of provisioning
       policies under the same framework.

    Chan, et al.                Standards Track                     [Page 4]

    RFC 3084                        COPS-PR                       March 2001

    1.1. Why COPS for Provisioning?

       COPS-PR has been designed within a framework that is optimized for
       efficiently provisioning policies across devices, based on the
       requirements defined in [RAP].  First, COPS-PR allows for efficient
       transport of attributes, large atomic transactions of data, and
       efficient and flexible error reporting.  Second, as it has a single
       connection between the policy client and server per area of policy
       control identified by a COPS Client-Type, it guarantees only one
       server updates a particular policy configuration at any given
       time.  Such a policy configuration is effectively locked, even from
       local console configuration, while the PEP is connected to a PDP
       via COPS.  COPS uses reliable TCP transport and, thus, uses a state
       sharing/synchronization mechanism and exchanges differential
       updates only.  If either the server or client are rebooted (or
       restarted) the other would know about it quickly.  Last, it is
       defined as a real-time event-driven communications mechanism,
       never requiring polling between the PEP and PDP.

    1.2. Interaction between the PEP and PDP

       When a device boots, it opens a COPS connection to its Primary
       PDP.  When the connection is established, the PEP sends information
       about itself to the PDP in the form of a configuration request.
       This information includes client specific information (e.g.,
       hardware type, software release, configuration information).
       During this phase the client may also specify the maximum COPS-PR
       message size supported.

       In response, the PDP downloads all provisioned policies that are
       currently relevant to that device.  On receiving the provisioned
       policies, the device maps them into its local QoS mechanisms, and
       installs them.  If conditions change at the PDP such that the PDP
       detects that changes are required in the provisioned policies
       currently in effect, then the PDP sends the changes (installs,
       updates, and/or deletes) in policy to the PEP, and the PEP updates
       its local configuration appropriately.

       If, subsequently, the configuration of the device changes (board
       removed, board added, new software installed, etc.) in ways not
       covered by policies already known to the PEP, then the PEP
       asynchronously sends this unsolicited new information to the PDP
       in an updated configuration request.  On receiving this new
       information, the PDP sends to the PEP any additional provisioned
       policies now needed by the PEP, or removes those policies that are
       no longer required.

    Chan, et al.                Standards Track                     [Page 5]

    RFC 3084                        COPS-PR                       March 2001

    2. Policy Information Base (PIB)

       The data carried by COPS-PR is a set of policy data.  The protocol
       assumes a named data structure, known as a Policy Information Base
       (PIB), to identify the type and purpose of unsolicited policy
       information that is "pushed" from the PDP to the PEP for
       provisioning policy or sent to the PDP from the PEP as a
       notification.  The PIB name space is common to both the PEP and the
       PDP and data instances within this space are unique within the
       scope of a given Client-Type and Request-State per TCP connection
       between a PEP and PDP.  Note that given a device might implement
       multiple COPS Client-Types, a unique instance space is to be
       provided for each separate Client-Type.  There is no sharing of
       instance data across the Client-Types implemented by a PEP, even
       if the classes being instantiated are of the same type and share
       the same instance identifier.

       The PIB can be described as a conceptual tree namespace where the
       branches of the tree represent structures of data or Provisioning
       Classes (PRCs), while the leaves represent various instantiations
       of Provisioning Instances (PRIs).  There may be multiple data
       instances (PRIs) for any given data structure (PRC).  For example,
       if one wanted to install multiple access control filters, the PRC
       might represent a generic access control filter type and each PRI
       might represent an individual access control filter to be applied.
       The tree might be represented as follows:

                 -------+-------+----------+---PRC--+--PRI
                        |       |          |        +--PRI
                        |       |          |
                        |       |          +---PRC-----PRI
                        |       |
                        |       +---PRC--+--PRI
                        |                +--PRI
                        |                +--PRI
                        |                +--PRI
                        |                +--PRI
                        |
                        +---PRC---PRI

                              Figure 2: The PIB Tree

       Instances of the policy classes (PRIs) are each identified by a
       Provisioning Instance Identifier (PRID).  A PRID is a name, carried
       in a COPS <Named ClientSI> or <Named Decision Data> object, which
       identifies a particular instance of a class.

    Chan, et al.                Standards Track                     [Page 6]

    RFC 3084                        COPS-PR                       March 2001

    2.1. Rules for Modifying and Extending PIBs

       As experience is gained with policy based management, and as new
       requirements arise, it will be necessary to make changes to PIBs.
       Changes to an existing PIB can be made in several ways.

        (1) Additional PRCs can be added to a PIB or an existing one
            deprecated.

        (2) Attributes can be added to, or deprecated from, an existing
            PRC.

        (3) An existing PRC can be extended or augmented with a new PRC
            defined in another (perhaps enterprise specific) PIB.

       The rules for each of these extension mechanisms is described in this
       sub-section.  All of these mechanisms for modifying a PIB allow for
       interoperability between PDPs and PEPs even when one party is using a
       new version of the PIB while the other is using an old version.

       Note that the SPPI [SPPI] provides the authoritative rules for
       updating BER encoded PIBs.  It is the purpose of the following
       section to explain how such changes affect senders and receivers of
       COPS messages.

    2.2. Adding PRCs to, or deprecating from, a PIB

       A published PIB can be extended with new PRCs by simply revising the
       document and adding additional PRCs.  These additional PRCs are
       easily identified with new PRIDs under the module's PRID Prefix.

       In the event that a PEP implementing the new PIB is being configured
       by a PDP implementing the old PIB, the PEP will simply not receive
       any instances of the new PRC.  In the event that the PEP is
       implementing the old PIB and the PDP the new one, the PEP may receive
       PRIs for the new PRC.  Under such conditions, the PEP MUST return an
       error to the PDP, and rollback to its previous (good) state.

       Similarly, existing PRCs can be deprecated from a PIB.  In this case,
       the PEP ignores any PRIs sent to it by a PDP implementing the old
       (non-deprecated) version of the PIB.  A PDP implementing the new
       version of the PIB simply does not send any instances of the
       deprecated class.

    Chan, et al.                Standards Track                     [Page 7]

    RFC 3084                        COPS-PR                       March 2001

    2.2.1. Adding or Deprecating Attributes of a BER Encoded PRC

       A PIB can be modified to deprecate existing attributes of a PRC or
       add new ones.

       When deprecating the attributes of a PRC, it must be remembered that,
       with the COPS-PR protocol, the attributes of the PRC are identified
       by their order in the sequence rather than an explicit label (or
       attribute OID).  Consequently, an ASN.1 value MUST be sent even for
       deprecated attributes so that a PDP and PEP implementing different
       versions of the PIB are inter-operable.

       For a deprecated attribute, if the PDP is using a BER encoded PIB,
       the PDP MUST send either an ASN.1 value of the correct type, or it
       may send an ASN.1 NULL value.  A PEP that receives an ASN.1 NULL for
       an attribute that is not deprecated SHOULD substitute a default
       value.  If it has no default value to substitute it MUST return an
       error to the PDP.

       When adding new attributes to a PIB, these new attributes must be
       added in sequence after the existing ones.  A PEP that receives a PRI
       with more attributes than it is expecting MUST ignore the additional
       attributes and send a warning back to the PDP.

       A PEP that receives a PRI with fewer attributes than it is expecting
       SHOULD assume default values for the missing attributes. It MAY send
       a warning back to the PDP.  If the missing attributes are required
       and there is no suitable default, the PEP MUST send an error back to
       the PDP.  In all cases the missing attributes are assumed to
       correspond to the last attributes of the PRC.

    2.3. COPS Operations Supported for a Provisioning Instance

       A Provisioning Instance (PRI) typically contains a value for each
       attribute defined for the PRC of which it is an instance and is
       identified uniquely, within the scope of a given COPS Client-Type and
       Request-State on a PEP, by a Provisioning Instance Identifier (PRID).
       The following COPS operations are supported on a PRI:

       o Install - This operation creates or updates a named instance of a
         PRC.  It includes two parameters: a PRID object to name the PRI and
         an Encoded Provisioning Instance Data (EPD) object with the
         new/updated values.  The PRID value MUST uniquely identify a single
         PRI (i.e., PRID prefix or PRC values are illegal).  Updates to an
         existing PRI are achieved by simply reinstalling the same PRID with
         the updated EPD data.

    Chan, et al.                Standards Track                     [Page 8]

    RFC 3084                        COPS-PR                       March 2001

       o Remove - This operation is used to delete an instance of a PRC. It
         includes one parameter, a PRID object, which names either the
         individual PRI to be deleted or a PRID prefix naming one or more
         complete classes of PRIs.  Prefix-based deletion supports efficient
         bulk policy removal.  The removal of an unknown/non-existent PRID
         SHOULD result in a warning to the PDP (no error).

    3. Message Content

       The COPS protocol provides for different COPS clients to define their
       own "named", i.e., client-specific, information for various messages.
       This section describes the messages exchanged between a COPS server
       (PDP) and COPS Policy Provisioning clients (PEP) that carry client-
       specific data objects.  All the COPS messages used by COPS-PR conform
       to the message specifications defined in the COPS base protocol
       [COPS].

       Note: The use of the '*' character represented throughout this
       document is consistent with the ABNF [RFC2234] and means 0 or more of
       the following entities.

    3.1. Request (REQ)  PEP -> PDP

       The REQ message is sent by policy provisioning clients to issue a
       'configuration request' to the PDP as specified in the COPS Context
       Object.  The Client Handle associated with the REQ message originated
       by a provisioning client MUST be unique for that client.  The Client
       Handle is used to identify a specific request state.  Thus, one
       client can potentially open several configuration request states,
       each uniquely identified by its handle.  Different request states are
       used to isolate similarly named configuration information into non-
       overlapping contexts (or logically isolated namespaces).  Thus, an
       instance of named information is unique relative to a particular
       client-type and is unique relative to a particular request state for
       that client-type, even if the information was similarly identified in
       other request states (i.e., uses the same PRID).  Thus, the Client
       Handle is also part of the instance identification of the
       communicated configuration information.

       The configuration request message serves as a request from the PEP to
       the PDP for provisioning policy data that the PDP may have for the
       PEP, such as access control lists, etc.  This includes policy the PDP
       may have at the time the REQ is received as well as any future policy
       data or updates to this data.

       The configuration request message should include provisioning client
       information to provide the PDP with client-specific configuration or
       capability information about the PEP.  The information provided by

    Chan, et al.                Standards Track                     [Page 9]

    RFC 3084                        COPS-PR                       March 2001

       the PEP should include client resources (e.g., queuing capabilities)
       and default policy configuration (e.g., default role combinations)
       information as well as incarnation data on existing policy.  This
       information typically does not include all the information previously
       installed by a PDP but rather should include checksums or shortened
       references to previously installed information for synchronization
       purposes.  This information from the client assists the server in
       deciding what types of policy the PEP can install and enforce.  The
       format of the information encapsulated in one or more of the COPS
       Named ClientSI objects is described in section 5.  Note that the
       configuration request message(s) is generated and sent to the PDP in
       response to the receipt of a Synchronize State Request (SSQ) message
       from the PDP.  Likewise, an updated configuration request message
       (using the same Client Handle value as the original request now being
       updated) may also be generated by the PEP and sent to the PDP at any
       time due to local modifications of the PEP's internal state.  In this
       way, the PDP will be synchronized with the PEP's relevant internal
       state at all times.

       The policy information supplied by the PDP MUST be consistent with
       the named decision data defined for the policy provisioning client.
       The PDP responds to the configuration request with a DEC message
       containing any available provisioning policy data.

       The REQ message has the following format:

                   <Request> ::= <Common Header>
                                  <Client Handle>
                                  <Context = config request>
                                  *(<Named ClientSI>)
                                  [<Integrity>]

       Note that the COPS objects IN-Int, OUT-Int and LPDPDecisions are not
       included in a COPS-PR Request.

    3.2. Decision (DEC)  PDP -> PEP

       The DEC message is sent from the PDP to a policy provisioning client
       in response to the REQ message received from the PEP.  The Client
       Handle MUST be the same Handle that was received in the corresponding
       REQ message.

       The DEC message is sent as an immediate response to a configuration
       request with the solicited message flag set in the COPS message
       header.  Subsequent DEC messages may also be sent at any time after
       the original DEC message to supply the PEP with additional/updated
       policy information without the solicited message flag set in the COPS
       message header (as they are unsolicited decisions).

    Chan, et al.                Standards Track                    [Page 10]

    RFC 3084                        COPS-PR                       March 2001

       Each DEC message may contain multiple decisions.  This means a single
       message can install some policies and delete others.  In general a
       single COPS-PR DEC message MUST contain any required remove decisions
       first, followed by any required install decisions.  This is used to
       solve a precedence issue, not a timing issue: the remove decision
       deletes what it specifies, except those items that are installed in
       the same message.

       The DEC message can also be used by the PDP to command the PEP to
       open a new Request State or Delete an existing Request-State as
       identified by the Client-Handle.  To accomplish this, COPS-PR defines
       a new flag for the COPS Decision Flags object.  The flag 0x02 is to
       be used by COPS-PR client-types and is hereafter referred to as the
       "Request-State" flag.  An Install decision (Decision Flags: Command-
       Code=Install) with the Request-State flag set in the COPS Decision
       Flags object will cause the PEP to issue a new Request with a new
       Client Handle or else specify the appropriate error in a COPS Report
       message.  A Remove decision (Decision Flags: Command-Code=Remove)
       with the Request-State flag set in the COPS Decision Flags object
       will cause the PEP to send a COPS Delete Request State (DRQ) message
       for the Request-State identified by the Client Handle in the DEC
       message.  Whenever the Request-State flag is set in the COPS Decision
       Flags object in the DEC message, no COPS Named Decision Data object
       can be included in the corresponding decision (as it serves no
       purpose for this decision flag).  Note that only one decision with
       the Request-State flag can be present per DEC message, and, if
       present, this MUST be the only decision in that message.  As
       described below, the PEP MUST respond to each and every DEC with a
       corresponding solicited RPT.

       A COPS-PR DEC message MUST be treated as a single "transaction",
       i.e., either all the decisions in a DEC message succeed or they all
       fail.  If they fail, the PEP will rollback to its previous good
       state, which is the last successful DEC transaction, if any.  This
       allows the PDP to delete some policies only if other policies can be
       installed in their place.  The DEC message has the following format:

       <Decision Message> ::= <Common Header>
                              <Client Handle>
                              *(<Decision>) | <Error>
                              [<Integrity>]

       <Decision> ::= <Context>
                      <Decision: Flags>
                      [<Named Decision Data: Provisioning >]

    Chan, et al.                Standards Track                    [Page 11]

    RFC 3084                        COPS-PR                       March 2001

       Note that the Named Decision Data (Provisioning) object is included
       in a COPS-PR Decision when it is an Install or Remove decision with
       no Decision Flags set.  Other types of COPS decision data objects
       (e.g., Stateless, Replacement) are not supported by COPS-PR client-
       types.  The Named Decision Data object MUST NOT be included in the
       decision if the Decision Flags object Command-Code is NULL (meaning
       there is no configuration information to install at this time) or if
       the Request-State flag is set in the Decision Flags object.

       For each decision in the DEC message, the PEP performs the operation
       specified in the Command-Code and Flags field in the Decision Flags
       object on the Named Decision Data.  For the policy provisioning
       clients, the format for this data is defined in the context of the
       Policy Information Base (see section 5).  In response to a DEC
       message, the policy provisioning client MUST send a RPT message, with
       the solicited message flag set, back to the PDP to inform the PDP of
       the action taken.

    3.3. Report State (RPT)  PEP -> PDP

       The RPT message is sent from the policy provisioning clients to the
       PDP to report accounting information associated with the provisioned
       policy, or to notify the PDP of changes in the PEP (Report-Type = '
       Accounting') related to the provisioning client.

       RPT is also used as a mechanism to inform the PDP about the action
       taken at the PEP in response to a DEC message.  For example, in
       response to an 'Install' decision, the PEP informs the PDP if the
       policy data is installed (Report-Type = 'Success') or not (Report-
       Type = 'Failure').  Reports that are in response to a DEC message
       MUST set the solicited message flag in their COPS message header.
       Each solicited RTP MUST be sent for its corresponding DEC in the
       order the DEC messages were received.  In case of a solicited
       failure, the PEP is expected to rollback to its previous (good) state
       as if the erroneous DEC transaction did not occur.  The PEP MUST
       always respond to a DEC with a solicited RPT even in response to a
       NULL DEC, in which case the Report-Type will be 'Success'.

       Reports can also be unsolicited and all unsolicited Reports MUST NOT
       set the solicited message flag in their COPS message header. Examples
       of unsolicited reports include 'Accounting' Report-Types, which were
       not triggered by a specific DEC messages, or 'Failure' Report-Types,
       which indicate a failure in a previously successfully installed
       configuration (note that, in the case of such unsolicited failures,
       the PEP cannot rollback to a previous "good" state as it becomes
       ambiguous under these asynchronous conditions what the correct state
       might be).

    Chan, et al.                Standards Track                    [Page 12]

    RFC 3084                        COPS-PR                       March 2001

       The RPT message may contain provisioning client information such as
       accounting parameters or errors/warnings related to a decision. The
       data format for this information is defined in the context of the
       policy information base (see section 5).  The RPT message has the
       following format:

                   <Report State> ::= <Common Header>
                                      <Client Handle>
                                      <Report Type>
                                      *(<Named ClientSI>)
                                      [<Integrity>]

    4. COPS-PR Protocol Objects

       The COPS Policy Provisioning clients encapsulate several new objects
       within the existing COPS Named Client-specific information object and
       Named Decision Data object.  This section defines the format of these
       new objects.

       COPS-PR classifies policy data according to "bindings", where a
       binding consists of a Provisioning Instance Identifier and the
       Provisioning Instance data, encoded within the context of the
       provisioning policy information base (see section 5).

       The format for these new objects is as follows:

               0                1               2                 3
       +---------------+---------------+---------------+---------------+
       |             Length            |     S-Num     |     S-Type    |
       +---------------+---------------+---------------+---------------+
       |                   32 bit unsigned integer                     |
       +---------------+---------------+---------------+---------------+

       S-Num and S-Type are similar to the C-Num and C-Type used in the base
       COPS objects.  The difference is that S-Num and S-Type are used only
       for COPS-PR clients and are encapsulated within the existing COPS
       Named ClientSI or Named Decision Data objects.  The S-Num identifies
       the general purpose of the object, and the S-Type describes the
       specific encoding used for the object.  All the object descriptions
       and examples in this document use the Basic Encoding Rules as the
       encoding type (S-Type = 1).  Additional encodings can be defined for
       the remaining S-Types in the future (for example, an additional S-
       Type could be used to carry XML string based encodings [XML] as an
       EPD of PRI instance data, where URNs identify PRCs [URN] and
       XPointers would be used for PRIDs).

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       Length is a two-octet value that describes the number of octets
       (including the header) that compose the object.  If the length in
       octets does not fall on a 32-bit word boundary, padding MUST be added
       to the end of the object so that it is aligned to the next 32-bit
       boundary before the object can be sent on the wire.  On the receiving
       side, a subsequent object boundary can be found by simply rounding up
       the stated object length of the current object to the next 32-bit
       boundary.  The values for the padding MUST be all zeros.

    4.1. Complete Provisioning Instance Identifier (PRID)

       S-Num = 1 (Complete PRID), S-Type = 1 (BER), Length = variable.

       This object is used to carry the identifier, or PRID, of a
       Provisioning Instance.  The identifier is encoded following the rules
       that have been defined for encoding SNMP Object Identifier (OID)
       values.  Specifically, PRID values are encoded using the
       Type/Length/Value (TLV) format and initial sub-identifier packing
       that is specified by the binary encoding rules [BER] used for Object
       Identifiers in an SNMP PDU.

               0                1               2                 3
       +---------------+---------------+---------------+---------------+
       |              Length           | S-Num = PRID  | S-Type = BER  |
       +---------------+---------------+---------------+---------------+
       |                     Instance Identifier                       |
       +---------------+---------------+---------------+---------------+

       For example, a (fictitious) PRID equal to 1.3.6.1.2.2.8.1 would be
       encoded as follows (values in hex):

             06 07 2B 06 01 02 02 08 01

       The entire PRID object would be encoded as follows:

             00 0D                        - Length
             01                           - S-Num
             01                           - S-Type (Complete PRID)
             06 07 2B 06 01 02 02 08 01   - Encoded PRID
             00 00 00                     - Padding

       NOTE: When encoding an xxxTable's xxxEntry Object-Type as defined by
       the SMI [V2SMI] and SPPI [SPPI], the OID will contain all the sub-
       identifiers up to and including the xxxEntry OID but not the columnar
       identifiers for the attributes within the xxxEntry's SEQUENCE.  The
       last (suffix) identifier is the INDEX of an instance of an entire

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       xxxEntry including its SEQUENCE of attributes encoded in the EPD
       (defined below).  This constitutes an instance (PRI) of a class (PRC)
       in terms of the SMI.

       A PRID for a scalar (non-columnar) value's OID is encoded directly as
       the PRC where the instance identifier suffix is always zero as there
       will be only one instance of a scalar value.  The EPD will then be
       used to convey the scalar value.

    4.2. Prefix PRID (PPRID)

       Certain operations, such as decision removal, can be optimized by
       specifying a PRID prefix with the intent that the requested operation
       be applied to all PRIs matching the prefix (for example, all
       instances of the same PRC).  PRID prefix objects MUST only be used in
       the COPS protocol <Remove Decision> operation where it may be more
       optimal to perform bulk decision removal using class prefixes instead
       of a sequence of individual <Remove Decision> operations.  Other COPS
       operations, e.g., <Install Decision> operations always require
       individual PRID specification.

       S-Num = 2 (Prefix PRID), S-Type = 1 (BER), Length = variable.

                  0                1               2                 3
        +---------------+---------------+---------------+---------------+
        |              Length           | S-Num = PPRID | S-Type = BER  |
        +---------------+---------------+---------------+---------------+
        ...                                                           ...
        |                          Prefix PRID                          |
        ...                                                           ...
        +---------------+---------------+---------------+---------------+

       Continuing with the previous example, a prefix PRID that is equal to
       1.3.6.1.2.2 would be encoded as follows (values in hex):

             06 05 2B 06 01 02 02

          The entire PPRID object would be encoded as follows:

             00 0B                        - Length
             02                           - S-Num = Prefix PRID
             01                           - S-Type = BER
             06 05 2B 06 01 02 02         - Encoded Prefix PRID
             00                           - Padding

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    4.3. Encoded Provisioning Instance Data (EPD)

       S-Num = 3 (EPD), S-Type = 1 (BER), Length = variable.

       This object is used to carry the encoded value of a Provisioning
       Instance.  The PRI value, which contains all of the individual values
       of the attributes that comprise the class (which corresponds to the
       SMI's xxxEntry Object-Type defining the SEQUENCE of attributes
       comprising a table [V2SMI][SPPI]), is encoded as a series of TLV
       sub-components.  Each sub-component represents the value of a single
       attribute and is encoded following the BER.  Note that the ordering
       of non-scalar (multiple) attributes within the EPD is dictated by
       their respective columnar OID suffix when defined in [V2SMI].  Thus,
       the attribute with the smallest columnar OID suffix will appear first
       and the attribute with the highest number columnar OID suffix will be
       last.

               0                1               2                 3
       +---------------+---------------+---------------+---------------+
       |             Length            | S-Num = EPD   | S-Type = BER  |
       +---------------+---------------+---------------+---------------+
       |                     BER Encoded PRI Value                     |
       +---------------+---------------+---------------+---------------+

       As an example, a fictional definition of an IPv4 packet filter class
       could be described using the SMI as follows:

       ipv4FilterIpFilter OBJECT IDENTIFIER ::= { someExampleOID 1 }

       -- The IP Filter Table

       ipv4FilterTable OBJECT-TYPE
           SYNTAX         SEQUENCE OF Ipv4FilterEntry
           MAX-ACCESS     not-accessible
           STATUS         current
           DESCRIPTION
               "Filter definitions.  A packet has to match all fields in
               a filter.  Wildcards may be specified for those fields
               that are not relevant."

           ::= { ipv4FilterIpFilter 1 }

       ipv4FilterEntry OBJECT-TYPE
           SYNTAX         Ipv4FilterEntry
           MAX-ACCESS     not-accessible
           STATUS         current
           DESCRIPTION
               "An instance of the filter class."

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           INDEX { ipv4FilterIndex }

           ::= { ipv4FilterTable 1 }

       Ipv4FilterEntry ::= SEQUENCE {
               ipv4FilterIndex        Unsigned32,
               ipv4FilterDstAddr      IpAddress,
               ipv4FilterDstAddrMask  IpAddress,
               ipv4FilterSrcAddr      IpAddress,
               ipv4FilterSrcAddrMask  IpAddress,
               ipv4FilterDscp         Integer32,
               ipv4FilterProtocol     Integer32,
               ipv4FilterDstL4PortMin Integer32,
               ipv4FilterDstL4PortMax Integer32,
               ipv4FilterSrcL4PortMin Integer32,
               ipv4FilterSrcL4PortMax Integer32,
               ipv4FilterPermit       TruthValue
       }

       ipv4FilterIndex OBJECT-TYPE
           SYNTAX         Unsigned32
           MAX-ACCESS     read-write
           STATUS         current
           DESCRIPTION
            "An integer index to uniquely identify this filter among all
             the filters."

           ::= { ipv4FilterEntry 1 }

       ipv4FilterDstAddr OBJECT-TYPE

           SYNTAX         IpAddress
           MAX-ACCESS     read-write
           STATUS         current
           DESCRIPTION
            "The IP address to match against the packet's destination IP
            address."

           ::= { ipv4FilterEntry 2 }

       ipv4FilterDstAddrMask OBJECT-TYPE
           SYNTAX         IpAddress
           MAX-ACCESS     read-write
           STATUS         current
           DESCRIPTION
            "A mask for the matching of the destination IP address.
            A zero bit in the mask means that the corresponding bit in

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            the address always matches."

           ::= { ipv4FilterEntry 3 }

       ipv4FilterSrcAddr OBJECT-TYPE
           SYNTAX         IpAddress
           MAX-ACCESS     read-write
           STATUS         current
           DESCRIPTION
               "The IP address to match against the packet's source IP
               address."

           ::= { ipv4FilterEntry 4 }

       ipv4FilterSrcAddrMask OBJECT-TYPE
           SYNTAX         IpAddress
           MAX-ACCESS     read-write
           STATUS         current
           DESCRIPTION
               "A mask for the matching of the source IP address."

           ::= { ipv4FilterEntry 5 }

       ipv4FilterDscp OBJECT-TYPE
           SYNTAX         Integer32 (-1 | 0..63)
           MAX-ACCESS     read-write
           STATUS         current
           DESCRIPTION
               "The value that the DSCP in the packet can have and
               match.  A value of -1 indicates that a specific
               DSCP value has not been defined and thus all DSCP values
               are considered a match."

           ::= { ipv4FilterEntry 6 }

       ipv4FilterProtocol OBJECT-TYPE
           SYNTAX         Integer32 (0..255)
           MAX-ACCESS     read-write
           STATUS         current
           DESCRIPTION
               "The IP protocol to match against the packet's protocol.
               A value of zero means match all."

           ::= { ipv4FilterEntry 7 }

       ipv4FilterDstL4PortMin OBJECT-TYPE
           SYNTAX         Integer32 (0..65535)
           MAX-ACCESS     read-write

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           STATUS         current
           DESCRIPTION
               "The minimum value that the packet's layer 4 destination
               port number can have and match this filter."

           ::= { ipv4FilterEntry 8 }

       ipv4FilterDstL4PortMax OBJECT-TYPE
           SYNTAX         Integer32 (0..65535)
           MAX-ACCESS     read-write
           STATUS         current
           DESCRIPTION
               "The maximum value that the packet's layer 4 destination
               port number can have and match this filter."

           ::= { ipv4FilterEntry 9 }

       ipv4FilterSrcL4PortMin OBJECT-TYPE
           SYNTAX         Integer32 (0..65535)
           MAX-ACCESS     read-write
           STATUS         current
           DESCRIPTION
               "The minimum value that the packet's layer 4 source port
               number can have and match this filter."

           ::= { ipv4FilterEntry 10 }

       ipv4FilterSrcL4PortMax OBJECT-TYPE
           SYNTAX         Integer32 (0..65535)
           MAX-ACCESS     read-write
           STATUS         current
           DESCRIPTION
               "The maximum value that the packet's layer 4 source port
               number can have and match this filter."

           ::= { ipv4FilterEntry 11 }

       ipv4FilterPermit OBJECT-TYPE
           SYNTAX         TruthValue
           MAX-ACCESS     read-write
           STATUS         current
           DESCRIPTION
               "If false, the evaluation is negated.  That is, a
               valid match will be evaluated as not a match and vice
               versa."

           ::= { ipv4FilterEntry 12 }

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       A fictional instance of the filter class defined above might then
       be encoded as follows:

       02 01 08          :ipv4FilterIndex/Unsigned32/Value = 8
       40 04 C0 39 01 05 :ipv4FilterDstAddr/IpAddress/Value = 192.57.1.5
       40 04 FF FF FF FF :ipv4FilterDstMask/IpAddress/Value=255.255.255.255
       40 04 00 00 00 00 :ipv4FilterSrcAddr/IpAddress/Value = 0.0.0.0
       40 04 00 00 00 00 :ipv4FilterSrcMask/IpAddress/Value = 0.0.0.0
       02 01 FF          :ipv4FilterDscp/Integer32/Value = -1 (not used)
       02 01 06          :ipv4FilterProtocol/Integer32/Value = 6 (TCP)
       05 00             :ipv4FilterDstL4PortMin/NULL/not supported
       05 00             :ipv4FilterDstL4PortMax/NULL/not supported
       05 00             :ipv4FilterSrcL4PortMin/NULL/not supported
       05 00             :ipv4FilterSrcL4PortMax/NULL/not supported
       02 01 01          :ipv4FilterPermit/TruthValue/Value = 1 (true)

       The entire EPD object for this instance would then be encoded as
       follows:

       00 30                        - Length
       03                           - S-Num = EPD
       01                           - S-Type = BER
       02 01 08                     - ipv4FilterIndex
       40 04 C0 39 01 05            - ipv4FilterDstAddr
       40 04 FF FF FF FF            - ipv4FilterDstMask
       40 04 00 00 00 00            - ipv4FilterSrcAddr
       40 04 00 00 00 00            - ipv4FilterSrcMask
       02 01 FF                     - ipv4FilterDscp
       02 01 06                     - ipv4FilterProtocol
       05 00                        - ipv4FilterDstL4PortMin
       05 00                        - ipv4FilterDstL4PortMax
       05 00                        - ipv4FilterSrcL4PortMin
       05 00                        - ipv4FilterSrcL4PortMax
       02 01 01                     - ipv4FilterPermit

       Note that attributes not supported within a class are still returned
       in the EPD for a PRI.  By convention, a NULL value is returned for
       attributes that are not supported.  In the previous example, source
       and destination port number attributes are not supported.

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    4.4. Global Provisioning Error Object (GPERR)

       S-Num = 4 (GPERR), S-Type = 1 (for BER), Length = 8.

                0                1               2                 3
       +---------------+---------------+---------------+---------------+
       |              Length           | S-Num = GPERR | S-Type = BER  |
       +---------------+---------------+---------------+---------------+
       |           Error-Code          |       Error Sub-code          |
       +---------------+---------------+---------------+---------------+

       The global provisioning error object has the same format as the Error
       object in COPS [COPS], except with C-Num and C-Type replaced by the
       S-Num and S-Type values shown.  The global provision error object is
       used to communicate general errors that do not map to a specific PRC.

       The following global error codes are defined:

         availMemLow(1)
         availMemExhausted(2)
         unknownASN.1Tag(3)     - The erroneous tag type SHOULD be
                                  specified in the Error Sub-Code field.
         maxMsgSizeExceeded(4)  - COPS message (transaction) was too big.
         unknownError(5)
         maxRequestStatesOpen(6)- No more Request-States can be created
                                  by the PEP (in response to a DEC
                                  message attempting to open a new
                                  Request-State).
         invalidASN.1Length(7)  - An ASN.1 object length was incorrect.
         invalidObjectPad(8)    - Object was not properly padded.
         unknownPIBData(9)      - Some of the data supplied by the PDP is
                                  unknown/unsupported by the PEP (but
                                  otherwise formatted correctly).  PRC
                                  specific error codes are to be used to
                                  provide more information.
         unknownCOPSPRObject(10)- Sub-code (octet 2) contains unknown
                                  object's S-Num and (octet 3) contains
                                  unknown object's S-Type.
         malformedDecision(11)  - Decision could not be parsed.

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    4.5. PRC Class Provisioning Error Object (CPERR)

       S-Num = 5 (CPERR), S-Type = 1 (for BER), Length = 8.

                0                1               2                 3
       +---------------+---------------+---------------+---------------+
       |              Length           | S-Num = CPERR | S-Type = BER  |
       +---------------+---------------+---------------+---------------+
       |           Error-Code          |       Error Sub-code          |
       +---------------+---------------+---------------+---------------+

       The class-specific provisioning error object has the same format as
       the Error object in COPS [COPS], except with C-Num and C-Type
       replaced by the S-Num and S-Type values shown.  The class-specific
       error object is used to communicate errors relating to specific PRCs
       and MUST have an associated Error PRID Object.

       The following Generic Class-Specific errors are defined:

         priSpaceExhausted(1) -     no more instances may currently be
                                    installed in the given class.
         priInstanceInvalid(2) -    the specified class instance is
                                    currently invalid prohibiting
                                    installation or removal.
         attrValueInvalid(3) -      the specified value for identified
                                    attribute is illegal.
         attrValueSupLimited(4) -   the specified value for the identified
                                    attribute is legal but not currently
                                    supported by the device.
         attrEnumSupLimited(5) -    the specified enumeration for the
                                    identified attribute is legal but not
                                    currently supported by the device.
         attrMaxLengthExceeded(6) - the overall length of the specified
                                    value for the identified attribute
                                    exceeds device limitations.
         attrReferenceUnknown(7) -  the class instance specified by the
                                    policy instance identifier does not
                                    exist.
         priNotifyOnly(8) -         the class is currently only supported
                                    for use by request or report messages
                                    prohibiting decision installation.
         unknownPrc(9) -            attempt to install a PRI of a class not
                                    supported by PEP.
         tooFewAttrs(10) -          recvd PRI has fewer attributes than
                                    required.
         invalidAttrType(11) -      recvd PRI has an attribute of the wrong
                                    type.

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         deletedInRef(12)  -        deleted PRI is still referenced by
                                    other (non) deleted PRIs
         priSpecificError(13) -     the Error Sub-code field contains the
                                    PRC specific error code

         Where appropriate (errors 3, 4, 5, 6, 7 above) the error sub-code
          SHOULD identify the OID sub-identifier of the attribute
          associated with the error.

    4.6. Error PRID Object (ErrorPRID)

       S-Num = 6 (ErrorPRID), S-Type = 1 (BER), Length = variable.

       This object is used to carry the identifier, or PRID, of a
       Provisioning Instance that caused an installation error or could not
       be installed or removed.  The identifier is encoded and formatted
       exactly as in the PRID object as described in section 4.1.

    5. COPS-PR Client-Specific Data Formats

       This section describes the format of the named client specific
       information for the COPS policy provisioning client.  ClientSI
       formats are defined for Decision message's Named Decision Data
       object, the Request message's Named ClientSI object and Report
       message's Named ClientSI object.  The actual content of the data is
       defined by the policy information base for a specific provisioning
       client-type (see below).

    5.1. Named Decision Data

       The formats encapsulated by the Named Decision Data object for the
       policy provisioning client-types depends on the type of decision.
       Install and Remove are the two types of decisions that dictate the
       internal format of the COPS Named Decision Data object and require
       its presence.  Install and Remove refer to the 'Install' and 'Remove'
       Command-Code, respectively, specified in the COPS Decision Flags
       Object when no Decision Flags are set.  The data, in general, is
       composed of one or more bindings.  Each binding associates a PRID
       object and a EPD object.  The PRID object is always present in both
       install and remove decisions, the EPD object MUST be present in the
       case of an install decision and MUST NOT be present in the case of a
       remove decision.

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       The format for this data is encapsulated within the COPS Named
       Decision Data object as follows:
         <Named Decision Data> ::= <<Install Decision> |
                                     <Remove Decision>>

         <Install Decision>    ::= *(<PRID> <EPD>)

         <Remove Decision>     ::= *(<PRID>|<PPRID>)

       Note that PRID objects in a Remove Decision may specify PRID prefix
       values.  Explicit and implicit deletion of installed policies is
       supported by a client.  Install Decision data MUST be explicit (i.e.,
       PRID prefix values are illegal and MUST be rejected by a client).

    5.2. ClientSI Request Data

       The provisioning client request data will use same bindings as
       described above.  The format for this data is encapsulated in the
       COPS Named ClientSI object as follows:

       <Named ClientSI: Request> ::= <*(<PRID> <EPD>)>

    5.3. Policy Provisioning Report Data

       The COPS Named ClientSI object is used in the RPT message in
       conjunction with the accompanying COPS Report Type object to
       encapsulate COPS-PR report information from the PEP to the PDP.
       Report types can be 'Success' or 'Failure', indicating to the PDP
       that a particular set of provisioning policies has been either
       successfully or unsuccessfully installed/removed on the PEP, or
       'Accounting'.

    5.3.1. Success and Failure Report-Type Data Format

       Report-types can be 'Success' or 'Failure' indicating to the PDP that
       a particular set of provisioning policies has been either
       successfully or unsuccessfully installed/removed on the PEP.  The
       provisioning report data consists of the bindings described above and
       global and specific error/warning information. Specific errors are
       associated with a particular instance.  For a 'Success' Report-Type,
       a specific error is an indication of a warning related to a specific
       policy that has been installed, but that is not fully implemented
       (e.g., its parameters have been approximated) as identified by the
       ErrorPRID object.  For a 'Failure' Report-Type, this is an error code
       specific to a binding, again, identified by the ErrorPRID object.
       Specific errors may also include regular <PRID><EPD> bindings to

    Chan, et al.                Standards Track                    [Page 24]

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       carry additional information in a generic manner so that the specific
       errors/warnings may be more verbosely described and associated with
       the erroneous ErrorPRID object.

       Global errors are not tied to a specific ErrorPRID.  In a 'Success'
       RPT message, a global error is an indication of a general warning at
       the PEP level (e.g., memory low).  In a 'Failure' RPT message, this
       is an indication of a general error at the PEP level (e.g., memory
       exhausted).

       In the case of a 'Failure' Report-Type the PEP MUST report at least
       the first error and SHOULD report as many errors as possible.  In
       this case the PEP MUST roll-back its configuration to the last good
       transaction before the erroneous Decision message was received.

       The format for this data is encapsulated in the COPS Named ClientSI
       object as follows:

       <Named ClientSI: Report> ::= <[<GPERR>] *(<report>)>

       <report> ::= <ErrorPRID> <CPERR> *(<PRID><EPD>)

    5.3.2. Accounting Report-Type Data Format

       Additionally, reports can be used to carry accounting information
       when specifying the 'Accounting' Report-Type.  This accounting report
       message will typically carry statistical or event information related
       to the installed configuration for use at the PDP.  This information
       is encoded as one or more <PRID><EPD> bindings that generally
       describe the accounting information being reported from the PEP to
       the PDP.

       The format for this data is encapsulated in the COPS Named ClientSI
       object as follows:

       <Named ClientSI: Report> ::= <*(<PRID><EPD>)>

       NOTE: RFC 2748 defines an optional Accounting-Timer (AcctTimer)
       object for use in the COPS Client-Accept message.  Periodic
       accounting reports for COPS-PR clients are also obligated to be paced
       by this timer.  Periodic accounting reports SHOULD NOT be generated
       by the PEP more frequently than the period specified by the COPS
       AcctTimer.  Thus, the period between new accounting reports SHOULD be
       greater-than or equal-to the period specified (if specified) in the
       AcctTimer.  If no AcctTimer object is specified by the PDP, then
       there are no constraints imposed on the PEP's accounting interval.

    Chan, et al.                Standards Track                    [Page 25]

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    6. Common Operation

       This section describes, in general, typical exchanges between a PDP
       and Policy Provisioning COPS client.

       First, a TCP connection is established between the client and server
       and the PEP sends a Client-Open message specifying a COPS- PR
       client-type (use of the ClientSI object within the Client-Open
       message is currently undefined for COPS-PR clients). If the PDP
       supports the specified provisioning client-type, the PDP responds
       with a Client-Accept (CAT) message.  If the client-type is not
       supported, a Client-Close (CC) message is returned by the PDP to the
       PEP, possibly identifying an alternate server that is known to
       support the policy for the provisioning client-type specified.

       After receiving the CAT message, the PEP can send requests to the
       server.  The REQ from a policy provisioning client contains a COPS
       'Configuration Request' context object and, optionally, any relevant
       named client specific information from the PEP.  The information
       provided by the PEP should include available client resources (e.g.,
       supported classes/attributes) and default policy configuration
       information as well as incarnation data on existing policy.  The
       configuration request message from a provisioning client serves two
       purposes.  First, it is a request to the PDP for any provisioning
       configuration data which the PDP may currently have that is suitable
       for the PEP, such as access control filters, etc., given the
       information the PEP specified in its REQ.  Also, the configuration
       request effectively opens a channel that will allow the PDP to
       asynchronously send policy data to the PEP, as the PDP decides is
       necessary, as long as the PEP keeps its request state open (i.e., as
       long as the PEP does not send a DRQ with the request state's Client
       Handle).  This asynchronous data may be new policy data or an update
       to policy data sent previously.  Any relevant changes to the PEP's
       internal state can be communicated to the PDP by the PEP sending an
       updated REQ message.  The PEP is free to send such updated REQ
       messages at any time after a CAT message to communicate changes in
       its local state.

       After the PEP sends a REQ, if the PDP has Policy Provisioning policy
       configuration information for the client, that information is
       returned to the client in a DEC message containing the Policy
       Provisioning client policy data within the COPS Named Decision Data
       object and specifying an "Install" Command-Code in the Decision Flags
       object.  If no filters are defined, the DEC message will simply
       specify that there are no filters using the "NULL Decision" Command-
       Code in the Decision Flags object.  As the PEP MUST specify a Client
       Handle in the request message, the PDP MUST process the Client Handle
       and copy it in the corresponding decision message.  A DEC message

    Chan, et al.                Standards Track                    [Page 26]

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       MUST be issued by the PDP with the Solicited Message Flag set in the
       COPS message header, regardless of whether or not the PDP has any
       configuration information for the PEP at the time of the request.
       This is to prevent the PEP from timing out the REQ and deleting the
       Client Handle.

       The PDP can then add new policy data or update/delete existing
       configurations by sending subsequent unsolicited DEC message(s) to
       the PEP, with the same Client Handle.  Previous configurations
       installed on the PEP are updated by the PDP by simply re-installing
       the same instance of configuration information again (effectively
       overwriting the old data).  The PEP is responsible for removing the
       Client handle when it is no longer needed, for example when an
       interface goes down, and informing the PDP that the Client Handle is
       to be deleted via the COPS DRQ message.

       For Policy Provisioning purposes, access state, and access requests
       to the policy server can be initiated by other sources besides the
       PEP.  Examples of other sources include attached users requesting
       network services via a web interface into a central management
       application, or H.323 servers requesting resources on behalf of a
       user for a video conferencing application.  When such a request is
       accepted, the edge device affected by the decision (the point where
       the flow is to enter the network) needs to be informed of the
       decision.  Since the PEP in the edge device did not initiate the
       request, the specifics of the request, e.g., flowspec, packet filter,
       and PHB to apply, needs to be communicated to the PEP by the PDP.
       This information is sent to the PEP using the Decision message
       containing Policy Provisioning Named Decision Data objects in the
       COPS Decision object as specified.  Any updates to the state
       information, for example in the case of a policy change or call tear
       down, is communicated to the PEP by subsequent unsolicited DEC
       messages containing the same Client Handle and the updated Policy
       Provisioning request state.  Updates can specify that policy data is
       to be installed, deleted, or updated (re-installed).

       PDPs may also command the PEP to open a new Request State or delete
       an exiting one by issuing a decision with the Decision Flags object's
       Request-State flag set.  If the command-code is "install", then the
       PDP is commanding the PEP to create a new Request State, and
       therefore issue a new REQ message specifying a new Client Handle or
       otherwise issue a "Failure" RPT specifying the appropriate error
       condition.  Each request state represents an independent and
       logically non-overlapping namespace, identified by the Client Handle,
       on which transactions (a.k.a., configuration installations,
       deletions, updates) may be performed.  Other existing Request States
       will be unaffected by the new request state as they are independent
       (thus, no instances of configuration data within one Request State

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    RFC 3084                        COPS-PR                       March 2001

       can be affected by DECs for another Request State as identified by
       the Client Handle).  If the command-code is "Remove", then the PDP is
       commanding the PEP to delete the existing Request-State specified by
       the DEC message's Client Handle, thereby causing the PEP to issue a
       DRQ message for this Handle.

       The PEP MUST acknowledge a DEC message and specify what action was
       taken by sending a RPT message with a "Success" or "Failure" Report-
       Type object with the Solicited Message Flag set in the COPS message
       header.  This serves as an indication to the PDP that the requestor
       (e.g., H.323 server) can be notified whether the request has been
       accepted by the network or not.  If the PEP needs to reject the DEC
       operation for any reason, a RPT message is sent with a Report-Type
       with the value "Failure" and optionally a Client Specific Information
       object specifying the policy data that was rejected.  Under such
       solicited report failure conditions, the PEP MUST always rollback to
       its previously installed (good) state as if the DEC never occurred.
       The PDP is then free to modify its decision and try again.

       The PEP can report to the PDP the current status of any installed
       request state when appropriate.  This information is sent in a
       Report-State (RPT) message with the "Accounting" flag set.  The
       request state that is being reported is identified via the associated
       Client Handle in the report message.

       Finally, Client-Close (CC) messages are used to cancel the
       corresponding Client-Open message.  The CC message informs the other
       side that the client-type specified is no longer supported.

    7. Fault Tolerance

       When communication is lost between PEP and PDP, the PEP attempts to
       re-establish the TCP connection with the PDP it was last connected
       to.  If that server cannot be reached, then the PEP attempts to
       connect to a secondary PDP, assumed to be manually configured (or
       otherwise known) at the PEP.

       When a connection is finally re-established with a PDP, the PEP sends
       a OPN message with a <LastPDPAddr> object providing the address of
       the most recent PDP for which it is still caching decisions.  If no
       decisions are being cached on the PEP (due to reboot or TTL timeout
       of state) the PEP MUST NOT include the last PDP address information.
       Based on this object, the PDP may request the PEP to re-synch its
       current state information (by issuing a COPS SSQ message).  If, after
       re-connecting, the PDP does not request synchronization, the client
       can assume the server recognizes it and the current state at the PEP
       is correct, so a REQ message need not be sent.  Still, any state
       changes which occurred at the PEP that the PEP could not communicate

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       to the PDP due to communication having been lost, MUST be reported to
       the PDP via the PEP sending an updated REQ message.  Whenever re-
       synchronization is requested, the PEP MUST reissue any REQ messages
       for all known Request-States and the PDP MUST issue DEC messages to
       delete either individual PRIDs or prefixes as appropriate to ensure a
       consistent known state at the PEP.

       While the PEP is disconnected from the PDP, the active request-state
       at the PEP is to be used for policy decisions.  If the PEP cannot
       re-connect in some pre-specified period of time, all installed
       Request-States are to be deleted and their associated Handles
       removed.  The same holds true for the PDP; upon detecting a failed
       TCP connection, the time-out timer is started for all Request-States
       associated with the PEP and these states are removed after the
       administratively specified period without a connection.

    8. Security Considerations

       The COPS protocol [COPS], from which this document derives, describes
       the mandatory security mechanisms that MUST be supported by all COPS
       implementations.  These mandatory security mechanisms are used by the
       COPS protocol to transfer opaque information from PEP to PDP and vice
       versa in an authenticated and secure manner.  COPS for Policy
       Provisioning simply defines a structure for this opaque information
       already carried by the COPS protocol.  As such, the security
       mechanisms described for the COPS protocol will also be deployed in a
       COPS-PR environment, thereby ensuring the integrity of the COPS-PR
       information being communicated.  Furthermore, in order to fully
       describe a practical set of structured data for use with COPS-PR, a
       PIB (Policy Information Base) will likely be written in a separate
       document.  The authors of such a PIB document need to be aware of the
       security concerns associated with the specific data they have
       defined.  These concerns MUST be fully specified in the security
       considerations section of the PIB document along with the required
       security mechanisms for  transporting this newly defined data.

    9. IANA Considerations

       COPS for Policy Provisioning follows the same IANA considerations for
       COPS objects as the base COPS protocol [COPS].  COPS-PR has defined
       one additional Decision Flag value of 0x02, extending the COPS base
       protocol only by this one value.  No new COPS Client- Types are
       defined by this document.

       COPS-PR also introduces a new object number space with each object
       being identified by its S-Num and S-Type value pair.  These objects
       are encapsulated within the existing COPS Named ClientSI or Named
       Decision Data objects [COPS] and, therefore, do not conflict with any

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    RFC 3084                        COPS-PR                       March 2001

       assigned numbers in the COPS base protocol.  Additional S-Num and S-
       Type pairs can only be added to COPS-PR using the IETF Consensus rule
       as defined in [IANA].  These two numbers are always to be treated as
       a pair, with one or more S-Types defined per each S-Num.  This
       document defines the S-Num values 1-6 and the S-Type 1 for each of
       these six values (note that the S-Type value of 2 is reserved for
       transport of XML encoded data).  A listing of all the S-Num and S-
       Type pairs defined by this document can be found in sections 4.1-4.6.

       Likewise, additional Global Provisioning error codes and Class-
       Specific Provisioning error codes defined for COPS-PR can only be
       added with IETF Consensus.  This document defines the Global
       Provisioning error code values 1-11 in section 4.4 for the Global
       Provisioning Error Object (GPERR).  This document also defines the
       Class-Specific error code values 1-13 in section 4.5 for the Class
       Provisioning Error Object (CPERR).

    10. Acknowledgements

       This document has been developed with active involvement from a
       number of sources.  The authors would specifically like to
       acknowledge the valuable input given by Michael Fine, Scott Hahn, and
       Carol Bell.

    11. References

       [COPS]    Boyle, J., Cohen, R., Durham, D., Herzog, S., Raja, R. and
                 A. Sastry, "The COPS (Common Open Policy Service)
                 Protocol", RFC 2748, January 2000.

       [RAP]     Yavatkar, R., Pendarakis, D. and R. Guerin, "A Framework
                 for Policy Based Admission Control", RFC 2753, January
                 2000.

       [COPRSVP] Boyle, J., Cohen, R., Durham, D., Herzog, S., Raja, R. and
                 A. Sastry, "COPS usage for RSVP", RFC 2749, January 2000.

       [ASN1]    Information processing systems - Open Systems
                 Interconnection, "Specification of Abstract Syntax Notation
                 One (ASN.1)", International Organization for
                 Standardization, International Standard 8824, December
                 1987.

       [BER]     Information processing systems - Open Systems
                 Interconnection - Specification of Basic Encoding Rules for
                 Abstract Syntax Notation One (ASN.1), International
                 Organization for Standardization. International Standard
                 8825, (December, 1987).

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    RFC 3084                        COPS-PR                       March 2001

       [RFC2475] Blake, S., Black, D., Carlson, M., Davies, E., Wang, Z. and
                 W. Weiss, "An Architecture for Differentiated Service," RFC
                 2475, December 1998.

       [SPPI]    McCloghrie, K., Fine, M., Seligson, J., Chan, K., Hahn, S.,
                 Sahita, R., Smith, A. and F. Reichmeyer, "Structure of
                 Policy Provisioning Information SPPI", Work in Progress.

       [V2SMI]   McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J.,
                 Rose, M. and S. Waldbusser, "Structure of Management
                 Information Version 2(SMIv2)", STD 58, RFC 2578, April
                 1999.

       [RFC2234] Crocker, D. and P. Overell, "Augmented BNF for Syntax
                 Specifications: ABNF", RFC 2234, November 1997.

       [IANA]    Alvestrand, H. and T. Narten, "Guidelines for writing an
                 IANA Considerations Section in RFCs", BCP 26, RFC 2434,
                 October 1998.

       [URN]     Moats, R., "Uniform Resource Names (URN) Syntax", RFC 2141,
                 May 1997.

       [XML]     World Wide Web Consortium (W3C), "Extensible Markup
                 Language (XML)," W3C Recommendation, February, 1998,
                 http://www.w3.org/TR/1998/REC-xml-19980210.

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    RFC 3084                        COPS-PR                       March 2001

    12. Authors' Addresses

       Kwok Ho Chan
       Nortel Networks, Inc.
       600 Technology Park Drive
       Billerica, MA 01821

       Phone: (978) 288-8175
       EMail: khchan@nortelnetworks.com

       David Durham
       Intel
       2111 NE 25th Avenue
       Hillsboro, OR 97124

       Phone: (503) 264-6232
       Email: david.durham@intel.com

       Silvano Gai
       Cisco Systems, Inc.
       170 Tasman Dr.
       San Jose, CA 95134-1706

       Phone: (408) 527-2690
       EMail: sgai@cisco.com

       Shai Herzog
       IPHighway Inc.
       69 Milk Street, Suite 304
       Westborough, MA 01581

       Phone: (914) 654-4810
       EMail: Herzog@iphighway.com

       Keith McCloghrie

       Phone: (408) 526-5260
       EMail: kzm@cisco.com

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    RFC 3084                        COPS-PR                       March 2001

       Francis Reichmeyer
       PFN, Inc.
       University Park at MIT
       26 Landsdowne Street
       Cambridge, MA 02139

       Phone: (617) 494 9980
       EMail: franr@pfn.com

       John Seligson
       Nortel Networks, Inc.
       4401 Great America Parkway
       Santa Clara, CA 95054

       Phone: (408) 495-2992
       Email: jseligso@nortelnetworks.com

       Raj Yavatkar

       Phone: (503) 264-9077
       EMail: raj.yavatkar@intel.com

       Andrew Smith
       Allegro Networks
       6399 San Ignacio Ave.
       San Jose, CA 95119, USA

       EMail: andrew@allegronetworks.com

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    RFC 3084                        COPS-PR                       March 2001

    13. Full Copyright Statement

       Copyright (C) The Internet Society (2001).  All Rights Reserved.

       This document and translations of it may be copied and furnished to
       others, and derivative works that comment on or otherwise explain it
       or assist in its implementation may be prepared, copied, published
       and distributed, in whole or in part, without restriction of any
       kind, provided that the above copyright notice and this paragraph are
       included on all such copies and derivative works.  However, this
       document itself may not be modified in any way, such as by removing
       the copyright notice or references to the Internet Society or other
       Internet organizations, except as needed for the purpose of
       developing Internet standards in which case the procedures for
       copyrights defined in the Internet Standards process must be
       followed, or as required to translate it into languages other than
       English.

       The limited permissions granted above are perpetual and will not be
       revoked by the Internet Society or its successors or assigns.

       This document and the information contained herein is provided on an
       "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
       TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
       BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
       HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
       MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

    Acknowledgement

       Funding for the RFC Editor function is currently provided by the
       Internet Society.

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