rfc3084
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]
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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 >]
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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).
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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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RFC 3084 COPS-PR March 2001
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
Chan, et al. Standards Track [Page 14]
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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
Chan, et al. Standards Track [Page 15]
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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."
Chan, et al. Standards Track [Page 16]
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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
Chan, et al. Standards Track [Page 17]
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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
Chan, et al. Standards Track [Page 18]
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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 }
Chan, et al. Standards Track [Page 19]
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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.
Chan, et al. Standards Track [Page 20]
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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.
Chan, et al. Standards Track [Page 22]
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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.
Chan, et al. Standards Track [Page 23]
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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
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RFC 3084 COPS-PR March 2001
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
Chan, et al. Standards Track [Page 27]
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
Chan, et al. Standards Track [Page 28]
RFC 3084 COPS-PR March 2001
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
Chan, et al. Standards Track [Page 29]
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).
Chan, et al. Standards Track [Page 30]
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.
Chan, et al. Standards Track [Page 31]
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
Chan, et al. Standards Track [Page 32]
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
Chan, et al. Standards Track [Page 33]
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.
Chan, et al. Standards Track [Page 34]
ERRATA
