Internet Draft

Internet Draft
Internet Draft Francis Reichmeyer
Expiration: December 1999 Shai Herzog
File: draft-ietf-rap-pr-00.txt IPHighway
Updates RFC 2205 Kwok Ho Chan
Nortel Networks
David Durham
Raj Yavatkar
Intel
Silvano Gai
Keith McCloghrie
Cisco Systems
Andrew Smith
Extreme Networks

COPS Usage for Policy Provisioning

June 25, 1999

Status of this Memo

This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026.

Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet-
Drafts.

Internet-Drafts are draft documents valid for a maximum of six
months and may be updated, replaced, or obsoleted by other documents
at any time. It is inappropriate to use Internet-Drafts as
reference material or to cite them other than as "work in progress."

The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt

The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.

Distribution of this memo is unlimited.

Internet Draft Expires December 1999 [Page 1]

Internet Draft COPS Usage for Policy Provisioning 25-Jun-99

Abstract

This document introduces a new client type for the COPS protocol to
support policy provisioning. This new client type uses is
independent of the type of policy and it is based on the concept of
named PIBs (Policy Information Bases).

Shai Herzog Expires December 1999 [Page 2]

Internet Draft COPS Usage for Policy Provisioning 25-Jun-99

Table of Contents

Abstract.............................................................2
Table of Contents....................................................3
1 Introduction......................................................4
1.1 Why not SNMP?...................................................5
1.2 Interaction between the PEP and PDP.............................6
2 Policy Information Base (PIB).....................................6
2.1 A Description of the PIB........................................8
2.2 COPS Operations Supported for a Policy Rule 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.................................10
4 COPS-PR Protocol Objects.........................................11
4.1 Binding Count (BC).............................................12
4.2 Policy Rule Identifier (PRID)..................................12
4.3 BER Encoded Policy Instance Data (BPD).........................13
4.4 Provisioning Error Object (PERR)...............................13
5 COPS-PR Client-Specific Data Formats.............................13
5.1 Named Decision Data............................................14
5.2 ClientSI Request Data..........................................14
5.3 Policy Provisioning Report Data................................14
6 Common Operations................................................15
7 Fault Tolerance..................................................17
7.1 Security Considerations........................................17
8 References.......................................................18
9 Author Information...............................................19
10 Full Copyright Notice...........................................20
Appendix A : A DiffServ COPS-PR Example..............................21

Shai Herzog Expires December 1999 [Page 3]

Internet Draft COPS Usage for Policy Provisioning 25-Jun-99

1 Introduction

The IETF RSVP Admission Policy (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 (PEP). 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 Provisioning.

The Outsourcing model addresses the kind of events at the PEP that
require instantaneous policy decision (authorization). The PEP,
being aware that it must perform a policy decision. However, being
unable to carry the task itself, the PEP delegates responsibility to
an external policy server (PDP). For example, in [COPS-RSVP] when a
reservation message arrives, the PEP is aware that it must decide
whether to admit or reject the request. It sends a specific query to
the PDP, and in most case, waits for a decision before admitting the
outstanding reservation.

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 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.

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

Figure 1: COPS Provisioning Model

Shai Herzog Expires December 1999 [Page 4]

Internet Draft COPS Usage for Policy Provisioning 25-Jun-99

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 cannot be mapped directly
to requests, and are issued mostly when the PDP responds to external
events or PDP events (policy/SLA updates).

This draft describes a new client type ("Provisioning") for COPS to
support policy provisioning. This new client type is independent of
the type of policy (QoS, VPNs, Security, etc.) and it is based on
the concept of PIBs (Policy Information Bases [PIB]).

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

1.1 Why not SNMP?

SNMP is a very popular network management protocol. One may question
using COPS-PR, rather than extending SNMP for policy provisioning.

There are several aspects intrinsic to SNMP that prevents it from
being a successful policy protocol.

SNMP uses a transactional model, and does not support the concept of
long term Client/Server connection. As a by product, servers may not
know that devices failed and vice versa. A hello polling may be a
cumbersome replacement, however it may not solve the problem if a
device may reboot in between polling messages.

The SNMP transactional model allows multiple servers to
simultaneously modify state of a network device. Given that SNMP
does not have resource locking facilities, a policy server would
have to constantly poll and verify that no other networking
management software or humans changed ANY of the configured
resources.

SNMP is based on UDP and is thus unreliable. The lack of reliability
is unacceptable for a policy protocol [RAP]. Provisioning policy is
assumed quite large and diverse. It is desired that a provisioning
protocol would be based on state sharing between client and server
such that only differential updates are sent. Such state sharing
requires a reliable transport mechanism.

Last, SNMP was not designed as a real-time operations protocol. Its
trap mechanism is inefficient and cumbersome and there is no
performance guarantees.

Shai Herzog Expires December 1999 [Page 5]

Internet Draft COPS Usage for Policy Provisioning 25-Jun-99

COPS was designed to overcome these shortcomings, based on the
requirements defined in [RAP]. It has a single connection between
client and server, it guarantees only one server updates the policy
configuration at any given time (and these are locked, even from
console configuration, while COPS is connected to a server).
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 high
priority (real-time) mechanism for the PEP device.

The COPS protocol is already used for policy control over RSVP. It
is highly desirable to use a single policy control protocol for
Quality of Service (QoS) mechanisms (if possible), rather than
invent a new one for each type of policy problem.

At the same time, useful mechanisms from SNMP were adopted. COPS-PR
uses a named Policy Information Base (PIB) which the model of SMI
and MIB and BER [BER] data encoding. This allows reuse of
experience, knowledge, tools and some code from the SNMP world.

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 which 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 and/or
deletes) in policy to the PEP, and the PEP updates its local QoS
mechanisms 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 sends
this unsolicited new information to the PDP. On receiving this new
information, the PDP sends to the PEP any additional provisioned
policies now needed by the PEP.

2 Policy Information Base (PIB)

This section defines data format for Provisioning Named ClientSI
objects (Named Client Specific Information). COPS-PR data is a

Shai Herzog Expires December 1999 [Page 6]

Internet Draft COPS Usage for Policy Provisioning 25-Jun-99

collection of policy-rules each identified by Policy Rule
Identification (PRID). The PRID is a globally unique name (hence,
"named ClientSI"), which describes the representation (format) and
semantics of the policy rule.

COPS-PR uses a named Policy Information Base (PIB) as its global
name space of provisioning policy. The PIB name space is common to
both the PEP and The PDP. The PIB can be described as a tree where
the branches of the tree represent classes (types) of policy rules
(PRC), while the leaves represent instances (contents) of policy
rules (PRI). There may be multiple instances of rules (PRI) for any
given rule type (PRC). For example, if one wanted to install
multiple access control filters, the PRC would represent a generic
access control filter type, and each PRI would represent an actual
access control filter to be installed).

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

Figure 2: The PIB Tree

The provisioning PIB is based on SMI and MIBs. The decision to use
this format as a basis opens-up the possibility of reusing SMI and
MIB knowledge, experience, and tools. Unlike COPS-RSVP its sibling,
COPS-PR requires a named structure to identify the type and purpose
of unsolicited policy information "pushed" to the client policy.

PRIs and PRCs are uniquely identified by PRIDs. PRIDs have a
hierarchical structure of the form 1.3.4.2.7, where the first part
identifies the PRC (e.g., 1.3.4) and the last part identifies the
instance (e.g. 2.7).

The policy tree names all the policy rule classes and instances and
this creates a common view of the policy organization between the
client (PEP) and the server (PDP). The PIB data on its own is self-
descriptive such that the receiving PEP understands the required
provisioning.

Consider the following example, of a set of FILTERs for marking
traffic with a certain diff-serv code point (DSCP). Each filter has

Shai Herzog Expires December 1999 [Page 7]

Internet Draft COPS Usage for Policy Provisioning 25-Jun-99

the following attributes: Protocol number, source address, source
port, destination address, destination port, and DSCP value to set.
Lets assume that the class FILTER's PRID is "$.1", where $
represents some prefix in the policy tree to which the class FILTER
belongs. A first filter would have a PRID of $.1.1, the second
$.1.2, etc.

Given that most provisioning operations require multiple attributes,
COPS-PR does not support operations on individual attributes within
a PRC class (e.g., source port). Instead, updates and deletions are
performed on PRC granularity.

2.1 A Description of the PIB

The PIB is described using SMI and PIBs. SMI and PIBs are defined
based on the ASN.1 data definition language [ASN1]. To simplify the
implementation and re-use the SNMP encoding/decoding code, the wire
representation of the policy information (PRIDs and BPDs) must
follow BER encoding [BER].

(1) (1.1)
If--+-General
|
| (1.2) (1.2.1) (1.2.1.1) (1.2.1.1.1)
+-Input----Filter--+-Mark-----+-SrcIP
| | |
| | +-SrcPrt
+-Output +-Pol-Rtng |(1.2.1.1.3)
| +-DstIP----+-D1 (1.2.1.1.3.1)
| | |
+-Access +-DstPrt +-D2
| |
+-Prot# +-D3
|
+-DSCP
{__________________ _____________________} {_______ _______}
\/ \/
PRC Branches PRI leaves

Figure 3: A PIB Example for DiffServ Marking Filter

Figure 3 describes a simple example of a possible PIB tree for
DiffServ Marking Filter. The numbers in brackets represent the
location of the PRC or PRI in the tree. The PRID of Filter2 (which
includes DstIP=D2) would be 1.2.1.1.2 (Notice that the last digit of
the PRCs (which describes the rule attributes) is dropped since
COPS-PR purposely blocks operations on individual attributes).

2.2 COPS Operations Supported for a Policy Rule Instance

Shai Herzog Expires December 1999 [Page 8]

Internet Draft COPS Usage for Policy Provisioning 25-Jun-99

A policy rule instance is made of multiple attributes (PRIs) and is
identified by a PRID. The following COPS operations are supported on
for a policy rule instance:

o Install � This operation creates or updates a named instance of a
PRC. It accepts two parameters: a PRID to name the PRI, and a PBD
with the new/updated values.

o Remove - This operation is used to delete an instance of a PRC.
It accepts one parameter, a PRID, to name the instance to be
deleted.

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.

Request (REQ) PEP -> PDP

The REQ message is sent by policy provisioning clients to issue a
'config request' to the PDP. The Client Handle associated with the
REQ message originated by a provisioning client must be unique for
that client but otherwise has no protocol significance at this time.

The config request message serves as a request from the PEP to the
PDP for provisioning policy data which 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.

The config request message may include provisioning client
information to provide the PDP with client-specific configuration or
capability information about the PEP. This information from the
client assists the server in deciding what types of policy that the
PEP can install and enforce. The format of the Provisioning ClientSI
data is described in the policy information base (see below).

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 config request with a DEC message containing
any available provisioning policy data.

The REQ message has the following format:

::=

[]

Shai Herzog Expires December 1999 [Page 9]

Internet Draft COPS Usage for Policy Provisioning 25-Jun-99

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 REQ message.

The DEC message is sent as an immediate response to a config request
with the solicited decision flag set. Subsequent DEC messages may
also be sent at any time after the original DEC message to supply
the PEP with additional/updated policy information. Updated policy
data carried in DEC message is correlated with the previous DEC by
matching the policy ID information in the provisioning client
decision data.

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

A COPS-PR DEC message contains a single "transaction", i.e. either
all the decisions in a DEC message succeed or they all fail. 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:

::=

[]+ |

::=

[]

For each decision on the DEC message, the PEP performs the operation
specified in the Flags field 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 below). In response
to a DEC message, the policy provisioning client sends a RPT message
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 the provisioning client.

Shai Herzog Expires December 1999 [Page 10]

Internet Draft COPS Usage for Policy Provisioning 25-Jun-99

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 = 'Installed') or not (Report-
Type = 'Not Installed').

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 below). The RPT message has the
following format:

::=

[]

4 COPS-PR Protocol Objects

We define a new COPS client type for the policy provisioning client:

Client Type = 2; Policy Provisioning Client

COPS messages sent between a Policy Provisioning client and a COPS
server contain a COPS Common Header with this Policy Provisioning
Client type specified:

The COPS Policy Provisioning client uses several new COPS protocol
objects that carry named client-specific information. This section
defines those new objects.

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

Shai Herzog Expires December 1999 [Page 11]

Internet Draft COPS Usage for Policy Provisioning 25-Jun-99

The format for these new objects is as follows:

0 1 2 3
+---------------+---------------+---------------+---------------+
| Length | S-Num = BC | S-Type = 1 |
+---------------+---------------+---------------+---------------+
| 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 ClientSI specific objects.

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 previous stated object length to the next 32-bit
boundary.

4.1 Binding Count (BC)

S-Num = 1, S-Type = 1, Length = 8.

This object specifies the number of Bindings that are contained in
the message.

4.2 Policy Rule Identifier (PRID)

S-Num = 2, S-Type = 1, Length = variable.

This object is used to carry the identifier, or PRID, of a Policy
Rule Instance.

Shai Herzog Expires December 1999 [Page 12]

Internet Draft COPS Usage for Policy Provisioning 25-Jun-99

0 1 2 3
+---------------+---------------+---------------+---------------+
| Length | S-Num = PRID | S-Type = 1 |
+---------------+---------------+---------------+---------------+
... ...
| Policy Rule Identifier |
... ...
+---------------+---------------+---------------+---------------+

4.3 BER Encoded Policy Instance Data (BPD)

S-Num = 3, S-Type = 1, Length = variable.

This object is used to carry the BER encoded value of a Policy Data
Instance.

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

4.4 Provisioning Error Object (PERR)

S-Num = 4, S-Type = 1, Length = 8.

The 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 policy provisioning client also adds the following error code:

Error Code 14 = Provisioning Error

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 named decision data, request data and report

Shai Herzog Expires December 1999 [Page 13]

Internet Draft COPS Usage for Policy Provisioning 25-Jun-99

data. The actual content of the data is defined by the policy
information base for the provisioning client type (see below).

5.1 Named Decision Data

The Named Decision Data for the policy provisioning client consists
of two types of decisions: Install and Remove, used with the
'Install' and 'Remove' Command-Code, respectively, in the COPS
Decision Object. The data, in general, is composed of one or more
bindings. Each binding associates a PRID object and a BPD object.
The PRID object is always present in both install and remove
decisions, the BPD object MUST be present in the case of an install
decision and MUST NOT be present in the case of a remove decision.

The format for the provisioning client named decision data is as
follows:

< Decision: Named Data> ::= |

::= [ ]+

::= []+

5.2 ClientSI Request Data

The provisioning client request data will use same bindings as
described above. The format for this data is as follows:

::= [ ]+

5.3 Policy Provisioning Report Data

The provisioning client report data is used in the RPT message in
conjunction with the accompanying COPS Report Type object. Report
types can be 'Commit' or 'No-Commit' 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 policy rule. In a
'Commit' RPT message, 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).
In a 'No Commit' RPT message, this is an error code specific to a
binding.

Global errors are not tied to a specific PRID. In a 'Commit' RPT
message, a global error is an indication of a general warning at the

Shai Herzog Expires December 1999 [Page 14]

Internet Draft COPS Usage for Policy Provisioning 25-Jun-99

PEP level (e.g., memory low). In a 'No Commit' RPT message, this is
an indication of a general error at the PEP level (e.g., memory
exhausted).

In the case of a 'No Commit' the PEP MUST report at least the first
error and should report as many errors as possible.

::= [] [report]+

::=

::=
[[[]+]]

::=

6 Common Operations

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 with the Client-Type = 2,
Policy Provisioning client. If the PDP supports the 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.

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 with and, optionally, any
relevant client specific information for the PEP. The config 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 for the PEP, such as access control
filters, etc. Also, the config request is a request to
asynchronously send policy data to the PEP, as the PDP decides is
necessary. This asynchronous data may be new policy data or an
update to policy data sent previously.

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 Decision object. If no filters are defined, the DEC message
will simply specify that there are no filters using the "NULL
Decision" Decision Flags object. The PEP MUST specify a client
handle in the request message. The PDP MUST process the client

Shai Herzog Expires December 1999 [Page 15]

Internet Draft COPS Usage for Policy Provisioning 25-Jun-99

handle and copy it in the decision message. 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 existing state by
sending subsequent DEC message(s) to the PEP, with the same Client
Handle. The PEP is responsible for removing the Client handle when
it is no longer needed, for example when the interface goes down,
and informing the PDP that the handle is to be deleted.

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) must 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, must be communicated to the PEP by the PDP. This information
is sent to the PEP using the Decision message containing Policy
Provisioning client specific 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 DEC messages containing the
same Client Handle and the updated Policy Provisioning request
state. Updates can specify that policy data is to be deleted or
installed.

The PEP acknowledges the DEC message and action taken by sending a
RPT message with a "Commit" or "No-Commit" Report-Type object. This
serves as an indication to the PDP that the requestor (e.g. H.323
server) can be notified that the request has been accepted by the
network. If the PEP needs to reject the DEC operation for any
reason, a RPT message is sent with a Report-Type of value "No-
Commit" and optionally a Client Specific Information object
specifying the policy data that was rejected. The PDP can then
respond to the requestor accordingly.

The PEP can report to the PDP the local status of any installed
request state when appropriate. This information is sent in a
Report-State (RPT) message with the "Accounting" flag set. The state
being reported on is referenced by the Client Handle associated with
the request state and the client specific data identifier.
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.

Shai Herzog Expires December 1999 [Page 16]

Internet Draft COPS Usage for Policy Provisioning 25-Jun-99

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 at this time to be manually
configured at the PEP.

When a connection is finally re-established, either with the primary
PDP or a secondary PDP, the PEP should provide the last PDP address
of the PDP for which it is still caching decisions. Based on this
information, the PDP may request the PEP to re-synch its current
state information (SSQ message). If no decisions are being cached on
the PEP (due to reboot or TTL timeout of state) the PEP must not
included the last PDP address information. If after re-connecting,
the PDP does not request the synchronization, the client can assume
the server recognizes it and the current state at the PEP is
correct. Any changes state changes which occurred at the PEP while
connection was lost must be reported to the PDP in a RPT message. If
re-synchronization is requested, the PEP should reissue its
configuration requests and the PDP should delete the appropriate
PRCs on the PEP (thus, removing all previous decisions below the
PRC, effectively resetting all state, and reverting to some static
or preconfigured decisions).

While the PEP is disconnected from the PDP, the 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 (TTL: Time To Live, see Section
3.3), the request state is to be deleted and the associated Handles
removed. The same holds true for the PDP; upon detecting a failed
TCP connection, the time-out timer is started for the request state
associated with the PEP and the state is removed after the specified
period without a connection.

7.1 Security Considerations

The use of COPS for Policy Provisioning introduces no new security
issues over the base COPS protocol. The use of IPSEC between PDP and
PEP, as described in [COPS] is sufficient.

Shai Herzog Expires December 1999 [Page 17]

Internet Draft COPS Usage for Policy Provisioning 25-Jun-99

8 References

[COPS] Boyle, J., Cohen, R., Durham, D., Herzog, S., Raja, R.,
Sastry, A., "The COPS (Common Open Policy Service)
Protocol", IETF , December 1998.

[RAP] Yavatkar, R., et al., "A Framework for Policy Based
Admission Control",IETF ,
November, 1998.

[E2E] Bernet, Y., Yavatka,r R., Ford, P., Baker, F., Nichols, K.,
Speer, M., "A Framework for End-to-End QoS Combining
RSVP/Intserv and Differentiated Services", IETF , November 1998.

[RSVP] Braden, R., Zhang, L., Berson, S., Herzog, S., and Jamin,
S., "Resource Reservation Protocol (RSVP) Version 1
Functional Specification", IETF RFC 2205, Proposed Standard,
September 1997.

[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).

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

[PIB] M. Fine, K. McCloghrie, S. Hahn, K. Chan, A. Smith, "An
Initial Quality of Service Policy Information Base for COPS-
PR Clients and Servers", draft-mfine-cops-pib-00.txt,
February 1999.

Shai Herzog Expires December 1999 [Page 18]

Internet Draft COPS Usage for Policy Provisioning 25-Jun-99

9 Author Information

Francis Reichmeyer IPHighway Inc.
Phone: (201) 585-0800 Parker Plaza, 16th Floor
Email: FranR@iphighway.com 400 Kelby St.
Fort-Lee, NJ 07024
Shai Herzog
Phone: (201) 585-0800
Email: Herzog@iphighway.com

Kwok Ho Chan Nortel Networks, Inc.
Phone: (978) 916-8175 600 Technology Park Drive
Email: khchan@nortelnetworks.com Billerica, MA 01821

David Durham Intel t hPhone: (503) 264-6232 2111 NE 25 A v enue
Email: david.durham@intel.com Hillsboro, OR 97124

Raj Yavatkar
Phone: (503) 264-9077
Email: raj.yavatkar@.intel.com

Silvano Gai Cisco Systems, Inc.
Phone: (408) 527-2690 170 Tasman Dr.
Email: sgai@cisco.com San Jose, CA 95134-1706

Keith McCloghrie
Phone: (408) 526-5260
Email: kzm@cisco.com

Andrew Smith Extreme Networks
Phone: (408) 342-0999 10460 Bandley Drive
Email: andrew@extremenetworks.com Cupertino, CA 95014

Shai Herzog Expires December 1999 [Page 19]

Internet Draft COPS Usage for Policy Provisioning 25-Jun-99

10 Full Copyright Notice

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.

Shai Herzog Expires December 1999 [Page 20]

Internet Draft COPS Usage for Policy Provisioning 25-Jun-99

Appendix A : A DiffServ COPS-PR Example

TBD

Shai Herzog Expires December 1999 [Page 21]