Internet DRAFT - draft-ietf-pce-association-policy
draft-ietf-pce-association-policy
PCE Working Group S. Litkowski
Internet-Draft Cisco Systems, Inc.
Intended status: Standards Track S. Sivabalan
Expires: July 25, 2021 Ciena
J. Tantsura
Apstra, Inc.
J. Hardwick
Metaswitch Networks
C. Li
Huawei Technologies
January 21, 2021
Path Computation Element (PCE) Communication Protocol (PCEP) extension
for associating Policies and Label Switched Paths (LSPs)
draft-ietf-pce-association-policy-16
Abstract
This document introduces a simple mechanism to associate policies to
a group of Label Switched Paths (LSPs) via an extension to the Path
Computation Element (PCE) Communication Protocol (PCEP). The
extension allows a PCEP speaker to advertise to a PCEP peer that a
particular LSP belongs to a particular Policy Association Group.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
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Internet-Drafts are draft documents valid for a maximum of six months
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time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on July 25, 2021.
Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.1. Policy based Constraints . . . . . . . . . . . . . . . . 5
4. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5. Policy Association Group . . . . . . . . . . . . . . . . . . 7
5.1. Policy Parameters TLV . . . . . . . . . . . . . . . . . . 7
6. Implementation Status . . . . . . . . . . . . . . . . . . . . 9
6.1. Cisco's Implementation . . . . . . . . . . . . . . . . . 9
7. Security Considerations . . . . . . . . . . . . . . . . . . . 9
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
8.1. Association object Type Indicators . . . . . . . . . . . 10
8.2. PCEP TLV Type Indicators . . . . . . . . . . . . . . . . 10
8.3. PCEP Errors . . . . . . . . . . . . . . . . . . . . . . . 11
9. Manageability Considerations . . . . . . . . . . . . . . . . 11
9.1. Control of Function and Policy . . . . . . . . . . . . . 11
9.2. Information and Data Models . . . . . . . . . . . . . . . 11
9.3. Liveness Detection and Monitoring . . . . . . . . . . . . 12
9.4. Verify Correct Operations . . . . . . . . . . . . . . . . 12
9.5. Requirements on Other Protocols . . . . . . . . . . . . . 12
9.6. Impact on Network Operations . . . . . . . . . . . . . . 12
10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 12
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
11.1. Normative References . . . . . . . . . . . . . . . . . . 13
11.2. Informative References . . . . . . . . . . . . . . . . . 13
Appendix A. Example of Policy Parameters . . . . . . . . . . . . 15
Appendix B. Contributor Addresses . . . . . . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17
1. Introduction
[RFC5440] describes the Path Computation Element Communication
Protocol (PCEP) which enables the communication between a Path
Computation Client (PCC) and a Path Control Element (PCE), or between
two PCEs based on the PCE architecture [RFC4655]. [RFC5394] provides
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additional details on policy within the PCE architecture and also
provides context for the support of PCE Policy.
PCEP Extensions for Stateful PCE Model [RFC8231] describes a set of
extensions to PCEP to enable active control of Multiprotocol Label
Switching Traffic Engineering (MPLS-TE) and Generalized MPLS (GMPLS)
tunnels. [RFC8281] describes the set-up and teardown of PCE-
initiated LSPs under the active stateful PCE model, without the need
for local configuration on the PCC, thus allowing for a dynamic
network. Currently, the LSPs can either be signaled via Resource
Reservation Protocol Traffic Engineering (RSVP-TE) or can be segment
routed as specified in [RFC8664].
[RFC8697] introduces a generic mechanism to create a grouping of LSPs
which can then be used to define associations between a set of LSPs
and a set of attributes (such as configuration parameters or
behaviors) and is equally applicable to stateful PCE (active and
passive modes) and stateless PCE.
This document specifies a PCEP extension to associate one or more
LSPs with policies using the generic association mechanism.
A PCEP speaker may want to influence the PCEP peer with respect to
path selection and other policies. This document describes a PCEP
extension to associate policies by creating Policy Association Group
(PAG) and encoding this association in PCEP messages. The
specification is applicable to both stateful and stateless PCEP
sessions.
Note that the actual policy definition and the associated parameters
are out of scope of this document.
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. Terminology
The following terminology is used in this document.
Association parameters: As described in [RFC8697], the combination
of the mandatory fields Association type, Association ID and
Association Source in the ASSOCIATION object uniquely identify the
association group. If the optional TLVs - Global Association
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Source or Extended Association ID are included, then they are
included in combination with mandatory fields to uniquely identify
the association group.
Association information: As described in [RFC8697], the ASSOCIATION
object could include other optional TLVs based on the association
types, that provide 'information' related to the association.
LSR: Label Switch Router.
MPLS: Multiprotocol Label Switching.
PAG: Policy Association Group.
PAT: Policy Association Type.
PCC: Path Computation Client; any client application requesting a
path computation to be performed by a Path Computation Element.
PCE: Path Computation Element; an entity (component, application, or
network node) that is capable of computing a network path or route
based on a network graph and applying computational constraints.
PCEP: Path Computation Element Communication Protocol.
3. Motivation
Paths computed using PCE can be subjected to various policies at both
the PCE and the PCC. For example, in a centralized traffic
engineering (TE) scenario, network operators may instantiate LSPs and
specify policies for traffic accounting, path monitoring, telemetry,
etc., for some LSPs via the Stateful PCE. Similarly, a PCC could
request a user-specific or service-specific policy to be applied at
the PCE, such as constraints relaxation policy to meet optimal QoS
and resiliency.
PCEP speakers can use the generic mechanism of [RFC8697] to associate
a set of LSPs with a policy, without the need to know the details of
such a policy. This simplifies network operations and avoids
frequent software upgrades, as well as provides the ability to
introduce new policies more quickly.
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PAG Y
{Service-Specific Policy
for constraint
Monitor LSP relaxation}
| |
| PAG X PCReq/PCRpt |
V {Monitor LSP} {PAG Y} V
+-----+ ----------------> +-----+
_ _ _ _ _ _| PCE | | | PCE |
| +-----+ | ----------> +-----+
| PCInitiate/PCUpd | | PCReq/PCRpt
|{PAG X} | | {PAG Y}
| | |
| .-----. | | .-----.
| ( ) | +----+ ( )
| .--( )--. | |PCC1|--.--( )--.
V ( ) | +----+ ( )
+---+ ( ) | ( )
|PCC|----( (G)MPLS network ) +----+ ( (G)MPLS network )
+---+ ( ) |PCC2|------( )
PAG X ( ) +----+ ( )
{Monitor '--( )--' '--( )--'
LSP} ( ) ( )
'-----' '-----'
Case 1: Policy requested by PCE Case 2: Policy requested by
and enforced by PCC PCC and enforced by
PCE
Figure 1: Sample use-cases for carrying policies over PCEP
3.1. Policy based Constraints
In the context of Policy-Enabled Path Computation Framework
[RFC5394], path computation policies may be applied at either a PCC
or a PCE or both. A Label Switching Router (LSR) with a policy
enabled PCC can receive
o a service request via signaling, including over a Network-Network
Interface (NNI) or User-Network Interface (UNI) reference point
o a configuration request over a management interface to establish a
service
The PCC may apply user-specific or service-specific policies to
decide how the path selection process should be constrained, that is,
which constraints, diversities, optimization criterion, and
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constraint relaxation strategies should be applied in order for the
service LSP(s) to have a likelihood to be successfully established
and provide necessary QoS and resilience against network failures.
The user-specific or service-specific policies applied to PCC and are
then passed to the PCE along with the Path computation request, in
the form of constraints [RFC5394].
PCEP speaker can use the generic mechanism as per [RFC8697] to
associate a set of LSPs with policies and its resulting path
computation constraints. This would simplify the path computation
message exchanges in PCEP.
4. Overview
As per [RFC8697], LSPs are associated with other LSPs with which they
interact by adding them to a common association group. Grouping can
also be used to define the association between LSPs and policies
associated to them. As described in [RFC8697], the association group
is uniquely identified by the combination of the following fields in
the ASSOCIATION object: Association Type, Association ID, Association
Source, and (if present) Global Association Source or Extended
Association ID. This document defines a new Association type, called
"Policy Association", of value 3 (early-allocated by IANA), based on
the generic ASSOCIATION object. This new Association type is also
called "PAT", for "Policy Association Type".
[RFC8697] specifies the mechanism for the capability advertisement of
the Association types supported by a PCEP speaker by defining a
ASSOC-Type-List TLV to be carried within an OPEN object. This
capability exchange for the PAT MUST be done before using the policy
association. Thus the PCEP speaker MUST include the PAT in the
ASSOC-Type-List TLV and MUST receive the same from the PCEP peer
before using the Policy Association Group (PAG) in PCEP messages.
The Policy Association type (3) is operator-configured (as specified
in [RFC8697]), i.e. the association is created by the operator
manually on the PCEP peers and an LSP belonging to this association
is conveyed via PCEP messages to the PCEP peer. There is no need to
convey an explicit Operator-configured Association Range, which could
only serve to artificially limit the available association IDs.
Thus, for Policy Association type, Operator-configured Association
Range MUST NOT be set, and MUST be ignored if received.
A PAG can have one or more LSPs. The association parameters
including association identifier, Association type (PAT), as well as
the association source IP address are manually configured by the
operator and are used to identify the PAG as described in [RFC8697].
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The Global Association Source and Extended Association ID MAY also be
included.
As per the processing rules specified in section 6.4 of [RFC8697], if
a PCEP speaker does not support this Policy Association type, it
would return a PCErr message with Error-Type 26 "Association Error"
and Error-Value 1 "Association type is not supported". The PAG and
the policy MUST be configured on the PCEP peers as per the operator-
configured association procedures. All further processing is as per
section 6.4 of [RFC8697]. If a PCE speaker receives PAG in a PCEP
message, and the policy association information is not configured, it
MUST return a PCErr message with Error-Type 26 "Association Error"
and Error-Value 4 "Association unknown".
Associating a particular LSP to multiple policy groups is allowed
from a protocol perspective, however, there is no assurance that the
PCEP speaker will be able to apply multiple policies. If a PCEP
speaker does not support handling of multiple policies for an LSP, it
MUST NOT add the LSP into the association group and MUST return a
PCErr with Error- Type 26 (Association Error) and Error-value 7
(Cannot join the association group).
5. Policy Association Group
Association groups and their memberships are defined using the
ASSOCIATION object defined in [RFC8697]. Two object types for IPv4
and IPv6 are defined. The ASSOCIATION object includes "Association
type" indicating the type of the association group. This document
add a new Association type (PAT).
PAG may carry optional TLVs including but not limited to -
o POLICY-PARAMETERS-TLV: Used to communicate opaque information
useful to apply the policy, described in Section 5.1.
o VENDOR-INFORMATION-TLV: Used to communicate arbitrary vendor
specific behavioral information, described in [RFC7470].
5.1. Policy Parameters TLV
The POLICY-PARAMETERS-TLV is an optional TLV that can be carried in
ASSOCIATION object (for PAT) to carry opaque information needed to
apply the policy at the PCEP peer. In some cases to apply a PCE
policy successfully, it is required to also associate some policy
parameters that need to be evaluated. This TLV is used to carry
those policy parameters. The TLV could include one or more policy
related parameters. The encoding format and the order MUST be known
to the PCEP peers, this could be done during the configuration of the
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policy (and its association parameters) for the PAG. The TLV format
is as per the format of the PCEP TLVs, as defined in [RFC5440], and
shown in Figure 2. Only one POLICY-PARAMETERS-TLV can be carried and
only the first occurrence is processed and any others MUST be
ignored.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=48 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// Policy Parameters //
| |
+---------------------------------------------------------------+
Figure 2: The POLICY-PARAMETERS-TLV format
The type of the POLICY-PARAMETERS-TLV is 48 (early-allocated by IANA)
and it has a variable length. The Value field is variable and padded
to a 4-byte alignment; padding is not included in the Length field.
The PCEP peer implementation needs to be aware of the encoding
format, order, and meaning of the 'Policy Parameters' well in advance
based on the policy. Note that from the protocol point of view this
data is opaque and can be used to carry parameters in any format
understood by the PCEP peers and associated to the policy. The exact
use of this TLV is beyond the scope of this document. Examples are
included for illustration purposes in Appendix A.
If the PCEP peer is unaware of the policy parameters associated with
the policy and it receives the POLICY-PARAMETERS-TLV, it MUST reject
the PCEP message and send a PCErr message with Error-Type 26
"Association Error" and Error-Value TBD3 "Not expecting policy
parameters". Further, if one or more parameters in the POLICY-
PARAMETERS-TLV received by the PCEP speaker are considered as
unacceptable in the context of the associated policy (e.g., out of
range value, badly encoded value...), the PCEP speaker MUST reject
the PCEP message and send a PCErr message with Error-Type 26
"Association Error" and Error-Value TBD4 "Unacceptable policy
parameters".
Note that, the vendor-specific behavioral information is encoded in
VENDOR-INFORMATION-TLV which can be used along with this TLV.
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6. Implementation Status
[Note to the RFC Editor - remove this section before publication, as
well as remove the reference to RFC 7942.]
This section records the status of known implementations of the
protocol defined by this specification at the time of posting of this
Internet-Draft, and is based on a proposal described in [RFC7942].
The description of implementations in this section is intended to
assist the IETF in its decision processes in progressing drafts to
RFCs. Please note that the listing of any individual implementation
here does not imply endorsement by the IETF. Furthermore, no effort
has been spent to verify the information presented here that was
supplied by IETF contributors. This is not intended as, and must not
be construed to be, a catalog of available implementations or their
features. Readers are advised to note that other implementations may
exist.
According to [RFC7942], "this will allow reviewers and working groups
to assign due consideration to documents that have the benefit of
running code, which may serve as evidence of valuable experimentation
and feedback that have made the implemented protocols more mature.
It is up to the individual working groups to use this information as
they see fit".
6.1. Cisco's Implementation
o Organization: Cisco Systems, Inc.
o Implementation: IOS-XR PCE and PCC.
o Description: The PCEP extension specified in this document is used
to convey traffic steering policies.
o Maturity Level: In shipping product.
o Coverage: Partial.
o Contact: mkoldych@cisco.com
7. Security Considerations
The security considerations described in [RFC8697], [RFC8231],
[RFC5394], and [RFC5440] apply to the extensions described in this
document as well. In particular, a malicious PCEP speaker could be
spoofed and used as an attack vector by creating spurious policy
associations as described in [RFC8697]. Further as described in
[RFC8697], a spurious LSP can have policies that are inconsistent
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with those of the legitimate LSPs of the group and thus cause
problems in handling of the policy for the legitimate LSPs. It
should be noted that policy association could provide an adversary
with the opportunity to eavesdrop on the relationship between the
LSPs. [RFC8697] suggest that the implementations and operators to
use indirect values as a way to hide any sensitive business
relationships. Thus, securing the PCEP session using Transport Layer
Security (TLS) [RFC8253], as per the recommendations and best current
practices in BCP 195 [RFC7525], is RECOMMENDED.
Further, extra care needs to be taken by the implementation with
respect to POLICY-PARAMETERS-TLV while decoding, verifying, and
applying these policy variables. This TLV parsing could be exploited
by an attacker and thus extra care must be taken while configuring
policy association that uses POLICY-PARAMETERS-TLV and making sure
that the data is easy to parse and verify before use. Ensuring
agreement among all relevant PCEP peers as to the format and layout
of the policy parameters information is key for the correct
operations. Note that, the parser for POLICY-PARAMETERS-TLV is
particularly sensitive since it is opque to PCEP and can be used to
convey data with many different internal structure/formats. The
choice of decoder is dependent on the additional metadata associated
with the policy and thus incur additional risk of using a wrong
decoder and getting garbage results. Use standard and well-known
policy formats could help alleviate those risks.
8. IANA Considerations
8.1. Association object Type Indicators
This document defines a new Association type. The sub-registry
"ASSOCIATION Type Field" of the "Path Computation Element Protocol
(PCEP) Numbers" registry was originally defined in [RFC8697]. IANA
is requested to confirm the early-allocated codepoint.
Value Name Reference
3 Policy Association [This.I-D]
8.2. PCEP TLV Type Indicators
The following TLV Type Indicator value is requested within the "PCEP
TLV Type Indicators" subregistry of the "Path Computation Element
Protocol (PCEP) Numbers" registry. IANA is requested to confirm the
early-allocated codepoint.
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Value Description Reference
48 POLICY-PARAMETERS-TLV [This.I-D]
8.3. PCEP Errors
This document defines new Error-Values for Error-type 26 "Association
Error" defined in [RFC8697]. IANA is requested to allocate new error
values within the "PCEP- ERROR Object Error Types and Values"
subregistry of the PCEP Numbers registry as follows:
Error-Type Meaning Error-value Reference
26 Association [RFC8697]
Error
TBD3: Not expecting [This.I-D]
policy parameters
TBD4: Unacceptable [This.I-D]
policy parameters
9. Manageability Considerations
9.1. Control of Function and Policy
An operator MUST be allowed to configure the policy associations at
PCEP peers and associate it with the LSPs. They MAY also allow
configuration to related policy parameters, and provide information
on the encoding format and order to parse the associated policy
parameters TLV.
9.2. Information and Data Models
[RFC7420] describes the PCEP MIB; there are no new MIB Objects for
this document.
The PCEP YANG module is defined in [I-D.ietf-pce-pcep-yang]. That
module supports associations as defined in [RFC8697] and thus
supports the Policy Association groups.
An implementation SHOULD allow the operator to view the PAG
configured. Further implementation SHOULD allow to view associations
reported by each peer, and the current set of LSPs in the PAG.
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9.3. Liveness Detection and Monitoring
Mechanisms defined in this document do not imply any new liveness
detection and monitoring requirements in addition to those already
listed in [RFC5440], [RFC8231], and [RFC8281].
9.4. Verify Correct Operations
Verifying the correct operation of a policy can be performed by
monitoring various parameters as described in [RFC5440] and
[RFC8231]. A PCEP implementation SHOULD provide information on
failed path computation because of appling policy and log error
events, e.g., parsing failure for policy parameters TLV.
9.5. Requirements on Other Protocols
Mechanisms defined in this document do not imply any new requirements
on other protocols.
9.6. Impact on Network Operations
Mechanisms defined in this document do not have any impact on network
operations in addition to those already listed in [RFC5440],
[RFC8231], and [RFC8281].
10. Acknowledgments
We would like to acknowledge and thank Santiago Alvarez, Zafar Ali,
Luis Tomotaki, Victor Lopez, Rob Shakir, and Clarence Filsfils for
working on earlier drafts with similar motivation.
A special thanks to the authors of [RFC8697], this document borrowed
some of the text from it. The authors would like to thank Aijun
Wang, Peng Shuping, and Gyan Mishra for their useful comments.
Thanks to Hari for shepherding this document. Thanks to Deborah
Brungard for providing comments and being the responsible AD for this
document.
Thanks to Nic Leymann for RTGDIR review.
Thanks to Benjamin Kaduk and Murray Kucherawy for the comments during
IESG review.
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11. References
11.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
Element (PCE) Communication Protocol (PCEP)", RFC 5440,
DOI 10.17487/RFC5440, March 2009,
<https://www.rfc-editor.org/info/rfc5440>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8231] Crabbe, E., Minei, I., Medved, J., and R. Varga, "Path
Computation Element Communication Protocol (PCEP)
Extensions for Stateful PCE", RFC 8231,
DOI 10.17487/RFC8231, September 2017,
<https://www.rfc-editor.org/info/rfc8231>.
[RFC8253] Lopez, D., Gonzalez de Dios, O., Wu, Q., and D. Dhody,
"PCEPS: Usage of TLS to Provide a Secure Transport for the
Path Computation Element Communication Protocol (PCEP)",
RFC 8253, DOI 10.17487/RFC8253, October 2017,
<https://www.rfc-editor.org/info/rfc8253>.
[RFC8697] Minei, I., Crabbe, E., Sivabalan, S., Ananthakrishnan, H.,
Dhody, D., and Y. Tanaka, "Path Computation Element
Communication Protocol (PCEP) Extensions for Establishing
Relationships between Sets of Label Switched Paths
(LSPs)", RFC 8697, DOI 10.17487/RFC8697, January 2020,
<https://www.rfc-editor.org/info/rfc8697>.
11.2. Informative References
[RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation
Element (PCE)-Based Architecture", RFC 4655,
DOI 10.17487/RFC4655, August 2006,
<https://www.rfc-editor.org/info/rfc4655>.
[RFC5905] Mills, D., Martin, J., Ed., Burbank, J., and W. Kasch,
"Network Time Protocol Version 4: Protocol and Algorithms
Specification", RFC 5905, DOI 10.17487/RFC5905, June 2010,
<https://www.rfc-editor.org/info/rfc5905>.
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[RFC5394] Bryskin, I., Papadimitriou, D., Berger, L., and J. Ash,
"Policy-Enabled Path Computation Framework", RFC 5394,
DOI 10.17487/RFC5394, December 2008,
<https://www.rfc-editor.org/info/rfc5394>.
[RFC7420] Koushik, A., Stephan, E., Zhao, Q., King, D., and J.
Hardwick, "Path Computation Element Communication Protocol
(PCEP) Management Information Base (MIB) Module",
RFC 7420, DOI 10.17487/RFC7420, December 2014,
<https://www.rfc-editor.org/info/rfc7420>.
[RFC7470] Zhang, F. and A. Farrel, "Conveying Vendor-Specific
Constraints in the Path Computation Element Communication
Protocol", RFC 7470, DOI 10.17487/RFC7470, March 2015,
<https://www.rfc-editor.org/info/rfc7470>.
[RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre,
"Recommendations for Secure Use of Transport Layer
Security (TLS) and Datagram Transport Layer Security
(DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May
2015, <https://www.rfc-editor.org/info/rfc7525>.
[RFC7942] Sheffer, Y. and A. Farrel, "Improving Awareness of Running
Code: The Implementation Status Section", BCP 205,
RFC 7942, DOI 10.17487/RFC7942, July 2016,
<https://www.rfc-editor.org/info/rfc7942>.
[RFC8281] Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "Path
Computation Element Communication Protocol (PCEP)
Extensions for PCE-Initiated LSP Setup in a Stateful PCE
Model", RFC 8281, DOI 10.17487/RFC8281, December 2017,
<https://www.rfc-editor.org/info/rfc8281>.
[RFC8664] Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W.,
and J. Hardwick, "Path Computation Element Communication
Protocol (PCEP) Extensions for Segment Routing", RFC 8664,
DOI 10.17487/RFC8664, December 2019,
<https://www.rfc-editor.org/info/rfc8664>.
[I-D.ietf-pce-pcep-yang]
Dhody, D., Hardwick, J., Beeram, V., and J. Tantsura, "A
YANG Data Model for Path Computation Element
Communications Protocol (PCEP)", draft-ietf-pce-pcep-
yang-15 (work in progress), October 2020.
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Appendix A. Example of Policy Parameters
An example could be a monitoring and telemetry policy P1 that is
dependent on a profile (GOLD/SILVER/BRONZE) as set by the operator.
The PCEP peers need to be aware of the policy P1 (and its associated
characteristics) in advance as well the fact that the policy
parameter will encode the profile of type string in the POLICY-
PARAMETERS-TLV. As an example, LSP1 could encode the PAG with the
POLICY-PARAMETERS-TLV with a string "GOLD".
Another example where the path computation at PCE could be dependent
on when the LSP was configured at the PCC. For such a policy P2, the
time-stamp can be encoded in the POLICY-PARAMETERS-TLV and the exact
encoding could be the 64-bit timestamp format as defined in
[RFC5905].
While the above example has a single field in the POLICY-PARAMETERS-
TLV, it is possible to include multiple fields, but the exact order,
encoding format and meanings need to be known in advance at the PCEP
peers.
Appendix B. Contributor Addresses
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Following have contributed extensively:
Mahendra Singh Negi
RtBrick Inc
N-17L, 18th Cross Rd, HSR Layout
Bangalore, Karnataka 560102
India
EMail: mahend.ietf@gmail.com
Dhruv Dhody
Huawei Technologies
Divyashree Techno Park, Whitefield
Bangalore, Karnataka 560066
India
EMail: dhruv.ietf@gmail.com
Following have contributed text that was incorporated:
Qin Wu
Huawei Technologies
101 Software Avenue, Yuhua District
Nanjing, Jiangsu 210012
China
EMail: sunseawq@huawei.com
Xian Zhang
Huawei Technologies
Bantian, Longgang District
Shenzhen 518129
P.R.China
EMail: zhang.xian@huawei.com
Udayasree Palle
EMail: udayasreereddy@gmail.com
Mike Koldychev
Cisco Systems, Inc.
Canada
EMail: mkoldych@cisco.com
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Authors' Addresses
Stephane Litkowski
Cisco Systems, Inc.
11 Rue Camille Desmoulins
Issy-les-Moulineaux 92130
France
EMail: slitkows@cisco.com
Siva Sivabalan
Ciena
385 Terry Fox Drive
Kanata, Ontario K2K 0L1
Canada
EMail: msiva282@gmail.com
Jeff Tantsura
Apstra, Inc.
EMail: jefftant.ietf@gmail.com
Jonathan Hardwick
Metaswitch Networks
100 Church Street
Enfield, Middlesex
UK
EMail: Jonathan.Hardwick@metaswitch.com
Cheng Li
Huawei Technologies
Huawei Campus, No. 156 Beiqing Rd.
Beijing 100095
China
EMail: c.l@huawei.com
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