PCE Working Group D. Dhody, Ed.
Internet-Draft Huawei Technologies
Intended status: Standards Track S. Sivabalan
Expires: December 31, 2017 Cisco Systems, Inc.
S. Litkowski
Orange
J. Tantsura
Individual
J. Hardwick
Metaswitch Networks
June 29, 2017
Path Computation Element communication Protocol extension for
associating Policies and LSPs
draft-ietf-pce-association-policy-01
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).
Status of This Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . 3
3.1. Policy based Constraints . . . . . . . . . . . . . . . . 5
4. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 5
5. Policy Association Group . . . . . . . . . . . . . . . . . . 6
6. Security Considerations . . . . . . . . . . . . . . . . . . . 6
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
7.1. Association object Type Indicators . . . . . . . . . . . 6
8. Manageability Considerations . . . . . . . . . . . . . . . . 7
8.1. Control of Function and Policy . . . . . . . . . . . . . 7
8.2. Information and Data Models . . . . . . . . . . . . . . . 7
8.3. Liveness Detection and Monitoring . . . . . . . . . . . . 7
8.4. Verify Correct Operations . . . . . . . . . . . . . . . . 7
8.5. Requirements On Other Protocols . . . . . . . . . . . . . 7
8.6. Impact On Network Operations . . . . . . . . . . . . . . 7
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 7
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
10.1. Normative References . . . . . . . . . . . . . . . . . . 7
10.2. Informative References . . . . . . . . . . . . . . . . . 8
Appendix A. Contributor Addresses . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
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].
PCEP Extensions for Stateful PCE Model [I-D.ietf-pce-stateful-pce]
describes a set of extensions to PCEP to enable active control of
MPLS-TE and GMPLS tunnels. [I-D.ietf-pce-pce-initiated-lsp]
describes the setup 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 RSVP-TE or can be segment routed as
specified in [I-D.ietf-pce-segment-routing].
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[I-D.ietf-pce-association-group] 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.
1.1. Requirements Language
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 [RFC2119].
2. Terminology
The following terminology is used in this document.
LSR: Label Switch Router.
MPLS: Multiprotocol Label Switching.
PAG: Policy Association Group.
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 MAY be subjected to various policies on both
PCE and PCC. For example, in a centralized traffic engineering
scenario, network operators may instantiate LSPs and specifies
policies for traffic steering, path monitoring, etc., for some LSPs
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via the stateful PCE. Similarly, a PCC may request a user- or
service-specific policy to be applied at the PCE, such as constraints
relaxation to meet optimal QoS and resiliency.
PCEP speaker can use the generic mechanism as per
[I-D.ietf-pce-association-group] to associate a set of LSPs with
policy, without the need to know the details of such policies, which
simplifies network operations, avoids frequent software upgrades, as
well provides an ability to introduce new policy faster.
PAG Y
{Service-Specific Policy
for constraint
Initiate & Monitor LSP relaxation}
| |
| PAG X PCReq |
V {Monitor LSP} {PAG Y} V
+-----+ ----------------> +-----+
_ _ _ _ _ _| PCE | | | PCE |
| +-----+ | ----------> +-----+
| PCEInitiate | | PCReq
|{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
Sample use-cases for carrying policies over PCEP session
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3.1. Policy based Constraints
In the context of policy-enabled path computation [RFC5394], path
computation policies may be applied at both a PCC and a PCE.
Consider an Label Switch Router (LSR) with a policy enabled PCC, it
receives a service request via signaling, including over a Network-
Network Interface (NNI) or User Network Interface (UNI) reference
point, or receives a configuration request over a management
interface to establish a service. The PCC may also apply user- or
service-specific policies to decide how the path selection process
should be constrained, that is, which constraints, diversities,
optimization criterion, and 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- 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
[I-D.ietf-pce-association-group] to associate a set of LSPs with
policy and its resulting path computation constraints. This
simplified the path computation message exchanges.
4. Overview
As per [I-D.ietf-pce-association-group], 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 association
between LSPs and policies associated to them. One new Association
Type is defined in this document, based on the generic Association
object -
o Association type = TBD1 ("Policy Association Type") for Policy
Association Group (PAG)
This Association-Type is operator-configured association in nature
and created by the operator manually on the PCEP peers. The LSP
belonging to this associations is conveyed via PCEP messages to the
PCEP peer. Operator-configured Association Range SHOULD NOT be set
for this association-type, and MUST be ignored, so that the full
range of association identifier can be utilized.
A PAG can have one or more LSPs and its associated policy(s). The
association identifier, type (Policy), as well as the association
source IP address is manually configured by the operator and is used
to identify the PAG.
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As per the processing rules, as specified in section 5.3 of
[I-D.ietf-pce-association-group], if a PCEP speaker does not support
this Policy association-type, it MUST return a PCErr message with
Error-Type TBD "Association Error" and Error-Value 1 "Association-
type is not supported". Since the PAG is opaque in nature, the PAG
and the policy MUST be set on the PCEP peers. If a PCE speaker
receives PAG in a PCEP message, and the association information is
not configured, it MUST return a PCErr message with Error-Type TBD
"Association Error" and Error- Value 4 "Association unknown". All
other processing is as per section 5.3 of
[I-D.ietf-pce-association-group].
5. Policy Association Group
Association groups and their memberships are defined using the
ASSOCIATION object defined in [I-D.ietf-pce-association-group]. 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 -
Association type = TBD1 ("Policy Association Type") for PAG.
PAG may carry optional TLVs including but not limited to -
o VENDOR-INFORMATION-TLV: Used to communicate arbitrary vendor
specific behavioral information, described in [RFC7470].
6. Security Considerations
This document defines one new type for association, which do not add
any new security concerns beyond those discussed in [RFC5440],
[I-D.ietf-pce-stateful-pce] and [I-D.ietf-pce-association-group] in
itself.
Some deployments may find policy associations and their implications
as extra sensitive and thus should employ suitable PCEP security
mechanisms like [I-D.ietf-pce-pceps].
7. IANA Considerations
7.1. Association object Type Indicators
This document defines the following new association type originally
defined in [I-D.ietf-pce-association-group].
Value Name Reference
TBD1 Policy Association Type [This I.D.]
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8. Manageability Considerations
8.1. Control of Function and Policy
An operator MUST BE allowed to configure the policy associations at
PCEP peers and associate it with the LSPs.
8.2. Information and Data Models
[RFC7420] describes the PCEP MIB, there are no new MIB Objects for
this document.
8.3. 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].
8.4. Verify Correct Operations
Mechanisms defined in this document do not imply any new operation
verification requirements in addition to those already listed in
[RFC5440].
8.5. Requirements On Other Protocols
Mechanisms defined in this document do not imply any new requirements
on other protocols.
8.6. 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].
9. Acknowledgments
A special thanks to author of [I-D.ietf-pce-association-group], this
document borrow some of the text from it.
10. References
10.1. 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,
<http://www.rfc-editor.org/info/rfc2119>.
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[RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
Element (PCE) Communication Protocol (PCEP)", RFC 5440,
DOI 10.17487/RFC5440, March 2009,
<http://www.rfc-editor.org/info/rfc5440>.
[I-D.ietf-pce-association-group]
Minei, I., Crabbe, E., Sivabalan, S., Ananthakrishnan, H.,
Dhody, D., and Y. Tanaka, "PCEP Extensions for
Establishing Relationships Between Sets of LSPs", draft-
ietf-pce-association-group-03 (work in progress), June
2017.
[I-D.ietf-pce-stateful-pce]
Crabbe, E., Minei, I., Medved, J., and R. Varga, "PCEP
Extensions for Stateful PCE", draft-ietf-pce-stateful-
pce-21 (work in progress), June 2017.
10.2. 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,
<http://www.rfc-editor.org/info/rfc4655>.
[RFC5394] Bryskin, I., Papadimitriou, D., Berger, L., and J. Ash,
"Policy-Enabled Path Computation Framework", RFC 5394,
DOI 10.17487/RFC5394, December 2008,
<http://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,
<http://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,
<http://www.rfc-editor.org/info/rfc7470>.
[I-D.ietf-pce-pceps]
Lopez, D., Dios, O., Wu, Q., and D. Dhody, "Secure
Transport for PCEP", draft-ietf-pce-pceps-14 (work in
progress), May 2017.
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[I-D.ietf-pce-pce-initiated-lsp]
Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "PCEP
Extensions for PCE-initiated LSP Setup in a Stateful PCE
Model", draft-ietf-pce-pce-initiated-lsp-10 (work in
progress), June 2017.
[I-D.ietf-pce-segment-routing]
Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W.,
and J. Hardwick, "PCEP Extensions for Segment Routing",
draft-ietf-pce-segment-routing-09 (work in progress),
April 2017.
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Appendix A. Contributor Addresses
Qin Wu
Huawei Technologies
101 Software Avenue, Yuhua District
Nanjing, Jiangsu 210012
China
EMail: sunseawq@huawei.com
Clarence Filsfils
Cisco Systems, Inc.
Pegasus Parc
De kleetlaan 6a, DIEGEM BRABANT 1831
BELGIUM
Email: cfilsfil@cisco.com
Xian Zhang
Huawei Technologies
Bantian, Longgang District
Shenzhen 518129
P.R.China
EMail: zhang.xian@huawei.com
Udayasree Palle
Huawei Technologies
Divyashree Techno Park, Whitefield
Bangalore, Karnataka 560066
India
EMail: udayasreereddy@gmail.com
Authors' Addresses
Dhruv Dhody (editor)
Huawei Technologies
Divyashree Techno Park, Whitefield
Bangalore, Karnataka 560066
India
EMail: dhruv.ietf@gmail.com
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Siva Sivabalan
Cisco Systems, Inc.
2000 Innovation Drive
Kanata, Ontario K2K 3E8
Canada
EMail: msiva@cisco.com
Stephane Litkowski
Orange
EMail: stephane.litkowski@orange.com
Jeff Tantsura
Individual
EMail: jefftant.ietf@gmail.com
Jonathan Hardwick
Metaswitch Networks
100 Church Street
Enfield, Middlesex
UK
EMail: Jonathan.Hardwick@metaswitch.com
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