PCE Working Group B. Rajagopalan
Internet-Draft V. Beeram
Intended status: Standards Track Juniper Networks
Expires: 25 April 2025 S. Peng
ZTE Corporation
M. Koldychev
Ciena Corporation
G. Mishra
Verizon Communications Inc.
22 October 2024
Path Computation Element Protocol(PCEP) Extension for Color
draft-ietf-pce-pcep-color-05
Abstract
Color is a 32-bit numerical attribute that is used to associate a
Traffic Engineering (TE) tunnel or policy with an intent or objective
(e.g. low latency). This document specifies extensions to Path
Computation Element Protocol (PCEP) to carry the color attribute.
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
and may be updated, replaced, or obsoleted by other documents at any
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on 25 April 2025.
Copyright Notice
Copyright (c) 2024 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
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Please review these documents carefully, as they describe your rights
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and restrictions with respect to this document. Code Components
extracted from this document must include Revised BSD License text as
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provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Protocol Operation . . . . . . . . . . . . . . . . . . . . . 3
3. Protocol Extensions . . . . . . . . . . . . . . . . . . . . . 4
3.1. Color Capability . . . . . . . . . . . . . . . . . . . . 4
3.2. Color TLV . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Security Considerations . . . . . . . . . . . . . . . . . . . 4
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
5.1. PCEP TLV Type Indicator . . . . . . . . . . . . . . . . . 5
5.2. STATEFUL-PCE-CAPABILITY TLV Flag Field . . . . . . . . . 5
5.3. PCEP-Error Object . . . . . . . . . . . . . . . . . . . . 5
5.4. LSP-ERROR-CODE TLV Error Code Field . . . . . . . . . . . 5
6. Implementation Status . . . . . . . . . . . . . . . . . . . . 6
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6
8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 7
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
9.1. Normative References . . . . . . . . . . . . . . . . . . 7
9.2. Informative References . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
A Traffic Engineering (TE) tunnel or Segment Routing (SR) policy can
be associated with an intent or objective (e.g. low latency) by
tagging it with a color. This color attribute is used as a guiding
criterion for mapping services onto the TE tunnel ([RFC9012]) or SR
policy ([RFC9256]). The term color used in this document is not to
be interpreted as the 'thread color' specified in [RFC3063] or the
'resource color' (or 'link color') specified in [RFC3630], [RFC5329],
[RFC5305] and [RFC7308].
[RFC8231] specifies extensions to the Path Computation Element
Protocol (PCEP) that enable the deployment of a stateful Path
Computation Element (PCE) model. These extensions allow a Path
Computation Client (PCC) to delegate control of the Label Switched
Paths (LSPs) associated with its TE Tunnels to a stateful PCE.
[RFC8281] specifies extensions that allow a PCE to instantiate and
manage PCE-initiated LSPs on a PCC under the stateful PCE model.
[RFC8664] specifies extensions that enable stateful control of SR
paths via PCEP.
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This document introduces extensions to PCEP to carry the color
attribute tagged with TE paths that are setup using RSVP-TE
([RFC8408]) or Segment Routing (SR) ([RFC8664]) or any other path
setup type supported under the stateful PCE model. The only
exception where the extensions defined in this document are not used
for carrying the color attribute is when an SR path is setup using
the extensions defined in [I-D.ietf-pce-segment-routing-policy-cp].
For these SR paths, the associated color is already included as part
of the SR policy identifier encoding.
The mechanism used at the PCC for appropriately mapping services onto
a TE path that is tagged with a color attribute is outside the 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. Protocol Operation
When the PCEP session is created, a PCEP (PCE/PCC) speaker sends an
Open message with an OPEN object that contains the STATEFUL-PCE-
CAPABILITY TLV, as defined in [RFC8231]. A new STATEFUL-PCE-
CAPABILITY TLV Flag (See Section 3.1) is introduced in this document
to enable the PCEP speaker to advertise color capability.
In PCRpt, PCUpd, and PCInitiate messages, the LSP object ([RFC8231],
[RFC8281]) is a mandatory inclusion and is used to carry information
specific to the target LSP. A new TLV called the Color TLV (see
Section 3.2), which MAY be carried in the LSP object, is introduced
in this document to carry the color attribute associated with the
LSP.
A PCEP speaker that has advertised color capability MUST NOT send
Color TLV encoded in the LSP object to a PCEP Peer that has not
advertised color capability. A PCEP speaker that advertises both
color capability and SR Policy Association capability
([I-D.ietf-pce-segment-routing-policy-cp]) SHOULD NOT send Color TLV
encoded in the LSP object for SR Paths. The Color TLV is ignored if
it shows up in the LSP object of a message which carries an
ASSOCIATION object of type SR Policy Association
([I-D.ietf-pce-segment-routing-policy-cp]). The color encoded in the
SR Policy Association takes precedence in such a scenario.
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If a PCC is unable to honor a color value passed in a PCUpd or a
PCInitiate message, the PCC MUST reject the message and send a PCErr
message with Error-type=19 (Invalid Operation) and error-value=TBD1
(Invalid color).
When LSPs that belong to the same TE tunnel are within the same Path
Protection Association Group [RFC8745], they are all expected to be
attached with the same color. If a PCEP speaker determines
inconsistency in the color associated with the LSPs belonging to the
same Path Protection Association Group, it MUST reject the message
carrying the inconsistent color and send a PCErr message with Error-
type=19 (Invalid Operation) and error-value=TB2 (Inconsistent color).
3. Protocol Extensions
3.1. Color Capability
Section 7.1.1 of [RFC8231] defines STATEFUL-PCE-CAPABILITY TLV flags.
The following flag is used to indicate if the speaker supports color
capability:
C-bit (Bit 20 - Early allocation by IANA): A PCE/PCC that supports
color capability must turn on this bit.
3.2. Color TLV
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 | Length=4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Color |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Color TLV
Type has the value 67 (Early allocation by IANA). Length carries a
value of 4. The 'color' field is 4-bytes long, and carries the
actual color value.
4. Security Considerations
This document defines a new TLV for color, and a new flag in
capability negotiation, which do not add any new security concerns
beyond those discussed in [RFC5440], [RFC8231] and [RFC8281].
An unauthorized PCE may maliciously associate the LSP with an
incorrect color. The procedures described in [RFC8253] and [RFC9325]
can be used to protect against this attack.
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5. IANA Considerations
5.1. PCEP TLV Type Indicator
This document introduces a new value in the "PCEP TLV Type
Indicators" sub-registry of the PCEP Numbers registry as follows:
Value Description Reference
----------------------------------------------
67 Color This document
Note: The code point specified for the new TLV Type Indicator is an
early allocation by IANA.
5.2. STATEFUL-PCE-CAPABILITY TLV Flag Field
This document introduces a new bit value in the "STATEFUL-PCE-
CAPABILITY TLV Flag Field" sub-registry of the PCEP Numbers registry
as follows:
Value Description Reference
----------------------------------------------
20 COLOR-CAPABILITY This document
Note: The code point specified for the new STATEFUL-PCE-CAPABILITY
TLV Flag is an early allocation by IANA.
5.3. PCEP-Error Object
This document introduces two new Error-values for Error-Type=19
(Invalid Operation) within the "PCEP-ERROR Object Error Types and
Values" registry of the "Path Computation Element Protocol (PCEP)
Numbers" registry group as follows:
Error- Meaning Error-value Reference
Type
------------------------------------------------------------------
19 Invalid Operation TBD1: Invalid Color This document
TBD2: Inconsistent Color This document
5.4. LSP-ERROR-CODE TLV Error Code Field
Note to IANA: IANA is requested to cancel the early allocation made
for this. This is not needed anymore. This section MUST be removed
after the early allocation made for this is cancelled.
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This document introduces a new error code in the "LSP-ERROR-CODE TLV
Error Code Field" sub-registry of the PCEP Numbers registry as
follows:
Value Meaning Reference
----------------------------------------------
9 Unsupported Color This document
Note: The code point specified for the new LSP-ERROR-CODE TLV Error
Code is an early allocation by IANA.
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".
At the time of publication of this version, there are no known
implementations. Juniper Networks has plans to implement the
extensions defined in this document.
7. Acknowledgments
The authors would like to thank Kaliraj Vairavakkalai, Colby Barth,
Natrajan Venkataraman, Tarek Saad, Dhruv Dhody, Adrian Farrel, Andrew
Stone, Diego Achaval and Narasimha Kommuri for their review and
suggestions.
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8. Contributors
The following people have contributed to this document
Quan Xiong
ZTE Corporation
Email: xiong.quan@zte.com.cn
9. References
9.1. 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>.
[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>.
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[RFC8408] Sivabalan, S., Tantsura, J., Minei, I., Varga, R., and J.
Hardwick, "Conveying Path Setup Type in PCE Communication
Protocol (PCEP) Messages", RFC 8408, DOI 10.17487/RFC8408,
July 2018, <https://www.rfc-editor.org/info/rfc8408>.
[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>.
[RFC8745] Ananthakrishnan, H., Sivabalan, S., Barth, C., Minei, I.,
and M. Negi, "Path Computation Element Communication
Protocol (PCEP) Extensions for Associating Working and
Protection Label Switched Paths (LSPs) with Stateful PCE",
RFC 8745, DOI 10.17487/RFC8745, March 2020,
<https://www.rfc-editor.org/info/rfc8745>.
[RFC9012] Patel, K., Van de Velde, G., Sangli, S., and J. Scudder,
"The BGP Tunnel Encapsulation Attribute", RFC 9012,
DOI 10.17487/RFC9012, April 2021,
<https://www.rfc-editor.org/info/rfc9012>.
[RFC9325] Sheffer, Y., Saint-Andre, P., and T. Fossati,
"Recommendations for Secure Use of Transport Layer
Security (TLS) and Datagram Transport Layer Security
(DTLS)", BCP 195, RFC 9325, DOI 10.17487/RFC9325, November
2022, <https://www.rfc-editor.org/info/rfc9325>.
9.2. Informative References
[I-D.ietf-pce-segment-routing-policy-cp]
Koldychev, M., Sivabalan, S., Barth, C., Peng, S., and H.
Bidgoli, "Path Computation Element Communication Protocol
(PCEP) Extensions for Segment Routing (SR) Policy
Candidate Paths", Work in Progress, Internet-Draft, draft-
ietf-pce-segment-routing-policy-cp-18, 14 October 2024,
<https://datatracker.ietf.org/doc/html/draft-ietf-pce-
segment-routing-policy-cp-18>.
[RFC3063] Ohba, Y., Katsube, Y., Rosen, E., and P. Doolan, "MPLS
Loop Prevention Mechanism", RFC 3063,
DOI 10.17487/RFC3063, February 2001,
<https://www.rfc-editor.org/info/rfc3063>.
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[RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering
(TE) Extensions to OSPF Version 2", RFC 3630,
DOI 10.17487/RFC3630, September 2003,
<https://www.rfc-editor.org/info/rfc3630>.
[RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic
Engineering", RFC 5305, DOI 10.17487/RFC5305, October
2008, <https://www.rfc-editor.org/info/rfc5305>.
[RFC5329] Ishiguro, K., Manral, V., Davey, A., and A. Lindem, Ed.,
"Traffic Engineering Extensions to OSPF Version 3",
RFC 5329, DOI 10.17487/RFC5329, September 2008,
<https://www.rfc-editor.org/info/rfc5329>.
[RFC7308] Osborne, E., "Extended Administrative Groups in MPLS
Traffic Engineering (MPLS-TE)", RFC 7308,
DOI 10.17487/RFC7308, July 2014,
<https://www.rfc-editor.org/info/rfc7308>.
[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>.
[RFC9256] Filsfils, C., Talaulikar, K., Ed., Voyer, D., Bogdanov,
A., and P. Mattes, "Segment Routing Policy Architecture",
RFC 9256, DOI 10.17487/RFC9256, July 2022,
<https://www.rfc-editor.org/info/rfc9256>.
Authors' Addresses
Balaji Rajagopalan
Juniper Networks
Email: balajir@juniper.net
Vishnu Pavan Beeram
Juniper Networks
Email: vbeeram@juniper.net
Shaofu Peng
ZTE Corporation
Email: peng.shaofu@zte.com.cn
Mike Koldychev
Ciena Corporation
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Email: mkoldych@proton.me
Gyan Mishra
Verizon Communications Inc.
Email: gyan.s.mishra@verizon.com
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