Internet DRAFT - draft-rajagopalan-pce-pcep-color
draft-rajagopalan-pce-pcep-color
PCE Working Group B. Rajagopalan
Internet-Draft V. Beeram
Intended status: Standards Track Juniper Networks
Expires: 7 July 2023 S. Peng
Q. Xiong
ZTE Corporation
M. Koldychev
Cisco Systems Inc.
G. Mishra
Verizon Communications Inc.
3 January 2023
Path Computation Element Protocol(PCEP) Extension for Color
draft-rajagopalan-pce-pcep-color-03
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 an extension to Path
Computation Element Protocol (PCEP) to carry the color attribute.
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].
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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Drafts is at https://datatracker.ietf.org/drafts/current/.
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 7 July 2023.
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Copyright Notice
Copyright (c) 2023 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/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
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provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Use case: RSVP-TE Color . . . . . . . . . . . . . . . . . . . 3
3. Protocol Operation . . . . . . . . . . . . . . . . . . . . . 3
4. TLV Format . . . . . . . . . . . . . . . . . . . . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . 5
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
6.1. PCEP TLV Type Indicator . . . . . . . . . . . . . . . . . 5
6.2. STATEFUL-PCE-CAPABILITY TLV Flag Field . . . . . . . . . 5
6.3. LSP-ERROR-CODE TLV Error Code Field . . . . . . . . . . . 5
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
8.1. Normative References . . . . . . . . . . . . . . . . . . 6
8.2. Informative References . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
A Traffic Engineering (TE) tunnel or policy can be associated with an
intent or objective (e.g. low latency) by marking it with a color.
This color attribute is used as a guiding criterion for mapping
services onto the TE tunnel or policy ([RFC9012]). 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].
Color is part of the tuple that identifies a Segment Routing (SR)
policy ([I-D.ietf-spring-segment-routing-policy]) and is included in
the Path Computation Element Protocol (PCEP) extensions defined for
carrying the SR policy identifiers
([I-D.ietf-pce-segment-routing-policy-cp]). The color encoding
specified in SR policy identifier cannot be reused for other types of
path setup.
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This document introduces a generic optional PCEP TLV called the Color
TLV to carry the color attribute and discusses its usage with RSVP-TE
Label Switched Paths (LSPs).
In addition to catering to the use-case discussed in this document,
the Color TLV can also be used to reference SR Composite Candidate
Paths as specified in ([I-D.ietf-pce-multipath]). An implementation
MAY also provide a local policy option to use this TLV to reference a
set of path constraints and optimization objectives.
2. Use case: RSVP-TE Color
The color attribute can be used as one of the guiding criteria in
selecting the RSVP-TE LSP as a next hop for service prefixes. While
the specific details of how the service prefixes are associated with
the appropriate RSVP-TE LSPs are outside the scope of this
specification, the envisioned high level usage of the color attribute
is as follows.
The service prefixes are marked with some indication of the type of
underlay they need. The underlay LSPs carry corresponding markings,
which we refer to as color in this specification, enabling an ingress
node to associate the service prefixes with the appropriate underlay
LSPs.
As an example, for a BGP-based service, the originating PE could
attach some community, e.g. the Color Extended Community [RFC9012]
with the service route. A receiving PE could use locally configured
policies to associate service routes carrying Color Extended
Community 'X' with underlay RSVP-TE LSPs of color 'Y'.
BGP Color Extended Community is commonly used to perform service
mapping, although this specification does not mandate its usage.
The procedure discussed for service mapping in this section can be
applied to any underlay path setup type.
3. Protocol Operation
The STATEFUL-PCE-CAPABILITY negotiation message is enhanced to carry
the color capability, which allows PCC (Path Computation Client) and
PCE (Path Computation Element) to determine how incompatibility
should be handled, should only one of them support color. An older
implementation that does not recognize the new color TLV would ignore
it upon receipt. This can sometimes result in undesirable behavior.
For example, if PCE passes color to a PCC that does not understand
colors, the LSP may not be used as intended. A PCE that clearly
knows the PCC's color capability can handle such cases better, and
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vice versa. Following are the rules for handling mismatch in color
capability.
A PCE that has color capability MUST NOT send color TLV to a PCC that
does not have color capability. A PCE that does not have color
capability can ignore color marking reported by PCC.
When a PCC is interacting with a PCE that does not have color
capability, the PCC
* SHOULD NOT report color to the PCE.
* MUST NOT override the local color, if it is configured, based on
any messages coming from the PCE.
Section 4 defines the format of the color TLV. The placement of the
TLV depends on the purpose for which it is used. For RSVP's service
mapping use case discussed in this document, the color TLV is carried
in the LSP Object defined in [RFC8231].
If a PCC is unable to honor a color value passed in an LSP Update
request, the PCC must keep the LSP in DOWN state, and include an LSP
Error Code value of "Unsupported Color" (TBA3) in LSP State Report
message.
When LSPs that belong to the same TE tunnel are with in the same Path
Protection Association Group [RFC8745], the color is attached only to
the primary LSP. If PCC receives color TLV for a secondary LSP, it
SHOULD respond with an error code of 4 (Unacceptable Parameters).
4. TLV Format
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 TBA1. Length carries a value of 4. The 'color'
field is 4-bytes long, and carries the actual color value.
Section 7.1.1 of RFC8231 [RFC8231] defines STATEFUL-PCE-CAPABILITY
flags. The following flag is used to indicate if the speaker
supports color capability:
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C-bit (TBA2): A PCE/PCC that supports color capability must turn
on this bit.
5. 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 [RFC7525]
can be used to protect against this attack.
6. IANA Considerations
6.1. PCEP TLV Type Indicator
IANA is requested to allocate a new value in the "PCEP TLV Type
Indicators" sub-registry of the PCEP Numbers registry as follows:
Value Description Reference
----------------------------------------------
TBA1 Color This document
6.2. STATEFUL-PCE-CAPABILITY TLV Flag Field
IANA is requested to allocate a new bit value in the "STATEFUL-PCE-
CAPABILITY TLV Flag Field" sub-registry of the PCEP Numbers registry
as follows:
Value Description Reference
----------------------------------------------
TBA2 COLOR-CAPABILITY This document
6.3. LSP-ERROR-CODE TLV Error Code Field
IANA is requested to allocate 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
----------------------------------------------
TBA3 Unsupported Color This document
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7. Acknowledgments
The authors would like to thank Kaliraj Vairavakkalai, Colby Barth,
Natrajan Venkataraman and Tarek Saad for their review and
suggestions.
8. References
8.1. Normative References
[RFC2119] Bradner, S. and RFC Publisher, "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., Le Roux, JL., Ed., and RFC Publisher,
"Path Computation Element (PCE) Communication Protocol
(PCEP)", RFC 5440, DOI 10.17487/RFC5440, March 2009,
<https://www.rfc-editor.org/info/rfc5440>.
[RFC7525] Sheffer, Y., Holz, R., Saint-Andre, P., and RFC Publisher,
"Recommendations for Secure Use of Transport Layer
Security (TLS) and Datagram Transport Layer Security
(DTLS)", RFC 7525, DOI 10.17487/RFC7525, May 2015,
<https://www.rfc-editor.org/info/rfc7525>.
[RFC8231] Crabbe, E., Minei, I., Medved, J., Varga, R., and RFC
Publisher, "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., Dhody, D., and
RFC Publisher, "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., Varga, R., and RFC
Publisher, "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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[RFC8745] Ananthakrishnan, H., Sivabalan, S., Barth, C., Minei, I.,
Negi, M., and RFC Publisher, "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., Scudder, J., and
RFC Publisher, "The BGP Tunnel Encapsulation Attribute",
RFC 9012, DOI 10.17487/RFC9012, April 2021,
<https://www.rfc-editor.org/info/rfc9012>.
8.2. Informative References
[I-D.ietf-pce-multipath]
Koldychev, M., Sivabalan, S., Saad, T., Beeram, V. P.,
Bidgoli, H., Yadav, B., Peng, S., and G. S. Mishra, "PCEP
Extensions for Signaling Multipath Information", Work in
Progress, Internet-Draft, draft-ietf-pce-multipath-07, 14
November 2022, <https://www.ietf.org/archive/id/draft-
ietf-pce-multipath-07.txt>.
[I-D.ietf-pce-segment-routing-policy-cp]
Koldychev, M., Sivabalan, S., Barth, C., Peng, S., and H.
Bidgoli, "PCEP extension to support Segment Routing Policy
Candidate Paths", Work in Progress, Internet-Draft, draft-
ietf-pce-segment-routing-policy-cp-08, 24 October 2022,
<https://www.ietf.org/archive/id/draft-ietf-pce-segment-
routing-policy-cp-08.txt>.
[I-D.ietf-spring-segment-routing-policy]
Filsfils, C., Talaulikar, K., Voyer, D., Bogdanov, A., and
P. Mattes, "Segment Routing Policy Architecture", Work in
Progress, Internet-Draft, draft-ietf-spring-segment-
routing-policy-22, 22 March 2022,
<https://www.ietf.org/archive/id/draft-ietf-spring-
segment-routing-policy-22.txt>.
[RFC3063] Ohba, Y., Katsube, Y., Rosen, E., Doolan, P., and RFC
Publisher, "MPLS Loop Prevention Mechanism", RFC 3063,
DOI 10.17487/RFC3063, February 2001,
<https://www.rfc-editor.org/info/rfc3063>.
[RFC3630] Katz, D., Kompella, K., Yeung, D., and RFC Publisher,
"Traffic Engineering (TE) Extensions to OSPF Version 2",
RFC 3630, DOI 10.17487/RFC3630, September 2003,
<https://www.rfc-editor.org/info/rfc3630>.
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[RFC5305] Li, T., Smit, H., and RFC Publisher, "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., Lindem, A., Ed., and
RFC Publisher, "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. and RFC Publisher, "Extended Administrative
Groups in MPLS Traffic Engineering (MPLS-TE)", RFC 7308,
DOI 10.17487/RFC7308, July 2014,
<https://www.rfc-editor.org/info/rfc7308>.
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
Quan Xiong
ZTE Corporation
Email: xiong.quan@zte.com.cn
Mike Koldychev
Cisco Systems Inc.
Email: mkoldych@cisco.com
Gyan Mishra
Verizon Communications Inc.
Email: gyan.s.mishra@verizon.com
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