Inter-Domain Routing R. Chen
Internet-Draft D. Zhao
Intended status: Standards Track ZTE Corporation
Expires: 8 January 2024 7 July 2023
PCEP extension to support CPs validity
draft-chen-pce-sr-policy-cp-validity-00
Abstract
[I-D.chen-spring-sr-policy-cp-validity]supplemented candidate path
validity criterion in [RFC9256]. It defines three validity control
parameters under candidate Path to control the validity judgment of
candidate Path.
This document defines PCEP extensions for signaling the validity
control parameters of a candidate path for an SR Policy.
Status of This Memo
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document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3
3. PCEP Extensions . . . . . . . . . . . . . . . . . . . . . . . 3
3.1. CP Validity TLV . . . . . . . . . . . . . . . . . . . . . 3
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . 4
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4
7. Normative References . . . . . . . . . . . . . . . . . . . . 4
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction
SR Policy architecture are specified in [RFC9256]. An SR Policy
comprises one or more candidate paths (CP) of which at a given time
one and only one may be active (i.e., installed in forwarding and
usable for steering of traffic). Each CP in turn may have one or
more SID-List of which one or more may be active; when multiple SID-
List are active then traffic is load balanced over them.
[I-D.chen-spring-sr-policy-cp-validity]supplemented candidate path
validity criterion in [RFC9256]. It defines three validity control
parameters under candidate Path to control the validity judgment of
candidate Path.
PCEP Extensions for Segment Routing [RFC8664] specifies extensions
that allow PCEP to work with basic SR-TE paths.
PCEP extension to support Segment Routing Policy Candidate Paths
[I-D.ietf-pce-segment-routing-policy-cp] specifies extensions that
allow PCEP to signal additional attributes of an SR Policy, which are
not covered by [RFC8664]. SR Policy is modeled in PCEP as an
Association and the SR Candidate Paths are the members of that
Association. Thus the PCE can take computation and control decisions
about the Candidate Paths, with the additional knowledge that these
Candidate Paths belong to the same SR Policy.
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This document defines PCEP extensions for signaling the validity
control parameters of a candidate path for an SR Policy.
2. 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 RFC 2119 [RFC2119].
3. PCEP Extensions
As defined in [RFC8697] , TE LSPs are associated by adding them to a
common association group by a PCEP peer.
[I-D.ietf-pce-segment-routing-policy-cp] defines SR Policy
Association (SRPA), and the SR Candidate Paths are the members of
this Association. We define the CP validity TLV in the SR Policy
Association (SRPA) object to signal the validity control parameters
of a candidate path.
3.1. CP Validity TLV
The format of the CP Validity TLV is defined as follows:
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 | Length | valid SL qty |valid SL weight|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| valid SL weight ratio |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1
where:
Type: to be assigned by IANA.
Length: the total length of the value field not including Type and
Length fields.
valid SL quantity：1-octet field which indicates the minimum number of
valid segment Lists under the active candidate path. When the number
of valid segment Lists under candidate path is greater than or equal
to this field, the candidate path is considered valid. 0 indicates no
requirement for SL quantity. 0xff indicates that the candidate path
is considered valid only if all the segment Lists are valid.
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valid SL weight: 4-octet field which indicates the minimum value of
the sum of the weights of the valid segment List under the active
candidate Path. When the sum of the weights of the valid segment
Lists under the candidate path is greater than or equal to this
field, the candidate Path is considered valid. 0 indicates no
requirement for weight.0xffffffff indicates that the candidate path
is considered valid only if all the segment Lists are valid.
valid SL weight ratio: 1-octet field which indicates the minimum
proportion WTV/WTA.
WTV: The sum weights of the valid segment list under the active CP.
WTA: The sum weights of all the segment lists under the active CP.
When WTV/WTA is greater than or equal to this field, the candidate
Path is considered valid.
0 indicates no requirement on weight proportion.100 indicates that
the candidate path is considered valid only if all the segment lists
are valid.
4. IANA Considerations
This document defines the new TLV for carrying additional information
about SR Policy and SR Candidate Paths. IANA is requested to make
the assignment of a new value for the existing "PCEP TLV Type
Indicators" registry as follows:
Value Description Reference
------- ------------------------- --------------
TBD CP Validity TLV This document
5. Security Considerations
Procedures and protocol extensions defined in this document do not
affect the security considerations discussed in
[I-D.ietf-pce-segment-routing-policy-cp].
6. Acknowledgements
TBD.
7. Normative References
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[I-D.chen-spring-sr-policy-cp-validity]
Chen, R., Zhao, D., and C. Lin, "Validity of SR Policy
Candidate Path", Work in Progress, Internet-Draft, draft-
chen-spring-sr-policy-cp-validity-00, 7 July 2023,
<https://datatracker.ietf.org/doc/html/draft-chen-spring-
sr-policy-cp-validity-00>.
[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-11, 20 June 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-pce-
segment-routing-policy-cp-11>.
[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>.
[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>.
[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>.
[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
Ran Chen
ZTE Corporation
Nanjing
China
Email: chen.ran@zte.com.cn
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Detao Zhao
ZTE Corporation
Nanjing
China
Email: zhao.detao@zte.com.cn
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