PCE Working Group C. Li
Internet-Draft H. Zheng
Intended status: Standards Track Huawei Technologies
Expires: July 14, 2020 S. Sivabalan
Cisco Systems, Inc.
January 11, 2020
Conveying Vendor-Specific Information in the Path Computation Element
(PCE) Communication Protocol (PCEP) extensions for stateful PCE.
draft-dhody-pce-stateful-pce-vendor-08
Abstract
A Stateful Path Computation Element (PCE) maintains information on
the current network state, including: computed Label Switched Path
(LSPs), reserved resources within the network, and pending path
computation requests. This information may then be considered when
computing new traffic engineered LSPs, and for associated and
dependent LSPs, received from Path Computation Clients (PCCs).
RFC 7470 defines a facility to carry vendor-specific information in
PCEP.
This document extends this capability for the stateful PCE messages.
Status of This Memo
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provisions of BCP 78 and BCP 79.
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Copyright Notice
Copyright (c) 2020 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. Procedures for the Vendor Information Object . . . . . . . . 3
3. Procedures for the Vendor Information TLV . . . . . . . . . . 5
4. Vendor Information Object and TLV . . . . . . . . . . . . . . 6
5. Manageability Considerations . . . . . . . . . . . . . . . . 6
5.1. Control of Function and Policy . . . . . . . . . . . . . 6
5.2. Information and Data Models . . . . . . . . . . . . . . . 6
5.3. Liveness Detection and Monitoring . . . . . . . . . . . . 6
5.4. Verify Correct Operations . . . . . . . . . . . . . . . . 6
5.5. Requirements On Other Protocols . . . . . . . . . . . . . 6
5.6. Impact On Network Operations . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
7. Security Considerations . . . . . . . . . . . . . . . . . . . 7
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 7
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
9.1. Normative References . . . . . . . . . . . . . . . . . . 7
9.2. Informative References . . . . . . . . . . . . . . . . . 8
Appendix A. Contributor Addresses . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
The Path Computation Element communication Protocol (PCEP) [RFC5440]
provides mechanisms for Path Computation Elements (PCEs) to perform
path computations in response to Path Computation Clients' (PCCs)
requests.
A stateful PCE is capable of considering, for the purposes of path
computation, not only the network state in terms of links and nodes
(referred to as the Traffic Engineering Database or TED) but also the
status of active services (previously computed paths, and currently
reserved resources, stored in the Label Switched Paths Database (LSP-
DB). [RFC8051] describes general considerations for a stateful PCE
deployment and examines its applicability and benefits, as well as
its challenges and limitations through a number of use cases.
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[RFC8231] describes a set of extensions to PCEP to provide stateful
control. A stateful PCE has access to not only the information
carried by the network's Interior Gateway Protocol (IGP), but also
the set of active paths and their reserved resources for its
computations. The additional state allows the PCE to compute
constrained paths while considering individual LSPs and their
interactions. [RFC8281] describes the set-up, maintenance and
teardown of PCE-initiated LSPs under the stateful PCE model. These
extensions added new messages in PCEP for stateful PCE.
[RFC7470] defined Vendor Information object that can be used to carry
arbitrary, proprietary information such as vendor-specific
constraints. It also defined VENDOR-INFORMATION-TLV that can be used
to carry arbitrary information within any existing or future PCEP
object that supports TLVs.
This document extend the usage of Vendor Information Object and
VENDOR-INFORMATION-TLV to stateful PCE. The VENDOR-INFORMATION-TLV
can be carried inside any of the new objects added in PCEP for
stateful PCE as per [RFC7470], this document extend the PCEP messages
to also include the Vendor Information Object as well.
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. Procedures for the Vendor Information Object
A Path Computation LSP State Report message [RFC8231] (also referred
to as PCRpt message) is a PCEP message sent by a PCC to a PCE to
report the current state of an LSP. A PCC that wants to convey
proprietary or vendor-specific information or metrics to a PCE does
so by including a Vendor Information object in the PCRpt message.
The contents and format of the object are described in Section 4 of
[RFC7470]. The PCE determines how to interpret the information in
the Vendor Information object by examining the Enterprise Number it
contains.
The Vendor Information object is OPTIONAL in a PCRpt message.
Multiple instances of the object MAY be used on a single PCRpt
message. Different instances of the object can have different
Enterprise Numbers.
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The format of the PCRpt message (with [RFC8231] as base) is updated
as follows:
<PCRpt Message> ::= <Common Header>
<state-report-list>
Where:
<state-report-list> ::= <state-report>[<state-report-list>]
<state-report> ::= [<SRP>]
<LSP>
<path>
[<vendor-info-list>]
Where:
<vendor-info-list> ::= <VENDOR-INFORMATION>
[<vendor-info-list>]
<path> is defined in [RFC8231].
A Path Computation LSP Update Request message (also referred to as
PCUpd message) is a PCEP message sent by a PCE to a PCC to update
attributes of an LSP. The Vendor Information object can be included
in a PCUpd message to convey proprietary or vendor-specific
information.
The format of the PCUpd message (with [RFC8231] as base) is updated
as follows:
<PCUpd Message> ::= <Common Header>
<update-request-list>
Where:
<update-request-list> ::= <update-request>
[<update-request-list>]
<update-request> ::= <SRP>
<LSP>
<path>
[<vendor-info-list>]
Where:
<vendor-info-list> ::= <VENDOR-INFORMATION>
[<vendor-info-list>]
<path> is defined in [RFC8231].
A Path Computation LSP Initiate Message (also referred to as
PCInitiate message) is a PCEP message sent by a PCE to a PCC to
trigger LSP instantiation or deletion. The Vendor Information object
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can be included in a PCInitiate message to convey proprietary or
vendor-specific information.
The format of the PCInitiate message (with [RFC8281] as base) is
updated as follows:
<PCInitiate Message> ::= <Common Header>
<PCE-initiated-lsp-list>
Where:
<PCE-initiated-lsp-list> ::= <PCE-initiated-lsp-request>
[<PCE-initiated-lsp-list>]
<PCE-initiated-lsp-request> ::=
(<PCE-initiated-lsp-instantiation>|
<PCE-initiated-lsp-deletion>)
<PCE-initiated-lsp-instantiation> ::= <SRP>
<LSP>
[<END-POINTS>]
<ERO>
[<attribute-list>]
[<vendor-info-list>]
Where:
<vendor-info-list> ::= <VENDOR-INFORMATION>
[<vendor-info-list>]
<PCE-initiated-lsp-deletion> and <attribute-list> is as per
[RFC8281].
A legacy implementation that does not recognize the Vendor
Information object will act according to the procedures set out in
[RFC8231] and [RFC8281]. An implementation that supports the Vendor
Information object, but receives one carrying an Enterprise Number
that it does not support, SHOULD ignore the object in the same way as
described in [RFC7470].
3. Procedures for the Vendor Information TLV
The Vendor Information TLV can be used to carry vendor-specific
information that applies to a specific PCEP object by including the
TLV in the object. This includes objects used in stateful PCE
extension such as SRP and LSP object. All the procedures as per
section 3 of [RFC7470].
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4. Vendor Information Object and TLV
[RFC7470] specify the format of VENDOR-INFORMATION Object and VENDOR-
INFORMATION-TLV.
5. Manageability Considerations
All manageability requirements and considerations listed in
[RFC5440], [RFC7470] and [RFC8231] apply to PCEP protocol extensions
defined in this document. In addition, requirements and
considerations listed in this section apply.
5.1. Control of Function and Policy
As stated in [RFC7470], this capability, the associated vendor
specific information and policy SHOULD made configurable. This
information can be used in stateful messages as well.
5.2. Information and Data Models
The PCEP YANG module is specified in [I-D.ietf-pce-pcep-yang]. It is
NOT RECOMMENDED that standard YANG module be augmented with details
of vendor information. It MAY be extended to include the use of this
information and the Enterprise Numbers that the object and TLVs
contain.
5.3. 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].
5.4. Verify Correct Operations
Mechanisms defined in this document do not imply any new operation
verification requirements in addition to those already listed in
[RFC5440] and [RFC8231].
5.5. Requirements On Other Protocols
Mechanisms defined in this document do not imply any new requirements
on other protocols.
5.6. Impact On Network Operations
Mechanisms defined in [RFC5440] and [RFC8231] also apply to PCEP
extensions defined in this document. Further, the mechanism
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described in this document can help the operator to request control
of the LSPs at a particular PCE.
6. IANA Considerations
There are no IANA consideration in this document.
7. Security Considerations
The protocol extensions defined in this document do not change the
nature of PCEP. Therefore, the security considerations set out in
[RFC5440], [RFC7470], [RFC8231] and [RFC8281] apply unchanged.
As stated in [RFC6952], PCEP implementations SHOULD support the TCP-
AO [RFC5925] and not use TCP MD5 because of TCP MD5's known
vulnerabilities and weakness. PCEP also support Transport Layer
Security (TLS) [RFC8253] as per the recommendations and best current
practices in [RFC7525].
8. Acknowledgments
Thanks to Avantika, Mahendra Singh Negi, Udayasree Palle and Swapna K
for their suggestions.
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>.
[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>.
[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>.
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[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>.
[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>.
9.2. Informative References
[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-13 (work in progress), October 2019.
[RFC5925] Touch, J., Mankin, A., and R. Bonica, "The TCP
Authentication Option", RFC 5925, DOI 10.17487/RFC5925,
June 2010, <https://www.rfc-editor.org/info/rfc5925>.
[RFC6952] Jethanandani, M., Patel, K., and L. Zheng, "Analysis of
BGP, LDP, PCEP, and MSDP Issues According to the Keying
and Authentication for Routing Protocols (KARP) Design
Guide", RFC 6952, DOI 10.17487/RFC6952, May 2013,
<https://www.rfc-editor.org/info/rfc6952>.
[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>.
[RFC8051] Zhang, X., Ed. and I. Minei, Ed., "Applicability of a
Stateful Path Computation Element (PCE)", RFC 8051,
DOI 10.17487/RFC8051, January 2017,
<https://www.rfc-editor.org/info/rfc8051>.
[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>.
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Appendix A. Contributor Addresses
Dhruv Dhody
Huawei Technologies
Divyashree Techno Park, Whitefield
Bangalore, Karnataka 560066
India
Authors' Addresses
Cheng Li
Huawei Technologies
Huawei Campus, No. 156 Beiqing Rd.
Beijing 100095
China
Email: chengli13@huawei.com
Haomian Zheng
Huawei Technologies
H1, Huawei Xiliu Beipo Village, Songshan Lake
Dongguan, Guangdong 523808
P.R.China
Email: zhenghaomian@huawei.com
Siva Sivabalan
Cisco Systems, Inc.
2000 Innovation Drive
Kanata, Ontario K2K 3E8
Canada
Email: msiva@cisco.com
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