Internet DRAFT - draft-ietf-pce-vn-association
draft-ietf-pce-vn-association
PCE Working Group Y. Lee
Internet-Draft Samsung
Intended status: Standards Track H. Zheng
Expires: 27 April 2023 Huawei Technologies
D. Ceccarelli
Ericsson
24 October 2022
Path Computation Element Communication Protocol (PCEP) extensions for
establishing relationships between sets of Label Switched Paths and
Virtual Networks
draft-ietf-pce-vn-association-11
Abstract
This document describes how to extend the Path Computation Element
(PCE) Communication Protocol (PCEP) association mechanism introduced
by the PCEP Association Group specification, to further associate
sets of Label Switched Paths (LSPs) with a higher-level structure
such as a Virtual Network (VN) requested by a customer or
application. This extended association mechanism can be used to
facilitate control of virtual network using the PCE architecture.
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
working documents as Internet-Drafts. The list of current Internet-
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
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 27 April 2023.
Copyright Notice
Copyright (c) 2022 IETF Trust and the persons identified as the
document authors. All rights reserved.
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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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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirement Language . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Operation Overview . . . . . . . . . . . . . . . . . . . . . 4
4. Extensions to PCEP . . . . . . . . . . . . . . . . . . . . . 6
5. Implementation Status . . . . . . . . . . . . . . . . . . . . 8
5.1. Huawei's Proof of Concept based on ONOS . . . . . . . . . 8
6. Security Considerations . . . . . . . . . . . . . . . . . . . 9
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
7.1. Association Object Type Indicator . . . . . . . . . . . . 9
7.2. PCEP TLV Type Indicator . . . . . . . . . . . . . . . . . 9
7.3. PCEP Error . . . . . . . . . . . . . . . . . . . . . . . 9
8. Manageability Considerations . . . . . . . . . . . . . . . . 10
8.1. Control of Function and Policy . . . . . . . . . . . . . 10
8.2. Information and Data Models . . . . . . . . . . . . . . . 10
8.3. Liveness Detection and Monitoring . . . . . . . . . . . . 10
8.4. Verify Correct Operations . . . . . . . . . . . . . . . . 10
8.5. Requirements On Other Protocols . . . . . . . . . . . . . 10
8.6. Impact On Network Operations . . . . . . . . . . . . . . 10
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
9.1. Normative References . . . . . . . . . . . . . . . . . . 10
9.2. Informative References . . . . . . . . . . . . . . . . . 11
Appendix A. Contributors . . . . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13
1. Introduction
The Path Computation Element Communication Protocol (PCEP) provides
mechanisms for Path Computation Elements (PCEs) to perform path
computations in response to requests from Path Computation Clients
(PCCs) [RFC5440].
[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.
[RFC8231] describes a set of extensions to PCEP to provide stateful
control. For its computations, a stateful PCE has access to not only
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the information carried by the network's Interior Gateway Protocol
(IGP), but also the set of active paths and their reserved resources.
The additional state allows the PCE to compute constrained paths
while considering individual Label Switched Paths (LSPs) and their
interactions.
[RFC8281] describes the setup, maintenance and teardown of PCE-
initiated LSPs under the stateful PCE model.
[RFC8697] introduces a generic mechanism to create a grouping of
LSPs. This grouping can then be used to define associations between
sets of LSPs or between a set of LSPs and a set of attributes.
[RFC8453] introduces a framework for Abstraction and Control of TE
Networks (ACTN) and describes various Virtual Network (VN) operations
initiated by a customer or application. A VN is a customer view of
the TE network. Depending on the agreement between client and
provider, various VN operations and VN views are possible.
[RFC8637] examines the PCE and ACTN architectures and describes how
the PCE architecture is applicable to ACTN. [RFC6805] and [RFC8751]
describes a hierarchy of stateful PCEs with Parent PCE coordinating
multi-domain path computation function between Child PCEs, and thus
making it the base for PCE applicability for ACTN. As [RFC8751]
explains, in the context of ACTN, the Child PCE is identified with
the Provisioning Network Controller (PNC), and the Parent PCE is
identified with the Multi-domain Service Coordinator (MDSC).
In this context, there is a need to associate a set of LSPs with a VN
"construct" to facilitate VN operations in the PCE architecture.
This association allows a PCE to identify which LSPs belong to a
certain VN. The PCE could then use this association to optimize all
LSPs belonging to the VN at once. The PCE could further take VN-
specific actions on the LSPs, such as relaxation of constraints,
policy actions, setting default behavior, etc.
This document specifies a PCEP extension to associate a set of LSPs
based on their Virtual Network (VN).
1.1. Requirement 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.
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2. Terminology
The terminology is as per [RFC4655], [RFC5440], [RFC6805], [RFC8231]
and [RFC8453].
3. Operation Overview
As per [RFC8697], LSPs are associated with other LSPs with which they
interact by adding them to a common association group.
An association group based on VN is useful for various optimizations
that should be applied by considering all the LSPs in the
association. This includes, but is not limited to -
* Path Computation: When computing a path for an LSP, it is useful
to analyze the impact of this LSP on the other LSPs belonging to
the same VN. The aim would be to optimize all LSPs belonging to
the VN rather than a single LSP. Also, the optimization criteria
(such as minimizing the load of the most loaded link (MLL)
[RFC5541]) could be applied for all the LSPs belonging to the VN
identified by the VN association.
* Path Re-Optimization: The PCE would like to use advanced path
computation algorithms and optimization techniques that consider
all the LSPs belonging to a VN, and optimize them all together
during the path re-optimization.
In this document we define a new association group called the VN
Association Group (VNAG). This grouping is used to define the
association between a set of LSPs and a virtual network.
The Association Object contains a field to identify the type of
association, and this document defines a new Association Type value
of TBD1 to indicate that the association is a "VN Association". The
Association Identifier in the Association Object is the VNAG
Identifier and is handled in the same way as the generic association
identifier defined in [RFC8697].
In this document, "VNAG object" refers to an Association Object with
the Association type set to "VN Association".
Local polices on the PCE define the computational and optimization
behavior for the LSPs in the VN. An LSP MUST NOT belong to more than
one VNAG. If an implementation encounters more than one VNAG object
in a PCEP message, it MUST process the first occurrence and it MUST
ignore the others.
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[RFC8697] specifies the mechanism by which a PCEP speaker can
advertise which association types it supports. This is done using
the ASSOC-Type-List TLV carried within an OPEN object. A PCEP
speaker MUST include the VN Association Type (TBD1) in the ASSOC-
Type-List TLV before using the VNAG object in a PCEP message. As per
[RFC8697], if the implementation does not support the VN Association
Type, it will return a PCErr message with Error-Type 26 "Association
Error" and Error-value 1 "Association Type is not supported".
The Association IDs (VNAG IDs) for this Association Type are dynamic
in nature (and created by the Parent PCE (MDSC) based on the VN
operations for the LSPs belonging to the same VN). Operator
configuration of VNAG IDs is not supported, so there is no need for
an Operator-Configured Association Range to be set. Thus, the VN
Association Type (TBD1) MUST NOT be present in the Operator-
Configured Association Range TLV if that TLV is present in the OPEN
object. If an implementation encounters the VN Association Type
(TBD1) in an Operator-Configured Association Range TLV, it MUST
ignore the associated Start-Assoc-ID and Range values.
This association is useful in a PCEP session between a parent PCE
(MDSC) and a child PCE (PNC). When computing the path, the child PCE
(PNC) refers to the VN association in the request from the parent PCE
(MDSC) and maps the VN to the associated LSPs and network resources.
From the perspective of the Parent PCE, it receives a virtual network
creation request by its customer, with the VN uniquely identified by
the Association parameters (section 6.1.4 of [RFC8697]) in the VNAG
or the Virtual Network identifier encoded in the VIRTUAL-NETWORK-TLV.
This VN may comprise multiple LSPs in the network in a single domain
or across multiple domains. The Parent PCE sends a PCInitiate
Message with this association information in the VNAG Object. This
in effect binds an LSP that is to be instantiated at the child PCE
with the VN. The VN association information MUST be included as a
part of the first PCRpt message. Figure 1 shows an example of a
typical VN operation using PCEP. It is worth noting that in a multi-
domain scenario, the different domains are controlled by different
child PCEs. In order to set up the cross-domain tunnel, multiple
segments need to be stitched, by the border nodes in each domain who
receive the instruction from their child PCE (PNC).
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******
..........*MDSC*..............................
. ****** .. MPI .
. . . PCEP .
. . . PCInitiate LSPx .
. . . with VNAG .
. . . .
. . . .
. . . .
v v v .
****** ****** ****** .
*PNC1* *PNC2* *PNC4* .
****** ****** ****** .
+---------------+ +---------------+ +---------------+ .
| |----| |----| C| .
| | | | | | .
|DOMAIN 1 |----|DOMAIN 2 |----|DOMAIN 4 | .
+---------------+ +---------------+ +---------------+ .
/ .
****** / .
*PNC3*<............/......................
****** /
+---------------+/
| |
| |
|DOMAIN 3 |
+---------------+
MDSC -> Parent PCE
PNC -> Child PCE
MPI -> PCEP
Figure 1: Example of VN operations in H-PCE Architecture
Whenever changes occur with the instantiated LSP in a domain network,
the domain child PCE reports the changes using a PCRpt Message in
which the VNAG Object indicates the relationship between the LSP and
the VN.
Whenever an update occurs with VNs in the Parent PCE (due to the
customer's request), the parent PCE sends an PCUpd Message to inform
each affected child PCE of this change.
4. Extensions to PCEP
The format of VNAG is as per the ASSOCIATION object [RFC8697].
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This document defines one new mandatory TLV "VIRTUAL-NETWORK-TLV".
Optionally, the new TLV can be jointly used with the existing
"VENDOR-INFORMATION-TLV" specified in [RFC7470] as described below:
* VIRTUAL-NETWORK-TLV: Used to communicate the Virtual Network
Identifier.
* VENDOR-INFORMATION-TLV: Used to communicate arbitrary vendor
specific behavioral information, described in [RFC7470].
The format of VIRTUAL-NETWORK-TLV is 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=TBD2 | Length (variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// Virtual Network Identifier //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: The VIRTUAL-NETWORK-TLV formats
Type (16-bits): TBD2 (to be allocated by IANA)
Length (16-bits): indicates the length of the value portion of the
TLV in octets and MUST be greater than 0. The TLV MUST be zero-
padded so that the TLV is 4-octet aligned.
Virtual Network Identifier (variable): a symbolic name for the VN
that uniquely identifies the VN. It SHOULD be a string of printable
ASCII [RFC0020] characters (i.e., 0x20 to 0x7E), without a NULL
terminator. The Virtual Network Identifier is a human-readable
string that identifies a VN, it can be specified with the association
information which may be conveyed in a VENDOR-INFORMATION-TLV. An
implementation uses the Virtual Network Identifier to maintain a
mapping to the VN association group and the LSPs associated with the
VN. The Virtual Network Identifier MAY be specified by the customer
or set via an operator policy or auto-generated by the PCEP speaker.
The VIRTUAL-NETWORK-TLV MUST be included in VNAG object. If a PCEP
speaker receives the VNAG object without the VIRTUAL-NETWORK-TLV, it
MUST send a PCErr message with Error-Type=6 (mandatory object
missing) and Error-Value=TBD3 (VIRTUAL-NETWORK-TLV missing) and close
the session.
The format of VENDOR-INFORMATION-TLV is defined in [RFC7470].
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If a PCEP speaker receives a VN ASSOCIATION object with a TLV that
violates the rules specified in this document, the PCEP speaker MUST
send a PCErr message with Error-Type = 10 (Reception of an invalid
object) and Error-value = 11 (Malformed object) and MUST close the
PCEP session.
5. 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".
5.1. Huawei's Proof of Concept based on ONOS
The PCE function was developed in the ONOS open source platform.
This extension was implemented on a private version as a proof of
concept to ACTN.
* Organization: Huawei
* Implementation: Huawei's PoC based on ONOS
* Description: PCEP as a southbound plugin was added to ONOS. To
support ACTN, this extension in PCEP is used. Refer
https://wiki.onosproject.org/display/ONOS/PCEP+Protocol
* Maturity Level: Prototype
* Coverage: Full
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* Contact: satishk@huawei.com
6. Security Considerations
The security considerations described in [RFC5440], [RFC8231] and
[RFC8281] apply to the extensions defined in this document as well.
One new Association Type (VN Association) for the ASSOCIATION object
is introduced in this document. Additional security considerations
related to LSP associations due to a malicious PCEP speaker are
described in [RFC8697] and apply to the VN Association type. Hence,
securing the PCEP session using Transport Layer Security (TLS)
[RFC8253] is RECOMMENDED.
7. IANA Considerations
7.1. Association Object Type Indicator
IANA is requested to make the assignment of a new value in the sub-
registry "ASSOCIATION Type Field" within the "Path Computation
Element Protocol (PCEP) Numbers" registry, as follows:
Value Name Reference
TBD1 VN Association Type [This I.D.]
7.2. PCEP TLV Type Indicator
IANA is requested to make the assignment of a new value for the
existing "PCEP TLV Type Indicators" sub-registry within the "Path
Computation Element Protocol (PCEP) Numbers" registry, as follows:
Value Name Reference
TBD2 VIRTUAL-NETWORK-TLV [This I.D.]
7.3. PCEP Error
IANA is requested to allocate new error value within the "PCEP-ERROR
Object Error Types and Values" sub-registry within the "Path
Computation Element Protocol (PCEP) Numbers" registry, as follows:
Error-Type Meaning
6 Mandatory Object missing
Error-value=TBD3: VIRTUAL-NETWORK TLV missing [This
I.D.]
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8. Manageability Considerations
8.1. Control of Function and Policy
An operator MUST be allowed to mark LSPs that belong to the same VN.
This could also be done automatically based on the VN configuration.
8.2. Information and Data Models
The PCEP YANG module [I-D.ietf-pce-pcep-yang] should support the
association between LSPs including VN association.
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
[RFC8637] describe the network operations when PCE is used for VN
operations. Section 3 further specifies the operations when VN
associations are used.
9. References
9.1. Normative References
[RFC0020] Cerf, V., "ASCII format for network interchange", STD 80,
RFC 20, DOI 10.17487/RFC0020, October 1969,
<https://www.rfc-editor.org/info/rfc20>.
[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>.
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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,
<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>.
[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>.
9.2. Informative References
[RFC4655] Farrel, A., Vasseur, J.-P., and J. Ash, "A Path
Computation Element (PCE)-Based Architecture", RFC 4655,
DOI 10.17487/RFC4655, August 2006,
<https://www.rfc-editor.org/info/rfc4655>.
[RFC6805] King, D., Ed. and A. Farrel, Ed., "The Application of the
Path Computation Element Architecture to the Determination
of a Sequence of Domains in MPLS and GMPLS", RFC 6805,
DOI 10.17487/RFC6805, November 2012,
<https://www.rfc-editor.org/info/rfc6805>.
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[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>.
[RFC8453] Ceccarelli, D., Ed. and Y. Lee, Ed., "Framework for
Abstraction and Control of TE Networks (ACTN)", RFC 8453,
DOI 10.17487/RFC8453, August 2018,
<https://www.rfc-editor.org/info/rfc8453>.
[RFC8637] Dhody, D., Lee, Y., and D. Ceccarelli, "Applicability of
the Path Computation Element (PCE) to the Abstraction and
Control of TE Networks (ACTN)", RFC 8637,
DOI 10.17487/RFC8637, July 2019,
<https://www.rfc-editor.org/info/rfc8637>.
[RFC5541] Le Roux, JL., Vasseur, JP., and Y. Lee, "Encoding of
Objective Functions in the Path Computation Element
Communication Protocol (PCEP)", RFC 5541,
DOI 10.17487/RFC5541, June 2009,
<https://www.rfc-editor.org/info/rfc5541>.
[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>.
[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>.
[RFC8751] Dhody, D., Lee, Y., Ceccarelli, D., Shin, J., and D. King,
"Hierarchical Stateful Path Computation Element (PCE)",
RFC 8751, DOI 10.17487/RFC8751, March 2020,
<https://www.rfc-editor.org/info/rfc8751>.
[I-D.ietf-pce-pcep-yang]
Dhody, D., Beeram, V. P., Hardwick, J., and J. Tantsura,
"A YANG Data Model for Path Computation Element
Communications Protocol (PCEP)", Work in Progress,
Internet-Draft, draft-ietf-pce-pcep-yang-20, 23 October
2022, <https://datatracker.ietf.org/api/v1/doc/document/
draft-ietf-pce-pcep-yang/>.
Appendix A. Contributors
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Dhruv Dhody
Huawei Technologies
Divyashree Technopark, Whitefield
Bangalore, Karnataka 560066
India
Email: dhruv.ietf@gmail.com
Qin Wu
Huawei Technologies
China
Email: bill.wu@huawei.com
Xian Zhang
Huawei Technologies
China
Email: zhang.xian@huawei.com
Adrian Farrel
Old Dog Consulting
Email: adrian@olddog.co.uk
Authors' Addresses
Young Lee
Samsung
Seoul
South Korea
Email: younglee.tx@gmail.com
Haomian Zheng
Huawei Technologies
H1, Huawei Xiliu Beipo Village, Songshan Lake
Dongguan
Guangdong, 523808
China
Email: zhenghaomian@huawei.com
Daniele Ceccarelli
Ericsson
Torshamnsgatan,48
Stockholm
Sweden
Email: daniele.ceccarelli@ericsson.com
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