PCE Working Group Y. Lee
Internet-Draft Samsung
Intended status: Standards Track H. Zheng
Expires: October 18, 2020 Huawei Technologies
D. Ceccarelli
Ericsson
April 16, 2020
Path Computation Element communication Protocol (PCEP) extensions for
Establishing Relationships between sets of LSPs and Virtual Networks
draft-ietf-pce-vn-association-02
Abstract
This document describes how to extend Path Computation Element (PCE)
Communication Protocol (PCEP) association mechanism introduced by the
PCEP Association Group specification, to further associate sets of
LSPs with a higher-level structure such as a virtual network (VN)
requested by clients or applications. This extended association
mechanism can be used to facilitate virtual network control using PCE
architecture.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on October 18, 2020.
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document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
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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. Applicability to H-PCE architecture . . . . . . . . . . . . . 7
6. Implementation Status . . . . . . . . . . . . . . . . . . . . 8
6.1. Huawei's Proof of Concept based on ONOS . . . . . . . . . 9
7. Security Considerations . . . . . . . . . . . . . . . . . . . 9
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
8.1. Association Object Type Indicator . . . . . . . . . . . . 9
8.2. PCEP TLV Type Indicator . . . . . . . . . . . . . . . . . 9
8.3. PCEP Error . . . . . . . . . . . . . . . . . . . . . . . 10
9. Manageability Considerations . . . . . . . . . . . . . . . . 10
9.1. Control of Function and Policy . . . . . . . . . . . . . 10
9.2. Information and Data Models . . . . . . . . . . . . . . . 10
9.3. Liveness Detection and Monitoring . . . . . . . . . . . . 10
9.4. Verify Correct Operations . . . . . . . . . . . . . . . . 10
9.5. Requirements On Other Protocols . . . . . . . . . . . . . 11
9.6. Impact On Network Operations . . . . . . . . . . . . . . 11
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 11
10.1. Normative References . . . . . . . . . . . . . . . . . . 11
10.2. Informative References . . . . . . . . . . . . . . . . . 12
Appendix A. Contributors . . . . . . . . . . . . . . . . . . . . 13
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 Path Computation Clients' (PCCs)
requests.
[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. A stateful PCE has access to not only the information
carried by the network's Interior Gateway Protocol (IGP), but also
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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 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 association between
sets of LSPs or between a set of LSPs and a set of attributes.
[RFC8453] describes various Virtual Network (VN) operations initiated
by a customer/application. In this context, there is a need for
associating a set of LSPs with a VN "construct" to facilitate VN
operations in PCE architecture. This association allows the PCEs to
identify which LSPs belong to a certain VN. The PCE could then use
this association to optimize all LSPs belonging to the VN together.
The PCE could further take VN specific actions on the LSPs such as
relaxation of constraints, policy actions, setting default behavior
etc.
[RFC8637] examines the PCE and ACTN architecture 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 PCE(s) and thus
making it the base for PCE applicability for ACTN. In this text
child PCE would be same as Provisioning Network Controller (PNC), and
the parent PCE as Multi-domain Service Coordinator (MDSC) [RFC8453].
This document specifies a PCEP extension to associate a set of LSPs
based on Virtual Network (VN) (or customer). A Virtual Network (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 as described in [RFC8453].
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 not limited to -
o Path Computation: When computing path for a LSP, the impact of
this LSP, on the other LSPs belonging to the same VN is useful to
analyze. The aim would be optimize overall VN and all LSPs,
rather than a single LSP. Also, the optimization criteria such as
minimize the load of the most loaded link (MLL) [RFC5541] and
other could be applied for all the LSP belonging to the same VN,
identified by the VN association.
o Path Re-Optimization: The child PCE or the parent PCE would like
to use advanced path computation algorithm and optimization
technique that consider all the LSPs belonging to a VN/customer
and optimize them all together during the re-optimization.
This association is useful in PCEP session between parent PCE (MDSC)
and child PCE (PNC). When computing the path, the child PCE (PNC)
refer to the VN association in the request from the parent PCE (MDSC)
and maps the VN to the associated LSPs and the network resources.
Based on this information, operator policy and various constraints,
the path is computed and replied to the parent PCE (MDSC). The VN
association information could be included as a part of response as
well. The figure describes a typical VN operations using PCEP for
illustration purpose. It is worth noting that in a multi-domain
scenario, the different domain is controlled by different child PCEs.
In order to set up the end-to-end tunnel, multiple segments need to
be stitched, by the border nodes in each domain who receives the
instruction from their child PCE (PNC).
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******
..........*MDSC*..............................
. ****** .. MPI .
. . . PCEP .
. . . PCInitiate LSPx .
. . . with VNAG = 10 .
. . . .
. . . .
. . . .
v v v .
****** ****** ****** .
*PNC1* *PNC2* *PNC4* .
****** ****** ****** .
+---------------+ +---------------+ +---------------+ .
|A |----| |----| C| .
| | | | | | .
|DOMAIN 1 |----|DOMAIN 2 |----|DOMAIN 4 | .
+------------B13+ +---------------+ +B43------------+ .
/ .
****** / .
*PNC3*<............/.....................
****** /
+---------------+/
B31 B34
| |
|DOMAIN 3 B|
+---------------+
MDSC -> Parent PCE
PNC -> Child PCE
MPI -> PCEP
In this draft, this grouping is used to define associations between a
set of LSPs and a virtual network, a new association group is defined
below -
o VN Association Group (VNAG)
One new Association type is defined as described in the Association
object -
o Association type = TBD1 ("VN Association") for VNAG
The scope and handling of VNAG identifier is similar to the generic
association identifier defined in [RFC8697] .
In this document VNAG object refers to an Association Object with the
Association type set to "VNAG".
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Local polices on the PCE MAY 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, it MUST consider the first occurrence and ignore the others.
[RFC8697] specify the mechanism for the capability advertisement of
the association types supported by a PCEP speaker by defining a
ASSOC-Type-List TLV to be carried within an OPEN object. This
capability exchange for the association type described in this
document (i.e. VN Association Type) MUST be done before using the
policy association. Thus the PCEP speaker MUST include the VN
Association Type (TBD1) in the ASSOC-Type-List TLV before using the
VNAG in the PCEP messages.
This Association-Type is dynamic in nature and created by the Parent
PCE (MDSC) for the LSPs belonging to the same VN or customer. These
associations are conveyed via PCEP messages to the PCEP peer.
Operator-configured Association Range MUST NOT be set for this
association-type and MUST be ignored.
4. Extensions to PCEP
The format of VNAG is as per the ASSOCIATION object [RFC8697].
This document defines one mandatory TLV "VIRTUAL-NETWORK-TLV" and one
new optional TLV "VENDOR-INFORMATION-TLV"; apart from this TLV,
VENDOR-INFORMATION-TLV can be used to carry arbitrary vendor specific
information.
o VIRTUAL-NETWORK-TLV: Used to communicate the VN Identifier.
o 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 Name //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: The VIRTUAL-NETWORK-TLV formats
Type: TBD2 (to be allocated by IANA)
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Length: Variable Length
Virtual Network Name (variable): an unique symbolic name for the VN.
It SHOULD be a string of printable ASCII characters, without a NULL
terminator. The VN name is a human-readable string that identifies a
VN and can be specified with the association information. An
implementation could use the VN name to maintain a mapping to the VN
association group and the LSPs associated with the VN. The VN name
MAY be specified by an operator 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].
5. Applicability to H-PCE architecture
The ability to compute shortest constrained TE LSPs in Multiprotocol
Label Switching (MPLS) and Generalized MPLS (GMPLS) networks across
multiple domains has been identified as a key motivation for PCE
development. [RFC6805] describes a Hierarchical PCE (H-PCE)
architecture which can be used for computing end-to-end paths for
inter-domain MPLS Traffic Engineering (TE) and GMPLS Label Switched
Paths (LSPs). Within the hierarchical PCE architecture, the parent
PCE is used to compute a multi-domain path based on the domain
connectivity information. A child PCE may be responsible for a
single domain or multiple domains, it is used to compute the intra-
domain path based on its domain topology information.
[RFC8751] introduces general considerations for stateful PCE(s) in
hierarchical PCE architecture. In particular, the behavior changes
and additions to the existing stateful PCE mechanisms in the context
of a H-PCE architecture.
In Stateful H-PCE architecture, the Parent PCE receives a virtual
network creation request by its client over its Northbound API. This
VN is uniquely identified by an Association ID in VNAG as well as the
VIRTUAL-NETWORK name. This VN may comprise multiple LSPs in the
network in a single domain or across multiple domains.
As the Parent PCE computes the optimum E2E paths for each tunnel in
VN, it MUST associate each LSP with the VN to which it belongs.
Parent PCE sends a PCInitiate Message with this association
information in the VNAG Object (See Section 4 for details). This in
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effect binds an LSP that is to be instantiated at the child PCE with
the VN.
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 (via the
client's request), the parent PCE sends an PCUpd Message to inform
each affected child PCE of this change.
The Child PCE could then use this association to optimize all LSPs
belonging to the same VN association together. The Child PCE could
further take VN specific actions on the LSPs such as relaxation of
constraints, policy actions, setting default behavior etc. The
parent PCE could also maintain all E2E LSP or per-domain path
segments under a single VN association.
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".
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6.1. 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.
o Organization: Huawei
o Implementation: Huawei's PoC based on ONOS
o 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
o Maturity Level: Prototype
o Coverage: Full
o Contact: satishk@huawei.com
7. Security Considerations
This document defines one new type for association, which do not add
any new security concerns beyond those discussed in [RFC5440],
[RFC8231] and [RFC8697] in itself.
Some deployments may find the Virtual Network Name and the VN
associations as extra sensitive; and thus should employ suitable PCEP
security mechanisms like TCP-AO [RFC5925] or [RFC8253].
8. IANA Considerations
8.1. Association Object Type Indicator
This document defines a new association type, originally defined in
[RFC8697], for path protection. IANA is requested to make the
assignment of a new value for the sub-registry "ASSOCIATION Type
Field" (request to be created in [RFC8697]), as follows:
Value Name Reference
TBD1 VN Association Type [This I.D.]
8.2. PCEP TLV Type Indicator
This document defines a new TLV for carrying additional information
of LSPs within a path protection association group. IANA is
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requested to make the assignment of a new value for the existing
"PCEP TLV Type Indicators" registry as follows:
Value Name Reference
TBD2 VIRTUAL-NETWORK-TLV [This I.D.]
8.3. PCEP Error
This document defines new Error-Type and Error-Value related to path
protection association. IANA is requested to allocate new error
values within the "PCEP-ERROR Object Error Types and Values" sub-
registry of the PCEP Numbers registry, as follows:
Error-Type Meaning
6 Mandatory Object missing
Error-value=TBD3: VIRTUAL-NETWORK TLV missing [This
I.D.]
9. Manageability Considerations
9.1. 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.
9.2. Information and Data Models
The PCEP YANG module [I-D.ietf-pce-pcep-yang] should support the
association between LSPs including VN association.
9.3. 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].
9.4. Verify Correct Operations
Mechanisms defined in this document do not imply any new operation
verification requirements in addition to those already listed in
[RFC5440].
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9.5. Requirements On Other Protocols
Mechanisms defined in this document do not imply any new requirements
on other protocols.
9.6. Impact On Network Operations
Mechanisms defined in this document do not have any impact on network
operations in addition to those already listed in [RFC5440].
10. References
10.1. 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>.
[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>.
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10.2. Informative References
[RFC4655] Farrel, A., Vasseur, J., 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>.
[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>.
[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>.
[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>.
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[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>.
[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>.
Appendix A. Contributors
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
Authors' Addresses
Young Lee
Samsung
Seoul
South Korea
Email: younglee.tx@gmail.com
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Haomian Zheng
Huawei Technologies
H1-1-A043S Huawei Industrial Base, Songshanhu
Dongguan, Guangdong 523808
China
Email: zhenghaomian@huawei.com
Daniele Ceccarelli
Ericsson
Torshamnsgatan,48
Stockholm
Sweden
Email: daniele.ceccarelli@ericsson.com
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