PCEP Extension for Distribution of Link-State and TE information for Optical Networks
draft-lee-pce-pcep-ls-optical-01
The information below is for an old version of the document.
| Document | Type |
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|---|---|---|---|
| Authors | Young Lee , Haomian Zheng , Daniele Ceccarelli , Wei Wang , Peter Choongul Park , Bin Yeong Yoon | ||
| Last updated | 2017-03-05 | ||
| RFC stream | (None) | ||
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draft-lee-pce-pcep-ls-optical-01
PCE Working Group Young Lee
Haomian Zheng
Internet Draft Huawei
Intended Status: Standard
Expires: September 2017 Daniele Ceccarelli
Ericsson
Wei Wang
Beijing Univ. of Posts and Telecom
Peter Park
KT
Bin Young Yoon
ETRI
March 5, 2017
PCEP Extension for Distribution of Link-State and TE information for
Optical Networks
draft-lee-pce-pcep-ls-optical-01
Abstract
In order to compute and provide optimal paths, Path Computation
Elements (PCEs) require an accurate and timely Traffic Engineering
Database (TED). Traditionally this Link State and TE information has
been obtained from a link state routing protocol (supporting traffic
engineering extensions).
This document extends the Path Communication Element Communication
Protocol (PCEP)_with Link-State and TE information for optical
networks.
Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with
the provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
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Internet-Draft PCEP LS for Optical Networks March 2017
other groups may also distribute working documents as Internet-
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This Internet-Draft will expire on September 5, 2017.
Copyright Notice
Copyright (c) 2017 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
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Table of Contents
1. Introduction...................................................3
2. Applicability..................................................5
3. Requirements for PCEP extension................................6
4. PCEP-LS extension for Optical Networks.........................6
4.1. Node Attributes TLV.......................................6
4.2. Link Attributes TLV.......................................7
5. PCEP-LS for Optical Network Abstraction........................8
6. Security Considerations........................................8
7. IANA Considerations............................................9
7.1. PCEP-LS Sub-TLV Type Indicators...........................9
8. References....................................................10
8.1. Normative References.....................................10
8.2. Informative References...................................11
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Appendix A. Contributor Addresses................................12
Author's Addresses...............................................13
1. Introduction
In Multiprotocol Label Switching (MPLS) and Generalized MPLS
(GMPLS), a Traffic Engineering Database (TED) is used in computing
paths for connection oriented packet services and for circuits. The
TED contains all relevant information that a Path Computation
Element (PCE) needs to perform its computations. It is important
that the TED should be complete and accurate anytime so that the PCE
can perform path computations.
In MPLS and GMPLS networks, Interior Gateway routing Protocols
(IGPs) have been used to create and maintain a copy of the TED at
each node. One of the benefits of the PCE architecture [RFC4655] is
the use of computationally more sophisticated path computation
algorithms and the realization that these may need enhanced
processing power not necessarily available at each node
participating in an IGP.
Section 4.3 of [RFC4655] describes the potential load of the TED on
a network node and proposes an architecture where the TED is
maintained by the PCE rather than the network nodes. However it does
not describe how a PCE would obtain the information needed to
populate its TED. PCE may construct its TED by participating in the
IGP ([RFC3630] and [RFC5305] for MPLS-TE; [RFC4203] and [RFC5307]
for GMPLS). An alternative is offered by [BGP-LS].
[RFC7399] touches upon this issue: "It has also been proposed that
the PCE Communication Protocol (PCEP) [RFC5440] could be extended to
serve as an information collection protocol to supply information
from network devices to a PCE. The logic is that the network devices
may already speak PCEP and so the protocol could easily be used to
report details about the resources and state in the network,
including the LSP state discussed in Sections 14 and 15."
[Stateful-PCE] 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. PCC can delegate the rights to modify the LSP
parameters to an Active Stateful PCE. This requires PCE to quickly
be updated on any changes in the Topology and TEDB, so that PCE can
meet the need for updating LSPs effectively and in a timely manner.
The fastest way for a PCE to be updated on TED changes is via a
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direct interface with each network node and with incremental update
from each network node.
[PCE-initiated] describes the setup, maintenance and teardown of
PCE-initiated LSPs under the stateful PCE model, without the need
for local configuration on the PCC, thus allowing for a dynamic
network that is centrally controlled and deployed. This model
requires timely topology and TED update at the PCE.
[PCEP-LS-Arch] proposes alternative architecture approaches for
learning and maintaining the Link State (and TE) information
directly on a PCE from network nodes as an alternative to IGPs and
BGP transport and investigate the impact from the PCE, routing
protocol, and network node perspectives.
[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 (H-PCE) architecture [RFC6805], the
Parent PCE (P-PCE) is used to compute a multi-domain path based on
the domain connectivity information. A Child PCE (C-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.
[Stateful H-PCE] presents general considerations for stateful PCE(s)
in hierarchical PCE architecture. In particular, the behavior
changes and additions to the existing stateful PCE mechanisms
(including PCE-initiated LSP setup and active PCE usage) in the
context of networks using the H-PCE architecture.
[PCEP-LS] describes a mechanism by which Link State and TE
information can be collected from packet networks and shared with
PCE with the PCEP itself. This is achieved using a new PCEP message
format.
[ACTN-Abstraction] describes various ways to support abstraction
topology including optical networks.
This draft describes an optical extension of [PCEP-LS] and explains
how encodings suggested by [PCEP-LS] can be used in the optical
network contexts. In the stateful H-PCE architecture, PCEP-LS is
applied in both C-PCE to NE as well as P-PCE to C-PCE. When PCEP-LS
is applied to P-PCE to C-PCE, the topology can be abstracted to hide
details of optical networks.
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2. Applicability
There are three main applicability of this alternative proposed by
this draft:
- Case 1: Where there is IGP running in optical network but
there is a need for a faster link-state and TE resource
collection at the PCE directly from an optical node (PCC) via
a PCC-PCE interface.
o A PCE may receive an incremental update (as opposed to
the entire TE information of the node/link).
Note: A PCE may receive full information from IGP using
existing mechanism. In some cases, the convergence of full
link-state and TE resource information of the entire network
may not be appropriate for certain applications. Incremental
update capability will enhance the accuracy of the TE
information at a given time.
- Case 2: Where there is no IGP running in the optical network
and there is a need for link-state and TE resource collections
at the PCE directly from an optical node (PCC) via a PCC-PCE
interface.
- Case 3: Where there is a need for transporting abstract
optical link-state and TE information from child PCE and to a
parent PCE in H-PCE [RFC6805] and [Stateful H-PCE] as well as
for Physical Network Controller (PNC) to Multi-Domain Service
Coordinator (MDSC) in Abstraction and Control of TE Networks
(ACTN) [ACTN-Frame]. [ACTN-Abstraction] discusses how
abstraction in optical networks can be done.
The applicability for Case 3 may arise as a consequence of
Case 1 and Case 2. When TE information changes occur in the
optical network, this may also affect abstracted TE
information and thus needs to be updated to Parent PCE/MSDC
from each child PCE/PNC.
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3. Requirements for PCEP extension
The key requirements associated with link-state (and TE)
distribution are identified for PCEP and listed in Section 4 of
[PCEP-LS]. These new functions required in PCEP to support
distribution of link-state (and TE) information are described in
Section 5 of [PCEP-LS]. Details of PCEP messages and related
Objects/TLVs are specified in Sections 8 and 9 of [PCEP-LS]. The key
requirements and new functions specified in [PCEP-LS] are equally
applicable to optical networks.
Section 4 in this draft will specify additional PCEP-LS extension
for Optical Networks. Section 5 will specify PCEP-LS extension for
Optical Network abstraction.
4. PCEP-LS extension for Optical Networks
This section provides additional PCEP-LS extension necessary to
support optical networks. All Objects/TLVs defined in [PCEP-LS] are
applicable to optical networks.
4.1. Node Attributes TLV
Node-Attributed TLV is defined in Section 9.2.10.1 in [PCEP-LS] as
follows. This TLV is applicable for LS Node Object-Type as defined
in [PCEP-LS].
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// Node Attributes Sub-TLVs (variable) //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The following 'Node Attribute' sub-TLVs are valid for optical
networks:
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+-----------+------------------+--------------+-------------------+
| Sub-TLV | Description | TLV/Sub-TLV | Length |Reference|
+-----------+------------------+--------------+---------+---------+
| TBD | Connectivity | 5/14 | variable|[RFC7579]|
| | Matrix | | |[RFC7580]|
| TBD | Resource Block | 6/1 | variable|[RFC7688]|
| | Information | | | |
| TBD | Resource Block | 6/2 | variable|[RFC7688]|
| | Accessibility | | | |
| TBD | Resource Block | 6/3 | variable|[RFC7688]|
| | Wavelength Const | | | |
| TBD | Resource Block | 6/4 | variable|[RFC7688]|
| | Pool State | | | |
| TBD | Resource Block | 6/5 | variable|[RFC7688]|
| | Shared Access | | | |
| | Wavelength Avail.| | | |
+------------------------------------------------------=----------+
4.2. Link Attributes TLV
Link-Attributes TLV is defined in Section 9.2.10.2 in [PCEP-LS] as
follows. This TLV is applicable for LS Link Object-Type as defined
in [PCEP-LS].
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// Link Attributes Sub-TLVs (variable) //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The following 'Link Attribute' sub-TLVs are valid for optical
networks:
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+-----------+-----------------+--------------+--------+----------+
| Sub-TLV | Description | TLV/Sub-TLV | Length |Reference |
| | | | | |
+-----------+-----------------+--------------+--------+----------+
| TBD | ISCD | 15 |Variable|[RFC4203] |
| | | | | |
| TBD | OTN-TDM SCSI | 15/1,2 |Variable|[RFC4203] |
| | | | |[RFC7138] |
| TBD | WSON-LSC SCSI | 15/1,2 |Variable|[RFC4203] |
| | | | |[RFC7688] |
| TBD | Flexi-grid SCSI | 15/1 |Variable|[FlexOSPF]|
| | | | | |
| TBD | Port Label | 34 |Variable|[RFC7579] |
| | Restriction | | |[RFC7580] |
| | | | |[FlexOSPF]|
+-----------+-----------------+--------------+--------+----------+
5. PCEP-LS for Optical Network Abstraction
This section provides additional PCEP-LS extension necessary to
support optical networks abstraction. Abstraction is primarily
applied to C-PCE and P-PCE although the same principle can be
applied to PCC (NE) to PCE.
Abstraction
For OTN networks, max bandwidth available may be per ODU 0/1/2/3
switching level or aggregated across all ODU switching levels (i.e.,
ODUj/k).
For WSON networks, max bandwidth available may be per
lambda/frequency level (OCh) or aggregated across all
lambda/frequency level. Per OCh level abstraction gives more
detailed data to the P-PCE at the expense of more information
processing. Either OCh-level or aggregated level abstraction should
factor in the RWA constraint (i.e., wavelength continuity) at the C-
PCE level. This means the C-PCE should have this capability and
advertise it as such.
6. Security Considerations
This document extends PCEP for LS (and TE) distribution including a
set of TLVs. Procedures and protocol extensions defined in this
document do not effect the overall PCEP security model. See
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[RFC5440], [I-D.ietf-pce-pceps]. The PCE implementation SHOULD
provide mechanisms to prevent strains created by network flaps and
amount of LS (and TE) information. Thus it is suggested that any
mechanism used for securing the transmission of other PCEP message
be applied here as well. As a general precaution, it is RECOMMENDED
that these PCEP extensions only be activated on authenticated and
encrypted sessions belonging to the same administrative authority.
7. IANA Considerations
This document requests IANA actions to allocate code points for the
protocol elements defined in this document.
7.1. PCEP-LS Sub-TLV Type Indicators
This document specifies a set of PCEP-LS Sub-TLVs. IANA is requested
to create an "PCEP-LS Sub-TLV Types" sub-registry in the "PCEP TLV
Type Indicators" for the sub-TLVs carried in the PCEP-LS TLV (Node
Attributes TLV and Link Attributes TLV).
+-----------+------------------+--------------+----------+
| Sub-TLV | Description | Ref Sub-TLV | Reference|
+-----------+------------------+--------------+----------+
| TBD | Connectivity | 5/14 | [RFC7579]|
| | Matrix | | [RFC7580]|
| TBD | Resource Block | 6/1 | [RFC7688]|
| | Information | | |
| TBD | Resource Block | 6/2 | [RFC7688]|
| | Accessibility | | |
| TBD | Resource Block | 6/3 | [RFC7688]|
| | Wavelength Const | | |
| TBD | Resource Block | 6/4 | [RFC7688]|
| | Pool State | | |
| TBD | Resource Block | 6/5 | [RFC7688]|
| | Shared Access | | |
| | Wavelength Avail.| | |
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| TBD | ISCD | 15 |[RFC4203] |
| | | | |
| TBD | OTN-TDM SCSI | 15/1,2 |[RFC4203] |
| | | |[RFC7138] |
| TBD | WSON-LSC SCSI | 15/1,2 |[RFC4203] |
| | | |[RFC7688] |
| TBD | Flexi-grid SCSI | 15/1 |[FlexOSPF]|
| | | | |
| TBD | Port Label | 34 |[RFC7579] |
| | Restriction | |[RFC7580] |
| | | |[FlexOSPF]|
+-----------+------------------+--------------+----------+
8. References
8.1. Normative References
[RFC4655] Farrel, A., Vasseur, J.-P., and J. Ash, "A Path
Computation Element (PCE)-Based Architecture", RFC 4655,
August 2006.
[RFC4674] Le Roux, J., Ed., "Requirements for Path Computation
Element (PCE) Discovery", RFC 4674, October 2006.
[RFC5088] Le Roux, JL., Ed., Vasseur, JP., Ed., Ikejiri, Y., and R.
Zhang, "OSPF Protocol Extensions for Path Computation
Element (PCE) Discovery", RFC 5088, January 2008.
[RFC5089] Le Roux, JL., Ed., Vasseur, JP., Ed., Ikejiri, Y., and R.
Zhang, "IS-IS Protocol Extensions for Path Computation
Element (PCE) Discovery", RFC 5089, January 2008.
[RFC5250] Berger, L., Bryskin, I., Zinin, A., and R. Coltun, "The
OSPF Opaque LSA Option", RFC 5250, July 2008.
[RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic
Engineering", RFC 5305, October 2008.
[RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
Element (PCE) Communication Protocol (PCEP)", RFC 5440,
March 2009.
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8.2. Informative References
[JMS] Java Message Service, Version 1.1, April 2002, Sun
Microsystems.
[RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic
Engineering (TE) Extensions to OSPF Version 2", RFC 3630,
September 2003.
[RFC4203] Kompella, K., Ed. and Y. Rekhter, Ed., "OSPF Extensions
in Support of Generalized Multi-Protocol Label Switching
(GMPLS)", RFC 4203, October 2005.
[RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation
Element (PCE)-Based Architecture", RFC 4655, August 2006.
[BGP-LS] Gredler, H., Medved, J., Previdi, S., Farrel, A., and
S.Ray, "North-Bound Distribution of Link-State and TE
information using BGP", draft-ietf-idr-ls-distribution,
work in progress.
[S-PCE-GMPLS] X. Zhang, et. al, "Path Computation Element (PCE)
Protocol Extensions for Stateful PCE Usage in GMPLS-
controlled Networks", draft-ietf-pce-pcep-stateful-pce-
gmpls, work in progress.
[RFC7399] A. Farrel and D. king, "Unanswered Questions in the Path
Computation Element Architecture", RFC 7399, October 2015.
[RFC7449] Y. Lee, G. Bernstein, "Path Computation Element
Communication Protocol (PCEP) Requirements for Wavelength
Switched Optical Network (WSON) Routing and Wavelength
Assignment", RFC 7449, February 2015.
[RFC4456] Bates, T., Chen, E., and R. Chandra, "BGP Route
Reflection: An Alternative to Full Mesh Internal BGP
(IBGP)", RFC 4456, April 2006.
[RFC6163] Y. Lee, G. Bernstein, W. Imajuku, "Framework for GMPLS
and PCE Control of Wavelength Switched Optical Networks",
RFC 6163,
[G.680] ITU-T Recommendation G.680, Physical transfer functions of
optical network elements, July 2007.
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[ACTN-Frame] D.Ceccarelli, and Y. Lee (Editors), "Framework for
Abstraction and Control of TE Networks", draft-ietf-teas-
actn-framework, work in progress.
[RFC6805] A. Farrel and D. King, "The Application of the Path
Computation Element Architecture to the Determination of a
Sequence of Domains in MPLS and GMPLS", RFC 6805, November
2012.
[PCEP-LS-Arch] Y. Lee, D. Dhody and D. Ceccarelli, "Architecture and
Requirement for Distribution of Link-State and TE
Information via PCEP", draft-leedhody-teas-pcep-ls, work
in progress.
[PCEP-LS] D. Dhody, Y. Lee and D. Ceccarelli "PCEP Extension for
Distribution of Link-State and TE Information.", work in
progress, September 21, 2015[Stateful-PCE] Crabbe, E.,
Minei, I., Medved, J., and R. Varga, "PCEP Extensions for
Stateful PCE", draft-ietf-pce-stateful-pce, work in
progress.
[PCE-Initiated] Crabbe, E., Minei, I., Sivabalan, S., and R. Varga,
"PCEP Extensions for PCE-initiated LSP Setup in a Stateful
PCE Model", draft-ietf-pce-pce-initiated-lsp, work in
progress.
[Stateful H-PCE] D. Dhody, Y. Lee and D. Ceccarelli, "Hierarchical
Stateful Path Computation Element (PCE)", draft-dhodylee-
pce-stateful-hpce, work-in-progress.
[FlexOSPF] X. Zhang, H. Zheng, R. Casellas, O. Gonzalez de Dios, D.
Ceccarelli, "GMPLS OSPF Extensions in support of Flexi-
grid DWDM networks", draft-ietf-ccamp-flexible-grid-ospf-
ext-05, work in progress.
[ACTN-Abstraction] Y. Lee, D. Dhody. D. Ceccarelli, and O. D. de
Dios, "Abstraction and Control of TE Networks (ACTN)
Abstraction Methods", draft-lee-teas-actn-abstraction,
work in progress.
Appendix A. Contributor Addresses
Dhruv Dhody
Huawei Technologies
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Divyashree Techno Park, Whitefield
Bangalore, Karnataka 560066
India
Email: dhruv.ietf@gmail.com
Author's Addresses
Young Lee
Huawei Technologies
5340 Legacy Drive, Building 3
Plano, TX 75023, USA
Email: leeyoung@huawei.com
Haomian Zheng
Huawei Technologies Co., Ltd.
F3-1-B R&D Center, Huawei Base,
Bantian, Longgang District
Shenzhen 518129 P.R.China
Email: zhenghaomian@huawei.com
Daniele Ceccarelli
Ericsson
Torshamnsgatan,48
Stockholm
Sweden
EMail: daniele.ceccarelli@ericsson.com
Wei Wang
Beijing University of Posts and Telecom
No. 10, Xitucheng Rd. Haidian District, Beijing 100876, P.R.China
Email: weiw@bupt.edu.cn
Peter Park
KT
Email: peter.park@kt.com
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Bin Yeong Yoon
ETRI
Email: byyun@etri.re.kr
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