wdiff rfc7449.original rfc7449.txt

Network Working Group Y. Lee
Internet Draft Engineering Task Force (IETF) Y. Lee, Ed.
Request for Comments: 7449 Huawei
Intended status:
Category: Informational G. Bernstein
Expires: April 2015 Bernstein, Ed.
ISSN: 2070-1721 Grotto Networking
Jonas
J. Martensson
Acreo
T. Takeda
NTT
T. Tsuritani
KDDI
O. G. Gonzalez de Dios
Telefonica

October 28, 2014

PCEP
January 2015

Path Computation Element Communication Protocol (PCEP) Requirements
for WSON Wavelength Switched Optical Network (WSON)
Routing and Wavelength Assignment

draft-ietf-pce-wson-routing-wavelength-15.txt

Abstract

This memo provides application-specific requirements for the Path
Computation Element communication Communication Protocol (PCEP) for the support of
Wavelength Switched Optical Networks (WSON). (WSONs). Lightpath provisioning
in WSONs requires a routing Routing and wavelength assignment Wavelength Assignment (RWA) process.
From a path computation perspective, wavelength assignment is the
process of determining which wavelength can be used on each hop of a
path and forms an additional routing constraint to optical light path
computation. Requirements for PCEP extensions in support of optical
impairments will be addressed in a separate document.

Status of this This Memo

This Internet-Draft document is submitted to IETF in full conformance with
the provisions of BCP 78 and BCP 79.

Internet-Drafts are working documents not an Internet Standards Track specification; it is
published for informational purposes.

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The list level of Internet
Standard; see Section 2 of RFC 5741.

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This Internet-Draft will expire on April 28, 2009.
http://www.rfc-editor.org/info/rfc7449.

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described in the Simplified BSD License.

Conventions used in this document

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 [RFC2119].

Table of Contents

1. Introduction...................................................3 Introduction ....................................................3
2. WSON RWA Processes & Architecture..............................4 and Architecture .............................4
3. Requirements...................................................6 Requirements ....................................................5
3.1. Path Computation Type Option..............................6 Option ...............................5
3.2. RWA Processing............................................6 Processing .............................................6
3.3. Bulk RWA Path Request/Reply...............................7 Request/Reply ................................6
3.4. RWA Path Re-optimization Request/Reply....................7 Reoptimization Request/Reply ......................7
3.5. Wavelength Range Constraint...............................8 Constraint ................................7
3.6. Wavelength Assignment Preference..........................8 Preference ...........................7
3.7. Signal Processing Signal-Processing Capability Restriction..................8 Restriction ...................8
4. Manageability Considerations...................................9 Considerations ....................................8
4.1. Control of Function and Policy............................9 Policy .............................8
4.2. Information and Data Models, e.g. Models (e.g., MIB module..............9 Module) .............9
4.3. Liveness Detection and Monitoring........................10 Monitoring ..........................9
4.4. Verifying Correct Operation..............................10 Operation ................................9
4.5. Requirements on Other Protocols and Functional Components10 Components ..9
4.6. Impact on Network Operation..............................10 Operation ................................9
5. Security Considerations.......................................10 Considerations .........................................9
6. IANA Considerations...........................................11
7. Acknowledgments...............................................11
8. References....................................................11
8.1. References .....................................................10
6.1. Normative References.....................................11
8.2. References ......................................10
6.2. Informative References...................................11 References ....................................10
Acknowledgments....................................................11
Authors' Addresses...............................................12
Intellectual Property Statement..................................13
Disclaimer of Validity...........................................13 Addresses.................................................11

1. Introduction

[RFC4655] defines the PCE-based architecture and explains how a Path
Computation Element (PCE) may compute Label Switched Paths (LSP) (LSPs) in
networks controlled by Multiprotocol Label Switching Traffic
Engineering (MPLS-TE) and Generalized MPLS (GMPLS)-controlled networks (GMPLS) at the request of
Path Computation Clients (PCCs). A PCC is shown to be any network
component that makes such a request and may be be, for instance instance, an
optical switching element within a Wavelength Division Multiplexing
(WDM) network. The PCE, itself, PCE itself can be located anywhere within the
network, and
network; it may be within an optical switching element, a Network
Management System (NMS) (NMS), or an Operational Support System (OSS), or
it may be an independent network server.

The PCE communication Path Computation Element Communication Protocol (PCEP) is the
communication protocol used between a PCC and PCE, and PCE; it may also be
used between cooperating PCEs. [RFC4657] sets out the common
protocol requirements for PCEP. Additional application-specific
requirements for PCEP are deferred to separate documents.

This document provides a set of application-specific PCEP
requirements for support of path computation in Wavelength Switched
Optical Networks (WSON). (WSONs). WSON refers to WDM-based optical networks
in which switching is performed selectively based on the wavelength
of an optical signal.

The path in WSON is referred to as a lightpath. A lightpath may span
multiple fiber links links, and the path should be assigned a wavelength
for each link.

A transparent optical network is made up of optical devices that can
switch but not convert from one wavelength to another. In a
transparent optical network, a lightpath operates on the same
wavelength across all fiber links that it traverses. In such case, cases,
the lightpath is said to satisfy the wavelength-continuity
constraint. Two lightpaths that share a common fiber link cannot be
assigned the same wavelength. To do otherwise would result in both
signals interfering with each other. Note that advanced additional
multiplexing techniques such as polarization based polarization-based multiplexing are
not addressed in this document since the physical layer physical-layer aspects are
not currently standardized. Therefore, assigning the proper
wavelength on a lightpath is an essential requirement in the optical
path computation process.

When a switching node has the ability to perform wavelength
conversion
conversion, the wavelength-continuity constraint can be relaxed, and
a lightpath may use different wavelengths on different links along
its path from origin to destination. It is, however, to be noted
that wavelength converters may be limited for cost reasons, while the
number of WDM channels that can be supported in a fiber is also
limited. As a WSON can be composed of network nodes that cannot
perform wavelength conversion, nodes with limited wavelength
conversion, and nodes with full wavelength conversion abilities,
wavelength assignment is an additional routing constraint to be
considered in all lightpath computations.

In this document document, we first review the processes for routing Routing and
wavelength assignment
Wavelength Assignment (RWA) used when wavelength continuity
constraints are present and then specify requirements for PCEP to
support RWA. Requirements for optical impairments will be addressed
in a separate document.

The remainder of this document uses terminology from [RFC4655].

2. WSON RWA Processes & Architecture

In [RFC6163] three alternative process architectures were given for
performing routing

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 [RFC2119].

2. WSON RWA Processes and Architecture

In [RFC6163], three alternative process architectures were given for
performing routing and wavelength assignment. These are shown
schematically in Figure 1. 1, where R stands for Routing, WA for
Wavelength Assignment, and DWA for Distributed Wavelength Assignment.

+-------------------+
| +-------+ +--+ | +-------+ +--+ +-------+ +---+
| | R | |WA| | | R |--->|WA| | R |--->|DWA|
| +-------+ +--+ | +-------+ +--+ +-------+ +---+
| Combined | Separate Processes Separate Processes
| Processes Process | WA performed in a
+-------------------+ distributed manner
(a) (b) (b')

Figure 1. 1: RWA process alternatives Process Alternatives

These alternatives have the following properties and impact on PCEP
requirements in this document.

(a) Combined Processes Process (R&WA)

Here path

Path selection and wavelength assignment are performed as a
single process. The requirements for PCC-PCE interaction with a
PCE implementing such a combined RWA process PCE is are addressed in
this document.

(b) Routing separate Separate from Wavelength Assignment (R+WA)

Here the

The routing process furnishes one or more potential paths to the
wavelength assignment process that then performs final path
selection and wavelength assignment. The requirements for
PCE-PCE PCE-
PCE interaction with one PCE implementing the routing process
and another implementing the wavelength assignment process are
not addressed in this document.

(b') Routing and distributed Distributed Wavelength Assignment (R+DWA)

Here a

A standard path computation (unaware of detailed wavelength
availability) takes place, and then wavelength assignment is
performed along this path in a distributed manner via signaling
(RSVP-TE). This alternative is a particular case of R+WA and it
should be covered by GMPLS PCEP
extensions and extensions; it does not present
new WSON-specific requirements.

In the previous section

The various process architectures for implementing RWA have been reviewed.
reviewed above. Figure 2 shows one typical PCE-
based PCE-based implementation,
which is referred to as the Combined Process (R&WA). With this
architecture, the two processes of routing and wavelength assignment
are accessed via a single PCE. This architecture is the base
architecture from which the requirements are specified in this
document.

+----------------------------+
+-----+ | +-------+ +--+ |
| | | |Routing| |WA| |
| PCC |<----->| +-------+ +--+ |
| | | |
+-----+ | PCE |
+----------------------------+

Figure 2. 2: Combined Process (R&WA) architecture Architecture

3. Requirements

The requirements for the PCC to PCE PCC-to-PCE interface of Figure 2 are
specified in this section.

3.1. Path Computation Type Option

A PCEP request MAY include the path computation type. This can be:

(i)

(a) Both Routing and Wavelength Assignment (RWA),

(ii) RWA, or

(b) Routing only.

This requirement is needed to differentiate between the currently
supported routing with distributed wavelength assignment option and
combined RWA. In case of For the distributed wavelength assignment option,
wavelength assignment will be performed at each node of the route.

3.2. RWA Processing

As discussed in Section 2, various RWA processing options should be
supported in a PCEP request/reply.

(a) When the request is a an RWA path computation type, the request
MUST further include the wavelength assignment options. At the
minimum, the following option options should be supported:

(i) Explicit Label Control (ELC) [RFC3473]

(ii) A set of recommended labels for each hop. The PCC can
select the label based on local policy.

Note that option (ii) may also be used in R+WA or R+DWA.

(b) In case of a an RWA computation type, the response MUST include
the wavelength(s) assigned to the path and an indication of
which label assignment option has been applied (ELC or label
set).

(c) In the case where a valid path is not found, the response MUST
include why the path is not found (e.g., network disconnected,
wavelength not found, or both, etc.). Note that 'wavelength not
found' may include several sub-cases such as wavelength
continuity not met, unsupported FEC/Modulation type, etc.

3.3. Bulk RWA Path Request/Reply

Sending simultaneous path requests for "routing only" computation is
supported by the PCEP specification [RFC5440]. To remain consistent consistent,
the following requirements are added.

(a) A PCEP request MUST be able to specify an option for bulk RWA
path request. Bulk requests. A bulk path request is provides an ability to
request a number of simultaneous RWA path requests.

(b) The PCEP response MUST include the path and the assigned
wavelength assigned for each RWA path request specified in the original
bulk request.

3.4. RWA Path Re-optimization Reoptimization Request/Reply

This section provides a number of requirements concerning RWA path
reoptimization processing in PCEP.

(a) For a re-optimization reoptimization request, the request MUST provide both the
path and current wavelength to be re-optimized reoptimized and MAY include
the following options:

a. Re-optimize

(i) Reoptimize the path keeping the same wavelength(s)

b. Re-optimize

(ii) Reoptimize wavelength(s) keeping the same path

c. Re-optimize

(iii) Reoptimize allowing both the wavelength and the path to
change

(b) The corresponding response to the re-optimized reoptimized request MUST
provide the re-optimized reoptimized path and wavelengths even when the
request asked for the path or the wavelength to remain
unchanged.

(c) In the case that the new path is not found, the response MUST
include why the path is not found (e.g., network disconnected,
wavelength not found, or both, etc.). Note that 'wavelength not
found' may include several sub-cases such as wavelength
continuity not met, unsupported FEC/Modulation type, etc.

3.5. Wavelength Range Constraint

For any RWA computation type request, the requester (PCC) MUST be
allowed to specify a restriction on the wavelengths to be used. The
requester MAY use this option to restrict the assigned wavelength for
explicit label labels or label set. sets. This restriction may may, for example example,
come from the tuning ability of a laser transmitter, any optical
element, or a policy-based restriction.

Note that the requester (e.g., PCC) is not required to furnish any
range restrictions.

3.6. Wavelength Assignment Preference

1. A

In a network with wavelength conversion capabilities (e.g., sparse 3R
regenerators), a request SHOULD be able to indicate whether a single,
continuous wavelength should be allocated or not. In other words,
the requesting PCC SHOULD be able to specify the precedence of
wavelength continuity even if wavelength conversion is available.

(a) An RWA computation type request MAY include the requester
preference for, e.g., for random assignment, descending order, ascending
order, etc. A response SHOULD follow the requestor requester preference
unless it conflicts with the operator's policy.

(b) A request for two or more paths MUST allow the requester to
include an option constraining the paths to have the same
wavelength(s) assigned. This is useful in the case of
protection with a single transponder (e.g., 1+1 link disjoint
paths).

In a network with wavelength conversion capabilities (e.g. sparse 3R
regenerators), a request SHOULD be able to indicate whether a
single, continuous wavelength should be allocated or not. In other
words, the requesting PCC SHOULD be able to specify the precedence
of wavelength continuity even if wavelength conversion is available.

3.7. Signal Processing Signal-Processing Capability Restriction

Signal processing

Signal-processing compatibility is an important constraint for
optical path computation. The signal type for an end-to-end optical
path must match at the source and at the destination.

The PCC MUST be allowed to specify the signal type at the endpoints
(i.e., at the source and at the destination). The following signal signal-
processing capabilities should be supported at a minimum:

o Modulation Type List

o FEC Type List

The PCC MUST also be allowed to state whether transit modification is
acceptable for the above signal processing signal-processing capabilities.

4. Manageability Considerations

Manageability of WSON Routing and Wavelength Assignment (RWA) RWA with PCE must address the following considerations:
considerations.

4.1. Control of Function and Policy

In addition to the parameters already listed in Section 8.1 of
[RFC5440], a PCEP implementation SHOULD allow configuring the
following PCEP session parameters on a PCC:

o The ability to send a WSON RWA request.

In addition to the parameters already listed in Section 8.1 of
[RFC5440], a PCEP implementation SHOULD allow configuring the
following PCEP session parameters on a PCE:

o The support for WSON RWA.

o The maximum number of bulk path requests associated with WSON RWA
per request message.

These parameters may be configured as default parameters for any PCEP
session the PCEP speaker participates in, or may apply to a specific
session with a given PCEP peer or a specific group of sessions with a
specific group of PCEP peers.

4.2. Information and Data Models, e.g. MIB module Models

As this document only concerns the requirements to support WSON RWA,
no additional MIB module is defined in this document. However, the
corresponding solution draft document will list the information that should
be added to the PCE MIB module defined in [PCEP-MIB]. [RFC7420].

4.3. Liveness Detection and Monitoring

No new mechanism is defined in this

This document does not define any new mechanisms that implies imply any new
liveness detection and monitoring requirements in addition to those
already listed in section Section 8.3 of [RFC5440].

4.4. Verifying Correct Operation

No new mechanism is defined in this

This document does not define any new mechanisms that implies imply any new
verification requirements in addition to those already listed in
section
Section 8.4 of [RFC5440]

4.5. Requirements on Other Protocols and Functional Components

If PCE discovery mechanisms ([RFC5089] and [RFC5088]) were to be
extended for technology-specific capabilities, advertising WSON RWA
path computation capability should be considered.

4.6. Impact on Network Operation

No new mechanism is defined in this

This document does not define any new mechanisms that implies imply any new
network operation requirements in addition to those already listed in section
Section 8.6 of [RFC5440].

5. Security Considerations

This document has no requirement for a change to the security models
within PCEP [RFC5440]. However However, the additional information
distributed in order to address the RWA problem represents a
disclosure of network capabilities that an operator may wish to keep
private. Consideration should be given to securing this information.

Solutions that address the requirements in this document need to
verify that existing PCEP security mechanisms adequately protect the
additional network capabilities and must include new mechanisms as
necessary.

6. IANA Considerations

This informational document does not make any requests for IANA
action.

7. Acknowledgments

The authors would like to thank Adrian Farrel, Cycil Margaria and
Ramon Casellas for many helpful comments that greatly improved the
contents of this draft.

This document was prepared using 2-Word-v2.0.template.dot.

8. References

8.1.

6.1. Normative References

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. 1997,
<http://www.rfc-editor.org/info/rfc2119>.

[RFC4655] Farrel, A., Vasseur, J., J.-P., and J. Ash, "A Path
Computation Element (PCE)-Based Architecture", RFC 4655,
August 2006. 2006, <http://www.rfc-editor.org/info/rfc4655>.

[RFC5440] Vasseur, JP., Ed. Ed., and JL. Le Roux, Ed., "Path Computation
Element (PCE) communication Protocol", Communication Protocol (PCEP)", RFC 5440,
March
2009.

8.2. 2009, <http://www.rfc-editor.org/info/rfc5440>.

6.2. Informative References

[RFC3473] L. Berger, L., Ed., "Generalized Multi-Protocol Label
Switching (GMPLS) Signaling Resource ReserVation Protocol-Traffic Protocol-
Traffic Engineering (RSVP-TE) Extensions", RFC 3473,
January 2003. 2003, <http://www.rfc-editor.org/info/rfc3473>.

[RFC4657] Ash, J. J., Ed., and J. Le Roux, Ed., "Path Computation
Element (PCE) Communication Protocol Generic
Requirements", RFC 4657, September 2006.

[RFC6163] Y. Lee, G. Bernstein, W. Imajuku, "Framework for GMPLS
and PCE Control of Wavelength Switched Optical Networks",
RFC 6163, April 2011. 2006,
<http://www.rfc-editor.org/info/rfc4657>.

[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. 2008,
<http://www.rfc-editor.org/info/rfc5088>.

[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.

[PCEP-MIB] 2008,
<http://www.rfc-editor.org/info/rfc5089>.

[RFC6163] Lee, Y., Ed., Bernstein, G., Ed., and W. Imajuku,
"Framework for GMPLS and Path Computation Element (PCE)
Control of Wavelength Switched Optical Networks (WSONs)",
RFC 6163, April 2011,
<http://www.rfc-editor.org/info/rfc6163>.

[RFC7420] Koushik, K, et al., "PCE communication protocol(PCEP) A., Stephan, E., Zhao, Q., King, D., and J.
Hardwick, "Path Computation Element Communication Protocol
(PCEP) Management Information Base", draft-ietf-pce-pcep-mib,
work in progress. Base (MIB) Module", RFC
7420, December 2014,
<http://www.rfc-editor.org/info/rfc7420>.

Acknowledgments

The authors would like to thank Adrian Farrel, Cycil Margaria, and
Ramon Casellas for many helpful comments that greatly improved the
content of this document.

Authors' Addresses

Young Lee (Ed.) (editor)
Huawei Technologies
5340 Legacy Drive, Building 3
Plano, TX 75245, USA 75245
United States

Phone: (469)277-5838 (469) 277-5838
Email: leeyoung@huawei.com

Greg Bernstein (Ed.) (editor)
Grotto Networking
Fremont, CA, USA CA
United States

Phone: (510) 573-2237
Email:
EMail: gregb@grotto-networking.com

Jonas Martensson
Acreo
Email:Jonas.Martensson@acreo.se
Isafjordsgatan 22
164 40 Kista
Sweden

EMail: Jonas.Martensson@acreo.se
Tomonori Takeda
NTT Corporation
3-9-11, Midori-Cho
Musashino-Shi, Tokyo 180-8585, 180-8585
Japan
Email: takeda.tomonori@lab.ntt.co.jp

EMail: tomonori.takeda@ntt.com

Takehiro Tsuritani
KDDI R&D Laboratories, Inc.
2-1-15 Ohara Kamifukuoka Saitama, 356-8502. 356-8502
Japan

Phone: +81-49-278-7357
Email: +81-49-278-7806
EMail: tsuri@kddilabs.jp

Oscar Gonzalez de Dios
Telefonica Investigacion y Desarrollo
C/ Emilio Vargas 6
Distrito Telefonica, ed. Sur 3, Pta 3, Ronda de la Comunicacion
Madrid, 28043 28050
Spain

Phone: +34 91 3374013
Email: ogondio@tid.es 913129647
EMail: oscar.gonzalezdedios@telefonica.com