Network Working Group Y. Lee
Internet Draft Huawei
Intended status: Standard Track
Expires: September 2010 G. Bernstein
Grotto Networking
Jonas Martensson
Acreo
T. Takeda
NTT
T. Tsuritani
KDDI
March 1, 2010
PCEP Requirements for WSON Routing and Wavelength Assignment
draft-ietf-pce-wson-routing-wavelength-01.txt
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
other groups may also distribute working documents as Internet-
Drafts.
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."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html
This Internet-Draft will expire on August 1, 2010.
Copyright Notice
Lee & Bernstein Expires September 1, 2010 [Page 1]
Internet-Draft PCEP Extension for WSON RWA March 2010
Copyright (c) 2010 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
(http://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 extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the BSD License.
Abstract
This memo provides application-specific requirements for the Path
Computation Element communication Protocol (PCEP) for the support of
Wavelength Switched Optical Networks (WSON). Lightpath provisioning
in WSONs requires a routing and 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 Optical impairments will be addressed
in a separate document.
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 RFC-2119 0.
Table of Contents
1. Introduction...................................................3
1.1. WSON RWA Processes........................................4
2. WSON PCE Architectures and Requirements........................5
2.1. RWA PCC to PCE Interface..................................6
2.1.1. A new RWA path request...............................6
2.1.2. An RWA path re-optimization request..................6
2.1.3. Wavelength Range Constraint..........................6
3. Manageability Considerations...................................7
3.1. Control of Function and Policy............................7
3.2. Information and Data Models, e.g. MIB module..............8
3.3. Liveness Detection and Monitoring.........................8
Lee & Bernstein Expires September 1, 2010 [Page 2]
Internet-Draft PCEP Extension for WSON RWA March 2010
3.4. Verifying Correct Operation...............................8
3.5. Requirements on Other Protocols and Functional Components.8
3.6. Impact on Network Operation...............................8
4. Security Considerations........................................8
5. IANA Considerations............................................9
6. Acknowledgments................................................9
7. References.....................................................9
7.1. Normative References......................................9
7.2. Informative References...................................10
Authors' Addresses...............................................10
Intellectual Property Statement..................................11
Disclaimer of Validity...........................................12
1. Introduction
[RFC4655] defines the PCE based Architecture and explains how a Path
Computation Element (PCE) may compute Label Switched Paths (LSP) in
Multiprotocol Label Switching Traffic Engineering (MPLS-TE) and
Generalized MPLS (GMPLS) networks 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 for instance an Optical Switching
Element within a Wavelength Division Multiplexing (WDM) network. The
PCE, itself, can be located anywhere within the network, and may be
within an optical switching element, a Network Management System
(NMS) or Operational Support System (OSS), or may be an independent
network server.
The PCE communications Protocol (PCEP) is the communication protocol
used between PCC and PCE, and 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). 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 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
Lee & Bernstein Expires September 1, 2010 [Page 3]
Internet-Draft PCEP Extension for WSON RWA March 2010
case, the lightpath is said to satisfy the wavelength-continuity
constraint. Two lightpaths that share a common fiber link can not 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 multiplexing are
not addressed in this document since the 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 the wavelength-continuity constraint can be relaxed, and a
lightpath may use different wavelengths on different links along its
route from origin to destination. It is, however, to be noted that
wavelength converters may be limited due to their relatively high
cost, 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 computation.
In this document we first review the processes for routing and
wavelength assignment (RWA) used when wavelength continuity
constraints are present and then specify requirements for PCEP to
support RWA.
The remainder of this document uses terminology from [RFC4655].
1.1. WSON RWA Processes
In [WSON-Frame] three alternative process architectures were given
for performing routing and wavelength assignment. These are shown
schematically in Figure 1.
+-------------------+
| +-------+ +--+ | +-------+ +--+ +-------+ +---+
| |Routing| |WA| | |Routing|--->|WA| |Routing|--->|DWA|
| +-------+ +--+ | +-------+ +--+ +-------+ +---+
| Combined | Separate Processes Separate Processes
| Processes | WA performed in a
+-------------------+ Distributed manner
(a) (b) (c)
Figure 1 RWA process alternatives.
Lee & Bernstein Expires September 1, 2010 [Page 4]
Internet-Draft PCEP Extension for WSON RWA March 2010
These alternatives have the following properties and impact on PCEP
requirements in this document.
1. Combined Processes (R&WA) - Here path selection and wavelength
assignment are performed as a single process. The requirements for
PCC-PCE interaction with such a combined RWA process PCE is
addressed in this document.
2. Routing separate from Wavelength Assignment (R+WA) - Here 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
interaction with one PCE implementing the routing process and
another implementing the wavelength assignment process are not
addressed in this document.
3. Routing and distributed Wavelength Assignment (R+DWA) - Here a
standard path computation (unaware of detailed wavelength
availability) takes place, then wavelength assignment is performed
along this path in a distributed manner via signaling (RSVP-TE).
This alternative should be covered by existing or emerging GMPLS
PCEP extensions and does not present new WSON specific
requirements.
2. WSON PCE Architectures and Requirements
In the previous section we reviewed various process architectures for
implementing RWA. In Figure 2 we reduce these alternatives to one
typical PCE based implementation, which is referred to as Combined
Process (R&WA). In Figure 2 we show the two processes of routing and
wavelength assignment accessed via a single PCE.
+----------------------------+
+-----+ | +-------+ +--+ |
| | | |Routing| |WA| |
| PCC |<----->| +-------+ +--+ |
| | | |
+-----+ | PCE |
+----------------------------+
Figure 2 Combined Process (R&WA) architecture
Lee & Bernstein Expires September 1, 2010 [Page 5]
Internet-Draft PCEP Extension for WSON RWA March 2010
2.1. RWA PCC to PCE Interface
The requirements for the PCC to PCE interface of Figure 2 are
specified in this section.
2.1.1. A new RWA path request
1. The PCReq Message MUST include the path computation type. This can
be: RWA, or only routing. This requirement is needed to
differentiate between the currently supported routing with
distribute wavelength assignment option and combined RWA.
2. The PCRep Message MUST include the route, wavelengths assigned to
the route and an indicator that says if the path has passed an
optical quality check. In the case where a valid path is not
found, the PCRep Message MUST include why the path is not found
(e.g., no route, wavelength not found, etc.)
2.1.2. An RWA path re-optimization request
1. For a re-optimization request, the PCReq Message MUST provide the
path to be re-optimized and include the following options:
a. Re-optimize the path keeping the same wavelength(s)
b. Re-optimize wavelength(s) keeping the same path
c. Re-optimize allowing both wavelength and the path to change
2. The corresponding PCRep Message for the re-optimized request MUST
provide the Re-optimized path and wavelengths. In case that the
path is not found, the PCRep Message MUST include why the path is
not found (e.g., no route, wavelength not found, both route and
wavelength not found, etc.)
2.1.3. Wavelength Range Constraint
For any PCReq Message that is associated with a request for
wavelength assignment the requester (PCC) MUST be able to specify a
restriction on the wavelengths to be used.
Note that the requestor (PCC) is NOT required to furnish any range
restrictions. This restriction is to be interpreted by the PCE as a
Lee & Bernstein Expires September 1, 2010 [Page 6]
Internet-Draft PCEP Extension for WSON RWA March 2010
constraint on the tuning ability of the origination laser
transmitter.
2.1.4. Wavelength Policy Constraint
The PCReq Message May include specific operator's policy information
for WA (E.g., random assignment, descending order, ascending order,
etc.)
3. Manageability Considerations
Manageability of WSON Routing and Wavelength Assignment (RWA) with
PCE must address the following considerations:
3.1. Control of Function and Policy
In addition to the parameters already listed in Section 8.1 of
[PCEP], 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
[PCEP], 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 synchronized path requests associated with
WSON RWA per request message.
o A set of WSON RWA specific policies (authorized sender, request
rate limiter, etc).
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.
Lee & Bernstein Expires September 1, 2010 [Page 7]
Internet-Draft PCEP Extension for WSON RWA March 2010
3.2. Information and Data Models, e.g. MIB module
Extensions to the PCEP MIB module defined in [PCEP-MIB] should be
defined, so as to cover the WSON RWA information introduced in this
document. A future revision of this document will list the
information that should be added to the MIB module.
3.3. 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 section 8.3 of [PCEP].
3.4. Verifying Correct Operation
Mechanisms defined in this document do not imply any new verification
requirements in addition to those already listed in section 8.4 of
[PCEP]
3.5. Requirements on Other Protocols and Functional Components
The PCE Discovery mechanisms ([RFC5089] and [RFC5088]) may be used to
advertise WSON RWA path computation capabilities to PCCs.
3.6. Impact on Network Operation
Mechanisms defined in this document do not imply any new network
operation requirements in addition to those already listed in section
8.6 of [PCEP].
4. Security Considerations
This document has no requirement for a change to the security models
within PCEP [PCEP]. 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.
Lee & Bernstein Expires September 1, 2010 [Page 8]
Internet-Draft PCEP Extension for WSON RWA March 2010
5. IANA Considerations
A future revision of this document will present requests to IANA for
codepoint allocation.
6. Acknowledgments
The authors would like to thank Adrian Farrel for many helpful
comments that greatly improved the contents of this draft.
This document was prepared using 2-Word-v2.0.template.dot.
7. References
7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3471] Berger, L., "Generalized Multi-Protocol Label Switching
(GMPLS) Signaling Functional Description", RFC 3471,
January 2003.
[RFC3473] Berger, L., Ed., "Generalized Multi-Protocol Label
Switching (GMPLS) Signaling Resource ReserVation Protocol-
Traffic Engineering (RSVP-TE) Extensions", RFC 3473,
January 2003.
[RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation
Element (PCE)-Based Architecture", RFC 4655, August 2006.
[RFC4657] Ash, J. and J. Le Roux, "Path Computation Element (PCE)
Communication Protocol Generic Requirements", RFC 4657,
September 2006.
[PCEP] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
Element (PCE) communication Protocol (PCEP) - Version 1",
draft-ietf-pce-pcep, work in progress.
Lee & Bernstein Expires September 1, 2010 [Page 9]
Internet-Draft PCEP Extension for WSON RWA March 2010
7.2. Informative References
[WSON-Frame] Bernstein, G. and Lee, Y. (Editors), and W. Imajuku, "A
Framework for the Control and Measurement of Wavelength
Switched Optical Networks (WSON) with Impairments
draft-bernstein-ccamp-wson-impairments-02.txt, work in
progress.
[WSON-IMP] Bernstein, G. and Lee, Y. (Editors), and D. Li, "Framework
for GMPLS and PCE Control of Wavelength Switched Optical
Networks", draft-bernstein-ccamp-wavelength-switched, work
in progress.
[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.
Authors' Addresses
Young Lee (Ed.)
Huawei Technologies
1700 Alma Drive, Suite 100
Plano, TX 75075, USA
Phone: (972) 509-5599 (x2240)
Email: ylee@huawei.com
Lee & Bernstein Expires September 1, 2010 [Page 10]
Internet-Draft PCEP Extension for WSON RWA March 2010
Greg Bernstein (Ed.)
Grotto Networking
Fremont, CA, USA
Phone: (510) 573-2237
Email: gregb@grotto-networking.com
Jonas Martensson
Acreo
Email:Jonas.Martensson@acreo.se
Tomonori Takeda
NTT Corporation
3-9-11, Midori-Cho
Musashino-Shi, Tokyo 180-8585, Japan
Email: takeda.tomonori@lab.ntt.co.jp
Takehiro Tsuritani
KDDI R&D Laboratories, Inc.
2-1-15 Ohara Kamifukuoka Saitama, 356-8502. Japan
Phone: +81-49-278-7357
Email: tsuri@kddilabs.jp
Intellectual Property Statement
The IETF Trust takes no position regarding the validity or scope of
any Intellectual Property Rights or other rights that might be
claimed to pertain to the implementation or use of the technology
described in any IETF Document or the extent to which any license
under such rights might or might not be available; nor does it
represent that it has made any independent effort to identify any
such rights.
Copies of Intellectual Property disclosures made to the IETF
Secretariat and any assurances of licenses to be made available, or
the result of an attempt made to obtain a general license or
permission for the use of such proprietary rights by implementers or
users of this specification can be obtained from the IETF on-line IPR
repository at http://www.ietf.org/ipr
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement
any standard or specification contained in an IETF Document. Please
address the information to the IETF at ietf-ipr@ietf.org.
Lee & Bernstein Expires September 1, 2010 [Page 11]
Internet-Draft PCEP Extension for WSON RWA March 2010
Disclaimer of Validity
All IETF Documents and the information contained therein are provided
on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE
REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE
IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL
WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY
WARRANTY THAT THE USE OF THE INFORMATION THEREIN WILL NOT INFRINGE
ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS
FOR A PARTICULAR PURPOSE.
Acknowledgment
Funding for the RFC Editor function is currently provided by the
Internet Society.
Lee & Bernstein Expires September 1, 2010 [Page 12]