draft-ietf-ccamp-wson-impairments-00.txt   draft-ietf-ccamp-wson-impairments-01.txt 
Network Working Group Y. Lee Network Working Group Y. Lee
Internet Draft Huawei Internet Draft Huawei
G. Bernstein G. Bernstein
Grotto Networking Grotto Networking
D. Li D. Li
Huawei Huawei
G. Martinelli G. Martinelli
Cisco Cisco
Intended status: Informational June 29, 2009 Intended status: Informational October 22, 2009
Expires: December 2009 Expires: April 2010
A Framework for the Control of Wavelength Switched Optical Networks A Framework for the Control of Wavelength Switched Optical Networks
(WSON) with Impairments (WSON) with Impairments
draft-ietf-ccamp-wson-impairments-00.txt draft-ietf-ccamp-wson-impairments-01.txt
Status of this Memo Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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Drafts. Drafts.
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and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
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material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
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This Internet-Draft will expire on December 29, 2009. This Internet-Draft will expire on April 22, 2009.
Copyright Notice Copyright Notice
Copyright (c) 2009 IETF Trust and the persons identified as the Copyright (c) 2009 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents in effect on the date of Provisions Relating to IETF Documents in effect on the date of
publication of this document (http://trustee.ietf.org/license-info). publication of this document (http://trustee.ietf.org/license-info).
Please review these documents carefully, as they describe your rights Please review these documents carefully, as they describe your rights
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and maintenance. This document discusses how the definition and and maintenance. This document discusses how the definition and
characterization of optical fiber, devices, subsystems, and network characterization of optical fiber, devices, subsystems, and network
elements contained in various ITU-T recommendations can be combined elements contained in various ITU-T recommendations can be combined
with GMPLS control plane protocols and mechanisms to support with GMPLS control plane protocols and mechanisms to support
Impairment Aware Routing and Wavelength Assignment (IA-RWA) in Impairment Aware Routing and Wavelength Assignment (IA-RWA) in
optical networks. optical networks.
Table of Contents Table of Contents
1. Introduction...................................................3 1. Introduction...................................................3
1.1. Revision History..........................................4
2. Motivation.....................................................4 2. Motivation.....................................................4
3. Impairment Aware Optical Path Computation......................5 3. Impairment Aware Optical Path Computation......................5
3.1. Optical Network Requirements and Constraints..............5 3.1. Optical Network Requirements and Constraints..............6
3.1.1. Categories of Impairment Aware Computation...........6 3.1.1. Categories of Impairment Aware Computation...........6
3.1.2. Impairment Computation and Information Sharing 3.1.2. Impairment Computation and Information Sharing
Constraints.................................................7 Constraints.................................................7
3.1.3. Impairment Estimation Functional Blocks..............8 3.1.3. Impairment Estimation Functional Blocks..............8
3.2. IA-RWA Computing and Control Plane Architectures..........9 3.2. IA-RWA Computing and Control Plane Architectures.........10
3.2.1. Combined Routing, WA, and IV........................10 3.2.1. Combined Routing, WA, and IV........................11
3.2.2. Separate Routing, WA, or IV.........................10 3.2.2. Separate Routing, WA, or IV.........................11
3.2.3. Distributed WA and/or IV............................11 3.2.3. Distributed WA and/or IV............................12
3.3. Mapping Network Requirements to Architectures............12 3.3. Mapping Network Requirements to Architectures............12
4. Protocol Implications.........................................14 4. Protocol Implications.........................................15
4.1. Information Model for Impairments........................15 4.1. Information Model for Impairments........................15
4.1.1. Properties of an Impairment Information Model.......16 4.1.1. Properties of an Impairment Information Model.......16
4.2. Routing..................................................17 4.2. Routing..................................................17
4.3. Signaling................................................17 4.3. Signaling................................................17
4.4. PCE......................................................17 4.4. PCE......................................................18
4.4.1. Combined IV & RWA...................................17 4.4.1. Combined IV & RWA...................................18
4.4.2. IV-Candidates + RWA.................................18 4.4.2. IV-Candidates + RWA.................................18
4.4.3. Approximate IA-RWA + Separate Detailed IV...........20 4.4.3. Approximate IA-RWA + Separate Detailed IV...........20
5. Security Considerations.......................................22 5. Security Considerations.......................................22
6. IANA Considerations...........................................22 6. IANA Considerations...........................................22
7. Acknowledgments...............................................22 7. Acknowledgments...............................................22
APPENDIX A: Overview of Optical Layer ITU-T Recommendations......23 APPENDIX A: Overview of Optical Layer ITU-T Recommendations......23
A.1. Fiber and Cables.........................................23 A.1. Fiber and Cables.........................................23
A.2. Devices..................................................24 A.2. Devices..................................................24
A.2.1. Optical Amplifiers..................................24 A.2.1. Optical Amplifiers..................................24
A.2.2. Dispersion Compensation.............................25 A.2.2. Dispersion Compensation.............................25
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to perform complex path computations are discussed in [RFC4655]. to perform complex path computations are discussed in [RFC4655].
Based on the existing ITU-T standards covering optical Based on the existing ITU-T standards covering optical
characteristics (impairments) and the knowledge of how the impact of characteristics (impairments) and the knowledge of how the impact of
impairments may be estimated along a path, this document provides a impairments may be estimated along a path, this document provides a
framework for impairment aware path computation and establishment framework for impairment aware path computation and establishment
utilizing GMPLS protocols and the PCE architecture. As in the utilizing GMPLS protocols and the PCE architecture. As in the
impairment free case covered in [WSON-Frame], a number of different impairment free case covered in [WSON-Frame], a number of different
control plane architectural options are described. control plane architectural options are described.
1.1. Revision History
Changes from 00 to 01:
Added discussion of regenerators to section 3.
Added to discussion of interface parameters in section 3.1.3.
Added to discussion of IV Candidates function in section 3.2.
2. Motivation 2. Motivation
There are deployment scenarios for WSON networks where not all There are deployment scenarios for WSON networks where not all
possible paths will yield suitable signal quality. There are possible paths will yield suitable signal quality. There are
multiple reasons behind this choice; here below is a non-exhaustive multiple reasons behind this choice; here below is a non-exhaustive
list of examples: list of examples:
o WSON is evolving using multi-degree optical cross connects in a o WSON is evolving using multi-degree optical cross connects in a
way that network topologies are changing from rings (and way that network topologies are changing from rings (and
interconnected rings) to a full mesh. Adding network equipment interconnected rings) to a full mesh. Adding network equipment
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nature of the signal transmitted between the sender and receiver and nature of the signal transmitted between the sender and receiver and
the nature of the communications channel between the sender and the nature of the communications channel between the sender and
receiver. The optical path utilized (along with the wavelength) receiver. The optical path utilized (along with the wavelength)
determines the communications channel. determines the communications channel.
The optical impairments incurred by the signal along the fiber and at The optical impairments incurred by the signal along the fiber and at
each optical network element along the path determine whether the BER each optical network element along the path determine whether the BER
performance or any other measure of signal quality can be met for a performance or any other measure of signal quality can be met for a
signal on a particular end-to-end path. signal on a particular end-to-end path.
The impairment-aware path calculation needs also to take into account
when regeneration happens along the path. Regeneration points could
happen for two reasons: (i) because of wavelength conversion to cope
with the RWA to avoid wavelength blocking (See [WSON-Frame]) or (ii)
because optical signal is too degraded. In both cases the optical
impairments estimation needs to be reset.
3.1. Optical Network Requirements and Constraints 3.1. Optical Network Requirements and Constraints
This section examines the various optical network requirements and This section examines the various optical network requirements and
constraints that an impairment aware optical control plane may have constraints that an impairment aware optical control plane may have
to operate under. These requirements and constraints motivate the IA- to operate under. These requirements and constraints motivate the IA-
RWA architectural alternatives to be presented in the following RWA architectural alternatives to be presented in the following
section. We can break the different optical networks contexts up section. We can break the different optical networks contexts up
along two main criteria: (a) the accuracy required in the estimation along two main criteria: (a) the accuracy required in the estimation
of impairment effects, and (b) the constraints on the impairment of impairment effects, and (b) the constraints on the impairment
estimation computation and/or sharing of impairment information. estimation computation and/or sharing of impairment information.
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+-----------------+ +-----------------+
Starting from functional block on the left the Optical Interface Starting from functional block on the left the Optical Interface
represents where the optical signal is transmitted or received and represents where the optical signal is transmitted or received and
defines the properties at the end points path. For WSON even the case defines the properties at the end points path. For WSON even the case
with no IA has to consider a minimum set of interface with no IA has to consider a minimum set of interface
characteristics. As an example, the document [G.698.1] reports the characteristics. As an example, the document [G.698.1] reports the
full set of those parameters for certain interfaces. In this function full set of those parameters for certain interfaces. In this function
only a significant subset of those parameters would be considered. In only a significant subset of those parameters would be considered. In
addition transmit and receive interface might consider a different addition transmit and receive interface might consider a different
subset of properties. subset of properties. In term of GMPLS, [WSON-Comp] provides a
minimum set of parameters to characterize the interface. During an
impairment estimation process these parameters may be sufficient or
not depending on the accepted level of approximation (Section 3.1.1).
The block "Optical Path" represents all kinds of impairments The block "Optical Path" represents all kinds of impairments
affecting a wavelength as it traverses the networks through links and affecting a wavelength as it traverses the networks through links and
nodes. In the case where the control plane has no IA this block will nodes. In the case where the control plane has no IA this block will
not be present. Otherwise, this function must be implemented in some not be present. Otherwise, this function must be implemented in some
way via the control plane. Options for this will be given in the next way via the control plane. Options for this will be given in the next
section on control plane architectural alternatives. section on control plane architectural alternatives.
The last block implements the decision function for path feasibility. The last block implements the decision function for path feasibility.
Depending on the IA level of approximation this function can be more Depending on the IA level of approximation this function can be more
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In this case an Impairment Validation (IV) process furnishes a set of In this case an Impairment Validation (IV) process furnishes a set of
paths between two nodes along with any wavelength restrictions such paths between two nodes along with any wavelength restrictions such
that the paths are valid with respect to optical impairments. These that the paths are valid with respect to optical impairments. These
paths and wavelengths may not be actually available in the network paths and wavelengths may not be actually available in the network
due to its current usage state. This set of paths would be returned due to its current usage state. This set of paths would be returned
in response to a request for a set of at most K valid paths between in response to a request for a set of at most K valid paths between
two specified nodes. Note that such a process never directly two specified nodes. Note that such a process never directly
discloses optical impairment information. discloses optical impairment information.
In this case the control plane simply make use of candidate paths but
does not know any optical impairment information. Another option is
when the path validity is assessed within the control plane. The
following cases highlight this situation.
o IV-Detailed Verification o IV-Detailed Verification
In this case an IV process is given a particular path and wavelength In this case an IV process is given a particular path and wavelength
through an optical network and is asked to verify whether the overall through an optical network and is asked to verify whether the overall
quality objectives for the signal over this path can be met. Note quality objectives for the signal over this path can be met. Note
that such a process never directly discloses optical impairment that such a process never directly discloses optical impairment
information. information.
o IV-Distributed o IV-Distributed
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[Imp-Info] G. Bernstein, Y. Lee, D. Li, "A Framework for the Control [Imp-Info] G. Bernstein, Y. Lee, D. Li, "A Framework for the Control
and Measurement of Wavelength Switched Optical Networks and Measurement of Wavelength Switched Optical Networks
(WSON) with Impairments", work in progress: draft- (WSON) with Impairments", work in progress: draft-
bernstein-wson-impairment-info-01.txt, March 2009. bernstein-wson-impairment-info-01.txt, March 2009.
[Martinelli] G. Martinelli (ed.) and A. Zanardi (ed.), "GMPLS [Martinelli] G. Martinelli (ed.) and A. Zanardi (ed.), "GMPLS
Signaling Extensions for Optical Impairment Aware Lightpath Signaling Extensions for Optical Impairment Aware Lightpath
Setup", Work in Progress: draft-martinelli-ccamp-optical- Setup", Work in Progress: draft-martinelli-ccamp-optical-
imp-signaling-02.txt, February 2008. imp-signaling-02.txt, February 2008.
[WSON-Comp] G. Bernstein, Y. Lee, Ben Mack-Crane, "WSON Signal
Characteristics and Network Element Compatibility
Constraints for GMPLS", work in progress: draft-bernstein-
ccamp-wson-signal.
Author's Addresses Author's Addresses
Greg M. Bernstein (ed.) Greg M. Bernstein (ed.)
Grotto Networking Grotto Networking
Fremont California, USA Fremont California, USA
Phone: (510) 573-2237 Phone: (510) 573-2237
Email: gregb@grotto-networking.com Email: gregb@grotto-networking.com
Young Lee (ed.) Young Lee (ed.)
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