draft-ietf-ccamp-rwa-wson-framework-07.txt   draft-ietf-ccamp-rwa-wson-framework-08.txt 
Network Working Group Y. Lee (ed.) Network Working Group Y. Lee (ed.)
Internet Draft Huawei Internet Draft Huawei
Intended status: Informational G. Bernstein (ed.) Intended status: Informational G. Bernstein (ed.)
Expires: April 2011 Grotto Networking Expires: June 2011 Grotto Networking
Wataru Imajuku Wataru Imajuku
NTT NTT
October 8, 2010 December 17, 2010
Framework for GMPLS and PCE Control of Wavelength Switched Optical Framework for GMPLS and PCE Control of Wavelength Switched Optical
Networks (WSON) Networks (WSON)
draft-ietf-ccamp-rwa-wson-framework-07.txt draft-ietf-ccamp-rwa-wson-framework-08.txt
Abstract Abstract
This document provides a framework for applying Generalized Multi- This document provides a framework for applying Generalized Multi-
Protocol Label Switching (GMPLS) and the Path Computation Element Protocol Label Switching (GMPLS) and the Path Computation Element
(PCE) architecture to the control of wavelength switched optical (PCE) architecture to the control of wavelength switched optical
networks (WSON). In particular, it examines the Routing and networks (WSON). In particular, it examines Routing and Wavelength
Wavelength Assignment (RWA) problem. Assignment (RWA) of optical paths.
This document focuses on topological elements and path selection This document focuses on topological elements and path selection
constraints that are common across different WSON environments as constraints that are common across different WSON environments as
such it does not address optical impairments in any depth. such it does not address optical impairments in any depth.
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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and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
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The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
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This Internet-Draft will expire on April 8, 2009. This Internet-Draft will expire on June 17, 2009.
Copyright Notice Copyright Notice
Copyright (c) 2010 IETF Trust and the persons identified as the Copyright (c) 2010 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction..................................................4 1. Introduction...................................................4
2. Terminology....................................................4 2. Terminology....................................................4
3. Wavelength Switched Optical Networks...........................6 3. Wavelength Switched Optical Networks...........................6
3.1. WDM and CWDM Links........................................6 3.1. WDM and CWDM Links........................................6
3.2. Optical Transmitters and Receivers........................8 3.2. Optical Transmitters and Receivers........................8
3.3. Optical Signals in WSONs..................................9 3.3. Optical Signals in WSONs..................................9
3.3.1. Optical Tributary Signals...........................10 3.3.1. Optical Tributary Signals...........................10
3.3.2. WSON Signal Characteristics.........................10 3.3.2. WSON Signal Characteristics.........................10
3.4. ROADMs, OXCs, Splitters, Combiners and FOADMs............11 3.4. ROADMs, OXCs, Splitters, Combiners and FOADMs............11
3.4.1. Reconfigurable Add/Drop Multiplexers and OXCs.......11 3.4.1. Reconfigurable Add/Drop Multiplexers and OXCs.......11
3.4.2. Splitters...........................................14 3.4.2. Splitters...........................................14
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Converters.................................................41 Converters.................................................41
6.1.5. Distributed Wavelength Assignment: Unidirectional, 6.1.5. Distributed Wavelength Assignment: Unidirectional,
Limited Converters.........................................41 Limited Converters.........................................41
6.1.6. Distributed Wavelength Assignment: Bidirectional, No 6.1.6. Distributed Wavelength Assignment: Bidirectional, No
Converters.................................................41 Converters.................................................41
6.2. Implications for GMPLS Routing...........................42 6.2. Implications for GMPLS Routing...........................42
6.2.1. Electro-Optical Element Signal Compatibility........42 6.2.1. Electro-Optical Element Signal Compatibility........42
6.2.2. Wavelength-Specific Availability Information........43 6.2.2. Wavelength-Specific Availability Information........43
6.2.3. WSON Routing Information Summary....................43 6.2.3. WSON Routing Information Summary....................43
6.3. Optical Path Computation and Implications for PCE........45 6.3. Optical Path Computation and Implications for PCE........45
6.3.1. Lightpath Constraints and Characteristics...........45 6.3.1. Optical path Constraints and Characteristics........45
6.3.2. Electro-Optical Element Signal Compatibility........46 6.3.2. Electro-Optical Element Signal Compatibility........45
6.3.3. Discovery of RWA Capable PCEs.......................46 6.3.3. Discovery of RWA Capable PCEs.......................46
7. Security Considerations.......................................47 7. Security Considerations.......................................46
8. IANA Considerations...........................................47 8. IANA Considerations...........................................47
9. Acknowledgments...............................................47 9. Acknowledgments...............................................47
10. References...................................................48 10. References...................................................48
10.1. Normative References....................................48 10.1. Normative References....................................48
10.2. Informative References..................................49 10.2. Informative References..................................49
11. Contributors.................................................51 11. Contributors.................................................52
Author's Addresses...............................................52 Author's Addresses...............................................53
Intellectual Property Statement..................................52 Intellectual Property Statement..................................53
Disclaimer of Validity...........................................53 Disclaimer of Validity...........................................54
12. Appendix A Revision History..................................53 12. Appendix A Revision History..................................54
1. Introduction 1. Introduction
Wavelength Switched Optical Networks (WSONs) are constructed from Wavelength Switched Optical Networks (WSONs) are constructed from
subsystems that include Wavelength Division Multiplexed (WDM) links, subsystems that include Wavelength Division Multiplexed (WDM) links,
tunable transmitters and receivers, Reconfigurable Optical Add/Drop tunable transmitters and receivers, Reconfigurable Optical Add/Drop
Multiplexers (ROADM), wavelength converters, and electro-optical Multiplexers (ROADM), wavelength converters, and electro-optical
network elements. A WSON is a WDM-based optical network in which network elements. A WSON is a WDM-based optical network in which
switching is performed selectively based on the center wavelength of switching is performed selectively based on the center wavelength of
an optical signal. an optical signal.
In order to provision an optical connection (a lightpath) through a In order to provision an optical connection (an optical path) through
WSON certain path continuity and resource availability constraints a WSON certain path continuity and resource availability constraints
must be met to determine viable and optimal paths through the must be met to determine viable and optimal paths through the
network. The generic problem of determining such paths is known as network. The determination of paths is known as Routing and
the Routing and Wavelength Assignment (RWA) problem. Wavelength Assignment (RWA).
Generalized Multi-Protocol Label Switching (GMPLS) [RFC3945] includes Generalized Multi-Protocol Label Switching (GMPLS) [RFC3945] includes
a set of control plane protocols that can be used to operate data a set of control plane protocols that can be used to operate data
networks ranging from packet switch capable networks, through those networks ranging from packet switch capable networks, through those
networks that use time division multiplexing, to WDM networks. The networks that use time division multiplexing, to WDM networks. The
Path Computation Element (PCE) architecture [RFC4655] defines Path Computation Element (PCE) architecture [RFC4655] defines
functional components that can be used to compute and suggest functional components that can be used to compute and suggest
appropriate paths in connection-oriented traffic-engineered networks. appropriate paths in connection-oriented traffic-engineered networks.
This document provides a framework for applying GMPLS protocols and This document provides a framework for applying GMPLS protocols and
the PCE architecture to the control and operation of WSONs. To aid the PCE architecture to the control and operation of WSONs. To aid
in this process this document also provides an overview of the in this process this document also provides an overview of the
subsystems and processes that comprise WSONs, and describes the RWA subsystems and processes that comprise WSONs, and describes RWA so
problem so that the information requirements, both static and that the information requirements, both static and dynamic, can be
dynamic, can be identified to explain how the information can be identified to explain how the information can be modeled for use by
modeled for use by GMPLS and PCE systems. This work will facilitate GMPLS and PCE systems. This work will facilitate the development of
the development of protocol solution models and protocol extensions protocol solution models and protocol extensions within the GMPLS and
within the GMPLS and PCE protocol families. PCE protocol families.
Note that this document focuses on the generic properties of links, Note that this document focuses on the generic properties of links,
switches and path selection constraints that occur in WSONs. switches and path selection constraints that occur in WSONs.
Different WSONs such as access, metro, and long haul may apply Different WSONs such as access, metro, and long haul may apply
different techniques for dealing with optical impairments hence this different techniques for dealing with optical impairments hence this
document does not address optical impairments in any depth. See document does not address optical impairments in any depth. See
[WSON-Imp] for more information on optical impairments and GMPLS. [WSON-Imp] for more information on optical impairments and GMPLS.
2. Terminology 2. Terminology
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PCC: Path Computation Client. Any client application requesting a PCC: Path Computation Client. Any client application requesting a
path computation to be performed by the Path Computation Element. path computation to be performed by the Path Computation Element.
PCE: Path Computation Element. An entity (component, application, or PCE: Path Computation Element. An entity (component, application, or
network node) that is capable of computing a network path or route network node) that is capable of computing a network path or route
based on a network graph and applying computational constraints. based on a network graph and applying computational constraints.
PCEP: PCE Communication Protocol. The communication protocol between PCEP: PCE Communication Protocol. The communication protocol between
a Path Computation Client and Path Computation Element. a Path Computation Client and Path Computation Element.
ROADM: Reconfigurable Optical Add/Drop Multiplexer. An wavelength ROADM: Reconfigurable Optical Add/Drop Multiplexer. A wavelength
selective switching element featuring input and output line side selective switching element featuring input and output line side
ports as well as add/drop side ports. ports as well as add/drop tributary ports.
RWA: Routing and Wavelength Assignment. RWA: Routing and Wavelength Assignment.
Transparent Network: A wavelength switched optical network that does Transparent Network: A wavelength switched optical network that does
not contain regenerators or wavelength converters. not contain regenerators or wavelength converters.
Translucent Network: A wavelength switched optical network that is Translucent Network: A wavelength switched optical network that is
predominantly transparent but may also contain limited numbers of predominantly transparent but may also contain limited numbers of
regenerators and/or wavelength converters. regenerators and/or wavelength converters.
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frequency grids of 12.5GHz, 25GHz, 50GHz, 100GHz, and other multiples frequency grids of 12.5GHz, 25GHz, 50GHz, 100GHz, and other multiples
of 100GHz around a 193.1THz center frequency. At the narrowest of 100GHz around a 193.1THz center frequency. At the narrowest
channel spacing this provides less than 4800 channels across the O channel spacing this provides less than 4800 channels across the O
through U bands. ITU-T Recommendation G.694.2, Spectral grids for WDM through U bands. ITU-T Recommendation G.694.2, Spectral grids for WDM
applications: CWDM wavelength grid [G.694.2] describes a CWDM grid applications: CWDM wavelength grid [G.694.2] describes a CWDM grid
defined in terms of wavelength increments of 20nm running from 1271nm defined in terms of wavelength increments of 20nm running from 1271nm
to 1611nm for 18 or so channels. The number of channels is to 1611nm for 18 or so channels. The number of channels is
significantly smaller than the 32 bit GMPLS label space defined for significantly smaller than the 32 bit GMPLS label space defined for
GMPLS, see [RFC3471]. A label representation for these ITU-T grids GMPLS, see [RFC3471]. A label representation for these ITU-T grids
is given in [Otani] and provides a common label format to be used in is given in [Otani] and provides a common label format to be used in
signaling lightpaths. Further, these ITU-T grid based labels can also signaling optical paths. Further, these ITU-T grid based labels can
be used to describe WDM links, ROADM ports, and wavelength converters also be used to describe WDM links, ROADM ports, and wavelength
for the purposes of path selection. converters for the purposes of path selection.
Many WDM links are designed to take advantage of particular fiber Many WDM links are designed to take advantage of particular fiber
characteristics or to try to avoid undesirable properties. For characteristics or to try to avoid undesirable properties. For
example dispersion shifted SMF [G.653] was originally designed for example dispersion shifted SMF [G.653] was originally designed for
good long distance performance in single channel systems, however good long distance performance in single channel systems, however
putting WDM over this type of fiber requires significant system putting WDM over this type of fiber requires significant system
engineering and a fairly limited range of wavelengths. Hence the engineering and a fairly limited range of wavelengths. Hence the
following information is needed as parameters to perform basic, following information is needed as parameters to perform basic,
impairment unaware, modeling of a WDM link: impairment unaware, modeling of a WDM link:
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represented by 32 bit integers. represented by 32 bit integers.
o Channel spacing: Currently there are five channel spacings used in o Channel spacing: Currently there are five channel spacings used in
DWDM systems and a single channel spacing defined for CWDM DWDM systems and a single channel spacing defined for CWDM
systems. systems.
For a particular link this information is relatively static, as For a particular link this information is relatively static, as
changes to these properties generally require hardware upgrades. Such changes to these properties generally require hardware upgrades. Such
information may be used locally during wavelength assignment via information may be used locally during wavelength assignment via
signaling, similar to label restrictions in MPLS or used by a PCE in signaling, similar to label restrictions in MPLS or used by a PCE in
solving the combined RWA problem. providing combined RWA.
3.2. Optical Transmitters and Receivers 3.2. Optical Transmitters and Receivers
WDM optical systems make use of optical transmitters and receivers WDM optical systems make use of optical transmitters and receivers
utilizing different wavelengths (frequencies). Some transmitters are utilizing different wavelengths (frequencies). Some transmitters are
manufactured for a specific wavelength of operation, that is, the manufactured for a specific wavelength of operation, that is, the
manufactured frequency cannot be changed. First introduced to reduce manufactured frequency cannot be changed. First introduced to reduce
inventory costs, tunable optical transmitters and receivers are inventory costs, tunable optical transmitters and receivers are
deployed in some systems, and allow flexibility in the wavelength deployed in some systems, and allow flexibility in the wavelength
used for optical transmission/reception. Such tunable optics aid in used for optical transmission/reception. Such tunable optics aid in
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Note that ITU-T recommendations specify many aspects of an optical Note that ITU-T recommendations specify many aspects of an optical
transmitter. Many of these parameters, such as spectral transmitter. Many of these parameters, such as spectral
characteristics and stability, are used in the design of WDM characteristics and stability, are used in the design of WDM
subsystems consisting of transmitters, WDM links and receivers subsystems consisting of transmitters, WDM links and receivers
however they do not furnish additional information that will however they do not furnish additional information that will
influence the Label Switched Path (LSP) provisioning in a properly influence the Label Switched Path (LSP) provisioning in a properly
designed system. designed system.
Also note that optical components can degrade and fail over time. Also note that optical components can degrade and fail over time.
This presents the possibility of the failure of a LSP (lightpath) This presents the possibility of the failure of a LSP (optical path)
without either a node or link failure. Hence, additional mechanisms without either a node or link failure. Hence, additional mechanisms
may be necessary to detect and differentiate this failure from the may be necessary to detect and differentiate this failure from the
others, e.g., one doesn't not want to initiate mesh restoration if others, e.g., one doesn't not want to initiate mesh restoration if
the source transmitter has failed, since the optical transmitter will the source transmitter has failed, since the optical transmitter will
still be failed on the alternate optical path. still be failed on the alternate optical path.
3.3. Optical Signals in WSONs 3.3. Optical Signals in WSONs
In WSONs the fundamental unit of switching is intuitively that of a In WSONs the fundamental unit of switching is intuitively that of a
"wavelength". The transmitters and receivers in these networks will "wavelength". The transmitters and receivers in these networks will
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have seen significant deployment including Differential Phase Shift have seen significant deployment including Differential Phase Shift
Keying (DPSK) and Phase Shaped Binary Transmission (PSBT). Keying (DPSK) and Phase Shaped Binary Transmission (PSBT).
According to [G.698.2] it is important to fully specify the bit rate According to [G.698.2] it is important to fully specify the bit rate
of the optical tributary signal. Hence it is seen that modulation of the optical tributary signal. Hence it is seen that modulation
format (optical tributary signal class) and bit rate are key format (optical tributary signal class) and bit rate are key
parameters in characterizing the optical tributary signal. parameters in characterizing the optical tributary signal.
3.3.2. WSON Signal Characteristics 3.3.2. WSON Signal Characteristics
An optical tributary signal defined in ITU-T [G.698.1] and [G.698.2] An optical tributary signal referenced in ITU-T [G.698.1] and
is referred to as the "signal" in this document. This corresponds to [G.698.2] is referred to as the "signal" in this document. This
the "lambda" LSP in GMPLS. For signal compatibility purposes with corresponds to the "lambda" LSP in GMPLS. For signal compatibility
electro-optical network elements, the following signal purposes with electro-optical network elements, the following signal
characteristics are considered: characteristics are considered:
1. Optical tributary signal class (modulation format). 1. Optical tributary signal class (modulation format).
2. FEC: whether forward error correction is used in the digital stream 2. FEC: whether forward error correction is used in the digital stream
and what type of error correcting code is used. and what type of error correcting code is used.
3. Center frequency (wavelength). 3. Center frequency (wavelength).
4. Bit rate. 4. Bit rate.
5. G-PID: general protocol identifier for the information format. 5. G-PID: general protocol identifier for the information format.
The first three items on this list can change as a WSON signal The first three items on this list can change as a WSON signal
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----------------- -----------------
A = #1 1 1 1 ... 1 A = #1 1 1 1 ... 1
The difference from a simple ROADM is that this is not a switched The difference from a simple ROADM is that this is not a switched
connectivity matrix but the fixed connectivity matrix of the device. connectivity matrix but the fixed connectivity matrix of the device.
3.4.3. Combiners 3.4.3. Combiners
An optical combiner is a device that combines the optical wavelengths An optical combiner is a device that combines the optical wavelengths
carried by multiple input ports into a single multi-wavelength output carried by multiple input ports into a single multi-wavelength output
output port. The various ports may have different wavelength port. The various ports may have different wavelength restrictions.
restrictions. It is generally the responsibility of those using the It is generally the responsibility of those using the combiner to
combiner to assure that wavelength collision does not occur on the assure that wavelength collision does not occur on the output port.
output port. The fixed connectivity matrix Amn for a combiner would The fixed connectivity matrix Amn for a combiner would look like:
look like:
Input Output Port Input Output Port
Port #1 Port #1
--- ---
#1: 1 #1: 1
#2 1 #2 1
A = #3 1 A = #3 1
... 1 ... 1
#N 1 #N 1
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tunable optics. In this case there are typically multiple tunable optics. In this case there are typically multiple
converters available since each on the use of an OEO switch can be converters available since each on the use of an OEO switch can be
thought of as a potential wavelength converter. thought of as a potential wavelength converter.
2. Wavelength conversion associated with ROADMs/OXCs. In this case 2. Wavelength conversion associated with ROADMs/OXCs. In this case
there may be a limited pool of wavelength converters available. there may be a limited pool of wavelength converters available.
Conversion could be either all optical or via an OEO method. Conversion could be either all optical or via an OEO method.
3. Wavelength conversion associated with fixed devices such as FOADMs. 3. Wavelength conversion associated with fixed devices such as FOADMs.
In this case there may be a limited amount of conversion. Also in In this case there may be a limited amount of conversion. Also in
this case the conversion may be used as part of light path routing. this case the conversion may be used as part of optical path
routing.
Based on the above considerations, wavelength converters are modeled Based on the above considerations, wavelength converters are modeled
as follows: as follows:
1. Wavelength converters can always be modeled as associated with 1. Wavelength converters can always be modeled as associated with
network elements. This includes fixed wavelength routing elements. network elements. This includes fixed wavelength routing elements.
2. A network element may have full wavelength conversion capability, 2. A network element may have full wavelength conversion capability,
i.e., any input port and wavelength, or a limited number of i.e., any input port and wavelength, or a limited number of
wavelengths and ports. On a box with a limited number of wavelengths and ports. On a box with a limited number of
converters there also may exist restrictions on which ports can converters there also may exist restrictions on which ports can
reach the converters. Hence regardless of where the converters reach the converters. Hence regardless of where the converters
actually are they can be associated with input ports. actually are they can be associated with input ports.
3. Wavelength converters have range restrictions that are either 3. Wavelength converters have range restrictions that are either
independent or dependent upon the input wavelength. independent or dependent upon the input wavelength.
In WSONs where wavelength converters are sparse a light path may In WSONs where wavelength converters are sparse an optical path may
appear to loop or "backtrack" upon itself in order to reach a appear to loop or "backtrack" upon itself in order to reach a
wavelength converter prior to continuing on to its destination. The wavelength converter prior to continuing on to its destination. The
lambda used on input to the wavelength converter would be different lambda used on input to the wavelength converter would be different
the lambda coming back from the wavelength converter. the lambda coming back from the wavelength converter.
A model for an individual O-E-O wavelength converter would consist A model for an individual O-E-O wavelength converter would consist
of: of:
o Input lambda or frequency range. o Input lambda or frequency range.
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conversions that can be performed. conversions that can be performed.
To model point 2 above, a similar technique can be used to model To model point 2 above, a similar technique can be used to model
ROADMs and optical switches, i.e., matrices to indicate possible ROADMs and optical switches, i.e., matrices to indicate possible
connectivity along with wavelength constraints for links/ports. Since connectivity along with wavelength constraints for links/ports. Since
wavelength converters are considered a scarce resource it will be wavelength converters are considered a scarce resource it will be
desirable to include as a minimum the usage state of individual desirable to include as a minimum the usage state of individual
wavelength converters in the pool. wavelength converters in the pool.
A three stage model is used as shown schematically in Figure 3. A three stage model is used as shown schematically in Figure 3.
(Schematic diagram of wavelength converter pool model). In this model (Schematic diagram of wavelength converter pool model). This model
it is assumed N input ports (fibers), P wavelength converters, and M represents N input ports (fibers), P wavelength converters, and M
output ports (fibers). Since not all input ports can necessarily output ports (fibers). Since not all input ports can necessarily
reach the converter pool, the model starts with a wavelength pool reach the converter pool, the model starts with a wavelength pool
input matrix WI(i,p) = {0,1} where input port i can reach potentially input matrix WI(i,p) = {0,1} where input port i can reach potentially
reach wavelength converter p. reach wavelength converter p.
Since not all wavelength can necessarily reach all the converters or Since not all wavelength can necessarily reach all the converters or
the converters may have limited input wavelength range there is a set the converters may have limited input wavelength range there is a set
of input port constraints for each wavelength converter. Currently it of input port constraints for each wavelength converter. Currently it
is assumed that a wavelength converter can only take a single is assumed that a wavelength converter can only take a single
wavelength on input. Each wavelength converter input port constraint wavelength on input. Each wavelength converter input port constraint
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3. Bit Rate restrictions. 3. Bit Rate restrictions.
4. FEC coding restrictions. 4. FEC coding restrictions.
5. Configurability: (a) none, (b) self-configuring, (c) required. 5. Configurability: (a) none, (b) self-configuring, (c) required.
These constraints are represented via simple lists. Note that the These constraints are represented via simple lists. Note that the
device may need to be "provisioned" via signaling or some other means device may need to be "provisioned" via signaling or some other means
to accept signals with some attributes versus others. In other cases to accept signals with some attributes versus others. In other cases
the devices maybe relatively transparent to some attributes, e.g., the devices maybe relatively transparent to some attributes, e.g.,
such as a 2R regenerator to bit rate. Finally, some devices maybe such as a 2R regenerator to bit rate. Finally, some devices may be
able to auto-detect some attributes and configure themselves, e.g., a able to auto-detect some attributes and configure themselves, e.g., a
3R regenerator with bit rate detection mechanisms and flexible phase 3R regenerator with bit rate detection mechanisms and flexible phase
locking circuitry. To account for these different cases item 5 has locking circuitry. To account for these different cases item 5 has
been added, which describes the devices configurability. been added, which describes the devices configurability.
Note that such input constraints also apply to the termination of the Note that such input constraints also apply to the termination of the
WSON signal. WSON signal.
3.7.2. Output Constraints 3.7.2. Output Constraints
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scope of the control plane. However, when the operations are to be scope of the control plane. However, when the operations are to be
performed on an LSP basis or on part of an LSP then the control plane performed on an LSP basis or on part of an LSP then the control plane
can be of assistance in their configuration. Per LSP, per node, fault can be of assistance in their configuration. Per LSP, per node, fault
and performance monitoring examples include setting up a "section and performance monitoring examples include setting up a "section
trace" (a regenerator overhead identifier) between two nodes, or trace" (a regenerator overhead identifier) between two nodes, or
intermediate optical performance monitoring at selected nodes along a intermediate optical performance monitoring at selected nodes along a
path. path.
4. Routing and Wavelength Assignment and the Control Plane 4. Routing and Wavelength Assignment and the Control Plane
A wavelength-convertible network with full wavelength-conversion From a control plane perspective, a wavelength-convertible network
capability at each node is equivalent to packet MPLS-labeled network with full wavelength-conversion capability at each node can be
or a circuit-switched Time-division multiplexing (TDM) network with controlled much like a packet MPLS-labeled network or a circuit-
full time slot interchange capability. In this case, the routing switched Time-division multiplexing (TDM) network with full time slot
problem needs to be addressed only at the level of the Traffic interchange capability is controlled. In this case, the path
Engineered (TE) link choice, and wavelength assignment can be selection process needs to identify the Traffic Engineered (TE) links
resolved locally by the switches on a hop-by-hop basis. to be used by an optical path, and wavelength assignment can be made
on a hop-by-hop basis.
However, in the limiting case of an optical network with no However, in the case of an optical network without wavelength
wavelength converters, a light path (optical signal) needs a route converters, an optical path needs to be routed from source to
from source to destination and must pick a single wavelength that can destination and must use a single wavelength that is available along
be used along that path without "colliding" with the wavelength used that path without "colliding" with a wavelength used by any other
by any other light path that may share an optical fiber. This is optical path that may share an optical fiber. This is sometimes
sometimes referred to as a "wavelength continuity constraint". referred to as a "wavelength continuity constraint".
In the general case of limited or no wavelength converters this In the general case of limited or no wavelength converters the
computation is known as the RWA problem. computation of both the links and wavelengths is known as RWA.
The inputs to the basic RWA problem are the requested light path's The inputs to basic RWA are the requested optical path's source and
source and destination, the network topology, the locations and destination, the network topology, the locations and capabilities of
capabilities of any wavelength converters, and the wavelengths any wavelength converters, and the wavelengths available on each
available on each optical link. The output from an algorithm solving optical link. The output from an algorithm providing RWA is an
the RWA problem is an explicit route through ROADMs, a wavelength for explicit route through ROADMs, a wavelength for optical transmitter,
the optical transmitter, and a set of locations (generally associated and a set of locations (generally associated with ROADMs or switches)
with ROADMs or switches) where wavelength conversion is to occur and where wavelength conversion is to occur and the new wavelength to be
the new wavelength to be used on each component link after that point used on each component link after that point in the route.
in the route.
It is to be noted that the choice of specific RWA algorithm is out of It is to be noted that the choice of specific RWA algorithm is out of
the scope for this document. However there are a number of different the scope for this document. However there are a number of different
approaches to dealing with the RWA algorithm that can affect the approaches to dealing with RWA algorithm that can affect the division
division of effort between path computation/routing and signaling. of effort between path computation/routing and signaling.
4.1. Architectural Approaches to RWA 4.1. Architectural Approaches to RWA
Two general computational approaches are taken to solving the RWA Two general computational approaches are taken to performing RWA.
problem. Some algorithms utilize a two step procedure of path Some algorithms utilize a two-step procedure of path selection
selection followed by wavelength assignment, and others solve the followed by wavelength assignment, and others perform RWA in a
problem in a combined fashion. combined fashion.
In the following, three different ways of performing RWA in In the following, three different ways of performing RWA in
conjunction with the control plane are considered. The choice of one conjunction with the control plane are considered. The choice of one
of these architectural approaches over another generally impacts the of these architectural approaches over another generally impacts the
demands placed on the various control plane protocols. demands placed on the various control plane protocols. The approaches
are provided for reference purposes only, and other approaches are
possible.
4.1.1. Combined RWA (R&WA) 4.1.1. Combined RWA (R&WA)
In this case, a unique entity is in charge of performing routing and In this case, a unique entity is in charge of performing routing and
wavelength assignment. This approach relies on a sufficient knowledge wavelength assignment. This approach relies on a sufficient knowledge
of network topology, of available network resources and of network of network topology, of available network resources and of network
nodes capabilities. This solution is compatible with most known RWA nodes capabilities. This solution is compatible with most known RWA
algorithms, and in particular those concerned with network algorithms, and in particular those concerned with network
optimization. On the other hand, this solution requires up-to-date optimization. On the other hand, this solution requires up-to-date
and detailed network information. and detailed network information.
Such a computational entity could reside in two different logical Such a computational entity could reside in two different places:
places:
o The PCE, which maintains a complete and updated view of network o In a PCE which maintains a complete and updated view of network
state, provides path computation services to nodes (PCCs). state and provides path computation services to nodes (PCCs).
o In the ingress node, in that case all nodes have the R&WA o In an ingress node, in which case all nodes have the R&WA
functionality; the knowledge of the network state is obtained by a functionality and network state is obtained by a periodic flooding
periodic flooding of information provided by the other nodes. of information provided by the other nodes.
4.1.2. Separated R and WA (R+WA) 4.1.2. Separated R and WA (R+WA)
In this case a first entity performs routing, while a second performs In this case, one entity performs routing, while a second performs
wavelength assignment. The first entity furnishes one or more paths wavelength assignment. The first entity furnishes one or more paths
to the second entity that will perform wavelength assignment and to the second entity which will perform wavelength assignment and
possibly final path selection. final path selection.
As the entities computing the path and the wavelength assignment are As the entities computing the path and the wavelength assignment are
separated, this constrains the class of RWA algorithms that may be separated, this constrains the class of RWA algorithms that may be
implemented. Although it may seem that algorithms optimizing a joint implemented. Although it may seem that algorithms optimizing a joint
usage of the physical and spectral paths are excluded from this usage of the physical and wavelength paths are excluded from this
solution, many practical optimization algorithms only consider a solution, many practical optimization algorithms only consider a
limited set of possible paths, e.g., as computed via a k-shortest limited set of possible paths, e.g., as computed via a k-shortest
path algorithm. Hence although there is no guarantee that the path algorithm. Hence, while there is no guarantee that the selected
selected final route and wavelength offers the optimal solution, by final route and wavelength offers the optimal solution, by allowing
allowing multiple routes to pass to the wavelength selection process multiple routes to pass to the wavelength selection process
reasonable optimization can be performed. reasonable optimization can be performed.
The entity performing the routing assignment needs the topology The entity performing the routing assignment needs the topology
information of the network, whereas the entity performing the information of the network, whereas the entity performing the
wavelength assignment needs information on the network's available wavelength assignment needs information on the network's available
resources and specific network node capabilities. resources and specific network node capabilities.
4.1.3. Routing and Distributed WA (R+DWA) 4.1.3. Routing and Distributed WA (R+DWA)
In this case a first entity performs routing, while wavelength In this case, one entity performs routing, while wavelength
assignment is performed on a hop-by-hop, distributed, manner along assignment is performed on a hop-by-hop, distributed, manner along
the previously computed route. This mechanism relies on updating of a the previously computed path. This mechanism relies on updating of a
list of potential wavelengths used to ensure conformance with the list of potential wavelengths used to ensure conformance with the
wavelength continuity constraint. wavelength continuity constraint.
As currently specified, the GMPLS protocol suite signaling protocol As currently specified, the GMPLS protocol suite signaling protocol
can accommodate such an approach. Per [RFC3471], the Label Set can accommodate such an approach. GMPLS, per [RFC3471], includes
selection works according to an AND scheme. Each hop restricts the support for the communication of the set of labels (wavelengths) that
Label Set sent to the next hop from the one received from the may be used between nodes via a Label Set. When conversion is not
previous hop by performing an AND operation between the wavelength performed at an intermediate node, a hop generates the Label Set it
referred by the labels the message includes with the one available on sends to the next hop based on the intersection of the Label Set
the ongoing interface. The constraint to perform this AND operation received from the previous hop and the wavelengths available on the
is up to the node local policy (even if one expects a consistent node's switch and ongoing interface. The generation of the outgoing
policy configuration throughout a given transparency domain). When Label Set is up to the node local policy (even if one expects a
wavelength conversion is performed at an intermediate node, a new consistent policy configuration throughout a given transparency
Label Set is generated. The output node selects one label in the domain). When wavelength conversion is performed at an intermediate
Label Set which it received; additionally the node can apply local node, a new Label Set is generated. The egress node selects one label
policy during label selection. in the Label Set which it received; additionally the node can apply
local policy during label selection. GMPLS also provides support for
the signaling of bidirectional optical paths.
Depending on these policies a spectral assignment may not be found or Depending on these policies a wavelength assignment may not be found
one consuming too many conversion resources relative to what a or one consuming too many conversion resources relative to what a
dedicated wavelength assignment policy would have achieved. Hence, dedicated wavelength assignment policy would have achieved. Hence,
this approach may generate higher blocking probabilities in a heavily this approach may generate higher blocking probabilities in a heavily
loaded network. loaded network.
On the one hand, this solution may be empowered with some signaling This solution may be facilitated via signaling extensions which ease
extensions to ease its functioning and possibly enhance its its functioning and possibly enhance its performance relatively to
performance relatively to blocking. Note that this approach requires blocking. Note that this approach requires less information
less information dissemination than the other techniques described. dissemination than the other techniques described.
The first entity may be a PCE or the ingress node of the LSP. This The first entity may be a PCE or the ingress node of the LSP.
solution is applicable inside networks where resource optimization is
not as critical.
4.2. Conveying information needed by RWA 4.2. Conveying information needed by RWA
The previous sections have characterized WSONs and lightpath The previous sections have characterized WSONs and optical path
requests. In particular, high level models of the information used by requests. In particular, high level models of the information used by
the RWA process were presented. This information can be viewed as RWA process were presented. This information can be viewed as either
either static, changing with hardware changes (including possibly relatively static, i.e., changing with hardware changes (including
failures), or dynamic, those that can change with subsequent possibly failures), or relatively dynamic, i.e., those that can
lightpath provisioning. The timeliness in which an entity involved in change with optical path provisioning. The time requirement in which
the RWA process is notified of such changes is fairly situational. an entity involved in RWA process needs to be notified of such
For example, for network restoration purposes, learning of a hardware changes is fairly situational. For example, for network restoration
failure or of new hardware coming online to provide restoration purposes, learning of a hardware failure or of new hardware coming
capability can be critical. online to provide restoration capability can be critical.
Currently there are various methods for communicating RWA relevant Currently there are various methods for communicating RWA relevant
information, these include, but are not limited to: information, these include, but are not limited to:
o Existing control plane protocols such as GMPLS routing and o Existing control plane protocols, i.e., GMPLS routing and
signaling. Note that routing protocols can be used to convey both signaling. Note that routing protocols can be used to convey both
static and dynamic information. static and dynamic information.
o Management protocols such as NetConf, SNMPv3, CLI, CORBA, or o Management protocols such as NetConf, SNMPv3, CLI, and CORBA.
others.
o Directory services and accompanying protocols. These are good for o Directory services and accompanying protocols. These are typically
the dissemination of relatively static information. Directory used for the dissemination of relatively static information.
services are not suited to manage information in dynamic and fluid Directory services are not suited to manage information in dynamic
environments. and fluid environments.
o Other techniques for dynamic information: messaging straight from o Other techniques for dynamic information, e.g., sending
NEs to PCE to avoid flooding. This would be useful if the number information directly from NEs to PCE to avoid flooding. This would
of PCEs is significantly less than number of WSON NEs. Or other be useful if the number of PCEs is significantly less than number
ways to limit flooding to "interested" NEs. of WSON NEs. Or other ways to limit flooding to "interested" NEs.
Mechanisms to improve scaling of dynamic information: Possible mechanisms to improve scaling of dynamic information
include:
o Tailor message content to WSON. For example the use of wavelength o Tailor message content to WSON. For example the use of wavelength
ranges, or wavelength occupation bit maps. ranges, or wavelength occupation bit maps.
o Utilize incremental updates if feasible. o Utilize incremental updates if feasible.
5. Modeling Examples and Control Plane Use Cases 5. Modeling Examples and Control Plane Use Cases
This section provides examples of the fixed and switch optical node This section provides examples of the fixed and switch optical node
and wavelength constraint models of Section 3. and WSON control and wavelength constraint models of Section 3. and WSON control
skipping to change at page 32, line 44 skipping to change at page 32, line 44
o All other nodes contain ROADMs and can therefore access all o All other nodes contain ROADMs and can therefore access all
wavelengths. wavelengths.
o Nodes N4, N5, N7 and N8 are multi-degree nodes, allowing any o Nodes N4, N5, N7 and N8 are multi-degree nodes, allowing any
wavelength to be optically switched between any of the links. Note wavelength to be optically switched between any of the links. Note
however, that this does not automatically apply to wavelengths however, that this does not automatically apply to wavelengths
that are being added or dropped at the particular node. that are being added or dropped at the particular node.
o Node N4 is an exception to that: This node can switch any o Node N4 is an exception to that: This node can switch any
wavelength from its add/drop ports to any of its outgoing links wavelength from its add/drop ports to any of its output links (L5,
(L5, L7 and L12 in this case). L7 and L12 in this case).
o The links from the routers are always only able to carry one o The links from the routers are only able to carry one wavelength
wavelength with the exception of links L8 and L9 which are capable with the exception of links L8 and L9 which are capable to
to add/drop any wavelength. add/drop any wavelength.
o Node N7 contains an OEO transponder (O1) connected to the node via o Node N7 contains an OEO transponder (O1) connected to the node via
links L13 and L14. That transponder operates in 3R mode and does links L13 and L14. That transponder operates in 3R mode and does
not change the wavelength of the signal. Assume that it can not change the wavelength of the signal. Assume that it can
regenerate any of the client signals, however only for a specific regenerate any of the client signals, however only for a specific
wavelength. wavelength.
Given the above restrictions, the node information for the eight Given the above restrictions, the node information for the eight
nodes can be expressed as follows: (where ID == identifier, SCM == nodes can be expressed as follows: (where ID == identifier, SCM ==
switched connectivity matrix, and FCM == fixed connectivity matrix). switched connectivity matrix, and FCM == fixed connectivity matrix).
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5.1.2. Describing the links 5.1.2. Describing the links
For the following discussion some simplifying assumptions are made: For the following discussion some simplifying assumptions are made:
o It is assumed that the WSON node support a total of four o It is assumed that the WSON node support a total of four
wavelengths designated WL1 through WL4. wavelengths designated WL1 through WL4.
o It is assumed that the impairment feasibility of a path or path o It is assumed that the impairment feasibility of a path or path
segment is independent from the wavelength chosen. segment is independent from the wavelength chosen.
For the discussion of the RWA operation to build LSPs between two For the discussion of RWA operation to build LSPs between two
routers, the wavelength constraints on the links between the routers routers, the wavelength constraints on the links between the routers
and the WSON nodes as well as the connectivity matrix of these links and the WSON nodes as well as the connectivity matrix of these links
needs to be specified: needs to be specified:
+Link+WLs supported +Possible output links+ +Link+WLs supported +Possible output links+
| L1 | WL1 | L3 | | L1 | WL1 | L3 |
+----+-----------------+---------------------+ +----+-----------------+---------------------+
| L2 | WL2 | L4 | | L2 | WL2 | L4 |
+----+-----------------+---------------------+ +----+-----------------+---------------------+
| L8 | WL1 WL2 WL3 WL4 | L5 L7 L12 | | L8 | WL1 WL2 WL3 WL4 | L5 L7 L12 |
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+----+-----------------+---------------------+ +----+-----------------+---------------------+
Note that the possible output links for the links connecting to the Note that the possible output links for the links connecting to the
routers is inferred from the switched connectivity matrix and the routers is inferred from the switched connectivity matrix and the
fixed connectivity matrix of the Nodes N1 through N8 and is show here fixed connectivity matrix of the Nodes N1 through N8 and is show here
for convenience, i.e., this information does not need to be repeated. for convenience, i.e., this information does not need to be repeated.
5.2. RWA Path Computation and Establishment 5.2. RWA Path Computation and Establishment
The calculation of optical impairment feasible routes is outside the The calculation of optical impairment feasible routes is outside the
scope of this framework document. In general impairment feasible scope of this document. In general impairment feasible routes serve
routes serve as an input to the RWA algorithm. as an input to RWA algorithm.
For the example use case shown here, assume the following feasible For the example use case shown here, assume the following feasible
routes: routes:
+Endpoint 1+Endpoint 2+Feasible Route + +Endpoint 1+Endpoint 2+Feasible Route +
| R1 | R2 | L1 L3 L5 L8 | | R1 | R2 | L1 L3 L5 L8 |
| R1 | R2 | L1 L3 L5 L9 | | R1 | R2 | L1 L3 L5 L9 |
| R1 | R2 | L2 L4 L6 L7 L8 | | R1 | R2 | L2 L4 L6 L7 L8 |
| R1 | R2 | L2 L4 L6 L7 L9 | | R1 | R2 | L2 L4 L6 L7 L9 |
| R1 | R2 | L2 L4 L6 L10 | | R1 | R2 | L2 L4 L6 L10 |
| R1 | R3 | L1 L3 L5 L12 L15 L18 | | R1 | R3 | L1 L3 L5 L12 L15 L18 |
| R1 | N7 | L2 L4 L6 L11 | | R1 | N7 | L2 L4 L6 L11 |
| N7 | R3 | L16 L17 | | N7 | R3 | L16 L17 |
| N7 | R2 | L16 L15 L12 L9 | | N7 | R2 | L16 L15 L12 L9 |
| R2 | R3 | L8 L12 L15 L18 | | R2 | R3 | L8 L12 L15 L18 |
| R2 | R3 | L8 L7 L11 L16 L17 | | R2 | R3 | L8 L7 L11 L16 L17 |
| R2 | R3 | L9 L12 L15 L18 | | R2 | R3 | L9 L12 L15 L18 |
| R2 | R3 | L9 L7 L11 L16 L17 | | R2 | R3 | L9 L7 L11 L16 L17 |
Given a request to establish a LSP between R1 and R2 the RWA Given a request to establish a LSP between R1 and R2 RWA algorithm
algorithm finds the following possible solutions: finds the following possible solutions:
+WL + Path + +WL + Path +
| WL1| L1 L3 L5 L8 | | WL1| L1 L3 L5 L8 |
| WL1| L1 L3 L5 L9 | | WL1| L1 L3 L5 L9 |
| WL2| L2 L4 L6 L7 L8| | WL2| L2 L4 L6 L7 L8|
| WL2| L2 L4 L6 L7 L9| | WL2| L2 L4 L6 L7 L9|
| WL2| L2 L4 L6 L10 | | WL2| L2 L4 L6 L10 |
Assume now that the RWA chooses WL1 and the Path L1 L3 L5 L8 for the Assume now that RWA algorithm yields WL1 and the Path L1 L3 L5 L8 for
requested LSP. the requested LSP.
Next, another LSP is signaled from R1 to R2. Given the established Next, another LSP is signaled from R1 to R2. Given the established
LSP using WL1, the following table shows the available paths: LSP using WL1, the following table shows the available paths:
+WL + Path + +WL + Path +
| WL2| L2 L4 L6 L7 L9| | WL2| L2 L4 L6 L7 L9|
| WL2| L2 L4 L6 L10 | | WL2| L2 L4 L6 L10 |
Assume now that the RWA chooses WL2 and the path L2 L4 L6 L7 L9 for Assume now that RWA algorithm yields WL2 and the path L2 L4 L6 L7 L9
the establishment of the new LSP. for the establishment of the new LSP.
Faced with another LSP request -this time from R2 to R3 - can not be A LSP request -this time from R2 to R3 - can not be fulfilled since
fulfilled since the only four possible paths (starting at L8 and L9) the only four possible paths (starting at L8 and L9) are already in
are already in use. use.
5.3. Resource Optimization 5.3. Resource Optimization
The preceding example gives rise to another use case: the The preceding example gives rise to another use case: the
optimization of network resources. Optimization can be achieved on a optimization of network resources. Optimization can be achieved on a
number of layers (e.g. through electrical or optical multiplexing of number of layers (e.g. through electrical or optical multiplexing of
client signals) or by re-optimizing the solutions found by the RWA client signals) or by re-optimizing the solutions found by a RWA
algorithm. algorithm.
Given the above example again, assume that the RWA algorithm should Given the above example again, assume that a RWA algorithm should
find a path between R2 and R3. The only possible path to reach R3 identify a path between R2 and R3. The only possible path to reach R3
from R2 needs to use L9. L9 however is blocked by one of the LSPs from R2 needs to use L9. L9 however is blocked by one of the LSPs
from R1. from R1.
5.4. Support for Rerouting 5.4. Support for Rerouting
It is also envisioned that the extensions to GMPLS and PCE support It is also envisioned that the extensions to GMPLS and PCE support
rerouting of wavelengths in case of failures. rerouting of wavelengths in case of failures.
Assume for this discussion that the only two LSPs in use in the Assume for this discussion that the only two LSPs in use in the
system are: system are:
LSP1: WL1 L1 L3 L5 L8 LSP1: WL1 L1 L3 L5 L8
LSP2: WL2 L2 L4 L6 L7 L9 LSP2: WL2 L2 L4 L6 L7 L9
Assume furthermore that the link L5 fails. The RWA can now find the Assume furthermore that the link L5 fails. An RWA algorithm can now
following alternate path and and establish that path: compute the following alternate path and establish that path:
R1 -> N7 -> R2 R1 -> N7 -> R2
Level 3 regeneration will take place at N7, so that the complete path Level 3 regeneration will take place at N7, so that the complete path
looks like this: looks like this:
R1 -> L2 L4 L6 L11 L13 -> O1 -> L14 L16 L15 L12 L9 -> R2 R1 -> L2 L4 L6 L11 L13 -> O1 -> L14 L16 L15 L12 L9 -> R2
5.5. Electro-Optical Networking Scenarios 5.5. Electro-Optical Networking Scenarios
In the following various networking scenarios are considered In the following various networking scenarios are considered
involving regenerators, OEO switches and wavelength converters. These involving regenerators, OEO switches and wavelength converters. These
scenarios can be grouped roughly by type and number of extensions to scenarios can be grouped roughly by type and number of extensions to
the GMPLS control plane that would be required. the GMPLS control plane that would be required.
5.5.1. Fixed Regeneration Points 5.5.1. Fixed Regeneration Points
In the simplest networking scenario involving regenerators, the In the simplest networking scenario involving regenerators,
regeneration is associated with a WDM link or entire node and is not regeneration is associated with a WDM link or an entire node and is
optional, i.e., all signals traversing the link or node will be not optional, i.e., all signals traversing the link or node will be
regenerated. This includes OEO switches since they provide regenerated. This includes OEO switches since they provide
regeneration on every port. regeneration on every port.
There maybe input constraints and output constraints on the There may be input constraints and output constraints on the
regenerators. Hence the path selection process will need to know from regenerators. Hence the path selection process will need to know from
an IGP or other means the regenerator constraints so that it can routing or other means the regenerator constraints so that it can
choose a compatible path. For impairment aware routing and wavelength choose a compatible path. For impairment aware routing and wavelength
assignment (IA-RWA) the path selection process will also need to know assignment (IA-RWA) the path selection process will also need to know
which links/nodes provide regeneration. Even for "regular" RWA, this which links/nodes provide regeneration. Even for "regular" RWA, this
regeneration information is useful since wavelength converters regeneration information is useful since wavelength converters
typically perform regeneration and the wavelength continuity typically perform regeneration and the wavelength continuity
constraint can be relaxed at such a point. constraint can be relaxed at such a point.
Signaling does not need to be enhanced to include this scenario since Signaling does not need to be enhanced to include this scenario since
there are no reconfigurable regenerator options on input, output or there are no reconfigurable regenerator options on input, output or
with respect to processing. with respect to processing.
skipping to change at page 38, line 28 skipping to change at page 38, line 28
the network in addition to fixed regenerators of the previous the network in addition to fixed regenerators of the previous
scenario. These regenerators are shared within a node and their scenario. These regenerators are shared within a node and their
application to a signal is optional. There are no reconfigurable application to a signal is optional. There are no reconfigurable
options on either input or output. The only processing option is to options on either input or output. The only processing option is to
"regenerate" a particular signal or not. "regenerate" a particular signal or not.
Regenerator information in this case is used in path computation to Regenerator information in this case is used in path computation to
select a path that ensures signal compatibility and IA-RWA criteria. select a path that ensures signal compatibility and IA-RWA criteria.
To setup an LSP that utilizes a regenerator from a node with a shared To setup an LSP that utilizes a regenerator from a node with a shared
regenerator pool one should be able to indicate that regeneration is regenerator pool it is necessary to indicate that regeneration is to
to take place at that particular node along the signal path. Such a take place at that particular node along the signal path. Such a
capability currently does not exist in GMPLS signaling. capability currently does not exist in GMPLS signaling.
5.5.3. Reconfigurable Regenerators 5.5.3. Reconfigurable Regenerators
This scenario is concerned with regenerators that require This scenario is concerned with regenerators that require
configuration prior to use on an optical signal. As discussed configuration prior to use on an optical signal. As discussed
previously, this could be due to a regenerator that must be previously, this could be due to a regenerator that must be
configured to accept signals with different characteristics, for configured to accept signals with different characteristics, for
regenerators with a selection of output attributes, or for regenerators with a selection of output attributes, or for
regenerators with additional optional processing capabilities. regenerators with additional optional processing capabilities.
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("opaque") nodes strategically placed. This takes advantage of the ("opaque") nodes strategically placed. This takes advantage of the
inherent regeneration capabilities of OEO switches. In the inherent regeneration capabilities of OEO switches. In the
planning of such networks one has to determine the optimal planning of such networks one has to determine the optimal
placement of the OEO switches. placement of the OEO switches.
3. Mostly transparent networks with a limited number of optical 3. Mostly transparent networks with a limited number of optical
switching nodes with "shared regenerator pools" that can be switching nodes with "shared regenerator pools" that can be
optionally applied to signals passing through these switches. optionally applied to signals passing through these switches.
These switches are sometimes called translucent nodes. These switches are sometimes called translucent nodes.
All three of these types of translucent networks fit within the All three types of translucent networks fit within the networking
networking scenarios of Section 5.5.1. and Section 5.5.2. above. scenarios of Section 5.5.1. and Section 5.5.2. above. And hence,
And hence, can be accommodated by the GMPLS extensions suggested in can be accommodated by the GMPLS extensions envisioned in this
this document. document.
6. GMPLS and PCE Implications 6. GMPLS and PCE Implications
The presence and amount of wavelength conversion available at a The presence and amount of wavelength conversion available at a
wavelength switching interface has an impact on the information that wavelength switching interface has an impact on the information that
needs to be transferred by the control plane (GMPLS) and the PCE needs to be transferred by the control plane (GMPLS) and the PCE
architecture. Current GMPLS and PCE standards can address the full architecture. Current GMPLS and PCE standards can address the full
wavelength conversion case so the following will only address the wavelength conversion case so the following will only address the
limited and no wavelength conversion cases. limited and no wavelength conversion cases.
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optical channels, the LSP encoding type (value = 13) "G.709 Optical optical channels, the LSP encoding type (value = 13) "G.709 Optical
Channel" from [RFC4328]. However a number of practical issues arise Channel" from [RFC4328]. However a number of practical issues arise
in the identification of wavelengths and signals, and distributed in the identification of wavelengths and signals, and distributed
wavelength assignment processes which are discussed below. wavelength assignment processes which are discussed below.
6.1.1. Identifying Wavelengths and Signals 6.1.1. Identifying Wavelengths and Signals
As previously stated a global fixed mapping between wavelengths and As previously stated a global fixed mapping between wavelengths and
labels simplifies the characterization of WDM links and WSON devices. labels simplifies the characterization of WDM links and WSON devices.
Furthermore such a mapping as described in [Otani] eases Furthermore such a mapping as described in [Otani] provides such a
communication between PCE and WSON PCCs. fixed mapping for communication between PCE and WSON PCCs.
6.1.2. WSON Signals and Network Element Processing 6.1.2. WSON Signals and Network Element Processing
It was seen in Section 3.3.2. that a WSON signal at any point along As discussed in Section 3.3.2. a WSON signal at any point along its
its path can be characterized by the (a) modulation format, (b) FEC, path can be characterized by the (a) modulation format, (b) FEC, (c)
(c) wavelength, (d)bit rate, and (d)G-PID. wavelength, (d)bit rate, and (d)G-PID.
Currently G-PID, wavelength (via labels), and bit rate (via bandwidth Currently G-PID, wavelength (via labels), and bit rate (via bandwidth
encoding) are supported in [RFC3471] and [RFC3473]. These RFCs can encoding) are supported in [RFC3471] and [RFC3473]. These RFCs can
accommodate the wavelength changing at any node along the LSP and can accommodate the wavelength changing at any node along the LSP and can
thus provide explicit control of wavelength converters. thus provide explicit control of wavelength converters.
In the fixed regeneration point scenario described in Section 5.5.1. In the fixed regeneration point scenario described in Section 5.5.1.
(Fixed Regeneration Points) no enhancements are required to signaling (Fixed Regeneration Points) no enhancements are required to signaling
since there are no additional configuration options for the LSP at a since there are no additional configuration options for the LSP at a
node. node.
skipping to change at page 40, line 37 skipping to change at page 40, line 37
another way, for an LSP, it is desirable to specify that certain another way, for an LSP, it is desirable to specify that certain
nodes along the path perform regeneration. Such a capability nodes along the path perform regeneration. Such a capability
currently does not exist in GMPLS signaling. currently does not exist in GMPLS signaling.
The case of configurable regenerators described in Section 5.5.3. The case of configurable regenerators described in Section 5.5.3.
(Reconfigurable Regenerators) is very similar to the previous except (Reconfigurable Regenerators) is very similar to the previous except
that now there are potentially many more items that can be configured that now there are potentially many more items that can be configured
on a per node basis for an LSP. on a per node basis for an LSP.
Note that the techniques of [RFC5420] which allow for additional LSP Note that the techniques of [RFC5420] which allow for additional LSP
attributes and their recording in an Record Route Object (RRO) object attributes and their recording in a Record Route Object (RRO) object
could be extended to allow for additional LSP attributes in an ERO. could be extended to allow for additional LSP attributes in an ERO.
This could allow one to indicate where optional 3R regeneration This could allow one to indicate where optional 3R regeneration
should take place along a path, any modification of LSP attributes should take place along a path, any modification of LSP attributes
such as modulation format, or any enhance processing such as such as modulation format, or any enhance processing such as
performance monitoring. performance monitoring.
6.1.3. Combined RWA/Separate Routing WA support 6.1.3. Combined RWA/Separate Routing WA support
In either the combined RWA or separate routing WA cases, the node In either the combined RWA or separate routing WA cases, the node
initiating the signaling will have a route from the source to initiating the signaling will have a route from the source to
destination along with the wavelengths (generalized labels) to be destination along with the wavelengths (generalized labels) to be
used along portions of the path. Current GMPLS signaling supports an used along portions of the path. Current GMPLS signaling supports an
Explicit Route Object (ERO) and within an ERO an ERO Label subobject Explicit Route Object (ERO) and within an ERO an ERO Label subobject
can be use to indicate the wavelength to be used at a particular can be used to indicate the wavelength to be used at a particular
node. In case the local label map approach is used the label sub- node. In case the local label map approach is used the label sub-
object entry in the ERO has to be translated appropriately. object entry in the ERO has to be interpreted appropriately.
6.1.4. Distributed Wavelength Assignment: Unidirectional, No 6.1.4. Distributed Wavelength Assignment: Unidirectional, No
Converters Converters
GMPLS signaling for a uni-directional lightpath LSP allows for the GMPLS signaling for a unidirectional optical path LSP allows for the
use of a label set object in the Resource Reservation Protocol - use of a label set object in the Resource Reservation Protocol -
Traffic Engineering (RSVP-TE) path message. The processing of the Traffic Engineering (RSVP-TE) path message. The processing of the
label set object to take the intersection of available lambdas along label set object to take the intersection of available lambdas along
a path can be performed resulting in the set of available lambda a path can be performed resulting in the set of available lambda
being known to the destination that can then use a wavelength being known to the destination that can then use a wavelength
selection algorithm to choose a lambda. selection algorithm to choose a lambda.
6.1.5. Distributed Wavelength Assignment: Unidirectional, Limited 6.1.5. Distributed Wavelength Assignment: Unidirectional, Limited
Converters Converters
In the case of wavelength converters, nodes with wavelength In the case of wavelength converters, nodes with wavelength
converters would need to make the decision as to whether to perform converters would need to make the decision as to whether to perform
conversion. One indicator for this would be that the set of available conversion. One indicator for this would be that the set of available
wavelengths which is obtained via the intersection of the incoming wavelengths which is obtained via the intersection of the incoming
label set and the output links available wavelengths is either null label set and the output links available wavelengths is either null
or deemed too small to permit successful completion. or deemed too small to permit successful completion.
At this point the node would need to remember that it will apply At this point the node would need to remember that it will apply
wavelength conversion and will be responsible for assigning the wavelength conversion and will be responsible for assigning the
wavelength on the previous lambda-contiguous segment when the RSVP-TE wavelength on the previous lambda-contiguous segment when the RSVP-TE
RESV message passes by. The node will pass on an enlarged label set RESV message is processed. The node will pass on an enlarged label
reflecting only the limitations of the wavelength converter and the set reflecting only the limitations of the wavelength converter and
output link. The record route option in RVSP-TE signaling can be used the output link. The record route option in RSVP-TE signaling can be
to show where wavelength conversion has taken place. used to show where wavelength conversion has taken place.
6.1.6. Distributed Wavelength Assignment: Bidirectional, No 6.1.6. Distributed Wavelength Assignment: Bidirectional, No
Converters Converters
There are potential issues in the case of a bi-directional lightpath There are cases of a bidirectional optical path which requires the
which requires the use of the same lambda in both directions. The use of the same lambda in both directions. The above procedure can be
above procedure can be used to determine the available bidirectional used to determine the available bidirectional lambda set if it is
lambda set if it is interpreted that the available label set is interpreted that the available label set is available in both
available in both directions. However, a problem, arises in that directions. In bidirectional LSPs setup, according to [RFC3471]
bidirectional LSPs setup, according to [RFC3471] Section 4.1. Section 4.1. (Architectural Approaches to RWA), is indicated by the
(Architectural Approaches to RWA), is indicated by the presence of an presence of an upstream label in the path message.
upstream label in the path message.
However, until the intersection of the available label sets is However, until the intersection of the available label sets is
obtained, e.g., at the destination node and the wavelength assignment determined along the path and at the destination node the upstream
algorithm has been run the upstream label information will not be label information may not be correct. This case can be supported
available. Hence currently distributed wavelength assignment with using current GMPLS mechanisms, but may not be as efficient as an
bidirectional lightpaths is not supported. optimized bidirectional single-label allocation mechanism.
6.2. Implications for GMPLS Routing 6.2. Implications for GMPLS Routing
GMPLS routing [RFC4202] currently defines an interface capability GMPLS routing [RFC4202] currently defines an interface capability
descriptor for "lambda switch capable" (LSC) which can be used to descriptor for "lambda switch capable" (LSC) which can be used to
describe the interfaces on a ROADM or other type of wavelength describe the interfaces on a ROADM or other type of wavelength
selective switch. In addition to the topology information typically selective switch. In addition to the topology information typically
conveyed via an IGP, it would be necessary to convey the following conveyed via an IGP, it would be necessary to convey the following
subsystem properties to minimally characterize a WSON: subsystem properties to minimally characterize a WSON:
skipping to change at page 43, line 6 skipping to change at page 43, line 6
tributary signal classes that can be processed by this network tributary signal classes that can be processed by this network
element or carried over this link. (configuration type) element or carried over this link. (configuration type)
2. Acceptable FEC codes. (configuration type) 2. Acceptable FEC codes. (configuration type)
3. Acceptable Bit Rate Set: a list of specific bit rates or bit rate 3. Acceptable Bit Rate Set: a list of specific bit rates or bit rate
ranges that the device can accommodate. Coarse bit rate info is ranges that the device can accommodate. Coarse bit rate info is
included with the optical tributary signal class restrictions. included with the optical tributary signal class restrictions.
4. Acceptable G-PID list: a list of G-PIDs corresponding to the 4. Acceptable G-PID list: a list of G-PIDs corresponding to the
"client" digital streams that is compatible with this device. "client" digital streams that is compatible with this device.
Note that since the bit rate of the signal does not change over the Note that since the bit rate of the signal does not change over the
LSP. This can be made as an LSP parameter and hence this information LSP. This can be communicated as an LSP parameter and hence this
would be available for any NE that needs to use it for configuration. information would be available for any NE that needs to use it for
Hence it is not necessary to have "configuration type" for the NE configuration. Hence it is not necessary to have "configuration type"
with respect to bit rate. for the NE with respect to bit rate.
Output constraints: Output constraints:
1. Output modulation: (a)same as input, (b) list of available types 1. Output modulation: (a)same as input, (b) list of available types
2. FEC options: (a) same as input, (b) list of available codes 2. FEC options: (a) same as input, (b) list of available codes
Processing capabilities: Processing capabilities:
1. Regeneration: (a) 1R, (b) 2R, (c) 3R, (d)list of selectable 1. Regeneration: (a) 1R, (b) 2R, (c) 3R, (d)list of selectable
regeneration types regeneration types
2. Fault and performance monitoring: (a) G-PID particular 2. Fault and performance monitoring: (a) G-PID particular
capabilities, (b) optical performance monitoring capabilities. capabilities, (b) optical performance monitoring capabilities.
Note that such parameters could be specified on an (a) Network Note that such parameters could be specified on an (a) Network
element wide basis, (b) a per port basis, (c) on a per regenerator element wide basis, (b) a per port basis, (c) on a per regenerator
basis. Typically such information has been on a per port basis, basis. Typically such information has been on a per port basis, see,
e.g., the GMPLS interface switching capability descriptor [RFC4202]. the GMPLS interface switching capability descriptor [RFC4202].
6.2.2. Wavelength-Specific Availability Information 6.2.2. Wavelength-Specific Availability Information
For wavelength assignment it is necessary to know which specific For wavelength assignment it is necessary to know which specific
wavelengths are available and which are occupied if a combined RWA wavelengths are available and which are occupied if a combined RWA
process or separate WA process is run as discussed in sections 4.1.1. process or separate WA process is run as discussed in sections 4.1.1.
4.1.2. This is currently not possible with GMPLS routing extensions. 4.1.2. This is currently not possible with GMPLS routing.
In the routing extensions for GMPLS [RFC4202], requirements for In the routing extensions for GMPLS [RFC4202], requirements for
layer-specific TE attributes are discussed. The RWA problem for layer-specific TE attributes are discussed. RWA for optical networks
optical networks without wavelength converters imposes an additional without wavelength converters imposes an additional requirement for
requirement for the lambda (or optical channel) layer: that of the lambda (or optical channel) layer: that of knowing which specific
knowing which specific wavelengths are in use. Note that currentDWDM wavelengths are in use. Note that current DWDM systems range from 16
systems range from 16 channels to 128 channels with advanced channels to 128 channels with advanced laboratory systems with as
laboratory systems with as many as 300 channels. Given these channel many as 300 channels. Given these channel limitations and if the
limitations and if the approach of a global wavelength to label approach of a global wavelength to label mapping or furnishing the
mapping or furnishing the local mappings to the PCEs is taken then local mappings to the PCEs is taken then representing the use of
representing the use of wavelengths via a simple bit-map is feasible wavelengths via a simple bit-map is feasible [WSON-Encode].
[WSON-Encode].
6.2.3. WSON Routing Information Summary 6.2.3. WSON Routing Information Summary
The following table summarizes the WSON information that could be The following table summarizes the WSON information that could be
conveyed via GMPLS routing and attempts to classify that information conveyed via GMPLS routing and attempts to classify that information
as to its static or dynamic nature and whether that information would as to its static or dynamic nature and whether that information would
tend to be associated with either a link or a node. tend to be associated with either a link or a node.
Information Static/Dynamic Node/Link Information Static/Dynamic Node/Link
------------------------------------------------------------------ ------------------------------------------------------------------
Connectivity matrix Static Node Connectivity matrix Static Node
Per port wavelength restrictions Static Node(1) Per port wavelength restrictions Static Node(1)
WDM link (fiber) lambda ranges Static Link WDM link (fiber) lambda ranges Static Link
WDM link channel spacing Static Link WDM link channel spacing Static Link
Optical transmitter range Static Optical transmitter range Static Link(2)
Link(2)
Wavelength conversion capabilities Static(3) Node Wavelength conversion capabilities Static(3) Node
Maximum bandwidth per wavelength Static Link Maximum bandwidth per wavelength Static Link
Wavelength availability Dynamic(4) Link Wavelength availability Dynamic(4) Link
Signal compatibility and processing Static/Dynamic Node Signal compatibility and processing Static/Dynamic Node
Notes: Notes:
1. These are the per port wavelength restrictions of an optical 1. These are the per port wavelength restrictions of an optical
device such as a ROADM and are independent of any optical device such as a ROADM and are independent of any optical
constraints imposed by a fiber link. constraints imposed by a fiber link.
skipping to change at page 45, line 10 skipping to change at page 45, line 7
Information Static/Dynamic Node/Link Information Static/Dynamic Node/Link
------------------------------------------------------------------ ------------------------------------------------------------------
Connectivity matrix Static Node Connectivity matrix Static Node
Wavelength conversion capabilities Static(3) Node Wavelength conversion capabilities Static(3) Node
Information models and compact encodings for this information is Information models and compact encodings for this information is
provided in [WSON-Info], [Gen-Encode] and [WSON-Encode]. provided in [WSON-Info], [Gen-Encode] and [WSON-Encode].
6.3. Optical Path Computation and Implications for PCE 6.3. Optical Path Computation and Implications for PCE
As previously noted the RWA problem can be computationally intensive. As previously noted RWA can be computationally intensive. Such
Such computationally intensive path computations and optimizations computationally intensive path computations and optimizations were
were part of the impetus for the PCE architecture [RFC4655]. part of the impetus for the PCE architecture [RFC4655].
The Path Computation Element Protocol (PCEP) defines the procedures The Path Computation Element Protocol (PCEP) defines the procedures
necessary to support both sequential [RFC5440] and global concurrent necessary to support both sequential [RFC5440] and global concurrent
path computations (PCE-GCO) [RFC5557], PCE is well positioned to path computations (PCE-GCO) [RFC5557], PCE is well positioned to
support WSON-enabled RWA computation with some protocol enhancement. support WSON-enabled RWA computation with some protocol enhancement.
Implications for PCE generally fall into two main categories: (a) Implications for PCE generally fall into two main categories: (a)
lightpath constraints and characteristics, (b) computation optical path constraints and characteristics, (b) computation
architectures. architectures.
6.3.1. Lightpath Constraints and Characteristics 6.3.1. Optical path Constraints and Characteristics
For the varying degrees of optimization that may be encountered in a For the varying degrees of optimization that may be encountered in a
network the following models of bulk and sequential lightpath network the following models of bulk and sequential optical path
requests are encountered: requests are encountered:
o Batch optimization, multiple lightpaths requested at one time o Batch optimization, multiple optical paths requested at one time
(PCE-GCO). (PCE-GCO).
o Lightpath(s) and backup lightpath(s) requested at one time (PCEP). o Optical path(s) and backup optical path(s) requested at one time
(PCEP).
o Single lightpath requested at a time (PCEP). o Single optical path requested at a time (PCEP).
PCEP and PCE-GCO can be readily enhanced to support all of the PCEP and PCE-GCO can be readily enhanced to support all of the
potential models of RWA computation. potential models of RWA computation.
Lightpath constraints include: Optical path constraints include:
o Bidirectional Assignment of wavelengths. o Bidirectional Assignment of wavelengths.
o Possible simultaneous assignment of wavelength to primary and o Possible simultaneous assignment of wavelength to primary and
backup paths. backup paths.
o Tuning range constraint on optical transmitter. o Tuning range constraint on optical transmitter.
6.3.2. Electro-Optical Element Signal Compatibility 6.3.2. Electro-Optical Element Signal Compatibility
skipping to change at page 46, line 28 skipping to change at page 46, line 23
The PCE should be able to respond to the PCC with the following: The PCE should be able to respond to the PCC with the following:
o The conformity of the requested optical characteristics associated o The conformity of the requested optical characteristics associated
with the resulting LSP with the source, sink and NE along the LSP. with the resulting LSP with the source, sink and NE along the LSP.
o Additional LSP attributes modified along the path (e.g., o Additional LSP attributes modified along the path (e.g.,
modulation format change, etc.). modulation format change, etc.).
6.3.3. Discovery of RWA Capable PCEs 6.3.3. Discovery of RWA Capable PCEs
The algorithms and network information needed for solving the RWA are The algorithms and network information needed for RWA are somewhat
somewhat specialized and computationally intensive hence not all PCEs specialized and computationally intensive hence not all PCEs within a
within a domain would necessarily need or want this capability. domain would necessarily need or want this capability. Hence, it
Hence, it would be useful via the mechanisms being established for would be useful via the mechanisms being established for PCE
PCE discovery [RFC5088] to indicate that a PCE has the ability to discovery [RFC5088] to indicate that a PCE has the ability to deal
deal with the RWA problem. Reference [RFC5088] indicates that a sub- with RWA. Reference [RFC5088] indicates that a sub-TLV could be
TLV could be allocated for this purpose. allocated for this purpose.
Recent progress on objective functions in PCE [RFC5541] would allow Recent progress on objective functions in PCE [RFC5541] would allow
the operators to flexibly request differing objective functions per the operators to flexibly request differing objective functions per
their need and applications. For instance, this would allow the their need and applications. For instance, this would allow the
operator to choose an objective function that minimizes the total operator to choose an objective function that minimizes the total
network cost associated with setting up a set of paths concurrently. network cost associated with setting up a set of paths concurrently.
This would also allow operators to choose an objective function that This would also allow operators to choose an objective function that
results in a most evenly distributed link utilization. results in a most evenly distributed link utilization.
This implies that PCEP would easily accommodate wavelength selection This implies that PCEP would easily accommodate wavelength selection
skipping to change at page 47, line 13 skipping to change at page 47, line 5
by the operators. by the operators.
7. Security Considerations 7. Security Considerations
This document has no requirement for a change to the security models This document has no requirement for a change to the security models
within GMPLS and associated protocols. That is the OSPF-TE, RSVP-TE, within GMPLS and associated protocols. That is the OSPF-TE, RSVP-TE,
and PCEP security models could be operated unchanged. and PCEP security models could be operated unchanged.
However satisfying the requirements for RWA using the existing However satisfying the requirements for RWA using the existing
protocols may significantly affect the loading of those protocols. protocols may significantly affect the loading of those protocols.
This makes the operation of the network more vulnerable to denial of This may make the operation of the network more vulnerable to denial
service attacks. Therefore additional care maybe required to ensure of service attacks. Therefore additional care maybe required to
that the protocols are secure in the WSON environment. ensure that the protocols are secure in the WSON environment.
Furthermore the additional information distributed in order to Furthermore the additional information distributed in order to
address the RWA problem represents a disclosure of network address RWA represents a disclosure of network capabilities that an
capabilities that an operator may wish to keep private. Consideration operator may wish to keep private. Consideration should be given to
should be given to securing this information. securing this information. For a general discussion on MPLS and GMPLS
related security issues, see the MPLS/GMPLS security framework
[RFC5920].
8. IANA Considerations 8. IANA Considerations
This document makes no request for IANA actions. This document makes no request for IANA actions.
9. Acknowledgments 9. Acknowledgments
The authors would like to thank Adrian Farrel for many helpful The authors would like to thank Adrian Farrel for many helpful
comments that greatly improved the contents of this draft. comments that greatly improved the contents of this draft.
skipping to change at page 48, line 29 skipping to change at page 48, line 29
(GMPLS) Architecture", RFC 3945, October 2004. (GMPLS) Architecture", RFC 3945, October 2004.
[RFC4202] Kompella, K. and Y. Rekhter, "Routing Extensions in Support [RFC4202] Kompella, K. and Y. Rekhter, "Routing Extensions in Support
of Generalized Multi-Protocol Label Switching (GMPLS)", RFC of Generalized Multi-Protocol Label Switching (GMPLS)", RFC
4202, October 2005. 4202, October 2005.
[RFC4328] Papadimitriou, D., "Generalized Multi-Protocol Label [RFC4328] Papadimitriou, D., "Generalized Multi-Protocol Label
Switching (GMPLS) Signaling Extensions for G.709 Optical Switching (GMPLS) Signaling Extensions for G.709 Optical
Transport Networks Control", RFC 4328, January 2006. Transport Networks Control", RFC 4328, January 2006.
[G.694.1] ITU-T Recommendation G.694.1, "Spectral grids for WDM [RFC4655] Farrel, A., Vasseur, JP., and Ash, J., "A Path Computation
applications: DWDM frequency grid", June, 2002. Element (PCE)-Based Architecture ", RFC 4655, August 2006.
[RFC5088] J.L. Le Roux, J.P. Vasseur, Yuichi Ikejiri, and Raymond [RFC5088] J.L. Le Roux, J.P. Vasseur, Yuichi Ikejiri, and Raymond
Zhang, "OSPF protocol extensions for Path Computation Zhang, "OSPF protocol extensions for Path Computation
Element (PCE) Discovery", January 2008. Element (PCE) Discovery", January 2008.
[RFC5212] Shiomoto, K., Papadimitriou, D., Le Roux, JL., Vigoureux, [RFC5212] Shiomoto, K., Papadimitriou, D., Le Roux, JL., Vigoureux,
M., and D. Brungard, "Requirements for GMPLS-Based Multi- M., and D. Brungard, "Requirements for GMPLS-Based Multi-
Region and Multi-Layer Networks (MRN/MLN)", RFC 5212, July Region and Multi-Layer Networks (MRN/MLN)", RFC 5212, July
2008. 2008.
skipping to change at page 49, line 14 skipping to change at page 49, line 14
[RFC5440] J.P. Vasseur and J.L. Le Roux (Editors), "Path Computation [RFC5440] J.P. Vasseur and J.L. Le Roux (Editors), "Path Computation
Element (PCE) Communication Protocol (PCEP)", RFC 5440, May Element (PCE) Communication Protocol (PCEP)", RFC 5440, May
2009. 2009.
[RFC5541] J.L. Le Roux, J.P. Vasseur, and Y. Lee, "Encoding of [RFC5541] J.L. Le Roux, J.P. Vasseur, and Y. Lee, "Encoding of
Objective Functions in Path Computation Element (PCE) Objective Functions in Path Computation Element (PCE)
communication and discovery protocols", RFC 5541, July communication and discovery protocols", RFC 5541, July
2009. 2009.
[WSON-Compat] G. Bernstein, Y. Lee, B. Mack-Crane, "WSON Signal 10.2. Informative References
Characteristics and Network Element Compatibility
Constraints for GMPLS", draft-bernstein-ccamp-wson-
compatibility, work in progress.
[WSON-Encode] G. Bernstein, Y. Lee, D. Li, and W. Imajuku, "Routing
and Wavelength Assignment Information Encoding for
Wavelength Switched Optical Networks", draft-ietf-ccamp-
wson-encode, work in progress.
[Gen-Encode] G. Bernstein, Y. Lee, D. Li, and W. Imajuku, "General [Gen-Encode] G. Bernstein, Y. Lee, D. Li, and W. Imajuku, "General
Network Element Constraint Encoding for GMPLS Controlled Network Element Constraint Encoding for GMPLS Controlled
Networks", draft-ietf-ccamp-general-constraint-encode, work Networks", draft-ietf-ccamp-general-constraint-encode, work
in progress. in progress.
[WSON-Imp] Y. Lee, G. Bernstein, D. Li, G. Martinelli, "A Framework
for the Control of Wavelength Switched Optical Networks
(WSON) with Impairments", draft-ietf-ccamp-wson-
impairments, work in progress.
[WSON-Info] Y. Lee, G. Bernstein, D. Li, W. Imajuku, "Routing and
Wavelength Assignment Information for Wavelength Switched
Optical Networks", draft-bernstein-ccamp-wson-info, work in
progress
10.2. Informative References
[RFC4655] Farrel, A., Vasseur, JP., and Ash, J., "A Path Computation
Element (PCE)-Based Architecture ", RFC 4655, August 2006.
[Otani] T. Otani, H. Guo, K. Miyazaki, D. Caviglia, "Generalized
Labels of Lambda-Switching Capable Label Switching Routers
(LSR)", work in progress: draft-otani-ccamp-gmpls-g-694-
lambda-labels, work in progress.
[G.652] ITU-T Recommendation G.652, Characteristics of a single-mode [G.652] ITU-T Recommendation G.652, Characteristics of a single-mode
optical fibre and cable, June 2005. optical fibre and cable, June 2005.
[G.653] ITU-T Recommendation G.653, Characteristics of a dispersion- [G.653] ITU-T Recommendation G.653, Characteristics of a dispersion-
shifted single-mode optical fibre and cable, December 2006. shifted single-mode optical fibre and cable, December 2006.
[G.654] ITU-T Recommendation G.654, Characteristics of a cut-off [G.654] ITU-T Recommendation G.654, Characteristics of a cut-off
shifted single-mode optical fibre and cable, December 2006. shifted single-mode optical fibre and cable, December 2006.
[G.655] ITU-T Recommendation G.655, Characteristics of a non-zero [G.655] ITU-T Recommendation G.655, Characteristics of a non-zero
dispersion-shifted single-mode optical fibre and cable, dispersion-shifted single-mode optical fibre and cable,
March 2006. March 2006.
[G.656] ITU-T Recommendation G.656, Characteristics of a fibre and [G.656] ITU-T Recommendation G.656, Characteristics of a fibre and
cable with non-zero dispersion for wideband optical cable with non-zero dispersion for wideband optical
transport, December 2006. transport, December 2006.
[G.671] ITU-T Recommendation G.671, Transmission characteristics of [G.671] ITU-T Recommendation G.671, Transmission characteristics of
optical components and subsystems, January 2005. optical components and subsystems, January 2005.
[G.694.1] ITU-T Recommendation G.694.1, "Spectral grids for WDM
applications: DWDM frequency grid", June, 2002.
[G.872] ITU-T Recommendation G.872, Architecture of optical [G.872] ITU-T Recommendation G.872, Architecture of optical
transport networks, November 2001. transport networks, November 2001.
[G.959.1] ITU-T Recommendation G.959.1, Optical Transport Network [G.959.1] ITU-T Recommendation G.959.1, Optical Transport Network
Physical Layer Interfaces, March 2006. Physical Layer Interfaces, March 2006.
[G.694.1] ITU-T Recommendation G.694.1, Spectral grids for WDM [G.694.1] ITU-T Recommendation G.694.1, Spectral grids for WDM
applications: DWDM frequency grid, June 2002. applications: DWDM frequency grid, June 2002.
[G.694.2] ITU-T Recommendation G.694.2, Spectral grids for WDM [G.694.2] ITU-T Recommendation G.694.2, Spectral grids for WDM
skipping to change at page 51, line 5 skipping to change at page 50, line 22
engineering considerations, February 2006. engineering considerations, February 2006.
[G.Sup43] ITU-T Series G Supplement 43, Transport of IEEE 10G base-R [G.Sup43] ITU-T Series G Supplement 43, Transport of IEEE 10G base-R
in optical transport networks (OTN), November 2006. in optical transport networks (OTN), November 2006.
[Imajuku] W. Imajuku, Y. Sone, I. Nishioka, S. Seno, "Routing [Imajuku] W. Imajuku, Y. Sone, I. Nishioka, S. Seno, "Routing
Extensions to Support Network Elements with Switching Extensions to Support Network Elements with Switching
Constraint", work in progress: draft-imajuku-ccamp-rtg- Constraint", work in progress: draft-imajuku-ccamp-rtg-
switching-constraint. switching-constraint.
[Otani] T. Otani, H. Guo, K. Miyazaki, D. Caviglia, "Generalized
Labels of Lambda-Switching Capable Label Switching Routers
(LSR)", work in progress: draft-otani-ccamp-gmpls-g-694-
lambda-labels, work in progress.
[RFC5920] Fang, L., "Security Framework for MPLS and GMPLS
Networks", RFC 5920, July 2010.[Otani]T. Otani, H. Guo, K.
Miyazaki, D. Caviglia, "Generalized Labels of Lambda-
Switching Capable Label Switching Routers (LSR)", work in
progress: draft-otani-ccamp-gmpls-g-694-lambda-labels, work
in progress.
[WSON-Compat] G. Bernstein, Y. Lee, B. Mack-Crane, "WSON Signal
Characteristics and Network Element Compatibility
Constraints for GMPLS", draft-bernstein-ccamp-wson-
compatibility, work in progress.
[WSON-Encode] G. Bernstein, Y. Lee, D. Li, and W. Imajuku, "Routing
and Wavelength Assignment Information Encoding for
Wavelength Switched Optical Networks", draft-ietf-ccamp-
wson-encode, work in progress.
[WSON-Imp] Y. Lee, G. Bernstein, D. Li, G. Martinelli, "A Framework
for the Control of Wavelength Switched Optical Networks
(WSON) with Impairments", draft-ietf-ccamp-wson-
impairments, work in progress.
[WSON-Info] Y. Lee, G. Bernstein, D. Li, W. Imajuku, "Routing and
Wavelength Assignment Information for Wavelength Switched
Optical Networks", draft-bernstein-ccamp-wson-info, work in
progress
11. Contributors 11. Contributors
Snigdho Bardalai Snigdho Bardalai
Fujitsu Fujitsu
Email: Snigdho.Bardalai@us.fujitsu.com Email: Snigdho.Bardalai@us.fujitsu.com
Diego Caviglia Diego Caviglia
Ericsson Ericsson
Via A. Negrone 1/A 16153 Via A. Negrone 1/A 16153
skipping to change at page 55, line 32 skipping to change at page 56, line 32
material from [WSON-Compat]. material from [WSON-Compat].
Created new section 6.1.2 on WSON Signals and Network Element Created new section 6.1.2 on WSON Signals and Network Element
Processing with material from [WSON-Compat]. Processing with material from [WSON-Compat].
Created new section 6.3.2. Electro-Optical Related PCEP Extensions Created new section 6.3.2. Electro-Optical Related PCEP Extensions
with material from [WSON-Compat]. with material from [WSON-Compat].
A.6 Changes from 05 A.6 Changes from 05
Removal of Section 1.2; Removal of section on lightpath temporal Removal of Section 1.2; Removal of section on optical path temporal
characteristics; Removal of details on wavelength assignment characteristics; Removal of details on wavelength assignment
algorithms; Removal of redundant summary in section 6. algorithms; Removal of redundant summary in section 6.
 End of changes. 97 change blocks. 
267 lines changed or deleted 275 lines changed or added

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