draft-ietf-ccamp-wavelength-switched-framework-00.txt   draft-ietf-ccamp-wavelength-switched-framework-01.txt 
Network Working Group G. Bernstein (ed.) Network Working Group G. Bernstein (ed.)
Internet Draft Grotto Networking Internet Draft Grotto Networking
Intended status: Informational Y. Lee (ed.) Intended status: Informational Y. Lee (ed.)
Expires: November 2008 Huawei Expires: April 2009 Huawei
Wataru Imajuku Wataru Imajuku
NTT NTT
May 13, 2008 October 31, 2008
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-wavelength-switched-framework-00.txt draft-ietf-ccamp-wavelength-switched-framework-01.txt
Status of this Memo Status of this Memo
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Copyright Notice Copyright Notice
Copyright (C) The IETF Trust (2008). Copyright (C) The IETF Trust (2008).
Abstract Abstract
This memo provides a framework for applying Generalized Multi- This memo 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 we provide control plane models for networks (WSON). In particular we provide control plane models for
skipping to change at page 2, line 37 skipping to change at page 2, line 37
1. Introduction...................................................3 1. Introduction...................................................3
2. Terminology....................................................4 2. Terminology....................................................4
3. Wavelength Switched Optical Networks...........................5 3. Wavelength Switched Optical Networks...........................5
3.1. WDM and CWDM Links........................................5 3.1. WDM and CWDM Links........................................5
3.2. Optical Transmitters......................................7 3.2. Optical Transmitters......................................7
3.2.1. Lasers...............................................7 3.2.1. Lasers...............................................7
3.2.2. Spectral Characteristics & Modulation Type...........8 3.2.2. Spectral Characteristics & Modulation Type...........8
3.2.3. Signal Rates and Error Correction....................9 3.2.3. Signal Rates and Error Correction....................9
3.3. ROADMs, OXCs, Splitters, Combiners and FOADMs............10 3.3. ROADMs, OXCs, Splitters, Combiners and FOADMs............10
3.3.1. Reconfigurable Add/Drop Multiplexers and OXCs.......10 3.3.1. Reconfigurable Add/Drop Multiplexers and OXCs.......10
3.3.2. Splitters...........................................11 3.3.2. Splitters...........................................12
3.3.3. Combiners...........................................12 3.3.3. Combiners...........................................12
3.3.4. Fixed Optical Add/Drop Multiplexers.................12 3.3.4. Fixed Optical Add/Drop Multiplexers.................12
3.4. Wavelength Converters....................................13 3.4. Wavelength Converters....................................13
4. Routing and Wavelength Assignment.............................15 4. Routing and Wavelength Assignment and the Control Plane.......15
4.1. Lightpath Temporal Characteristics.......................16 4.1. Architectural Approaches to RWA..........................16
4.2. RWA Algorithmic Approaches: Combined vs. Two-step........17 4.1.1. Combined RWA (R&WA).................................16
4.3. RWA Computation Architectures............................17 4.1.2. Separated R and WA (R+WA)...........................17
4.4. Conveying information needed by RWA......................18 4.1.3. Routing and Distributed WA (R+DWA)..................17
5. GMPLS & PCE Implications......................................19 4.2. Conveying information needed by RWA......................18
5.1. Implications for GMPLS signaling.........................19 4.3. Lightpath Temporal Characteristics.......................19
5.1.1. Identifying Wavelengths and Signals.................19 5. GMPLS & PCE Implications......................................20
5.1. Implications for GMPLS signaling.........................20
5.1.1. Identifying Wavelengths and Signals.................20
5.1.2. Combined RWA/Separate Routing WA support............20 5.1.2. Combined RWA/Separate Routing WA support............20
5.1.3. Distributed Wavelength Assignment: Unidirectional, No 5.1.3. Distributed Wavelength Assignment: Unidirectional, No
Converters.................................................20 Converters.................................................21
5.1.4. Distributed Wavelength Assignment: Unidirectional, 5.1.4. Distributed Wavelength Assignment: Unidirectional,
Limited Converters.........................................21 Limited Converters.........................................22
5.1.5. Distributed Wavelength Assignment: Bidirectional, No 5.1.5. Distributed Wavelength Assignment: Bidirectional, No
Converters.................................................21 Converters.................................................22
5.2. Implications for GMPLS Routing...........................21 5.2. Implications for GMPLS Routing...........................23
5.2.1. Need for Wavelength-Specific Maximum Bandwidth 5.2.1. Need for Wavelength-Specific Maximum Bandwidth
Information................................................22 Information................................................23
5.2.2. Need for Wavelength-Specific Availability Information22 5.2.2. Need for Wavelength-Specific Availability Information24
5.2.3. Relationship to Link Bundling and Layering..........23 5.2.3. Relationship to Link Bundling and Layering..........24
5.2.4. WSON Routing Information Summary....................23 5.2.4. WSON Routing Information Summary....................24
5.3. Optical Path Computation and Implications for PCE........25 5.3. Optical Path Computation and Implications for PCE........26
5.3.1. Lightpath Constraints and Characteristics...........25 5.3.1. Lightpath Constraints and Characteristics...........26
5.3.2. Computation Architecture Implications...............26 5.3.2. Computation Architecture Implications...............27
5.3.3. Discovery of RWA Capable PCEs.......................26 5.3.3. Discovery of RWA Capable PCEs.......................27
5.4. Scaling Implications.....................................26 5.4. Scaling Implications.....................................27
5.4.1. Routing.............................................27 5.4.1. Routing.............................................28
5.4.2. Signaling...........................................27 5.4.2. Signaling...........................................28
5.4.3. Path computation....................................27 5.4.3. Path computation....................................28
6. Security Considerations.......................................27 5.5. Summary of Impacts by RWA Architecture...................28
7. IANA Considerations...........................................27 6. Security Considerations.......................................29
8. Acknowledgments...............................................27 7. IANA Considerations...........................................29
9. References....................................................29 8. Acknowledgments...............................................30
9.1. Normative References.....................................29 9. References....................................................31
9.2. Informative References...................................30 9.1. Normative References.....................................31
10. Contributors.................................................32 9.2. Informative References...................................32
Author's Addresses...............................................32 10. Contributors.................................................35
Intellectual Property Statement..................................33 Author's Addresses...............................................35
Disclaimer of Validity...........................................34 Intellectual Property Statement..................................36
Disclaimer of Validity...........................................37
1. Introduction 1. Introduction
From its beginning Generalized Multi-Protocol Label Switching (GMPLS) From its beginning Generalized Multi-Protocol Label Switching (GMPLS)
was intended to control wavelength switched optical networks (WSON) was intended to control wavelength switched optical networks (WSON)
with the GMPLS architecture document [RFC3945] explicitly mentioning with the GMPLS architecture document [RFC3945] explicitly mentioning
both wavelength and waveband switching and equating wavelengths both wavelength and waveband switching and equating wavelengths
(lambdas) with GMPLS labels. In addition a discussion of optical (lambdas) with GMPLS labels. In addition a discussion of optical
impairments and other constraints on optical routing can be found in impairments and other constraints on optical routing can be found in
[RFC4054]. However, optical technologies have advanced in ways that [RFC4054]. However, optical technologies have advanced in ways that
make them significantly different from other circuit switched make them significantly different from other circuit switched
technologies such as Time Division Multiplexing (TDM). Service technologies such as Time Division Multiplexing (TDM). Service
providers have already deployed many of these new optical providers have already deployed many of these new optical
technologies such as ROADMs and tunable lasers and desire the same technologies such as ROADMs and tunable lasers and desire the same
automation and restoration capabilities that GMPLS has provided to automation and restoration capabilities that GMPLS has provided to
TDM and packet switched networks. Another important application of an TDM and packet switched networks. Another important application of an
automated control plane such as GMPLS is the possibility to improve, automated control plane such as GMPLS is the possibility to improve,
via recovery schemes, the availability of the network. One of the via recovery schemes, the availability of the network. One of the
key points of GMPLS based recovery schemes is the capability to key points of GMPLS based recovery schemes is the capability to
survive multiple failures while legacy protection mechanism such as survive multiple failures while legacy protection mechanism such as
1+1 path protection can survive to a single failure. Moreover this 1+1 path protection can survive from a single failure. Moreover this
improved availability can be obtained using less network resources. improved availability can be obtained using less network resources.
This document will focus on the unique properties of links, switches This document will focus on the unique properties of links, switches
and path selection constraints that occur in WSONs. Different WSONs and path selection constraints that occur in WSONs. Different WSONs
such as access, metro and long haul may apply different techniques such as access, metro and long haul may apply different techniques
for dealing with optical impairments hence this document will NOT for dealing with optical impairments hence this document will NOT
address optical impairments in any depth, but instead focus on address optical impairments in any depth, but instead focus on
properties that are common across a variety of WSONs. properties that are common across a variety of WSONs.
This memo provides a framework for applying GMPLS and the Path This memo provides a framework for applying GMPLS and the Path
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networks in which switching is performed selectively based on the networks in which switching is performed selectively based on the
center wavelength of an optical signal. center wavelength of an optical signal.
3. Wavelength Switched Optical Networks 3. Wavelength Switched Optical Networks
WSONs come in a variety of shapes and sizes from continent spanning WSONs come in a variety of shapes and sizes from continent spanning
long haul networks, to metropolitan networks, to residential access long haul networks, to metropolitan networks, to residential access
networks. In all these cases we are concerned with those properties networks. In all these cases we are concerned with those properties
that constrain the choice of wavelengths that can be used, i.e., that constrain the choice of wavelengths that can be used, i.e.,
restrict the wavelength label set, impact the path selection process, restrict the wavelength label set, impact the path selection process,
and limit the topological connectivity. To do so we will examine and and limit the topological connectivity. In the following we examine
model some major subsystems of a WSON: WDM links, Optical and model some major subsystems of a WSON with an emphasis on those
Transmitters, ROADMs, and Wavelength Converters. aspects that are of relevance to the control plane. In particular we
look at WDM links, Optical Transmitters, ROADMs, and Wavelength
Converters.
3.1. WDM and CWDM Links 3.1. WDM and CWDM Links
WDM and CWDM links run over optical fibers, and optical fibers come WDM and CWDM links run over optical fibers, and optical fibers come
in a wide range of types that tend to be optimized for various in a wide range of types that tend to be optimized for various
applications from access networks, metro, long haul, and submarine applications from access networks, metro, long haul, and submarine
links to name a few. ITU-T and IEC standards exist for various types links to name a few. ITU-T and IEC standards exist for various types
of fibers. For the purposes here we are concerned only with single of fibers. For the purposes here we are concerned only with single
mode fibers (SMF). The following SMF fiber types are typically mode fibers (SMF). The following SMF fiber types are typically
encountered in optical networks: encountered in optical networks:
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might not be applicable for fast protection applications. might not be applicable for fast protection applications.
o Spectral Characteristics and stability: The spectral shape of the o Spectral Characteristics and stability: The spectral shape of the
laser's emissions and its frequency stability put limits on laser's emissions and its frequency stability put limits on
various properties of the overall WDM system. One relatively easy various properties of the overall WDM system. One relatively easy
to characterize constraint is the finest channel spacing on which to characterize constraint is the finest channel spacing on which
the transmitter can be used. the transmitter can be used.
Note that ITU-T recommendations specify many other aspects of a Note that ITU-T recommendations specify many other aspects of a
laser's such as spectral characteristics and stability. Many of these laser's such as spectral characteristics and stability. Many of these
parameters a key in designing WDM subsystems consisting of parameters are key in designing WDM subsystems consisting of
transmitters, WDM links and receivers however they do not furnish transmitters, WDM links and receivers however they do not furnish
additional information that will influence label switched path (LSP) additional information that will influence label switched path (LSP)
provisioning in a properly designed system. provisioning in a properly designed system.
Also note that lasers transmitters as a component can degrade and Also note that lasers transmitters as a component can degrade and
fail over time. This presents the possibility of the failure of a LSP fail over time. This presents the possibility of the failure of a LSP
(lightpath) without either a node or link failure. Hence, additional (lightpath) without either a node or link failure. Hence, additional
mechanisms may be necessary to detect and differentiate this failure mechanisms may be necessary to detect and differentiate this failure
from the others, e.g., one doesn't not want to initiate mesh from the others, e.g., one doesn't not want to initiate mesh
restoration if the source transmitter has failed, since the laser restoration if the source transmitter has failed, since the laser
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given signal type. The use of different FECs can lead to different given signal type. The use of different FECs can lead to different
overall signal rates. If the FEC and rate used is not compatible overall signal rates. If the FEC and rate used is not compatible
between the sender and receiver the signal can not be correctly between the sender and receiver the signal can not be correctly
processed. Note that the rates of "standard" signals may be extended processed. Note that the rates of "standard" signals may be extended
to accommodate different payloads. For example there are to accommodate different payloads. For example there are
transmitters capable of directly mapping 10GE LAN-PHY traffic into transmitters capable of directly mapping 10GE LAN-PHY traffic into
G.709 ODU2 frame with slightly higher clock rate [G.Sup43]. G.709 ODU2 frame with slightly higher clock rate [G.Sup43].
3.3. ROADMs, OXCs, Splitters, Combiners and FOADMs 3.3. ROADMs, OXCs, Splitters, Combiners and FOADMs
Definitions of various optical devices and their parameters can be
found in [G.671], we only look at a subset of these and their non-
impairement related properties.
3.3.1. Reconfigurable Add/Drop Multiplexers and OXCs 3.3.1. Reconfigurable Add/Drop Multiplexers and OXCs
Reconfigurable add/drop optical multiplexers (ROADM) have matured and Reconfigurable add/drop optical multiplexers (ROADM) have matured and
are available in different forms and technologies [Basch06]. This is are available in different forms and technologies [Basch06]. This is
a key technology that allows wavelength based optical switching. A a key technology that allows wavelength based optical switching. A
classic degree-2 ROADM is shown in Figure 1. classic degree-2 ROADM is shown in Figure 1.
Line side ingress +---------------------+ Line side egress Line side ingress +---------------------+ Line side egress
--->| |---> --->| |--->
| | | |
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Figure 1 Degree-2 ROADM Figure 1 Degree-2 ROADM
The key feature across all ROADM types is their highly asymmetric The key feature across all ROADM types is their highly asymmetric
switching capability. In the ROADM of Figure 1, the "add" ingress switching capability. In the ROADM of Figure 1, the "add" ingress
ports can only egress on the line side egress port and not on any of ports can only egress on the line side egress port and not on any of
the "drop" egress ports. The degree of a ROADM or switch is given by the "drop" egress ports. The degree of a ROADM or switch is given by
the number of line side ports (ingress and egress) and does not the number of line side ports (ingress and egress) and does not
include the number of "add" or "drop" ports. Sometimes the "add" include the number of "add" or "drop" ports. Sometimes the "add"
"drop" ports are also called tributary ports. As the degree of the "drop" ports are also called tributary ports. As the degree of the
ROADM increases beyond two it can have properties of both a switch ROADM increases beyond two it can have properties of both a switch
(OXC)and a multiplexer and hence we must know the potential (OXC) and a multiplexer and hence we must know the switched
connectivity offered by such a network element to effectively utilize connectivity offered by such a network element to effectively utilize
it. A straight forward way to do this is via a "potential it. A straight forward way to do this is via a "switched
connectivity" matrix A where Amn = 0 or 1, depending upon whether a connectivity" matrix A where Amn = 0 or 1, depending upon whether a
wavelength on ingress port m can be connected to egress port n wavelength on ingress port m can be connected to egress port n
[Imajuku]. For the ROADM of Figure 1 the potential connectivity [Imajuku]. For the ROADM of Figure 1 the switched connectivity matrix
matrix can be expressed as can be expressed as
Ingress Egress Port Ingress Egress Port
Port #1 #2 #3 #4 #5 Port #1 #2 #3 #4 #5
-------------- --------------
#1: 1 1 1 1 1 #1: 1 1 1 1 1
#2 1 0 0 0 0 #2 1 0 0 0 0
A = #3 1 0 0 0 0 A = #3 1 0 0 0 0
#4 1 0 0 0 0 #4 1 0 0 0 0
#5 1 0 0 0 0 #5 1 0 0 0 0
Where ingress ports 2-5 are add ports, egress ports 2-5 are drop Where ingress ports 2-5 are add ports, egress ports 2-5 are drop
ports and ingress port #1 and egress port #1 are the line side (WDM) ports and ingress port #1 and egress port #1 are the line side (WDM)
ports. ports.
For ROADMs this matrix will be very sparse, and for OXCs the For ROADMs this matrix will be very sparse, and for OXCs the
complement of the matrix will be very sparse hence even relatively complement of the matrix will be very sparse, compact encodings and
high degree ROADMs/OXCs can be compactly characterized. usage including high degree ROADMs/OXCs are given in [WSON-Encode].
Additional constraints may also apply to the various ports in a Additional constraints may also apply to the various ports in a
ROADM/OXC. In the literature of optical switches and ROADMs the ROADM/OXC. In the literature of optical switches and ROADMs the
following restrictions/terms are used: following restrictions/terms are used:
Colored port: An ingress or more typically an egress (drop) port Colored port: An ingress or more typically an egress (drop) port
restricted to a single channel of fixed wavelength. restricted to a single channel of fixed wavelength.
Colorless port: An ingress or more typically an egress (drop) port Colorless port: An ingress or more typically an egress (drop) port
restricted to a single channel of arbitrary wavelength. restricted to a single channel of arbitrary wavelength.
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o Single wavelength, full range port o Single wavelength, full range port
o Single wavelength, fixed lambda port o Single wavelength, fixed lambda port
o Multiple wavelengths, reduced range port (like wave band o Multiple wavelengths, reduced range port (like wave band
switching) switching)
To model these restrictions we need two pieces of information for To model these restrictions we need two pieces of information for
each port: (a) number of wavelengths, (b) wavelength range and each port: (a) number of wavelengths, (b) wavelength range and
spacing. Note that this information is relatively static. spacing. Note that this information is relatively static. More
complicated wavelength constraints are modeled in [WSON-Info].
3.3.2. Splitters 3.3.2. Splitters
An optical splitter consists of a single ingress port and two or more An optical splitter consists of a single ingress port and two or more
egress ports. The ingress optical signaled is essentially copied egress ports. The ingress optical signaled is essentially copied
(with loss) to all egress ports. (with loss) to all egress ports.
Using the modeling notions of section 3.3.1. the ingress and egress Using the modeling notions of section 3.3.1. the ingress and egress
ports of a splitter would have the same wavelength restrictions. In ports of a splitter would have the same wavelength restrictions. In
addition we can describe a splitter by a connectivity matrix Amn as addition we can describe a splitter by a connectivity matrix Amn as
follows: follows:
Ingress Egress Port Ingress Egress Port
Port #1 #2 #3 ... #N Port #1 #2 #3 ... #N
----------------- -----------------
A = #1 1 1 1 ... 1 A = #1 1 1 1 ... 1
The difference from a simple ROADM is that this is not a "potential" The difference from a simple ROADM is that this is not a switched
connectivity matrix but the fixed connectivity of the device. Hence connectivity matrix but the fixed connectivity matrix of the device.
to differentiate between a simple ROADM and a splitter we'd need an
indicator as to whether the device is reconfigurable.
3.3.3. Combiners 3.3.3. Combiners
A optical combiner is somewhat the dual of a splitter in that it has A optical combiner is somewhat the dual of a splitter in that it has
a single multi-wavelength egress port and multiple ingress ports. a single multi-wavelength egress port and multiple ingress ports.
The contents of all the ingress ports are copied and combined to the The contents of all the ingress ports are copied and combined to the
single egress port. The various ports may have different wavelength single egress port. The various ports may have different wavelength
restrictions. It is generally the responsibility of those using the restrictions. It is generally the responsibility of those using the
combiner to assure that wavelength collision does not occur on the combiner to assure that wavelength collision does not occur on the
egress port. The connectivity matrix Amn for a combiner would look egress port. The fixed connectivity matrix Amn for a combiner would
like: look like:
Ingress Egress Port Ingress Egress 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
Once again this connectivity is fixed.
3.3.4. Fixed Optical Add/Drop Multiplexers 3.3.4. Fixed Optical Add/Drop Multiplexers
A fixed optical add/drop multiplexer can alter the course of an A fixed optical add/drop multiplexer can alter the course of an
ingress wavelength in a preset way. In particular a particular ingress wavelength in a preset way. In particular a particular
wavelength (or waveband) from a line side ingress port would be wavelength (or waveband) from a line side ingress port would be
dropped to a particular "tributary" egress port. Depending on the dropped to a particular "tributary" egress port. Depending on the
device's fixed configuration that same wavelength may or may not be device's fixed configuration that same wavelength may or may not be
"continued" to the line side egress port ("drop and continue" "continued" to the line side egress port ("drop and continue"
operation). Further there may exist tributary ingress ports ("add" operation). Further there may exist tributary ingress ports ("add"
ports) whose signals are combined with each other and "continued" ports) whose signals are combined with each other and "continued"
line side signals. line side signals.
In general to represent the routing properties of an FOADM we need In general to represent the routing properties of an FOADM we need a
the connectivity matrix Amn as previously discussed and we need the fixed connectivity matrix Amn as previously discussed and we need the
precise wavelength restrictions for all ingress and egress ports. precise wavelength restrictions for all ingress and egress ports.
From the wavelength restrictions on the tributary egress ports (drop From the wavelength restrictions on the tributary egress ports (drop
ports) we can see what wavelengths have been dropped. From the ports) we can see what wavelengths have been dropped. From the
wavelength restrictions on the tributary ingress (add) ports we can wavelength restrictions on the tributary ingress (add) ports we can
see which wavelengths have been added to the line side egress port. see which wavelengths have been added to the line side egress port.
Finally from the added wavelength information and the line side Finally from the added wavelength information and the line side
egress wavelength restrictions we can infer which wavelengths have egress wavelength restrictions we can infer which wavelengths have
been continued. been continued.
To summarize, the modeling methodology introduced in section 3.3.1. To summarize, the modeling methodology introduced in section 3.3.1.
consisting of a connectivity matrix and port wavelength restrictions consisting of a connectivity matrix and port wavelength restrictions
can be used to describe a large set of fixed optical devices such as can be used to describe a large set of fixed optical devices such as
combiners, splitters and FOADMs with the inclusion of an indicator as combiners, splitters and FOADMs. Hybrid devices consisting of both
to whether the device is Fixed or Reconfigurable and the appropriate switched and fixed parts are modeled in [WSON-Info].
interpretations detailed previously.
3.4. Wavelength Converters 3.4. Wavelength Converters
Wavelength converters take an ingress optical signal at one Wavelength converters take an ingress optical signal at one
wavelength and emit an equivalent content optical signal at another wavelength and emit an equivalent content optical signal at another
wavelength on egress. There are currently two approaches to building wavelength on egress. There are currently two approaches to building
wavelength converters. One approach is based on optical to electrical wavelength converters. One approach is based on optical to electrical
to optical (OEO) conversion with tunable lasers on egress. This to optical (OEO) conversion with tunable lasers on egress. This
approach can be dependent upon the signal rate and format, i.e., this approach can be dependent upon the signal rate and format, i.e., this
is basically an electrical regenerator combined with a tunable laser. is basically an electrical regenerator combined with a tunable laser.
The other approach performs the wavelength conversion, optically via The other approach performs the wavelength conversion, optically via
non-linear optical effects, similar in spirit to the familiar non-linear optical effects, similar in spirit to the familiar
frequency mixing used in radio frequency systems, but significantly frequency mixing used in radio frequency systems, but significantly
harder to implement. Such processes/effects may place limits on the harder to implement. Such processes/effects may place limits on the
range of achievable conversion. These may depend on the wavelength of range of achievable conversion. These may depend on the wavelength of
the input signal and the properties of the converter as opposed to the input signal and the properties of the converter as opposed to
the only the properties of the converter in the OEO case. Different only the properties of the converter in the OEO case. Different WSON
WSON system designs may choose to utilize this component to varying system designs may choose to utilize this component to varying
degrees or not at all. degrees or not at all.
Current or envisioned contexts for wavelength converters are: Current or envisioned contexts for wavelength converters are:
1. Wavelength conversion associated with OEO switches and tunable 1. Wavelength conversion associated with OEO switches and tunable
laser transmitters. In this case there are plenty of converters to laser transmitters. In this case there are plenty of converters to
go around since we can think of each tunable output laser go around since we can think of each tunable output laser
transmitter on an OEO switch as a potential wavelength converter. transmitter on an OEO switch as a potential wavelength converter.
2. Wavelength conversion associated with ROADMs/OXCs. In this case we 2. Wavelength conversion associated with ROADMs/OXCs. In this case we
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reach a wavelength converter prior to continuing on to its reach a wavelength converter prior to continuing on to its
destination. The lambda used on the "detour" out to the wavelength destination. The lambda used on the "detour" out to the wavelength
converter would be different from that coming back from the "detour" converter would be different from that coming back from the "detour"
to the wavelength converter. to the wavelength converter.
A model for an O-E-O wavelength converter would consist of: A model for an O-E-O wavelength converter would consist of:
o Input lambda or frequency range o Input lambda or frequency range
o Output lambda or frequency range o Output lambda or frequency range
o Equivalent regeneration level (1R, 2R, 3R) o Equivalent regeneration level (1R, 2R, 3R)
o Signal restrictions if a 2R or 3R regeneration: formats and rates o Signal restrictions if a 2R or 3R regeneration: formats and rates
[FFS: Model for an all optical wavelength converter] [FFS: Model for an all optical wavelength converter]
4. Routing and Wavelength Assignment 4. Routing and Wavelength Assignment and the Control Plane
In wavelength switched optical networks consisting of tunable lasers In wavelength switched optical networks consisting of tunable lasers
and wavelength selective switches with wavelength converters on every and wavelength selective switches with wavelength converters on every
interface, path selection is similar to the MPLS and TDM circuit interface, path selection is similar to the MPLS and TDM circuit
switched cases in that the labels, in this case wavelengths switched cases in that the labels, in this case wavelengths
(lambdas), have only local significance. That is, a wavelength- (lambdas), have only local significance. That is, a wavelength-
convertible network with full wavelength-conversion capability at convertible network with full wavelength-conversion capability at
each node is equivalent to a circuit-switched TDM network with full each node is equivalent to a circuit-switched TDM network with full
time slot interchange capability; thus, the routing problem needs to time slot interchange capability; thus, the routing problem needs to
be addressed only at the level of the traffic engineered (TE) link be addressed only at the level of the traffic engineered (TE) link
skipping to change at page 16, line 7 skipping to change at page 16, line 13
the optical transmitter, and a set of locations (generally associated the optical transmitter, and a set of locations (generally associated
with ROADMs or switches) where wavelength conversion is to occur and with ROADMs or switches) where wavelength conversion is to occur and
the new wavelength to be used on each component link after that point the new wavelength to be used on each component link after that point
in the route. in the route.
It is to be noted that choice of specific RWA algorithm is out of the It is to be noted that choice of specific RWA algorithm is out of the
scope for this document. However there are a number of different 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 the RWA algorithm that can affect the
division of effort between signaling, routing and PCE. division of effort between signaling, routing and PCE.
4.1. Lightpath Temporal Characteristics 4.1. Architectural Approaches to RWA
Key inputs that can affect the choice of solution to the RWA process
are those associated with the temporal characteristics of a light
path connection. For our purposes here we look at the timeliness of
connection establishment/teardown, and the duration of the
connection.
Connection Establishment/Teardown Timeliness can be thought of in
approximately three time frames:
1. Time Critical: For example those lightpath establishments used for
restoration of service or other high priority real time service
requests.
2. Soft time bounds: This is a more typical new connection request.
While expected to be responsive, there should be more time to take
into account network optimization.
3. Scheduled or Advanced reservations. Here lightpath connections are
requested significantly ahead of their intended "in service" time.
There is the potential for significant network optimization if
multiple lightpaths can be computed in parallel to achieve network
optimization objectives.
Lightpath connection duration has typically been thought of as
approximately three time frames:
1. Dynamic: those lightpaths with relatively short duration (holding
times).
2. Pseudo-static: lightpaths with moderately long durations.
3. Static: lightpaths with long durations. Two general computational approaches are taken to solving the RWA
problem some algorithms utilize a two step procedure of path
selection followed by wavelength assignment, and others solve the
problem in a combined fashion.
Different types of RWA algorithms have been developed for dealing In the following, three different ways of performing RWA in
with dynamic versus pseudo-static conditions. These can address conjunction with the control plane are considered. The choice of one
service provider's needs for: (a) network optimization, (b) of these architectural approaches over another generally impacts the
restoration, and (c) highly dynamic lightpath provisioning. demands placed on the various control plane protocols.
Hence we can model timescale related lightpath requirements via the 4.1.1. Combined RWA (R&WA)
following notions:
o Batch or Sequential light path connection requests In this case, a unique entity is in charge of performing routing and
o Timeliness of Connection establishment wavelength assignment. This choice assumes that computational entity
has sufficient WSON network link/nodal information and topology to be
able to compute RWA. This solution relies on a sufficient knowledge
of network topology, of available network resources and of network
nodes capabilities. This knowledge has to be accessible to the entity
performing the routing and wavelength assignment.
o Duration of lightpath connection This solution is compatible with most known RWA algorithms, and in
particular those concerned with network optimization. On the other
hand, this solution requires up-to-date and detailed network
information dissemination.
4.2. RWA Algorithmic Approaches: Combined vs. Two-step Such a computational entity could reside in two different logical
places:
When solving the RWA problem some algorithms that solve the problem o In a separate Path Computation Element (PCE) which hence owns the
in a two step procedure of path selection followed by wavelength complete and updated knowledge of network state and provides path
assignment, and others that solve the problem in a combined fashion. computation services to node.
These different types of algorithms can have different
characteristics with respect to computational complexity and
optimality that can influence how and where they may be used.
Given a path, the following are a non-exhaustive subset of wavelength o In the Ingress node, in that case all nodes have the R&WA
assignment (WA) approaches discussed in [HZang00]: functionality; the knowledge of the network state is obtained by a
periodic flooding of information provided by the other nodes.
1. Random: Looks at all available wavelengths for the light path then 4.1.2. Separated R and WA (R+WA)
chooses from those available at random.
2. First Fit: Wavelengths are ordered, first available (on all links) In this case a first entity performs routing, while a second performs
is chosen. wavelength assignment. The first entity furnishes one or more paths
to the second entity that will perform wavelength assignment and
possibly final path selection.
3. Most Used: Out of the wavelengths available on the path attempts As the entities computing the path and the wavelength assignment are
to select most use wavelength in network. separated, this constrains the class of RWA algorithms that may be
implemented. Although it may seem that algorithms optimizing a joint
usage of the physical and spectral paths are excluded from this
solution, many practical optimization algorithms only consider a
limited set of possible paths, e.g., as computed via a k-shortest
path algorithm [Ozdaglar03]. Hence although there is no guarantee
that the selected final route and wavelength offers the optimal
solution by allowing multiple routes to pass to the wavelength
selection process reasonable optimization can be performed.
4. Least Loaded: For multi-fiber networks. Chooses the wavelength j The entity performing the routing assignment needs the topology
that maximizes minimum of the difference between the number of information of the network, whereas the entity performing the
fibers on link l and the number of fibers on link l with wavelength assignment needs information on the network available
wavelength j occupied. resources and on network nodes capabilities.
As can be seen from the above short list, wavelength assignment 4.1.3. Routing and Distributed WA (R+DWA)
methods have differing information or processing requirements. When a
two step RWA algorithm is used there is also the possibility of
utilizing the signaling system to perform distributed wavelength
assignment. The details would differ according to the WA algorithm
chosen but at a minimum all would take an intersection of available
wavelength sets as seen at each link along the path to produce the
available wavelength set for the path.
4.3. RWA Computation Architectures In this case a first entity performs routing, while wavelength
assignment is performed on a hop-by-hop manner along the previously
computed route. This mechanism relies on updating of a list of
potential wavelengths used to ensure the wavelength continuity
constraint.
The previous discussion leads to the following possible RWA As currently specified, the GMPLS protocol suite signaling protocol
computation architectures. As will be seen in the GMPLS/PCE can accommodate such an approach. Per [RFC3471], the Label Set
evaluation section these architectures have different impacts on selection works according to an AND scheme. Each hop restricts the
their needs with respect to protocol extensions. Label Set sent to the next hop from the one received from the
previous hop by performing an AND operation between the wavelength
referred by the labels it includes with the one available on the
ongoing interface. The constraint to perform this AND operation is up
to the node local policy (even if one expects a consistent policy
configuration throughout a given transparency domain). When
wavelength conversion is performed at an intermediate node, a new
Label Set is generated. The egress nodes selects one label in the
Label Set received at the node, which is also up to the node local
policy.
o Combined RWA --- Both routing and wavelength assignment are Depending on these policies a spectral assignment may not be found or
performed at a single computational entity. This choice assumes one consuming too many conversion resources relatively to what a
that computational entity has sufficient WSON network link/nodal dedicated wavelength assignment policy would have achieved. Hence,
information and topology to be able to compute RWA. The amount of this may generate higher blocking probabilities in a heavily loaded
information can vary depending on the RWA approach/algorithm network.
utilized. Good for network optimization and for smaller WSONs.
o Separate Routing and WA --- Separate entities perform routing and On the one hand, this solution may be empowered with some signaling
wavelength assignment. The path obtained from the routing extensions to ease its functioning and possibly enhance its
computational entity must be furnished to the entity performing performances relatively to blocking. On the other hand this solution
wavelength assignment. Good for offloading some of the is not stressing the information dissemination processes.
computational burden and for reducing the number of entities that
need exact network link wavelength utilization, i.e., there can be
fewer nodes that perform WA than perform routing.
o Routing with Distributed WA --- Routing is performed at a The first entity may be a PCE or the ingress node of the LSP. This
computational entity while wavelength assignment is performed in a solution is applicable inside network where resource optimization is
distributed fashion across nodes along the path. Good in that it not the most crucial constraint.
does not require exact network link wavelength information at any
node, but can have higher blocking probabilities compared to other
methods.
4.4. 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 lightpath
requests. In particular high level models of the information by the requests. In particular high level models of the information by the
RWA process were presented. We can view this information as either RWA process were presented. We can view this information as either
static, changing with hardware changes (including possibly failures), static, changing with hardware changes (including possibly failures),
or dynamic, can change with subsequent lightpath provisioning. The or dynamic, can change with subsequent lightpath provisioning. The
timeliness in which an entity involved in the RWA process is notified timeliness in which an entity involved in the RWA process is notified
of such changes is fairly situational. For example, for network of such changes is fairly situational. For example, for network
restoration purposes, learning of a hardware failure or of new restoration purposes, learning of a hardware failure or of new
hardware coming online to provide restoration capability can be hardware coming online to provide restoration capability can be
skipping to change at page 19, line 15 skipping to change at page 19, line 8
o Other techniques for dynamic information: messaging straight from o Other techniques for dynamic information: messaging straight from
NEs to PCE to avoid flooding. This would be useful if the number NEs to PCE to avoid flooding. This would be useful if the number
of PCEs is significantly less than number of WSON NEs. Or other of PCEs is significantly less than number of WSON NEs. Or other
ways to limit flooding to "interested" NEs. ways to limit flooding to "interested" NEs.
Mechanisms to improve scaling of dynamic information: Mechanisms to improve scaling of dynamic information:
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. Utilize incremental updates if feasible.
4.3. Lightpath Temporal Characteristics
The temporal characteristics of a light path connection is another
aspect that can affect the choice of solution to the RWA process. For
our purposes here we look at the timeliness of connection
establishment/teardown, and the duration of the connection.
Connection Establishment/Teardown Timeliness can be thought of in
approximately three time frames:
1. Time Critical: For example those lightpath establishments used for
restoration of service or other high priority real time service
requests.
2. Soft time bounds: This is a more typical new connection request.
While expected to be responsive, there should be more time to take
into account network optimization.
3. Scheduled or Advanced reservations. Here lightpath connections are
requested significantly ahead of their intended "in service" time.
There is the potential for significant network optimization if
multiple lightpaths can be computed concurrently to achieve network
optimization objectives.
Lightpath connection duration has typically been thought of as
approximately three time frames:
1. Dynamic: those lightpaths with relatively short duration (holding
times).
2. Pseudo-static: lightpaths with moderately long durations.
3. Static: lightpaths with long durations.
Different types of RWA algorithms have been developed for dealing
with dynamic versus pseudo-static conditions. These can address
service provider's needs for: (a) network optimization, (b)
restoration, and (c) highly dynamic lightpath provisioning.
Hence we can model timescale related lightpath requirements via the
following notions:
o Batch or Sequential light path connection requests
o Timeliness of Connection establishment
o Duration of lightpath connection
5. GMPLS & PCE Implications 5. GMPLS & 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 with 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.
5.1. Implications for GMPLS signaling 5.1. Implications for GMPLS signaling
Basic support for WSON signaling already exists in GMPLS with the Basic support for WSON signaling already exists in GMPLS with the
lambda (value 9) LSP encoding type [RFC3471], or for G.709 compatible lambda (value 9) LSP encoding type [RFC3471], or for G.709 compatible
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.
skipping to change at page 20, line 26 skipping to change at page 21, line 17
object entry in the ERO has to be translated appropriately. object entry in the ERO has to be translated appropriately.
5.1.3. Distributed Wavelength Assignment: Unidirectional, No 5.1.3. Distributed Wavelength Assignment: Unidirectional, No
Converters Converters
GMPLS signaling for a uni-directional lightpath LSP allows for the GMPLS signaling for a uni-directional lightpath LSP allows for the
use of a label set object in the RSVP-TE path message. The processing use of a label set object in the RSVP-TE path message. The processing
of the label set object to take the intersection of available lambdas of the label set object to take the intersection of available lambdas
along a path can be performed resulting in the set of available along a path can be performed resulting in the set of available
lambda being known to the destination that can then use a wavelength lambda being known to the destination that can then use a wavelength
selection algorithm to choose a lambda. The algorithms that can be selection algorithm to choose a lambda. For example, the following is
used would be limited to the information available at the destination a non-exhaustive subset of wavelength assignment (WA) approaches
node. The information requirements of the methods discussed in discussed in [HZang00]:
section 4.2. are as follows:
1. Random: Looks at all available wavelengths for the light path then
chooses from those available at random.
2. First Fit: Wavelengths are ordered, first available (on all links)
is chosen.
3. Most Used: Out of the wavelengths available on the path attempts
to select most use wavelength in network.
4. Least Loaded: For multi-fiber networks. Chooses the wavelength j
that maximizes minimum of the difference between the number of
fibers on link l and the number of fibers on link l with
wavelength j occupied.
As can be seen from the above short list, wavelength assignment
methods have differing information or processing requirements. The
information requirements of these methods are as follows:
1. Random: nothing more than the available wavelength set. 1. Random: nothing more than the available wavelength set.
2. First Fit: nothing more than the available wavelength set. 2. First Fit: nothing more than the available wavelength set.
3. Most Used: the available wavelength set and information on global 3. Most Used: the available wavelength set and information on global
wavelength use in the network. wavelength use in the network.
4. Least Loaded: the available wavelength set and information 4. Least Loaded: the available wavelength set and information
concerning the wavelength dependent loading for each link (this concerning the wavelength dependent loading for each link (this
skipping to change at page 21, line 9 skipping to change at page 22, line 16
assignment could be derived from suitably enhanced GMPLS routing. assignment could be derived from suitably enhanced GMPLS routing.
Note however this information need not be accurate enough for Note however this information need not be accurate enough for
combined RWA computation. Currently, GMPLS signaling does not provide combined RWA computation. Currently, GMPLS signaling does not provide
a way to indicate that a particular wavelength assignment algorithm a way to indicate that a particular wavelength assignment algorithm
should be used. should be used.
5.1.4. Distributed Wavelength Assignment: Unidirectional, Limited 5.1.4. Distributed Wavelength Assignment: Unidirectional, Limited
Converters Converters
The previous outlined the case with no wavelength converters. In the The previous outlined the case with no wavelength converters. In the
case of wavelength converters nodes with wavelength converters would case of wavelength converters, nodes with wavelength converters would
need to make the decision as to whether to perform conversion. One need to make the decision as to whether to perform conversion. One
indicator for this would be that the set of available wavelengths indicator for this would be that the set of available wavelengths
which is obtained via the intersection of the incoming label set and which is obtained via the intersection of the incoming label set and
the egress links available wavelengths is either null or deemed too the egress links available wavelengths is either null or deemed too
small to permit successful completion. 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 passes by. The node will pass on an enlarged label set
skipping to change at page 22, line 43 skipping to change at page 24, line 6
system in general supports ITU-T NRZ signals up to NRZ 10Gbps. system in general supports ITU-T NRZ signals up to NRZ 10Gbps.
Further suppose that the first 20 channels are carrying 1Gbps Further suppose that the first 20 channels are carrying 1Gbps
Ethernet, then the maximum bandwidth would be 320Gbps and the maximum Ethernet, then the maximum bandwidth would be 320Gbps and the maximum
reservable bandwidth would be 120Gbps (12 wavelengths). reservable bandwidth would be 120Gbps (12 wavelengths).
Alternatively, consider the case where the first 8 channels are Alternatively, consider the case where the first 8 channels are
carrying 2.5Gbps SDH STM-16 channels, then the maximum bandwidth carrying 2.5Gbps SDH STM-16 channels, then the maximum bandwidth
would still be 320Gbps and the maximum reservable bandwidth would be would still be 320Gbps and the maximum reservable bandwidth would be
240Gbps (24 wavelengths). 240Gbps (24 wavelengths).
Such information would be useful in the routing with distributed WA Such information would be useful in the routing with distributed WA
approach of section 4.3. approach of section 4.1.3.
5.2.2. Need for Wavelength-Specific Availability Information 5.2.2. Need for Wavelength-Specific Availability Information
Even if we know the number of available wavelengths on a link, we Even if we know the number of available wavelengths on a link, we
actually need to know which specific wavelengths are available and actually need to know which specific wavelengths are available and
which are occupied if we are going to run a combined RWA process or which are occupied if we are going to run a combined RWA process or
separate WA process as discussed in section 4.3. This is currently separate WA process as discussed in sections 4.1.1. 4.1.2. This is
not possible with GMPLS routing extensions. currently not possible with GMPLS routing extensions.
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. The RWA problem for
optical networks without wavelength converters imposes an additional optical networks without wavelength converters imposes an additional
requirement for the lambda (or optical channel) layer: that of requirement for the lambda (or optical channel) layer: that of
knowing which specific wavelengths are in use. Note that current knowing which specific wavelengths are in use. Note that current
dense WDM (DWDM) systems range from 16 channels to 128 channels with dense WDM (DWDM) systems range from 16 channels to 128 channels with
advanced laboratory systems with as many as 300 channels. Given these advanced laboratory systems with as many as 300 channels. Given these
channel limitations and if we take the approach of a global channel limitations and if we take the approach of a global
wavelength to label mapping or furnishing the local mappings to the wavelength to label mapping or furnishing the local mappings to the
skipping to change at page 26, line 6 skipping to change at page 27, line 6
o Tuning range constraint on optical transmitter. o Tuning range constraint on optical transmitter.
Lightpath characteristics can include: Lightpath characteristics can include:
o Duration information (how long this connection may last) o Duration information (how long this connection may last)
o Timeliness/Urgency information (how quickly is this connection o Timeliness/Urgency information (how quickly is this connection
needed) needed)
5.3.2. Computation Architecture Implications 5.3.2. Computation Architecture Implications
When a PCE performs a combined RWA computation per section 4.3. it When a PCE performs a combined RWA computation per section 4.1.1. it
requires accurate an up to date wavelength utilization on all links requires accurate an up to date wavelength utilization on all links
in the network. in the network.
When a PCE is used to perform wavelength assignment (WA) in the When a PCE is used to perform wavelength assignment (WA) in the
separate routing WA architecture then the entity requesting WA needs separate routing WA architecture then the entity requesting WA needs
to furnish the pre-selected route to the PCE as well as any of the to furnish the pre-selected route to the PCE as well as any of the
lightpath constraints/characteristics previously mentioned. This lightpath constraints/characteristics previously mentioned. This
architecture also requires the PCE performing WA to have accurate and architecture also requires the PCE performing WA to have accurate and
up to date network wavelength utilization information. up to date network wavelength utilization information.
skipping to change at page 27, line 28 skipping to change at page 28, line 28
capability. capability.
5.4.3. Path computation 5.4.3. Path computation
If a PCE is handling path computation requests for end-to-end If a PCE is handling path computation requests for end-to-end
wavelength services within the WSON, then the complexity of the wavelength services within the WSON, then the complexity of the
network and number of service path computation requests being sent to network and number of service path computation requests being sent to
the PCE may have an impact on the PCEs ability to process requests in the PCE may have an impact on the PCEs ability to process requests in
a timely manner. a timely manner.
5.5. Summary of Impacts by RWA Architecture
The following table summarizes for each RWA strategy the list of
mandatory ("M") and optional ("O") control plane features according
to GMPLS architectural blocks:
o Information required by the path computation entity,
o LSP request parameters used in either PCC to PCE situations or in
signaling,
o RSVP-TE LSP signaling parameters used in LSP establishment.
The table shows which enhancements are common to all architectures
(R&WA, R+WA, R+DWA), which apply only to R&WA and R+WA (R+&WA), and
which apply only to R+DWA.
+-------------------------------------+-----+-------+-------+-------+
| | |Common | R+&WA | R+DWA |
| Feature | ref +---+---+---+---+---+---+
| | | M | O | M | O | M | O |
+-------------------------------------+-----+---+---+---+---+---+---+
| Generalized Label for Wavelength |5.1.1| x | | | | | |
+-------------------------------------+-----+---+---+---+---+---+---+
| Flooding of information for the | | | | | | | |
| routing phase | | | | | | | |
| Node features | 3.3 | | | | | | |
| Node type | | | x | | | | |
| spectral X-connect constraint | | | | x | | | |
| port X-connect constraint | | | | x | | | |
| Transponders availability | | | x | | | | |
| Transponders features | 3.2 | | x | | | | |
| Converter availability | | | | x | | | |
| Converter features | 3.4 | | | x | | | x |
| TE-parameters of WDM links | 3.1 | x | | | | | |
| Total Number of wavelength | | x | | | | | |
| Number of wavelengths available | | x | | | | | |
| Grid spacing | | x | | | | | |
| Wavelength availability on links | 5.2 | | | x | | | |
+-------------------------------------+-----+---+---+---+---+---+---+
| LSP request parameters | | | | | | | |
| Signal features | 5.1 | | x | | | x | |
| Modulation format | | | x | | | x | |
| Modulation parameters | | | x | | | x | |
| Specification of RWA method | 5.1 | | x | | | x | |
| LSP time features | 4.3 | | x | | | | |
+-------------------------------------+-----+---+---+---+---+---+---+
| Enriching signaling messages | | | | | | | |
| Signal features | 5.1 | | | | | x | |
+-------------------------------------+-----+---+---+---+---+---+---+
6. Security Considerations 6. 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 makes the operation of the network more vulnerable to denial of
service attacks. Therefore additional care maybe required to ensure service attacks. Therefore additional care maybe required to ensure
skipping to change at page 29, line 42 skipping to change at page 31, line 42
applications: DWDM frequency grid", June, 2002. applications: DWDM frequency grid", June, 2002.
[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.
[PCE-GCO] Y. Lee, J.L. Le Roux, D. King, and E. Oki, "Path [PCE-GCO] Y. Lee, J.L. Le Roux, D. King, and E. Oki, "Path
Computation Element Communication Protocol (PCECP) Computation Element Communication Protocol (PCECP)
Requirements and Protocol Extensions In Support of Global Requirements and Protocol Extensions In Support of Global
Concurrent Optimization", work in progress, draft-ietf-pce- Concurrent Optimization", work in progress, draft-ietf-pce-
global-concurrent-optimization-02.txt, November 2007. global-concurrent-optimization-05.txt, November 2007.
[PCEP] J.P. Vasseur and J.L. Le Roux (Editors), "Path Computation [PCEP] J.P. Vasseur and J.L. Le Roux (Editors), "Path Computation
Element (PCE) Communication Protocol (PCEP)", work in Element (PCE) Communication Protocol (PCEP)", work in
progress, draft-ietf-pce-pcep-12.txt, February 2008. progress, draft-ietf-pce-pcep-16.txt, February 2008.
[PCE-OF] J.L. Le Roux, J.P. Vasseur, and Y. Lee, "Encoding of [PCE-OF] 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", work in progress, communication and discovery protocols", work in progress,
draft-ietf-pce-of-02.txt, February 2008. draft-ietf-pce-of-05.txt, February 2008.
[WSON-Encode] G. Bernstein, Y. Lee, D. Li, and W. Imajuku, "Routing
and Wavelength Assignment Information Encoding for
Wavelength Switched Optical Networks", draft-bernstein-
ccamp-wson-encode-00.txt, July 2008.
[WSON-Info] G. Bernstein, Y. Lee, D. Li, W. Imajuku," Routing and [WSON-Info] G. Bernstein, Y. Lee, D. Li, W. Imajuku," Routing and
Wavelength Assignment Information for Wavelength Switched Wavelength Assignment Information for Wavelength Switched
Optical Networks", draft-bernstein-ccamp-wson-info-02.txt, Optical Networks", draft-bernstein-ccamp-wson-info-03.txt,
February, 2008. July, 2008.
9.2. Informative References 9.2. Informative References
[HZang00] H. Zang, J. Jue and B. Mukherjeee, "A review of routing and [HZang00] H. Zang, J. Jue and B. Mukherjeee, "A review of routing and
wavelength assignment approaches for wavelength-routed wavelength assignment approaches for wavelength-routed
optical WDM networks", Optical Networks Magazine, January optical WDM networks", Optical Networks Magazine, January
2000. 2000.
[Coldren04] Larry A. Coldren, G. A. Fish, Y. Akulova, J. S. [Coldren04] Larry A. Coldren, G. A. Fish, Y. Akulova, J. S.
Barton, L. Johansson and C. W. Coldren, "Tunable Barton, L. Johansson and C. W. Coldren, "Tunable
skipping to change at page 31, line 16 skipping to change at page 33, line 19
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
optical components and subsystems, January 2005.
[G.872] ITU-T Recommendation G.872, Architecture of optical
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
applications: CWDM wavelength grid, December 2003. applications: CWDM wavelength grid, December 2003.
[G.Sup39] ITU-T Series G Supplement 39, Optical system design and [G.Sup39] ITU-T Series G Supplement 39, Optical system design and
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-02.txt, July 2007. switching-constraint-02.txt, July 2007.
[Ozdaglar03] Asuman E. Ozdaglar and Dimitri P. Bertsekas, ''Routing
and wavelength assignment in optical networks,'' IEEE/ACM
Transactions on Networking, vol. 11, 2003, pp. 259 -272.
[RFC4054] Strand, J. and A. Chiu, "Impairments and Other Constraints [RFC4054] Strand, J. and A. Chiu, "Impairments and Other Constraints
on Optical Layer Routing", RFC 4054, May 2005. on Optical Layer Routing", RFC 4054, May 2005.
[RFC4606] Mannie, E. and D. Papadimitriou, "Generalized Multi- [RFC4606] Mannie, E. and D. Papadimitriou, "Generalized Multi-
Protocol Label Switching (GMPLS) Extensions for Synchronous Protocol Label Switching (GMPLS) Extensions for Synchronous
Optical Network (SONET) and Synchronous Digital Hierarchy Optical Network (SONET) and Synchronous Digital Hierarchy
(SDH) Control", RFC 4606, August 2006. (SDH) Control", RFC 4606, August 2006.
10. Contributors 10. Contributors
skipping to change at page 32, line 34 skipping to change at page 35, line 34
NEC Corp. NEC Corp.
1753 Simonumabe, Nakahara-ku, Kawasaki, Kanagawa 211-8666 1753 Simonumabe, Nakahara-ku, Kawasaki, Kanagawa 211-8666
Japan Japan
Phone: +81 44 396 3287 Phone: +81 44 396 3287
Email: i-nishioka@cb.jp.nec.com Email: i-nishioka@cb.jp.nec.com
Lyndon Ong Lyndon Ong
Ciena Ciena
Email: Lyong@Ciena.com Email: Lyong@Ciena.com
Pierre Peloso
Alcatel-Lucent
Route de Villejust - - 91620 Nozay - France
Email: pierre.peloso@alcatel-lucent.fr
Jonathan Sadler Jonathan Sadler
Tellabs Tellabs
Email: Jonathan.Sadler@tellabs.com Email: Jonathan.Sadler@tellabs.com
Author's Addresses Author's Addresses
Greg Bernstein (ed.) Greg M. Bernstein (ed.)
Grotto Networking Grotto Networking
Fremont, CA, USA Fremont California, USA
Phone: (510) 573-2237 Phone: (510) 573-2237
Email: gregb@grotto-networking.com Email: gregb@grotto-networking.com
Young Lee (ed.) Young Lee (ed.)
Huawei Technologies Huawei Technologies
1700 Alma Drive, Suite 100 1700 Alma Drive, Suite 100
Plano, TX 75075 Plano, TX 75075
USA USA
Phone: (972) 509-5599 (x2240) Phone: (972) 509-5599 (x2240)
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