draft-ietf-ccamp-rwa-wson-framework-00.txt   draft-ietf-ccamp-rwa-wson-framework-01.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: June 2009 Grotto Networking Expires: August 2009 Grotto Networking
Wataru Imajuku Wataru Imajuku
NTT NTT
December 5, 2008 February 9, 2009
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-00.txt draft-ietf-ccamp-rwa-wson-framework-01.txt
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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
key wavelength switched optical network subsystems and processes. The key wavelength switched optical network subsystems and processes. The
subsystems include wavelength division multiplexed links, tunable subsystems include wavelength division multiplexed links, tunable
laser transmitters, reconfigurable optical add/drop multiplexers laser transmitters, reconfigurable optical add/drop multiplexers
(ROADM) and wavelength converters. (ROADM) and wavelength converters.
Lightpath provisioning, in general, requires the routing and Lightpath provisioning, in general, requires the routing and
skipping to change at page 2, line 27 skipping to change at page 2, line 33
could be realized via GMPLS/PCE and/or extended GMPLS/PCE protocols. could be realized via GMPLS/PCE and/or extended GMPLS/PCE protocols.
This memo does NOT address optical impairments in any depth and This memo does NOT address optical impairments in any depth and
focuses on topological elements and path selection constraints that focuses on topological elements and path selection constraints that
are common across different WSON environments. It is expected that a are common across different WSON environments. It is expected that a
variety of different techniques will be applied to optical variety of different techniques will be applied to optical
impairments depending on the type of WSON, such as access, metro or impairments depending on the type of WSON, such as access, metro or
long haul. long haul.
Table of Contents Table of Contents
1. Introduction...................................................3 1. Introduction...................................................4
2. Terminology....................................................4 1.1. Revision History..........................................5
1.1.1. Changes from 00......................................5
2. Terminology....................................................5
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........................................6
3.2. Optical Transmitters......................................7 3.2. Optical Transmitters......................................8
3.2.1. Lasers...............................................7 3.2.1. Lasers...............................................8
3.2.2. Spectral Characteristics & Modulation Type...........8 3.2.2. Spectral Characteristics & Modulation Type...........9
3.2.3. Signal Rates and Error Correction....................9 3.2.3. Signal Rates and Error Correction...................10
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...........................................12 3.3.2. Splitters...........................................12
3.3.3. Combiners...........................................12 3.3.3. Combiners...........................................13
3.3.4. Fixed Optical Add/Drop Multiplexers.................12 3.3.4. Fixed Optical Add/Drop Multiplexers.................13
3.4. Wavelength Converters....................................13 3.4. Wavelength Converters....................................14
4. Routing and Wavelength Assignment and the Control Plane.......15 3.4.1. Wavelength Converter Pool Modeling..................16
4.1. Architectural Approaches to RWA..........................16 4. Routing and Wavelength Assignment and the Control Plane.......19
4.1.1. Combined RWA (R&WA).................................16 4.1. Architectural Approaches to RWA..........................20
4.1.2. Separated R and WA (R+WA)...........................17 4.1.1. Combined RWA (R&WA).................................21
4.1.3. Routing and Distributed WA (R+DWA)..................17 4.1.2. Separated R and WA (R+WA)...........................21
4.2. Conveying information needed by RWA......................18 4.1.3. Routing and Distributed WA (R+DWA)..................22
4.3. Lightpath Temporal Characteristics.......................19 4.2. Conveying information needed by RWA......................22
5. GMPLS & PCE Implications......................................20 4.3. Lightpath Temporal Characteristics.......................23
5.1. Implications for GMPLS signaling.........................20 5. Modeling Examples and Control Plane Use Cases.................24
5.1.1. Identifying Wavelengths and Signals.................20 5.1. Network Modeling for GMPLS/PCE Control...................24
5.1.2. Combined RWA/Separate Routing WA support............20 5.1.1. Describing the WSON nodes...........................25
5.1.3. Distributed Wavelength Assignment: Unidirectional, No 5.1.2. Describing the links................................27
Converters.................................................21 5.2. RWA Path Computation and Establishment...................28
5.1.4. Distributed Wavelength Assignment: Unidirectional, 5.3. Resource Optimization....................................29
Limited Converters.........................................22 5.4. Support for Rerouting....................................30
5.1.5. Distributed Wavelength Assignment: Bidirectional, No 6. GMPLS & PCE Implications......................................30
Converters.................................................22 6.1. Implications for GMPLS signaling.........................30
5.2. Implications for GMPLS Routing...........................23 6.1.1. Identifying Wavelengths and Signals.................31
5.2.1. Need for Wavelength-Specific Maximum Bandwidth 6.1.2. Combined RWA/Separate Routing WA support............31
Information................................................23 6.1.3. Distributed Wavelength Assignment: Unidirectional, No
5.2.2. Need for Wavelength-Specific Availability Information24 Converters.................................................31
5.2.3. Relationship to Link Bundling and Layering..........24 6.1.4. Distributed Wavelength Assignment: Unidirectional,
5.2.4. WSON Routing Information Summary....................24 Limited Converters.........................................32
5.3. Optical Path Computation and Implications for PCE........26 6.1.5. Distributed Wavelength Assignment: Bidirectional, No
5.3.1. Lightpath Constraints and Characteristics...........26 Converters.................................................33
5.3.2. Computation Architecture Implications...............27 6.2. Implications for GMPLS Routing...........................33
5.3.3. Discovery of RWA Capable PCEs.......................27 6.2.1. Need for Wavelength-Specific Maximum Bandwidth
5.4. Scaling Implications.....................................27 Information................................................34
5.4.1. Routing.............................................28 6.2.2. Need for Wavelength-Specific Availability Information34
5.4.2. Signaling...........................................28 6.2.3. Relationship to Link Bundling and Layering..........35
5.4.3. Path computation....................................28 6.2.4. WSON Routing Information Summary....................35
5.5. Summary of Impacts by RWA Architecture...................28 6.3. Optical Path Computation and Implications for PCE........36
6. Security Considerations.......................................29 6.3.1. Lightpath Constraints and Characteristics...........36
7. IANA Considerations...........................................29 6.3.2. Computation Architecture Implications...............37
8. Acknowledgments...............................................30 6.3.3. Discovery of RWA Capable PCEs.......................37
9. References....................................................31 6.4. Scaling Implications.....................................38
9.1. Normative References.....................................31 6.4.1. Routing.............................................38
9.2. Informative References...................................32 6.4.2. Signaling...........................................38
10. Contributors.................................................35 6.4.3. Path computation....................................38
Author's Addresses...............................................35 6.5. Summary of Impacts by RWA Architecture...................39
Intellectual Property Statement..................................36 7. Security Considerations.......................................40
Disclaimer of Validity...........................................37 8. IANA Considerations...........................................40
9. Acknowledgments...............................................40
10. References...................................................41
10.1. Normative References....................................41
10.2. Informative References..................................42
11. Contributors.................................................45
Author's Addresses...............................................45
Intellectual Property Statement..................................46
Disclaimer of Validity...........................................46
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
skipping to change at page 4, line 35 skipping to change at page 5, line 5
transmitters, reconfigurable optical add/drop multiplexers (ROADM) transmitters, reconfigurable optical add/drop multiplexers (ROADM)
and wavelength converters. and wavelength converters.
Lightpath provisioning, in general, requires the routing and Lightpath provisioning, in general, requires the routing and
wavelength assignment (RWA) process. This process is reviewed and the wavelength assignment (RWA) process. This process is reviewed and the
information requirements, both static and dynamic for this process information requirements, both static and dynamic for this process
are presented, along with alternative implementation architectures are presented, along with alternative implementation architectures
that could be realized via various combinations of extended GMPLS and that could be realized via various combinations of extended GMPLS and
PCE protocols. PCE protocols.
1.1. Revision History
1.1.1. Changes from 00
o Added new first level section on modeling examples and control
plane use cases.
o Added new third level section on wavelength converter pool
modeling
o Editorial clean up of English and updated references.
2. Terminology 2. Terminology
CWDM: Coarse Wavelength Division Multiplexing. CWDM: Coarse Wavelength Division Multiplexing.
DWDM: Dense Wavelength Division Multiplexing. DWDM: Dense Wavelength Division Multiplexing.
FOADM: Fixed Optical Add/Drop Multiplexer. FOADM: Fixed Optical Add/Drop Multiplexer.
OXC: Optical cross connect. A symmetric optical switching element in OXC: Optical cross connect. A symmetric optical switching element in
which a signal on any ingress port can reach any egress port. which a signal on any ingress port can reach any egress port.
skipping to change at page 6, line 36 skipping to change at page 7, line 18
maybe deleted or moved to an appendix in a future draft] maybe deleted or moved to an appendix in a future draft]
Current technology breaks up the bandwidth capacity of fibers into Current technology breaks up the bandwidth capacity of fibers into
distinct channels based on either wavelength or frequency. There are distinct channels based on either wavelength or frequency. There are
two standards covering wavelengths and channel spacing. ITU-T two standards covering wavelengths and channel spacing. ITU-T
recommendation [G.694.1] describes a DWDM grid defined in terms of recommendation [G.694.1] describes a DWDM grid defined in terms of
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] describes a CWDM grid through U bands. ITU-T recommendation [G.694.2] describes a CWDM grid
define 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 allocated to significantly smaller than the 32 bit GMPLS label space allocated to
lambda switching. A fixed mapping between the GMPLS label space and lambda switching. A label representation for these ITU-T grids is
these ITU-T WDM grids as proposed in [Otani] would not only allow a given in [Otani] and allows a common vocabulary to be used in
common vocabulary to be used in signaling lightpaths but also in signaling lightpaths. Further, these ITU-T grid based labels can and
describing WDM links, ROADM ports, and wavelength converters for the also be used to describe WDM links, ROADM ports, and wavelength
purposes path selection. converters for the purposes path selection.
With a tremendous existing base of fiber many WDM links are designed With a tremendous existing base of fiber many WDM links are designed
to take advantage of particular fiber characteristics or to try to to take advantage of particular fiber characteristics or to try to
avoid undesirable properties. For example dispersion shifted SMF avoid undesirable properties. For example dispersion shifted SMF
[G.653] was originally designed for good long distance performance in [G.653] was originally designed for good long distance performance in
single channel systems, however putting WDM over this type of fiber single channel systems, however putting WDM over this type of fiber
requires much system engineering and a fairly limited range of requires much system engineering and a fairly limited range of
wavelengths. Hence for our basic, impairment unaware, modeling of a wavelengths. Hence for our basic, impairment unaware, modeling of a
WDM link we will need the following information: WDM link we will need the following information:
skipping to change at page 7, line 43 skipping to change at page 8, line 25
flexibility in the wavelength used for optical transmission and aids flexibility in the wavelength used for optical transmission and aids
in the control of path selection. in the control of path selection.
Fundamental modeling parameters from the control plane perspective Fundamental modeling parameters from the control plane perspective
optical transmitters are: optical transmitters are:
o Tunable: Is this transmitter tunable or fixed. o Tunable: Is this transmitter tunable or fixed.
o Tuning range: This is the frequency or wavelength range over which o Tuning range: This is the frequency or wavelength range over which
the laser can be tuned. With the fixed mapping of labels to the laser can be tuned. With the fixed mapping of labels to
lambda's of [Otani] this can be expressed as a doublet (lambda1, lambdas of [Otani] this can be expressed as a doublet (lambda1,
lambda2) or (freq1, freq2) where lambda1 and lambda2 or freq1 and lambda2) or (freq1, freq2) where lambda1 and lambda2 or freq1 and
freq2 are the labels representing the lower and upper bounds in freq2 are the labels representing the lower and upper bounds in
wavelength or frequency. wavelength or frequency.
o Tuning time: Tuning times highly depend on the technology used. o Tuning time: Tuning times highly depend on the technology used.
Thermal drift based tuning may take seconds to stabilize, whilst Thermal drift based tuning may take seconds to stabilize, whilst
electronic tuning might provide sub-ms tuning times. Depending on electronic tuning might provide sub-ms tuning times. Depending on
the application this might be critical. For example, thermal drift the application this might be critical. For example, thermal drift
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 are key in designing WDM subsystems consisting of parameters are used in the design of 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
skipping to change at page 10, line 9 skipping to change at page 10, line 36
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 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- found in [G.671], we only look at a subset of these and their non-
impairement related properties. impairment 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
--->| |---> --->| |--->
skipping to change at page 11, line 40 skipping to change at page 12, line 24
In general a port on a ROADM could have any of the following In general a port on a ROADM could have any of the following
wavelength restrictions: wavelength restrictions:
o Multiple wavelengths, full range port o Multiple wavelengths, full range port
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 (for example 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. More spacing. Note that this information is relatively static. More
complicated wavelength constraints are modeled in [WSON-Info]. 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
skipping to change at page 14, line 52 skipping to change at page 15, line 38
at the same time the regeneration process becomes more dependent on at the same time the regeneration process becomes more dependent on
the signal characteristics such as format and rate. the signal characteristics such as format and rate.
In WSONs where wavelength converters are sparse we may actually see a In WSONs where wavelength converters are sparse we may actually see a
light path appear to loop or ''backtrack'' upon itself in order to light path appear to loop or ''backtrack'' upon itself in order to
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 individual 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]
3.4.1. Wavelength Converter Pool Modeling
A WSON node may include multiple wavelength converters. These are
usually arranged into some type of pool to promote resource sharing.
There are a number of different approaches used in the design of
switches with converter pools. However, from the point of view of
path computation we need to know the following:
1. The nodes that support wavelength conversion.
2. The accessibility and availability of a wavelength converter to
convert from a given ingress wavelength on a particular ingress
port to a desired egress wavelength on a particular egress port.
3. Limitations on the types of signals that can be converted and the
conversions that can be performed.
To model point 2 above we can use a similar technique as used to
model ROADMs and optical switches, i.e., a matrices to indicate
possible connectivity along with wavelength constraints for
links/ports. Since wavelength converters are considered a scarce
resource we will also want our model to include as a minimum the
usage state of individual wavelength converters in the pool. Models
that incorporate more state to further reveal blocking conditions on
ingress or egress to particular converters are for further study.
We utilize a three stage model as shown schematically in Figure 2. In
this model we assume N ingress ports (fibers), P wavelength
converters, and M egress ports (fibers). Since not all ingress ports
can necessarily reach the converter pool, the model starts with a
wavelength pool ingress matrix WI(i,p) = {0,1} whether ingress port i
can reach potentially reach wavelength converter p.
Since not all wavelength can necessarily reach all the converters or
the converters may have limited input wavelength range we have a set
of ingress port constraints for each wavelength converter. Currently
we assume that a wavelength converter can only take a single
wavelength on input. We can model each wavelength converter ingress
port constraint via a wavelength set mechanism.
Next we have a state vector WC(j) = {0,1} dependent upon whether
wavelength converter j in the pool is in use. This is the only state
kept in the converter pool model. This state is not necessary for
modeling "fixed" transponder system, i.e., systems where there is no
sharing. In addition, this state information may be encoded in a
much more compact form depending on the overall connectivity
structure [WC-Pool].
After that, we have a set of wavelength converter egress wavelength
constraints. These constraints indicate what wavelengths a particular
wavelength converter can generate or are restricted to generating due
to internal switch structure.
Finally, we have a wavelength pool egress matrix WE(p,k) = {0,1}
depending on whether the output from wavelength converter p can reach
egress port k. Examples of this method being used to model wavelength
converter pools for several switch architectures from the literature
are given in reference [WC-Pool].
I1 +-------------+ +-------------+ E1
----->| | +--------+ | |----->
I2 | +------+ WC #1 +-------+ | E2
----->| | +--------+ | |----->
| Wavelength | | Wavelength |
| Converter | +--------+ | Converter |
| Pool +------+ WC #2 +-------+ Pool |
| | +--------+ | |
| Ingress | | Egress |
| Connection | . | Connection |
| Matrix | . | Matrix |
| | . | |
| | | |
IN | | +--------+ | | EM
----->| +------+ WC #P +-------+ |----->
| | +--------+ | |
+-------------+ ^ ^ +-------------+
| |
| |
| |
| |
Ingress wavelength Egress wavelength
constraints for constraints for
each converter each converter
Figure 2 Schematic diagram of wavelength converter pool model.
Example: Shared Per Node
In Figure 3 below we show a simple optical switch in a four
wavelength DWDM system sharing wavelength converters in a general
"per node" fashion.
___________ +------+
| |--------------------------->| |
| |--------------------------->| C |
/| | |--------------------------->| o | E1
I1 /D+--->| |--------------------------->| m |
+ e+--->| | | b |====>
====>| M| | Optical | +-----------+ +----+ | i |
+ u+--->| Switch | | WC Pool | |O S|-->| n |
\x+--->| | | +-----+ | |p w|-->| e |
\| | +----+->|WC #1|--+->|t i| | r |
| | | +-----+ | |i t| +------+
| | | | |c c| +------+
/| | | | +-----+ | |a h|-->| |
I2 /D+--->| +----+->|WC #2|--+->|l |-->| C | E2
+ e+--->| | | +-----+ | | | | o |
====>| M| | | +-----------+ +----+ | m |====>
+ u+--->| | | b |
\x+--->| |--------------------------->| i |
\| | |--------------------------->| n |
| |--------------------------->| e |
|___________|--------------------------->| r |
+------+
Figure 3 An optical switch featuring a shared per node wavelength
converter pool architecture.
In this case the ingress and egress pool matrices are simply:
+-----+ +-----+
| 1 1 | | 1 1 |
WI =| |, WE =| |
| 1 1 | | 1 1 |
+-----+ +-----+
Example: Shared Per Link
In Figure 4 we show a different wavelength pool architecture know as
"shared per fiber". In this case the ingress and egress pool matrices
are simply:
+-----+ +-----+
| 1 0 | | 1 0 |
WI =| |, WE =| |
| 0 1 | | 0 1 |
+-----+ +-----+
___________ +------+
| |--------------------------->| |
| |--------------------------->| C |
/| | |--------------------------->| o | E1
I1 /D+--->| |--------------------------->| m |
+ e+--->| | | b |====>
====>| M| | Optical | +-----------+ | i |
+ u+--->| Switch | | WC Pool | | n |
\x+--->| | | +-----+ | | e |
\| | +----+->|WC #1|--+---------->| r |
| | | +-----+ | +------+
| | | | +------+
/| | | | +-----+ | | |
I2 /D+--->| +----+->|WC #2|--+---------->| C | E2
+ e+--->| | | +-----+ | | o |
====>| M| | | +-----------+ | m |====>
+ u+--->| | | b |
\x+--->| |--------------------------->| i |
\| | |--------------------------->| n |
| |--------------------------->| e |
|___________|--------------------------->| r |
+------+
Figure 4 An optical switch featuring a shared per fiber wavelength
converter pool architecture.
4. Routing and Wavelength Assignment and the Control Plane 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
skipping to change at page 16, line 16 skipping to change at page 20, line 41
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. 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 solving the RWA
problem some algorithms utilize a two step procedure of path problem. Some algorithms utilize a two step procedure of path
selection followed by wavelength assignment, and others solve the selection followed by wavelength assignment, and others solve the
problem in a combined fashion. problem in a 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.
4.1.1. Combined RWA (R&WA) 4.1.1. Combined RWA (R&WA)
skipping to change at page 17, line 25 skipping to change at page 21, line 51
usage of the physical and spectral paths are excluded from this usage of the physical and spectral 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 [Ozdaglar03]. Hence although there is no guarantee path algorithm [Ozdaglar03]. Hence although there is no guarantee
that the selected final route and wavelength offers the optimal that the selected final route and wavelength offers the optimal
solution by allowing multiple routes to pass to the wavelength solution by allowing multiple routes to pass to the wavelength
selection process reasonable optimization can be performed. selection process 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 available wavelength assignment needs information on the network's available
resources and on network nodes capabilities. resources and on 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 a first entity performs routing, while wavelength
assignment is performed on a hop-by-hop manner along the previously assignment is performed on a hop-by-hop manner along the previously
computed route. This mechanism relies on updating of a list of computed route. This mechanism relies on updating of a list of
potential wavelengths used to ensure the wavelength continuity potential wavelengths used to ensure conformance with the wavelength
constraint. 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. Per [RFC3471], the Label Set
selection works according to an AND scheme. Each hop restricts the selection works according to an AND scheme. Each hop restricts the
Label Set sent to the next hop from the one received from the Label Set sent to the next hop from the one received from the
previous hop by performing an AND operation between the wavelength previous hop by performing an AND operation between the wavelength
referred by the labels it includes with the one available on the referred by the labels the message includes with the one available on
ongoing interface. The constraint to perform this AND operation is up the ongoing interface. The constraint to perform this AND operation
to the node local policy (even if one expects a consistent policy is up to the node local policy (even if one expects a consistent
configuration throughout a given transparency domain). When policy configuration throughout a given transparency domain). When
wavelength conversion is performed at an intermediate node, a new wavelength conversion is performed at an intermediate node, a new
Label Set is generated. The egress nodes selects one label in the 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 Label Set received at the node, which is also up to the node local
policy. policy.
Depending on these policies a spectral assignment may not be found or Depending on these policies a spectral assignment may not be found or
one consuming too many conversion resources relatively to what a 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 may generate higher blocking probabilities in a heavily loaded this approach may generate higher blocking probabilities in a heavily
network. loaded network.
On the one hand, this solution may be empowered with some signaling On the one hand, this solution may be empowered with some signaling
extensions to ease its functioning and possibly enhance its extensions to ease its functioning and possibly enhance its
performances relatively to blocking. On the other hand this solution performances relatively to blocking. Note that this approach requires
is not stressing the information dissemination processes. less information dissemination than the others.
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. This
solution is applicable inside network where resource optimization is solution is applicable inside networks where resource optimization is
not the most crucial constraint. 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 lightpath
requests. In particular high level models of the information by the requests. In particular, high level models of the information used by
RWA process were presented. We can view this information as either the RWA process were presented. We can view this information as
static, changing with hardware changes (including possibly failures), either static, changing with hardware changes (including possibly
or dynamic, can change with subsequent lightpath provisioning. The failures), or dynamic, those that can change with subsequent
timeliness in which an entity involved in the RWA process is notified lightpath provisioning. The timeliness in which an entity involved in
of such changes is fairly situational. For example, for network the RWA process is notified of such changes is fairly situational.
restoration purposes, learning of a hardware failure or of new
hardware coming online to provide restoration capability can be For example, for network restoration purposes, learning of a hardware
critical. failure or of new hardware coming 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 such as 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 information currently static and dynamic information. Static information currently
conveyed includes items like router options and such. conveyed includes items like router options and such.
o Management protocols such as NetConf, SNMPv3, CLI, CORBA, or o Management protocols such as NetConf, SNMPv3, CLI, CORBA, or
others. others.
skipping to change at page 19, line 12 skipping to change at page 23, line 37
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.
Utilize incremental updates if feasible. Utilize incremental updates if feasible.
4.3. Lightpath Temporal Characteristics 4.3. Lightpath Temporal Characteristics
The temporal characteristics of a light path connection is another The temporal characteristics of a light path connection can affect
aspect that can affect the choice of solution to the RWA process. For the choice of solution to the RWA process. For our purposes here we
our purposes here we look at the timeliness of connection look at the timeliness of connection establishment/teardown, and the
establishment/teardown, and the duration of the connection. duration of the connection.
Connection Establishment/Teardown Timeliness can be thought of in Connection Establishment/Teardown Timeliness can be thought of in
approximately three time frames: approximately three time frames:
1. Time Critical: For example those lightpath establishments used for 1. Time Critical: For example those lightpath establishments used for
restoration of service or other high priority real time service restoration of service or other high priority real time service
requests. requests.
2. Soft time bounds: This is a more typical new connection request. 2. Soft time bounds: This is a more typical new connection request.
While expected to be responsive, there should be more time to take While expected to be responsive, there should be more time to take
skipping to change at page 20, line 4 skipping to change at page 24, line 30
Different types of RWA algorithms have been developed for dealing Different types of RWA algorithms have been developed for dealing
with dynamic versus pseudo-static conditions. These can address with dynamic versus pseudo-static conditions. These can address
service provider's needs for: (a) network optimization, (b) service provider's needs for: (a) network optimization, (b)
restoration, and (c) highly dynamic lightpath provisioning. restoration, and (c) highly dynamic lightpath provisioning.
Hence we can model timescale related lightpath requirements via the Hence we can model timescale related lightpath requirements via the
following notions: following notions:
o Batch or Sequential light path connection requests o Batch or Sequential light path connection requests
o Timeliness of Connection establishment o Timeliness of Connection establishment
o Duration of lightpath connection o Duration of lightpath connection
5. GMPLS & PCE Implications 5. Modeling Examples and Control Plane Use Cases
This section provides examples of the fixed and switch optical node
and wavelength constraint models of section 3. and WSON control plane
use cases related to path computation, establishment, rerouting, and
optimization.
5.1. Network Modeling for GMPLS/PCE Control
Consider a network containing three routers (R1 through R3), eight
WSON nodes (N1 through N8) and 18 links (L1 through L18) and one OEO
converter (O1) in a topology shown below.
+--+ +--+ +--+ +--------+
+-L3-+N2+-L5-+ +--------L12--+N6+--L15--+ N8 +--
| +--+ |N4+-L8---+ +--+ ++--+---++
| | +-L9--+| | | |
+--+ +-+-+ ++-+ || | L17 L18
| ++-L1--+ | | ++++ +----L16---+ | |
|R1| | N1| L7 |R2| | | |
| ++-L2--+ | | ++-+ | ++---++
+--+ +-+-+ | | | + R3 |
| +--+ ++-+ | | +-----+
+-L4-+N3+-L6-+N5+-L10-+ ++----+
+--+ | +--------L11--+ N7 +----
+--+ ++---++
| |
L13 L14
| |
++-+ |
|O1+-+
+--+
5.1.1. Describing the WSON nodes
The eight WSON nodes in this example have the following properties:
o Nodes N1, N2, N3 have fixed OADMs (FOADMs) installed and can
therefore only access a static and pre-defined set of wavelengths
o All other nodes contain ROADMs and can therefore access all
wavelengths.
o Nodes N4, N5, N7 and N8 are multi-degree nodes, allowing any
wavelength to be optically switched between any of the links. Note
however, that this does not automatically apply to wavelengths
that are being added or dropped at the particular node.
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
(L5, L7 and L12 in this case)
o The links from the routers are always only able to carry one
wavelength with the exception of links L8 and L9 which are capable
to add/drop any wavelength.
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
not change the wavelength of the signal. Assume that it can
regenerate any of the client signals, however only for a specific
wavelength.
Given the above restrictions, the node information for the eight
nodes can be expressed as follows: (where ID == identifier, SCM ==
switched connectivity matrix, and FCM == fixed connectivity matrix).
+ID+SCM +FCM +
| | |L1 |L2 |L3 |L4 | | |L1 |L2 |L3 |L4 | |
| |L1 |0 |0 |0 |0 | |L1 |0 |0 |1 |0 | |
|N1|L2 |0 |0 |0 |0 | |L2 |0 |0 |0 |1 | |
| |L3 |0 |0 |0 |0 | |L3 |1 |0 |0 |1 | |
| |L4 |0 |0 |0 |0 | |L4 |0 |1 |1 |0 | |
+--+---+---+---+---+---+---+---+---+---+---+---+---+
| | |L3 |L5 | | | | |L3 |L5 | | | |
|N2|L3 |0 |0 | | | |L3 |0 |1 | | | |
| |L5 |0 |0 | | | |L5 |1 |0 | | | |
+--+---+---+---+---+---+---+---+---+---+---+---+---+
| | |L4 |L6 | | | | |L4 |L6 | | | |
|N3|L4 |0 |0 | | | |L4 |0 |1 | | | |
| |L6 |0 |0 | | | |L6 |1 |0 | | | |
+--+---+---+---+---+---+---+---+---+---+---+---+---+
| | |L5 |L7 |L8 |L9 |L12| |L5 |L7 |L8 |L9 |L12|
| |L5 |0 |1 |1 |1 |1 |L5 |0 |0 |0 |0 |0 |
|N4|L7 |1 |0 |1 |1 |1 |L7 |0 |0 |0 |0 |0 |
| |L8 |1 |1 |0 |1 |1 |L8 |0 |0 |0 |0 |0 |
| |L9 |1 |1 |1 |0 |1 |L9 |0 |0 |0 |0 |0 |
| |L12|1 |1 |1 |1 |0 |L12|0 |0 |0 |0 |0 |
+--+---+---+---+---+---+---+---+---+---+---+---+---+
| | |L6 |L7 |L10|L11| | |L6 |L7 |L10|L11| |
| |L6 |0 |1 |0 |1 | |L6 |0 |0 |1 |0 | |
|N5|L7 |1 |0 |0 |1 | |L7 |0 |0 |0 |0 | |
| |L10|0 |0 |0 |0 | |L10|1 |0 |0 |0 | |
| |L11|1 |1 |0 |0 | |L11|0 |0 |0 |0 | |
+--+---+---+---+---+---+---+---+---+---+---+---+---+
| | |L12|L15| | | | |L12|L15| | | |
|N6|L12|0 |1 | | | |L12|0 |0 | | | |
| |L15|1 |0 | | | |L15|0 |0 | | | |
+--+---+---+---+---+---+---+---+---+---+---+---+---+
| | |L11|L13|L14|L16| | |L11|L13|L14|L16| |
| |L11|0 |1 |0 |1 | |L11|0 |0 |0 |0 | |
|N7|L13|1 |0 |0 |0 | |L13|0 |0 |1 |0 | |
| |L14|0 |0 |0 |1 | |L14|0 |1 |0 |0 | |
| |L16|1 |0 |1 |0 | |L16|0 |0 |1 |0 | |
+--+---+---+---+---+---+---+---+---+---+---+---+---+
| | |L15|L16|L17|L18| | |L15|L16|L17|L18| |
| |L15|0 |1 |0 |0 | |L15|0 |0 |0 |1 | |
|N8|L16|1 |0 |0 |0 | |L16|0 |0 |1 |0 | |
| |L17|0 |0 |0 |0 | |L17|0 |1 |0 |0 | |
| |L18|0 |0 |0 |0 | |L18|1 |0 |1 |0 | |
+--+---+---+---+---+---+---+---+---+---+---+---+---+
5.1.2. Describing the links
For the following discussion some simplifying assumptions are made:
o It is assumed that the WSON node support a total of four
wavelengths designated WL1 through WL4.
o It is assumed that the impairment feasibility of a path or path
segment is independent from the wavelength chosen.
For the discussion of the RWA operation to build LSPs between two
routers, the wavelength constraints on the links between the routers
and the WSON nodes as well as the connectivity matrix of these links
needs to be specified:
+Link+WLs supported +Possible egress links+
| L1 | WL1 | L3 |
+----+-----------------+---------------------+
| L2 | WL2 | L4 |
+----+-----------------+---------------------+
| L8 | WL1 WL2 WL3 WL4 | L5 L7 L12 |
+----+-----------------+---------------------+
| L9 | WL1 WL2 WL3 WL4 | L5 L7 L12 |
+----+-----------------+---------------------+
| L10| WL2 | L6 |
+----+-----------------+---------------------+
| L13| WL1 WL2 WL3 WL4 | L11 L14 |
+----+-----------------+---------------------+
| L14| WL1 WL2 WL3 WL4 | L13 L16 |
+----+-----------------+---------------------+
| L17| WL2 | L16 |
+----+-----------------+---------------------+
| L18| WL1 | L15 |
+----+-----------------+---------------------+
Note that the possible egress links for the links connecting to the
routers is inferred from the Switched Connectivity Matrix and the
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.
5.2. RWA Path Computation and Establishment
The calculation of optical impairment feasible routes is outside the
scope of this framework document. In general impairment feasible
routes serve as an input to the RWA algorithm.
For the example use case shown here, assume the following feasible
routes:
+Endpoint 1+Endpoint 2+Feasible Route +
| R1 | R2 | L1 L3 L5 L8 |
| R1 | R2 | L1 L3 L5 L9 |
| R1 | R2 | L2 L4 L6 L7 L8 |
| R1 | R2 | L2 L4 L6 L7 L9 |
| R1 | R2 | L2 L4 L6 L10 |
| R1 | R3 | L1 L3 L5 L12 L15 L18 |
| R1 | N7 | L2 L4 L6 L11 |
| N7 | R3 | L16 L17 |
| N7 | R2 | L16 L15 L12 L9 |
| R2 | R3 | L8 L12 L15 L18 |
| R2 | R3 | L8 L7 L11 L16 L17 |
| R2 | R3 | L9 L12 L15 L18 |
| R2 | R3 | L9 L7 L11 L16 L17 |
Given a request to establish a LSP between R1 and R2 the RWA
algorithm finds the following possible solutions:
+WL + Path +
| WL1| L1 L3 L5 L8 |
| WL1| L1 L3 L5 L9 |
| WL2| L2 L4 L6 L7 L8|
| WL2| L2 L4 L6 L7 L9|
| WL2| L2 L4 L6 L10 |
Assume now that the RWA chooses WL1 and the Path L1 L3 L5 L8 for the
requested LSP.
Next, another LSP is signaled from R1 to R2. Given the established
LSP using WL1, the following table shows the available paths:
+WL + Path +
| WL2| L2 L4 L6 L7 L9|
| WL2| L2 L4 L6 L10 |
Assume now that the RWA chooses WL2 and the path L2 L4 L6 L7 L9 for
the establishment of the new LSP.
Faced with another LSP request -this time from R2 to R3 - can not be
fulfilled since the only four possible paths (starting at L8 and L9)
are already in use.
5.3. Resource Optimization
The preceding example gives rise to another use case: The
optimization of network resources. Optimization can be achieved on a
number of layers (e.g. through electrical or optical multiplexing of
client signals) or by re-optimizing the solutions found by the RWA
algorithm.
Given the above example again, assume that the RWA algorithm should
find 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 R1.
5.4. Support for Rerouting
It is also envisioned that the extensions to GMPLS and PCE support
rerouting of wavelengths in case of failures.
Assume for this discussion that the only two LSPs in use in the
system are:
LSP1: WL1 L1 L3 L5 L8
LSP2: WL2 L2 L4 L6 L7 L9
Assume furthermore that the link L5 fails. The RWA can now find the
following alternate path and and establish that path:
R1 -> N7 -> R2
Level 3 regeneration will take place at N7, so that the complete path
looks like this:
R1 -> L2 L4 L6 L11 L13 -> O1 -> L14 L16 L15 L12 L9 -> R2
6. 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 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.
5.1. Implications for GMPLS signaling 6.1. 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.
5.1.1. 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] eases
communication between PCE and WSON PCCs. communication between PCE and WSON PCCs.
An alternative to a global network map of labels to wavelengths would An alternative to a global network map of labels to wavelengths would
be to use LMP to assign the map for each link then convey that be to use LMP to assign the map for each link then convey that
information to any path computation entities, e.g., label switch information to any path computation entities, e.g., label switch
routers or stand alone PCEs. The local label map approach will routers or stand alone PCEs. The local label map approach will
require the label-set contents in the RSVP-TE Path message to be require the label-set contents in the RSVP-TE Path message to be
translated every time the map changes between an incoming link and translated every time the map changes between an incoming link and
the outgoing link. the outgoing link.
In the future, it maybe worthwhile to define traffic parameters for In the future, it maybe worthwhile to define traffic parameters for
lambda LSPs that include a signal type field that includes modulation lambda LSPs that include a signal type field that includes modulation
format/rate information. This is similar to what was done in format/rate information. This is similar to what was done in
reference [RFC4606] for SONET/SDH signal types. reference [RFC4606] for SONET/SDH signal types.
5.1.2. Combined RWA/Separate Routing WA support 6.1.2. 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 use 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 translated appropriately.
5.1.3. Distributed Wavelength Assignment: Unidirectional, No 6.1.3. 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. For example, the following is selection algorithm to choose a lambda. For example, the following is
a non-exhaustive subset of wavelength assignment (WA) approaches a non-exhaustive subset of wavelength assignment (WA) approaches
discussed in [HZang00]: discussed in [HZang00]:
skipping to change at page 22, line 12 skipping to change at page 32, line 40
information or via supplemental information passed via the information or via supplemental information passed via the
signaling protocol. signaling protocol.
In case (3) above the global information needed by the wavelength In case (3) above the global information needed by the wavelength
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 6.1.4. 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
reflecting only the limitations of the wavelength converter and the reflecting only the limitations of the wavelength converter and the
egress link. The record route option in RVSP-TE signaling can be used egress link. The record route option in RVSP-TE signaling can be used
to show where wavelength conversion has taken place. to show where wavelength conversion has taken place.
5.1.5. Distributed Wavelength Assignment: Bidirectional, No 6.1.5. Distributed Wavelength Assignment: Bidirectional, No
Converters Converters
There are potential issues in the case of a bi-directional lightpath There are potential issues in the case of a bi-directional lightpath
which requires the use of the same lambda in both directions. We can which requires the use of the same lambda in both directions. We can
try to use the above procedure to determine the available try to use the above procedure to determine the available
bidirectional lambda set if we use the interpretation that the bidirectional lambda set if we use the interpretation that the
available label set is available in both directions. However, a available label set is available in both directions. However, a
problem, arises in that bidirectional LSPs setup, according to problem, arises in that bidirectional LSPs setup, according to
[RFC3471] section 4.1, is indicated by the presence of an upstream [RFC3471] section 4.1, is indicated by the presence of an upstream
label in the path message. 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 obtained, e.g., at the destination node and the wavelength assignment
algorithm has been run the upstream label information will not be algorithm has been run the upstream label information will not be
available. Hence currently distributed wavelength assignment with available. Hence currently distributed wavelength assignment with
bidirectional lightpaths is not supported. bidirectional lightpaths is not supported.
5.2. 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 we can use to descriptor for "lambda switch capable" (LSC) which we can use 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, we would need to convey the following subsystem conveyed via an IGP, we would need to convey the following subsystem
properties to minimally characterize a WSON: properties to minimally characterize a WSON:
1. WDM Link properties (allowed wavelengths). 1. WDM Link properties (allowed wavelengths).
skipping to change at page 23, line 30 skipping to change at page 34, line 7
4. Wavelength Converter properties (per network element, may change if 4. Wavelength Converter properties (per network element, may change if
a common limited shared pool is used). a common limited shared pool is used).
In most cases we should be able to combine items (1) and (2) into the In most cases we should be able to combine items (1) and (2) into the
information in item (3). Except for the number of wavelength information in item (3). Except for the number of wavelength
converters that are available in a shared pool, and the previous converters that are available in a shared pool, and the previous
information is fairly static. In the next two sections we discuss information is fairly static. In the next two sections we discuss
dynamic available link bandwidth information. dynamic available link bandwidth information.
5.2.1. Need for Wavelength-Specific Maximum Bandwidth Information 6.2.1. Need for Wavelength-Specific Maximum Bandwidth Information
Difficulties are encountered when trying to use the bandwidth Difficulties are encountered when trying to use the bandwidth
accounting methods of [RFC4202] and [RFC3630] to describe the accounting methods of [RFC4202] and [RFC3630] to describe the
availability of wavelengths on a WDM link. The current RFCs give availability of wavelengths on a WDM link. The current RFCs give
three link resource measures: Maximum Bandwidth, Maximum Reservable three link resource measures: Maximum Bandwidth, Maximum Reservable
Bandwidth, and Unreserved Bandwidth. Although these can be used to Bandwidth, and Unreserved Bandwidth. Although these can be used to
describe a WDM span they do not provide the fundamental information describe a WDM span they do not provide the fundamental information
needed for RWA. We are not given the maximum bandwidth per wavelength needed for RWA. We are not given the maximum bandwidth per wavelength
for the span. If we did then we could use the aforementioned measures for the span. If we did then we could use the aforementioned measures
to tell us the maximum wavelength count and the number of available to tell us the maximum wavelength count and the number of available
skipping to change at page 24, line 8 skipping to change at page 34, line 33
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 4.1.3. approach of section 4.1.3.
5.2.2. Need for Wavelength-Specific Availability Information 6.2.2. 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 sections 4.1.1. 4.1.2. This is separate WA process as discussed in sections 4.1.1. 4.1.2. This is
currently 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
PCEs then representing the use of wavelengths via a simple bit-map is PCEs then representing the use of wavelengths via a simple bit-map is
feasible. feasible.
5.2.3. Relationship to Link Bundling and Layering 6.2.3. Relationship to Link Bundling and Layering
When dealing with static DWDM systems, particularly from a SONET/SDH When dealing with static DWDM systems, particularly from a SONET/SDH
or G.709 digital wrapper layer, each lambda looks like a separate or G.709 digital wrapper layer, each lambda looks like a separate
link. Typically a bunch of unnumbered links, as supported in GMPLS link. Typically a bunch of unnumbered links, as supported in GMPLS
routing extensions [RFC4202], would be used to describe a static DWDM routing extensions [RFC4202], would be used to describe a static DWDM
system. In addition these links can be bundled into a TE link system. In addition these links can be bundled into a TE link
([RFC4202], [RFC4201]) for more efficient dissemination of resource ([RFC4202], [RFC4201]) for more efficient dissemination of resource
information. However, in the case discussed here we want to control a information. However, in the case discussed here we want to control a
dynamic WDM layer and must deal with wavelengths as labels and not dynamic WDM layer and must deal with wavelengths as labels and not
just as links or component links from the perspective of an upper just as links or component links from the perspective of an upper
(client) layer. In addition, a typical point to point optical cable (client) layer. In addition, a typical point to point optical cable
contains many optical fibers and hence it may be desirable to bundle contains many optical fibers and hence it may be desirable to bundle
these separate fibers into a TE link. Note that in the no wavelength these separate fibers into a TE link. Note that in the no wavelength
conversion or limited wavelength conversion situations that we will conversion or limited wavelength conversion situations that we will
need information on wavelength usage on the individual component need information on wavelength usage on the individual component
links. links.
5.2.4. WSON Routing Information Summary 6.2.4. 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)
skipping to change at page 26, line 5 skipping to change at page 36, line 26
we only need the following information: we only need the following information:
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]. provided in [WSON-Info].
5.3. 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 the RWA problem can be computationally intensive
[HZang00]. Such computationally intensive path computations and [HZang00]. Such computationally intensive path computations and
optimizations were part of the impetus for the PCE (path computation optimizations were part of the impetus for the PCE (path computation
element) architecture. element) architecture.
As the PCEP defines the procedures necessary to support both As the PCEP defines the procedures necessary to support both
sequential [PCEP] and global concurrent path computations [PCE-GCO], sequential [PCEP] and global concurrent path computations [PCE-GCO],
PCE is well positioned to support WSON-enabled RWA computation with PCE is well positioned to support WSON-enabled RWA computation with
some protocol enhancement. 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 lightpath constraints and characteristics, (b) computation
architectures. architectures.
5.3.1. Lightpath Constraints and Characteristics 6.3.1. Lightpath 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 lightpath
requests are encountered: requests are encountered:
o Batch optimization, multiple lightpaths requested at one time. o Batch optimization, multiple lightpaths requested at one time.
o Lightpath(s) and backup lightpath(s) requested at one time. o Lightpath(s) and backup lightpath(s) requested at one time.
o Single lightpath requested at a time. o Single lightpath requested at a time.
skipping to change at page 27, line 4 skipping to change at page 37, line 29
backup paths. backup paths.
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
6.3.2. Computation Architecture Implications
When a PCE performs a combined RWA computation per section 4.1.1. 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.
When a PCE is used to perform routing in a routing with distribute WA When a PCE is used to perform routing in a routing with distribute WA
architecture, then the PCE does not necessarily need the most up to architecture, then the PCE does not necessarily need the most up to
date network wavelength utilization information, however timely date network wavelength utilization information, however timely
information can contributed to reducing failed signaling attempts information can contributed to reducing failed signaling attempts
related to blocking. related to blocking.
5.3.3. 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 solving the RWA are
somewhat specialized and computationally intensive hence not all PCEs somewhat specialized and computationally intensive hence not all PCEs
within a domain would necessarily need or want this capability. within a domain would necessarily need or want this capability.
Hence, it would be useful via the mechanisms being established for Hence, it would be useful via the mechanisms being established for
PCE discovery [RFC5088] to indicate that a PCE has the ability to PCE discovery [RFC5088] to indicate that a PCE has the ability to
deal with the RWA problem. Reference [RFC5088] indicates that a sub- deal with the RWA problem. Reference [RFC5088] indicates that a sub-
TLV could be allocated for this purpose. TLV could be allocated for this purpose.
Recent progress on objective functions in PCE [PCE-OF] would allow Recent progress on objective functions in PCE [PCE-OF] would allow
skipping to change at page 27, line 46 skipping to change at page 38, line 23
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
algorithm in its objective function to be able to optimize the path algorithm in its objective function to be able to optimize the path
computation from the perspective of wavelength assignment if chosen computation from the perspective of wavelength assignment if chosen
by the operators. by the operators.
5.4. Scaling Implications 6.4. Scaling Implications
This section provides a summary of the scaling issue for WSON This section provides a summary of the scaling issue for WSON
routing, signaling and path computation introduced by the concepts routing, signaling and path computation introduced by the concepts
discussed in this document. discussed in this document.
5.4.1. Routing 6.4.1. Routing
In large WSONs label availability and cross connect capability In large WSONs label availability and cross connect capability
information being advertised may generate a significant amount of information being advertised may generate a significant amount of
routing information. routing information.
5.4.2. Signaling 6.4.2. Signaling
When dealing with a large number of simultaneous end-to-end When dealing with a large number of simultaneous end-to-end
wavelength service requests and service deletions the network may wavelength service requests and service deletions the network may
have to process a significant number of forward and backward service have to process a significant number of forward and backward service
messages. Also, similar situation possibly happens in the case of messages. Also, similar situation possibly happens in the case of
link or node failure, if the WSON support dynamic restoration link or node failure, if the WSON support dynamic restoration
capability. capability.
5.4.3. Path computation 6.4.3. 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 6.5. Summary of Impacts by RWA Architecture
The following table summarizes for each RWA strategy the list of The following table summarizes for each RWA strategy the list of
mandatory ("M") and optional ("O") control plane features according mandatory ("M") and optional ("O") control plane features according
to GMPLS architectural blocks: to GMPLS architectural blocks:
o Information required by the path computation entity, o Information required by the path computation entity,
o LSP request parameters used in either PCC to PCE situations or in o LSP request parameters used in either PCC to PCE situations or in
signaling, signaling,
skipping to change at page 29, line 30 skipping to change at page 40, line 7
| Signal features | 5.1 | | x | | | x | | | Signal features | 5.1 | | x | | | x | |
| Modulation format | | | x | | | x | | | Modulation format | | | x | | | x | |
| Modulation parameters | | | x | | | x | | | Modulation parameters | | | x | | | x | |
| Specification of RWA method | 5.1 | | x | | | x | | | Specification of RWA method | 5.1 | | x | | | x | |
| LSP time features | 4.3 | | x | | | | | | LSP time features | 4.3 | | x | | | | |
+-------------------------------------+-----+---+---+---+---+---+---+ +-------------------------------------+-----+---+---+---+---+---+---+
| Enriching signaling messages | | | | | | | | | Enriching signaling messages | | | | | | | |
| Signal features | 5.1 | | | | | x | | | Signal features | 5.1 | | | | | x | |
+-------------------------------------+-----+---+---+---+---+---+---+ +-------------------------------------+-----+---+---+---+---+---+---+
6. 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 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
that the protocols are secure in the WSON environment. 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 the RWA problem represents a disclosure of network
capabilities that an operator may wish to keep private. Consideration capabilities that an operator may wish to keep private. Consideration
should be given to securing this information. should be given to securing this information.
7. IANA Considerations 8. IANA Considerations
This document makes no request for IANA actions. This document makes no request for IANA actions.
8. 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.
This document was prepared using 2-Word-v2.0.template.dot. This document was prepared using 2-Word-v2.0.template.dot.
9. References 10. References
9.1. Normative References 10.1. Normative References
[RFC3471] Berger, L., "Generalized Multi-Protocol Label Switching [RFC3471] Berger, L., "Generalized Multi-Protocol Label Switching
(GMPLS) Signaling Functional Description", RFC 3471, (GMPLS) Signaling Functional Description", RFC 3471,
January 2003. January 2003.
[RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering [RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering
(TE) Extensions to OSPF Version 2", RFC 3630, September (TE) Extensions to OSPF Version 2", RFC 3630, September
2003. 2003.
[RFC3945] Mannie, E., "Generalized Multi-Protocol Label Switching [RFC3945] Mannie, E., "Generalized Multi-Protocol Label Switching
skipping to change at page 31, line 42 skipping to change at page 41, 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-05.txt, November 2007. global-concurrent-optimization-08.txt, January 2009.
[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-19.txt, November 2008. progress, draft-ietf-pce-pcep-19.txt, November 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-05.txt, February 2008. draft-ietf-pce-of-06.txt, December 2008.
[WSON-Encode] G. Bernstein, Y. Lee, D. Li, and W. Imajuku, "Routing [WSON-Encode] G. Bernstein, Y. Lee, D. Li, and W. Imajuku, "Routing
and Wavelength Assignment Information Encoding for and Wavelength Assignment Information Encoding for
Wavelength Switched Optical Networks", draft-bernstein- Wavelength Switched Optical Networks", draft-bernstein-
ccamp-wson-encode-01.txt, November 2008. ccamp-wson-encode-01.txt, November 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-03.txt, Optical Networks", draft-bernstein-ccamp-wson-info-03.txt,
July, 2008. July, 2008.
9.2. Informative References 10.2. 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
Seiconductor Lasers: A Tutorial", Journal of Lightwave Seiconductor Lasers: A Tutorial", Journal of Lightwave
Technology, vol. 22, no. 1, pp. 193-202, January 2004. Technology, vol. 22, no. 1, pp. 193-202, January 2004.
skipping to change at page 35, line 5 skipping to change at page 44, line 10
Transactions on Networking, vol. 11, 2003, pp. 259 -272. 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 [WC-Pool] G. Bernstein, Y. Lee, "Modeling WDM Switching Systems
including Wavelength Converters" to appear www.grotto-
networking.com, 2008.
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
Genoa Italy Genoa Italy
skipping to change at page 35, line 43 skipping to change at page 45, line 43
Pierre Peloso Pierre Peloso
Alcatel-Lucent Alcatel-Lucent
Route de Villejust - - 91620 Nozay - France Route de Villejust - - 91620 Nozay - France
Email: pierre.peloso@alcatel-lucent.fr Email: pierre.peloso@alcatel-lucent.fr
Jonathan Sadler Jonathan Sadler
Tellabs Tellabs
Email: Jonathan.Sadler@tellabs.com Email: Jonathan.Sadler@tellabs.com
Dirk Schroetter
Cisco
Email: dschroet@cisco.com
Author's Addresses Author's Addresses
Greg M. Bernstein (ed.) Greg M. Bernstein (ed.)
Grotto Networking Grotto Networking
Fremont California, USA Fremont California, USA
Phone: (510) 573-2237 Phone: (510) 573-2237
Email: gregb@grotto-networking.com Email: gregb@grotto-networking.com
Young Lee (ed.) Young Lee (ed.)
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)
Email: ylee@huawei.com Email: ylee@huawei.com
Wataru Imajuku Wataru Imajuku
skipping to change at page 36, line 23 skipping to change at page 46, line 26
Wataru Imajuku Wataru Imajuku
NTT Network Innovation Labs NTT Network Innovation Labs
1-1 Hikari-no-oka, Yokosuka, Kanagawa 1-1 Hikari-no-oka, Yokosuka, Kanagawa
Japan Japan
Phone: +81-(46) 859-4315 Phone: +81-(46) 859-4315
Email: imajuku.wataru@lab.ntt.co.jp Email: imajuku.wataru@lab.ntt.co.jp
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