draft-ietf-ccamp-rwa-wson-framework-03.txt   draft-ietf-ccamp-rwa-wson-framework-04.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: March 2010 Grotto Networking Expires: April 2010 Grotto Networking
Wataru Imajuku Wataru Imajuku
NTT NTT
September 8, 2009 October 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-03.txt draft-ietf-ccamp-rwa-wson-framework-04.txt
Status of this Memo Status of this Memo
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Copyright Notice Copyright Notice
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Please review these documents carefully, as they describe your rights Please review these documents carefully, as they describe your rights
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address potential incompatibilities between some types of optical address potential incompatibilities between some types of optical
signals and some types of network elements and links. signals and some types of network elements and links.
Table of Contents Table of Contents
1. Introduction...................................................4 1. Introduction...................................................4
1.1. Revision History..........................................4 1.1. Revision History..........................................4
1.1.1. Changes from 00......................................4 1.1.1. Changes from 00......................................4
1.1.2. Changes from 01......................................5 1.1.2. Changes from 01......................................5
1.1.3. Changes from 02......................................5 1.1.3. Changes from 02......................................5
1.2. Related Documents ........................................5 1.2. Related Documents ........................................6
2. Terminology....................................................6 2. Terminology....................................................6
3. Wavelength Switched Optical Networks...........................7 3. Wavelength Switched Optical Networks...........................7
3.1. WDM and CWDM Links........................................7 3.1. WDM and CWDM Links........................................7
3.2. Optical Transmitters......................................9 3.2. Optical Transmitters......................................9
3.2.1. Lasers...............................................9 3.2.1. Lasers...............................................9
3.2.2. WSON Signal Parameters..............................10 3.2.2. WSON Signal Parameters..............................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...........................................13
3.3.3. Combiners...........................................13 3.3.3. Combiners...........................................14
3.3.4. Fixed Optical Add/Drop Multiplexers.................13 3.3.4. Fixed Optical Add/Drop Multiplexers.................14
3.4. Wavelength Converters....................................14 3.4. Wavelength Converters....................................15
3.4.1. Wavelength Converter Pool Modeling..................15 3.4.1. Wavelength Converter Pool Modeling..................16
4. Routing and Wavelength Assignment and the Control Plane.......19 4. Routing and Wavelength Assignment and the Control Plane.......20
4.1. Architectural Approaches to RWA..........................20 4.1. Architectural Approaches to RWA..........................21
4.1.1. Combined RWA (R&WA).................................21 4.1.1. Combined RWA (R&WA).................................22
4.1.2. Separated R and WA (R+WA)...........................21 4.1.2. Separated R and WA (R+WA)...........................22
4.1.3. Routing and Distributed WA (R+DWA)..................22 4.1.3. Routing and Distributed WA (R+DWA)..................23
4.2. Conveying information needed by RWA......................22 4.2. Conveying information needed by RWA......................23
4.3. Lightpath Temporal Characteristics.......................23 4.3. Lightpath Temporal Characteristics.......................24
5. Modeling Examples and Control Plane Use Cases.................24 5. Modeling Examples and Control Plane Use Cases.................25
5.1. Network Modeling for GMPLS/PCE Control...................24 5.1. Network Modeling for GMPLS/PCE Control...................25
5.1.1. Describing the WSON nodes...........................25 5.1.1. Describing the WSON nodes...........................26
5.1.2. Describing the links................................27 5.1.2. Describing the links................................28
5.2. RWA Path Computation and Establishment...................28 5.2. RWA Path Computation and Establishment...................29
5.3. Resource Optimization....................................29 5.3. Resource Optimization....................................30
5.4. Support for Rerouting....................................30 5.4. Support for Rerouting....................................31
6. GMPLS & PCE Implications......................................30 6. GMPLS & PCE Implications......................................31
6.1. Implications for GMPLS signaling.........................30 6.1. Implications for GMPLS signaling.........................31
6.1.1. Identifying Wavelengths and Signals.................31 6.1.1. Identifying Wavelengths and Signals.................32
6.1.2. Combined RWA/Separate Routing WA support............31 6.1.2. Combined RWA/Separate Routing WA support............32
6.1.3. Distributed Wavelength Assignment: Unidirectional, No 6.1.3. Distributed Wavelength Assignment: Unidirectional, No
Converters.................................................31 Converters.................................................32
6.1.4. Distributed Wavelength Assignment: Unidirectional, 6.1.4. Distributed Wavelength Assignment: Unidirectional,
Limited Converters.........................................32 Limited Converters.........................................33
6.1.5. Distributed Wavelength Assignment: Bidirectional, No 6.1.5. Distributed Wavelength Assignment: Bidirectional, No
Converters.................................................32 Converters.................................................33
6.2. Implications for GMPLS Routing...........................33 6.2. Implications for GMPLS Routing...........................34
6.2.1. Wavelength-Specific Availability Information........33 6.2.1. Wavelength-Specific Availability Information........34
6.2.2. WSON Routing Information Summary....................34 6.2.2. WSON Routing Information Summary....................35
6.3. Optical Path Computation and Implications for PCE........35 6.3. Optical Path Computation and Implications for PCE........36
6.3.1. Lightpath Constraints and Characteristics...........35 6.3.1. Lightpath Constraints and Characteristics...........36
6.3.2. Discovery of RWA Capable PCEs.......................36 6.3.2. Discovery of RWA Capable PCEs.......................37
6.4. Summary of Impacts by RWA Architecture...................36 6.4. Summary of Impacts by RWA Architecture...................37
7. Security Considerations.......................................37 7. Security Considerations.......................................38
8. IANA Considerations...........................................38 8. IANA Considerations...........................................39
9. Acknowledgments...............................................38 9. Acknowledgments...............................................39
10. References...................................................39 10. References...................................................40
10.1. Normative References....................................39 10.1. Normative References....................................40
10.2. Informative References..................................40 10.2. Informative References..................................41
11. Contributors.................................................43 11. Contributors.................................................44
Author's Addresses...............................................43 Author's Addresses...............................................45
Intellectual Property Statement..................................44 Intellectual Property Statement..................................45
Disclaimer of Validity...........................................45 Disclaimer of Validity...........................................46
1. Introduction 1. Introduction
This memo provides a framework for applying GMPLS and the Path This memo provides a framework for applying GMPLS and the Path
Computation Element (PCE) architecture to the control of WSONs. In Computation Element (PCE) architecture to the control of WSONs. In
particular we provide control plane models for key wavelength particular we provide control plane models for key wavelength
switched optical network subsystems and processes. The subsystems switched optical network subsystems and processes. The subsystems
include wavelength division multiplexed links, tunable laser include wavelength division multiplexed links, tunable laser
transmitters, reconfigurable optical add/drop multiplexers (ROADM) transmitters, reconfigurable optical add/drop multiplexers (ROADM)
and wavelength converters. and wavelength converters.
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In section 6 removed discussion of "Relationship to link bundling and In section 6 removed discussion of "Relationship to link bundling and
layering". layering".
In section 6 removed discussion of "Computation Architecture In section 6 removed discussion of "Computation Architecture
Implications" as this material was redundant with text that occurs Implications" as this material was redundant with text that occurs
earlier in the document. earlier in the document.
In section 6 removed discussion of "Scaling Implications" as this In section 6 removed discussion of "Scaling Implications" as this
material was redundant with text that occurs earlier in the document. material was redundant with text that occurs earlier in the document.
1.1.4. Changes from 03
In Section 3.3.1 added 4-degree ROADM example and its connectivity
matrix.
1.2. Related Documents 1.2. Related Documents
This framework document covers essential concepts and models for the This framework document covers essential concepts and models for the
application and extension of the control plane to WSONs. The application and extension of the control plane to WSONs. The
following documents address specific aspects of WSONs and complement following documents address specific aspects of WSONs and complement
this draft. this draft.
o [WSON-Info] This document provides an information model needed by o [WSON-Info] This document provides an information model needed by
the routing and wavelength assignment (RWA) process in WSON. the routing and wavelength assignment (RWA) process in WSON.
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#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, compact encodings and complement of the matrix will be very sparse, compact encodings and
examples, including high degree ROADMs/OXCs, are given in [WSON- examples, including high degree ROADMs/OXCs, are given in [WSON-
Encode]. Encode]. A classic degree-4 ROADM is shown in Figure 2.
+-----------------------+
Line side-1 --->| |---> Line side-2
ingress (I1) | | egress (E2)
Line side-1 <---| |<--- Line side-2
Egress (E1) | | Ingress (I2)
| ROADM |
Line side-3 --->| |---> Line side-4
ingress (I3) | | egress (E4)
Line side-3 <---| |<--- Line side-4
Egress (E3) | | Ingress (I4)
| |
+-----------------------+
| O | O | O | O
| | | | | | | |
O | O | O | O |
Tributary Side: E5 I5 E6 I6 E7 I7 E8 I8
Figure 2 Degree-4 ROADM
Note that this example is 4-degree example with one (potentially
multi-channel) add/drop per line side port.
Note also that the connectivity constraints for typical ROADM designs
are "bi-directional", i.e. if ingress port X can be connected to
egress port Y, typically ingress port Y can be connected to egress
port X, assuming the numbering is done in such a way that ingress X
and egress X correspond to the same line side direction or the same
add/drop port. This makes the connectivity matrix symmetrical as
shown below.
Ingress Egress Port
Port E1 E2 E3 E4 E5 E6 E7 E8
-----------------------
I1 0 1 1 1 0 1 0 0
I2 1 0 1 1 0 0 1 0
A = I3 1 1 0 1 1 0 0 0
I4 1 1 1 0 0 0 0 1
I5 0 0 1 0 0 0 0 0
I6 1 0 0 0 0 0 0 0
I7 0 1 0 0 0 0 0 0
I8 0 0 0 1 0 0 0 0
where I5/E5 are add/drop ports to/from line side-3, I6/E6 are
add/drop ports to/from line side-1, I7/E7 are add/drop ports to/from
line side-2 and I8/E8 are add/drop ports to/from line side-4. Note
that diagonal elements are zero since I assume that loopback is not
supported. If ports support loopback, diagonal elements would be one.
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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3. Limitations on the types of signals that can be converted and the 3. Limitations on the types of signals that can be converted and the
conversions that can be performed. conversions that can be performed.
To model point 2 above we can use a similar technique as used to To model point 2 above we can use a similar technique as used to
model ROADMs and optical switches, i.e., matrices to indicate model ROADMs and optical switches, i.e., matrices to indicate
possible connectivity along with wavelength constraints for possible connectivity along with wavelength constraints for
links/ports. Since wavelength converters are considered a scarce links/ports. Since wavelength converters are considered a scarce
resource we will also want our model to include as a minimum the resource we will also want our model to include as a minimum the
usage state of individual wavelength converters in the pool. usage state of individual wavelength converters in the pool.
We utilize a three stage model as shown schematically in Figure 2. In We utilize a three stage model as shown schematically in Figure 3. In
this model we assume N ingress ports (fibers), P wavelength this model we assume N ingress ports (fibers), P wavelength
converters, and M egress ports (fibers). Since not all ingress ports converters, and M egress ports (fibers). Since not all ingress ports
can necessarily reach the converter pool, the model starts with a can necessarily reach the converter pool, the model starts with a
wavelength pool ingress matrix WI(i,p) = {0,1} whether ingress port i wavelength pool ingress matrix WI(i,p) = {0,1} whether ingress port i
can reach potentially reach wavelength converter p. can reach potentially reach wavelength converter p.
Since not all wavelength can necessarily reach all the converters or Since not all wavelength can necessarily reach all the converters or
the converters may have limited input wavelength range we have a set the converters may have limited input wavelength range we have a set
of ingress port constraints for each wavelength converter. Currently of ingress port constraints for each wavelength converter. Currently
we assume that a wavelength converter can only take a single we assume that a wavelength converter can only take a single
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+-------------+ ^ ^ +-------------+ +-------------+ ^ ^ +-------------+
| | | |
| | | |
| | | |
| | | |
Ingress wavelength Egress wavelength Ingress wavelength Egress wavelength
constraints for constraints for constraints for constraints for
each converter each converter each converter each converter
Figure 2 Schematic diagram of wavelength converter pool model. Figure 3 Schematic diagram of wavelength converter pool model.
Example: Shared Per Node Example: Shared Per Node
In Figure 3 below we show a simple optical switch in a four In Figure 4 below we show a simple optical switch in a four
wavelength DWDM system sharing wavelength converters in a general wavelength DWDM system sharing wavelength converters in a general
"per node" fashion. "per node" fashion.
___________ +------+ ___________ +------+
| |--------------------------->| | | |--------------------------->| |
| |--------------------------->| C | | |--------------------------->| C |
/| | |--------------------------->| o | E1 /| | |--------------------------->| o | E1
I1 /D+--->| |--------------------------->| m | I1 /D+--->| |--------------------------->| m |
+ e+--->| | | b |====> + e+--->| | | b |====>
====>| M| | Optical | +-----------+ +----+ | i | ====>| M| | Optical | +-----------+ +----+ | i |
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I2 /D+--->| +----+->|WC #2|--+->|l |-->| C | E2 I2 /D+--->| +----+->|WC #2|--+->|l |-->| C | E2
+ e+--->| | | +-----+ | | | | o | + e+--->| | | +-----+ | | | | o |
====>| M| | | +-----------+ +----+ | m |====> ====>| M| | | +-----------+ +----+ | m |====>
+ u+--->| | | b | + u+--->| | | b |
\x+--->| |--------------------------->| i | \x+--->| |--------------------------->| i |
\| | |--------------------------->| n | \| | |--------------------------->| n |
| |--------------------------->| e | | |--------------------------->| e |
|___________|--------------------------->| r | |___________|--------------------------->| r |
+------+ +------+
Figure 3 An optical switch featuring a shared per node wavelength Figure 4 An optical switch featuring a shared per node wavelength
converter pool architecture. converter pool architecture.
In this case the ingress and egress pool matrices are simply: In this case the ingress and egress pool matrices are simply:
+-----+ +-----+ +-----+ +-----+
| 1 1 | | 1 1 | | 1 1 | | 1 1 |
WI =| |, WE =| | WI =| |, WE =| |
| 1 1 | | 1 1 | | 1 1 | | 1 1 |
+-----+ +-----+ +-----+ +-----+
Example: Shared Per Link Example: Shared Per Link
In Figure 4 we show a different wavelength pool architecture know as In Figure 5 we show a different wavelength pool architecture know as
"shared per fiber". In this case the ingress and egress pool matrices "shared per fiber". In this case the ingress and egress pool matrices
are simply: are simply:
+-----+ +-----+ +-----+ +-----+
| 1 1 | | 1 0 | | 1 1 | | 1 0 |
WI =| |, WE =| | WI =| |, WE =| |
| 1 1 | | 0 1 | | 1 1 | | 0 1 |
+-----+ +-----+ +-----+ +-----+
___________ +------+ ___________ +------+
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/| | | | +-----+ | | | /| | | | +-----+ | | |
I2 /D+--->| +----+->|WC #2|--+---------->| C | E2 I2 /D+--->| +----+->|WC #2|--+---------->| C | E2
+ e+--->| | | +-----+ | | o | + e+--->| | | +-----+ | | o |
====>| M| | | +-----------+ | m |====> ====>| M| | | +-----------+ | m |====>
+ u+--->| | | b | + u+--->| | | b |
\x+--->| |--------------------------->| i | \x+--->| |--------------------------->| i |
\| | |--------------------------->| n | \| | |--------------------------->| n |
| |--------------------------->| e | | |--------------------------->| e |
|___________|--------------------------->| r | |___________|--------------------------->| r |
+------+ +------+
Figure 4 An optical switch featuring a shared per fiber wavelength Figure 5 An optical switch featuring a shared per fiber wavelength
converter pool architecture. 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
skipping to change at page 43, line 47 skipping to change at page 44, line 47
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 Dirk Schroetter
Cisco Cisco
Email: dschroet@cisco.com Email: dschroet@cisco.com
Jonas Martensson
Acreo
Electrum 236
16440 Kista, Sweden
Email:Jonas.Martensson@acreo.se
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)
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