Solution Brief

Nortel Common Photonic Layer

Nortel Common Photonic Layer (CPL)represents a significant development inthe ongoing evolution to an adaptive,all-optical intelligent network. CPL lever-ages years of proven expertise in devel-oping and deploying optical networksolutions and separates the optical lineside from the service side. This service/photonic separation enables Nortel todeliver a highly flexible, optimized andintelligent common photonic layer tometro, regional and long haul networks.This common approach eliminates theboundaries between each, therebycreating one converged, easy-to-operate,all-optical network.

Nortel CPL offers enterprise customers,service providers and cable operators a

cost-optimized solution for transport oftelephony, data, video and cable servicesin metro, regional and long haulnetworks alike.

CPL was designed to take the complexityout of DWDM photonic networking bydeveloping the necessary intelligence,automated functions and control intothe optical transport layer hardware andsoftware. By simplifying service delivery,from the planning phase through to thein-service turn-up phase, the CPL isgeared to reducing time to service signifi-cantly through new operational tools andarchitecture flexibility. The platform effi-ciently delivers value-rich services end-to-end, while reducing the total cost ofownership.

The CPL conceptAs shown in Figure 1, CPL is separatefrom the service layer in order to providea set of building blocks that can beconfigured to provide cost-optimizedmetro, regional, long haul and ultralong haul DWDM transport applica-tions. The service-enabling networkelements complement the photonic layerto deliver the reach and capacity require-ments of these various applications. Assuch, the key goal of CPL is to dramati-cally simplify the transport layer toensure that the multiservice switches,DWDM terminals, optical core switchesand other service elements that connectinto it can have their services carriedend-to-end — seamlessly and efficiently.

Key platform benefits

Scalability

CPL offers an initial system with asignificantly small footprint that scalesmodularly and provides a pay-as-you-golike structure that can grow as revenue-generating opportunities or capacityexhaust drive expansion of the network.Initial deployments can start with a fewwavelengths on one span and then growor even branch into a larger networkwithout requiring an expensive OEO(optical-electrical-optical) boundary.

The innovative architecture does notrequire a traditional backplane but isbuilt on an efficient modular designwhere low-power individual compo-nents are interconnected using anEthernet virtual backplane for datacommunications and where optical fiberis used to connect the signal paththrough the modules. Each site isdeployed with the footprint thatmatches its required capacity withoutlimiting the future scalability.

CPL uses the same set of buildingblocks that can be deployed in applica-tions requiring anywhere between 10sof km up to 2,000-km reach betweenterminal points, without Raman ampli-fication. It is the DWDM platform ofchoice for metro, regional and long haulapplications, providing common spares,documentation, training and user inter-face across the network. CPL allows aseamless evolution to 40-Gbps basednetworking over existing 10 Gbps lineson any fiber type (new/old, clean/dirty)without network re-engineering or thedeployment of dispersion compensatingmodules or Polarization Mode Dispersion(PMD) compensators.

Operational simplicity

CPL has been designed from the startwith the goal of introducing new levelsof operational simplicity into themarket. The platform provides highlyautomated functions for the followingnetwork deployment activities:

• Pre-deployment network planning:The Optical Modeler tool helps deter-mine the appropriate placement ofcomponents in the network in orderto guarantee integrity of the signaltransmission through the end of life ofthe product. The resulting design iscaptured in pre-configuration down-load files that can be exported to theEMS (Element Management System)to accelerate the provisioning of thesystem upon deployment.

• Initial system turn-up and incre-mental wavelength additions: Uponsystem turn-up or in-service additionof new wavelengths, the embeddedDomain Optical Control or DOCsoftware performs a series of auto-mated processes for equipment provi-sioning. Combined with in-skinelectronic Variable Optical Attenuators

(VOAs), rapid initialization andadjustment of system components isachieved for a complete deploy-and-forget process.

• Fault-tolerant distributed controlarchitecture: CPL offers a dynamicand continuous system optimizationto ensure optimal performance of thewavelengths transported end-to-end.This autonomous process alerts theoperations center of any degradationwarning signs that cannot be correctedautomatically. Since the DOC soft-ware is fully distributed throughoutthe system, any failure or disruptionof any part of the communicationsnetwork will not affect the rest of thesystem.

Network flexibility

CPL provides an eROADM (EnhancedReconfigurable Optical Add/DropMultiplexer) architecture that deliversany wavelength, anywhere, anytime,without impact to the existing traffic.The eROADM is a CPL functionalmodule that enables dynamic “on thefly” optical branching to up to fivedifferent optical paths in addition tofacilitating basic add/drop of individualwavelengths. Unlike first-generationROADMs with colored ports, eROADMsare “colorless”, which means any wave-length (color) can be added/droppedon any port. With the eROADM:

• Service providers and cable operatorscan redirect wavelengths to any span,using CPL’s unconstrained opticalswitch architecture

• Optical branching at strategic fiberjunctions is fully enabled with theeROADM agility by enabling thererouting of light paths withoutrequiring conversion back toelectrical signals

2

Long haul 2,000 km

Regional600 km

Metro200 km

2.5G 10G 40G λ’s

Any service from16 Mbps to 10 Gbps

Service-enablingNetwork Elements• Multiservice switches• SONET/SDH ADMs• Optical switches• DWDM terminals

CommonPhotonicLayer

OADM/ROADMsite

Figure 1. The Common Photonic Layer concept

• Wavelengths are managed opticallythrough the eROADMs, thus limitingthe need for fiber interconnections,while helping to reduce the chanceof causing outages due to incorrectmanipulation of equipment

The flexibility offered with CPL’seROADM solution provides efficientmanagement of transiting wavelengthsat add/drop and branching locationswhere previously more costly OEObandwidth management was required.Wavelengths can be managed at thesingle channel level, eliminatingstranded bandwidth, thereby increasingnetwork utilization and efficiency. TheDOC software provides continualnetwork optimization during reconfigu-rations and network expansions for afully automated process.

Direction Independent Access (DIA)

Unlike other ROADM configurationsthat are directionally dependant where aTX/RX pair connected to a filter can

only be sent out of the site in the direc-tion of the line ports of the WSS it isconnected to, CPL allows DirectionIndependent Access (DIA) where eachdirection can be remotely reconfigured.The DIA allows the user to determinethe optical direction of a channel out ofa site via software and not a physicalconnection.

The DIA uses standard WSS, amplifierand Optical Power Monitor (OPM)components to create the directionallyindependent access point. This simpli-fies the planning of ROADMsites/networks by allowing wavelengthsto be remotely redirected to anotherdirection as the bandwidth requirementschange. DIA supports directionalcontrol of 44 (100GHz on eCMD44)or 88 (50GHz on CMD44) wave-lengths where each optical direction hascapacity up to 88 wavelengths via acombination of passthrough, DIAadd/drop and local add/drop.

Architectural advantagesThe main individual components thatmake up the architecture of CPL aredetailed as follows:

Channel mux/demux (CMD)The CMD is a 4-port or 8-portmux/demux filter that feeds into one ofthe nine ports on the GMD. Both typesof CMDs can coexist on the same lineto offer anywhere between 36 and 72wavelengths on the DWDM system.CPL also supports a CMD44 modulethat allows service providers, cable oper-ators and enterprises to access anyspecific wavelength, among 44 in the Cband with enhanced network flexibility.Any DWDM source that is ITU grid-compliant can be transported, providingan open photonic interworking solu-tion. With the CMD architecture, wave-lengths with different reach requirementscan be carried concurrently on theDWDM system. For example, regionalreach wavelengths and long haul reachwavelengths can be deployed to enablean application such as the one describedin Figure 1.

3

Channelaccess site

Amplifiersites

Amplifiersites

eROADM/WSS

Common Photonic Layer

λ 1

λ n

Optical Metro 5200

Optical Metro 3500

Optical MultiserviceEdge 6500

Ethernet RoutingSwitch 8600

Routers

Vendor “X”

Optical CrossConnect

DX/HDX/HDXc

GMD

CMD

Service Layer

Figure 2. Common Photonic Layer architecture

Group mux/demux (GMD)The GMD provides a second stagemux/demux capability and supportsnine CMD filters capable of offering atotal of up to 72 ITU-compliant wave-lengths in the C band. This architectureallows capacity to be added incremen-tally for a smooth evolution path. TheGMD, in its capacity as the VirtualShelf Processor (VSP), provides a commu-nications infrastructure in order for theCPL node to interface with other nodes,elements within the node, and theoutside world.

Wavelength Selective Switch (WSS)The WSS is the key enabler foreROADM solutions for the terminationor rerouting of any wavelength to anyport across the network. Single ormultiple wavelengths that are droppedat one site can be re-inserted with newtraffic and rerouted to a different loca-tion, eliminating bandwidth stranding.The WSS can connect up to fivedifferent nodes at an eROADM sitewhile supporting local add/drop traffic.

AmplifierThe Amplifier is a low-noise, high-output power module with fast transientcontrol and self-provisioned variablegain control that delivers enhancedreach capabilities to ensure each wave-length is amplified equitably. Variousamplifier modules are offered with

CPL to provide cost-optimized metro,regional and long haul/ultra long haulapplications.

Domain Optical Control (DOC)The DOC software resides on eachof the modules described above andperforms continuous background check,eVOA and optical output power opti-mization, fault isolation functions toensure that the network runs at optimalstate with the least human interventionand time consumption. With thisfeature, the requirement for expensivetest equipment and time to performsystem optimization is significantlylowered.

Network managementfor CPLCPL is fully integrated into the OpticalNetwork Manager (formerly known asPreside). Comprehensive screen layoutsprovide the Network Elements’ health ata glance, pull-down menus for simpleaccess to nodal management functions,and all relevant nodal managementinformation. Faults are centralized onthe Optical Network Manager andinventory, provisioning and perform-ance management can all be controlledvia a common Graphical User Interface.Through the Optical Network Manager,the user can drill down onto the CraftInterface of the Network Element for

full management options.

The Optical Network Manager providesa proven interface to manage CPL andall the subtending service layer opticalequipment to offer a centralized, inte-grated solution at the NetworkOperation Center.

SummaryCPL dramatically simplifies DWDMline systems to enable significantCapex/Opex savings and exploit thissimplicity to drastically reduce the timeto deploy value-rich services.

In support of these objectives, the plat-form provides the smallest initial/finalfootprint solution with significantlylower power consumption, deliveringseamless scalability and in-servicecapacity expansion from 2 to 88 wave-lengths and beyond. Its building blocksare optimized to offer cost-efficientmetro, regional and long haul reachconfigurations. The automated toolsand intelligent software perform networkoptimization and accelerate the end-to-end provisioning/addition of wave-lengths. The flexible architecture allowsthese wavelengths to be deliveredanywhere, anytime. CPL integrates witha proven network management platformand easy-to-use optical planning tools.CPL is truly the platform of choice forall DWDM network applications.

4

The key goal of the Common Photonic Layer is to dramatically

simplify the transport layer to ensure that the multiservice

switches, DWDM terminals, optical core switches and other

service elements that connect into it can have their services

carried end-to-end — seamlessly and efficiently.

5

CPL system features

Wavelengths supported 44 (100GHz), 88 (50GHz) or any combination to deliver between

(2.5G, 10G, 40G-ready) 44 and 88 wavelengths

Supported service layer Optical Metro 3500/5200, Optical Multiservice Edge 6500,

Network Elements Optical Cross Connect DX/HDX/HDXc, other products including multi-vendor

support (any ITU-compliant optical signal)

Reach From 10s of km to 2000 km — and beyond — depending on service platform

connected to CPL

Optical control Auto wavelength discovery, continuous dynamic system optimization,

fault isolation

Supported configurations Point-to-point, Ring, Mesh (i.e., service layer protection schemes)

OAM&P management features

Communication ports 10BaseT, RS232/modem craft access, 10/100BaseT internal (private),

external (COLAN), Ethernet wayside ports at every site

Element/Network SNMP, TL1, craft interface, Optical Network Manager,

Management Ethernet wayside channel (10/100BaseT clear channel)

Typical power consumption and footprint per site (CPL equipment)

Fulfilled channel access site (36 wavelengths) = 155 W (0.5 rack)

Fulfilled channel access site (72 wavelengths) = 255 W (0.5 rack)

Fulfilled line amplification site (72 wavelengths) = 115 W (0.25 rack)

eROADM site (36 wavelengths — 100% add/drop access) = 350 W (1 rack)

Other features:

Fiber management, OSMINE and NEBS3/ETSI compliant

The Common Photonic Layer offers an initial

system with a significantly small footprint that

scales modularly and provides a pay-as-you-go

like structure that can grow as revenue-gener-

ating opportunities or capacity exhaust drive

expansion of the network.

Nortel is a recognized leader in delivering communications capabilities that make thepromise of Business Made Simple a reality for our customers. Our next-generationtechnologies, for both service provider and enterprise networks, support multimediaand business-critical applications. Nortel’s technologies are designed to help eliminatetoday’s barriers to efficiency, speed and performance by simplifying networks andconnecting people to the information they need, when they need it. Nortel does busi-ness in more than 150 countries around the world. For more information, visit Nortelon the Web at www.nortel.com. For the latest Nortel news, visitwww.nortel.com/news.

For more information, contact your Nortel representative, or call 1-800-4 NORTELor 1-800-466-7835 from anywhere in North America.

Nortel, the Nortel logo, Nortel Business Made Simple and the Globemark are trade-marks of Nortel Networks. All other trademarks are the property of their owners.

Copyright © 2010 Nortel Networks. All rights reserved. Information in this docu-ment is subject to change without notice. Nortel assumes no responsibility for anyerrors that may appear in this document.

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