network reconfigurability flexibility

8/6/2019 Network Reconfigurability Flexibility

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WDM reduced bandwidthost, but replaced “digital”ransport with an “analog”ptical network.

Today’s “analog” WDMetworks are at odds witharriers’ service needs.

The various needs of arriers should not be

raded off against eachther.

From Digital to Analog

The past few years have seen the introduction and wide-spread implementation of

Wavelength Division Multiplexing (WDM) systems, first in long-haul networks, followedby use in metro and regional networks. In all cases, a key driver for these deploymentsarose from the need to scale network capacity beyond that which was possible withSONET/SDH Add/Drop Multiplexers (ADMs) operating at either 2.5Gb/s or 10Gb/s.

In addition, metro WDM systems also provided the only means for service providers tooffer end-user connectivity for native Gigabit Ethernet (GbE), Fibre Channel, FICON and2.5Gb/s and 10Gb/s transparent services, provisioned directly over wavelengths. Thishas allowed metro service providers to provide value-added high-bandwidth services forenterprise remote storage connectivity, inter-campus LANs, ISP data centers, and inter-connections between backbone and metro Points of Presence (PoPs) and carrier hotels.

However as operators migrated their broadband service platforms from SONET/SDH

digital transport systems to WDM systems, optical transport networks becameincreasingly analog, relying on the amplification, manipulation and management of wavelengths, rather than of digital “bits” as used to be the case. In becomingincreasingly analog, WDM networks lost the “plug and play” engineering simplicity of SONET/SDH systems, and required operators to consider many new technology issuessuch as optical reach, dispersion, optical Performance Monitoring (PM), wavelengthbanding, power levels, wavelength planning, and the number of end-to-end nodal“hops” between service end points.

In other words, the end-to-end service provisioning, centralized management, digitalPMs and ease of sub-wavelength grooming of SONET/SDH systems was lost, havingbeen exchanged for wavelength scalability and transparency.

These inherent trade-offs are often at odds with service providers’ business models andnetwork requirements. Ideally, network operators seek a common, robust, cost-effectiveservice platform that enables them to solve today’s challenges, including ever greaternetwork complexity and increased competitive challenges, while meeting customers’new service requirements. Such a service platform must therefore address the followingissues:

Capacity: A next-generation broadband service platform must inherently scalebeyond the 10Gb/s capacity limitation of OC-192/STM-64 SONET/SDHsystems, and offer WDM capacity to 40 wavelengths, and beyond. In addition,it must support service interfaces beyond 10Gb/s, such as emerging 40Gb/s andfuture 100Gb/s Gigabit Ethernet services.

Reconfiguration: Forecast tolerant networks must be easily reconfigurable tosupport unplanned or changing service demands, and eliminate fixedbandwidth allocation between customer sites. Ideally, service providers will beable to provision any service, from any node, to any customer, without complexand costly re-engineering of the network.

Services: Operators require a common service platform that supports both



Carriers need Reconfigurability and

capacity Service flexibility and

bandwidth efficiency Operational savings

and highly reliablenetworks

Any new service platformmust inherently reduce allspects of operationalosts.

New “all-optical”echnologies such as

ROADMs perpetuatenalog engineering issuesnherent in today’s WDMetworks.

existing TDM services, from OC-3/STM-1 to OC-192/STM-64, and a wide rangeof data and storage service interfaces including Gigabit Ethernet, 10GE, FibreChannel, ESCON/FICON; with the ability to easily support additional newservice interfaces as required. Also important is future architecture support forintelligent optical services based on standardized inter-network signaling andcontrol.

Flexibility: Each network node must support sub-wavelength aggregation andmultiplexing from OC-3/STM-1 to 10Gb/s across all directions, and also enablebandwidth grooming both within, and across wavelengths, in response tochanging service patterns and network usage.

Efficiency: A metro transport platform must be able to maximize capacityefficiency and offer the lowest “cost per managed bit”, by operating at 10Gb/sper wavelength, while also minimizing the need for sub-tending equipmentwhen aggregating multiple lower order sub-10Gb/s services.

Reliability: Operators to must not only track end-user Service LevelAgreements (SLAs), but must also ensure that networks provide 99.999%availability for business-critical applications. This requires an infrastructure thatfacilitates accurate and robust performance monitoring (PM), provides pre-emptive alarming, facilitates rapid fault identification and isolation, and providesthe option for rapid sub-50 millisecond protection for any service.

Management: Any “carrier-grade” broadband service platform must providecentralized real-time network management. A robust standards-compliantcontrol plane is necessary to enable automated end-to-end service provisioningto rapidly respond to changes in network status and customer demands. Finally,operators must provide their end-customers the option of customer networkmanagement (CNM) for service turn-up, management, and monitoring of

network performance and alarms.

Operational Simplicity: In addition to all the requirements above, a next-generation network must significantly simplify all aspects of an operator’snetwork architecture and operations, including network planning, engineering,installation, turn-up, capacity growth, spares, power, space, training anddocumentation.

Recent advances in WDM technology have tried to alleviate some of the constraintsinherent in early systems which limited many of the above requirements from beingadequately addressed. The most prominent of these has been the development of Reconfigurable Optical ADMs (ROADMs) for use in both metro and long-haul WDMsystems to allow “any wavelength” and “per wavelength” access at any node, therebyaccelerating service delivery and simplifying wavelength planning.

However when using ROADMs operators are still required to engineer the end-to-end“analog” wavelength path between the service ingress and egress points on thenetwork, and must contend with all the wavelength planning issues inherent in “all-optical” systems. In addition, ROADMs do not address the need for sub-wavelengthservice management, grooming, and add/drop. Finally, current WDM systems do not



arge-scale Photonicntegration enables ultra-ow cost OEOs, and Digital

Optical Networks.

A Digital Optical Networkombines the benefits of

igital transport with thecale of WDM.

offer the robust digital PMs, network diagnostics, and end-to-end service managementcapabilities inherent in SONET/SDH networks, and in many cases are not inherently“service-ready” for future 40Gb/s and 100GE services.

In all cases, the governing industry assumption underlying all WDM technologydevelopment has been that add/drop must be done “all optically”, as the use of digitalrepeaters to implement Optical-Electrical-Optical (OEO) signal conversion andmanipulation in the electronic domain, as in SONET/SDH transport, would beprohibitively expensive. This paradigm has in fact been correct; until now!

Introducing Digital Optical Networks

A Digital Optical Network re-defines metro, regional and long-haul optical networks bycombining the capacity of WDM with the traffic management, provisioning flexibility,engineering simplicity and reliability of digital transport systems. The implementation of a Digital Optical Network is uniquely enabled through the development of large-scalePhotonic Integrated Circuits (PICs) which monolithically integrate upwards of sixty or

more discrete optical components onto an optical circuit (see figure 1).

This allows the construction of a “WDM system on a chip” with a PIC capacity of 100Gb/s today, and more in the future. This unprecedented level of optical componentintegration and packaging consolidation brings to the industry what has long eluded it,ultra-low cost OEO’s, and for the first time brings the economics of “Moore’s Law” tooptical networking.

Figure 1: Large-scale Photonic Integrated Circuits enable monolithic integration of over 60 discrete opticalcomponents.

These developments now make it feasible for service providers to cost-effectivelyimplement “digital” transport within the WDM layer of the network, and avoid theanalog optical engineering compromises imposed by current metro and long-haul WDMtechnologies. In addition, the use of cost-effective OEO at each node leverages thecapabilities of silicon electronics and system software to provide value-added servicefunctions such as sub-wavelength multiplexing, grooming and add/drop to maximizeservice delivery flexibility and enable rapid network reconfiguration. In addition, digital



Key network functions areost-effectively enabled byoftware and electronics –ot complex opticalomponents.

A Digital Node providesost-effective “digital”ccess for:

digital PMssub - λ groomingsimple add/dropflexible networkreconfiguration

transport re-equips operators with the comprehensive digital OA&M and performancemonitoring capabilities required to provide accurate network diagnostics andend-to-end service management of all end-user services.

The fundamental building block of a Digital Optical Network is the Digital Node (seefigure 2). A Digital Node provides high capacity WDM optical transport and full sub-wavelength add/drop and bandwidth management of optical payloads, using aswitching architecture similar to that of a SONET/SDH ADM, but within the WDM layer.

This enables bandwidth management of transparent broadband services across the fullWDM capacity of the network, providing truly “hitless” sub-wavelength provisioning andgrooming of customer circuits at every node. Service add/drop is done simply byadding client-side interfaces and cross-connecting via the electronic switch to/from theWDM line operating at 10Gb/s per wavelength.

In the process of providing frequent cost-effective digital access, a Digital OpticalNetwork reduces the “analog” optical portions of the network to allow “plug and play”

deployment and operation, and significantly simplifies network planning, engineering,installation and operation.

Figure 2: A Digital Node provides cost-effective OEO conversion, allowing electronic access andmanipulation of network traffic.

Digital Optical Network Benefits

Forecast-Tolerant Capacity

The WDM line-side capacity of a Digital Node is provisioned in increments of 100Gb/s,using large-scale photonic integrated circuits that combine ten wavelengths operating at10Gb/s each into a single system circuit pack. Thus a Digital Node supporting 400Gb/s



A Digital Node maximizesdd/drop flexibility and re-onfigurability required byhanging and unplannedervice demands.

New and existing servicesre supported through a

wide range of interface

ptions.

of WDM capacity can be built using only four WDM circuit packs, yielding importantsavings in space and power, simplifying nodal fiber management, and reducinginstallation complexity and cost. In addition, the cost savings of PICs allows highly cost-effective deployment of network capacity in increments of 100Gb/s, thereby increasingservice velocity when adding new customers, and reducing the cost and complexityassociated with channel growth in typical WDM systems where capacity is deployed10Gb/s at a time.

Unconstrained Network Reconfiguration

The advent of the Digital Node finally brings to high-capacity optical transport networksthe capability to provide true unconstrained in-service reconfiguration of any WDMnode. This allows service providers to respond quickly, cost-effectively, and withoutservice interruption to changes in customers’ service demands and bandwidth forecasts.A Digital Node can be seamlessly provisioned to provide add/drop anywhere from zeroto 100% of the WDM line capacity, allowing new customers to be connected to existing

network sites without the need to pre-allocate wavelengths or re-engineer nodes due towavelength banding constraints, as is common in current WDM systems. Any sub-wavelength SONET/SDH or data service can be dropped at any node simply byequipping the required service interface, without the need to separately order a widevariety of sub-tending aggregation or multiplexing platforms. Finally, because all WDMcapacity is digitally accessible at all nodes, capacity planning and wavelengthengineering are simplified using the capability for sub-wavelength grooming available ateach Digital Node.

Supporting New and Existing Services

A Digital Node inherently separates the WDM line optics from the client-side tributaryoptics, allowing a wide variety of end-user service interfaces to be implemented without

any impact on system design, network engineering, service continuity, or bandwidthefficiency. A Digital Node can support interfaces for legacy SONET/SDH TDM servicesfrom OC-3/STM-1 to OC-192/STM-64, emerging data services such as Gigabit Ethernetand 10 Gigabit Ethernet (10GE) LAN PHY and WAN PHY, and Fibre Channel and FICONStorage Area Network (SAN) services. In addition, since the line capacity of a DigitalNode is provisioned in increments of 100Gb/s of virtual capacity, a Digital OpticalNetwork provides a future-proof platform to support future ultra-broadband servicessuch as 40Gb/s SONET/SDH, or 100Gb/s Gigabit Ethernet, without changes to networkengineering rules or network architecture.

Bandwidth Management Flexibility

Digital bandwidth management capabilities inherent to a Digital Optical Network enablesub-wavelength bandwidth grooming using electronic switching at each Digital Node.The ability to connect any client service to any portion of the WDM bandwidth therebyavoids either stranding wavelengths, as can happen in banded WDM add/droparchitectures. End-to-end cross-connection of client services to the WDM capacity canbe remotely and automatically provisioned without requiring manual rebalancing of optical amplifier gain and wavelength power levels when adding or droppingwavelengths, as is typical of all existing analog WDM systems. An Infinera Digital



Digital” add/dropliminates the complexetwork planning andngineering inherent in

ROADMs.

Network control andeliability is significantlynhanced through robustdigital” PMs at everyode.

Optical Network therefore reduces add/drop provisioning time and engineeringcomplexity compared to systems which require a “truck roll” and often a complexprovisioning operation to equip new transponders or optical add/drop filters across thenetwork. The integration of optical transport and bandwidth management within aDigital Node significantly enhances and simplifies the ability of the optical layer toprovide value-added management of broadband services for carriers and largeenterprise customers, and results in considerable equipment savings over solutions thattie add/drop of services to a specific, dedicated wavelength.

Maximizing Network Efficiency

The inherent ability of a Digital Node to provide sub-wavelength access to the entireWDM capacity of the network thereby allows operators to extract the required customerservice from any wavelength, for example an OC-3, GbE, Fibre Channel, or STM-16,while maximizing bandwidth efficiency by operating at 10Gb/s per wavelength. Thisreduces the need for external aggregation or multiplexing systems at the edges of thenetwork, or for optical cross connects (OXC) within the core for wavelength grooming of

pass-through circuits. In contrast, today’s metro and long-haul WDM systems, includingnew “all-optical” ROADM-based systems, often dedicate each service to a wavelength,leading to considerable bandwidth inefficiency when required to transport moderatebandwidth services such as GbE, Fibre Channel, or OC-48/STM-16. This forces networkoperators to make one of two compromises for sub-10Gb/s services. Either theydedicate a wavelength to each service, such as a GbE or OC-48, in which case theyreduce the “bandwidth efficiency” of their DWDM system by 75% or more compared tooperating at 10Gb/s per wavelength. Or they can deploy an OEO interface, such as“SONET-on-a-blade” or “thin mux”, to improve bandwidth efficiency per wavelength.However this limits grooming and aggregation to within a single 10Gb/s wavelength,and imposes an expensive and inefficient wavelength point-to-point architecture, sincethe same OEO interface must be deployed at every node where any sub-wavelengthadd/drop is required.

Enhancing Network Reliability

The implications of re-introducing the benefits of “SONET/SDH-like” digital transportwithin metro and long-haul WDM networks are profound for carriers. With thedeployment of a Digital Optical Network they regain the protection and monitoringcapabilities that have made SONET/SDH networks highly reliable and manageable. Inother words, Digital Optical Networks not only address the desire for servicereconfiguration targeted by ROADM systems, but also provide much greatermanageability, network diagnostics, and robust protection capabilities. Ultra-low costdigital regeneration at each Digital Node enables frequent signal clean-up andperformance monitoring (PM) through electronic access to digital wrapper orSONET/SDH overhead. This provides valuable information on network performance toallow faster and more accurate fault identification and trouble-shooting to ensure serviceproviders provide the Service Level Agreements (SLAs) demanded by their customers.In addition, a Digital Node can provide a wide range of optical layer protection optionsfor individual sub-wavelengths services, including Dedicated 1+1 Optical PathProtection Ring (O-UPSR), Y-Cable Protection with O-UPSR, Shared protection rings, and1:N linear section restoration.



A GMPLS control planenables end-to-end service

management andprovisioning.

A Digital Optical Networkimplifies all aspects of arrier operations.

End-to-End Service Management

The bandwidth management capabilities of a Digital Node enables a subtle, butimportant step forward in end-to-end network management; by incorporating adistributed control plane for the optical transport layer, a Digital Optical Networkprovides unparalleled end-to-end service management and automated serviceprovisioning capabilities to increase service velocity and customer satisfaction. Infinera’sDigital Optical Network incorporates a GMPLS control plane to support automatedtopology discovery, dynamic “point and click” automated service provisioning, allowingend-to-end remote activation of 1G, 2.5G and 10G circuits within the WDM networklayer. A distributed GMPLS control plane also provides the foundation for introducingmesh-based service restoration capabilities, as well as secure, reliable, end-to-end,multi-domain “bandwidth on demand” UNI and optical VPN services, based onstandards defined by the Optical Internetworking Forum (OIF) and the ITU-T standardsfor Automatically Switched Optical Networks (ASON), G.8080, and AutomaticallySwitched Transport Networks (ASTN), allowing service providers to evolve their optical

networks into true broadband service delivery platforms.

Operational Simplicity of Digital

The implications of re-introducing the benefits of “SONET/SDH-like” digital transportwithin metro and long-haul WDM networks are profound for carriers. With thedeployment of a Digital Optical Network they regain the ability to deliver a broad rangeof new and existing broadband services at every node, without being constrained by thenumber of “hops” a service takes across the network; what percentage of add/drop ispossible per site; complex wavelength planning and engineering; and without needinghighly accurate service forecasts. They also regain the network performance, protectionand control that have made SONET/SDH networks highly reliable and manageable. Inother words, Digital Optical Networks not only address the desire for service

reconfiguration targeted by ROADM systems, but with much greater flexibility,manageability and simplicity. Through the use of large-scale photonic integratedcircuits that enable “WDM on a chip”, carriers are able to cost-effectively deploy opticalnetworks in increments of 100Gb/s, thereby significantly reducing the many costsassociated with initial system deployment, incremental channel growth, space andpower consumption, sparing and training. Taken together, these benefits will allowforward-looking metro, national and international service providers deploying DigitalOptical Networks to rapidly meet new and changing customer demands for broadbandservices, while in the process lowering their capital budgets and simplifying theirnetwork operations.

Implementing a Digital Optical NetworkA Digital Optical Network defines a new network architecture concept that integratesthe robustness, flexibility and end-to-end service management of digital transport withthe capacity of WDM and economics of large-scale photonic integration. Theimplementation of a Digital Optical Network provides carriers with significantoperational, architecture, and economic benefits.



Digital Optical Networksprovide a common, cost-

ffective core serviceplatform for metro, regionalnd long haul applications.

The feature richness, flexibility and cost-effectiveness of a Digital Node enables the useof a profit-enabling, common system platform across a wide range of metro, regionaland long-haul network applications to reach more customers, more cost-effectively, withbetter performance, while unifying network architecture and simplifying operations.

In metro and regional networks, Digital Nodes can be deployed to increase networkcapacity, enable rapid remote nodal reconfiguration, and allow on-demand, in-serviceadd/drop of any service through a wide range of interfaces. In long-haul and ultra long-haul (ULH) networks, a Digital Optical Network can be implemented incrementally on aroute-by-route basis where required to increase capacity, expand connectivity, simplifyengineering and operations, or to cost-effectively increase a service provider’saddressable market by increasing the number of “on-net” sites.

Digital Optical Networks can be extended in a “building block” fashion as required bynetwork growth or service requirements, to create a distance-insensitive service deliveryplatform, irrespective of capacity, service type, geographical scale or network topologythat meets today’s, and tomorrow’s, market requirements.

www.infinera.com

Specifications subject to change without notice.

Document Number: DS-005.003/0106© Copyright 2004-2006 Infinera Corporation. All rights reserved.Infinera DTN™, IQ™, and Digital Optical Networking™ are trademarks of InfineraCorporation.



Infinera Corporation1322 Bordeaux DriveSunnyvale, CA 94089 USATelephone: +1 408 572 5200Fax: +1 408 572 5454www.infinera.com

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network reconfigurability flexibility

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