Solution Brief Common Photonic Layer Common Photonic Layer (CPL) represents a significant development in the ongoing evolution to an adaptive, all-optical intelligent network. CPL leverages years of proven expertise in developing and deploying optical network solutions and separates the optical line side from the service side. This service/ photonic separation enables to deliver a highly flexible, optimized and intelligent common photonic layer to metro, regional and long haul networks. This common approach eliminates the boundaries between each, thereby creating one converged, easy-to-operate, all-optical network. CPL offers enterprise customers, service providers and cable operators a cost-optimized solution for transport of telephony, data, video and cable services in metro, regional and long haul networks alike. CPL was designed to take the complexity out of DWDM photonic networking by developing the necessary intelligence, automated functions and control into the optical transport layer hardware and software. By simplifying service delivery, from the planning phase through to the in-service turn-up phase, the CPL is geared to reducing time to service significantly through new operational tools and architecture flexibility. The platform efficiently delivers value-rich services end-toend, while reducing the total cost of ownership. The CPL concept As shown in Figure 1, CPL is separate from the service layer in order to provide a set of building blocks that can be configured to provide cost-optimized metro, regional, long haul and ultra long haul DWDM transport applications. The service-enabling network elements complement the photonic layer to deliver the reach and capacity requirements of these various applications. As such, the key goal of CPL 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.
Key platform benefits Scalability CPL 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 revenuegenerating opportunities or capacity exhaust drive expansion of the network. Initial deployments can start with a few wavelengths on one span and then grow or even branch into a larger network without requiring an expensive OEO (optical-electrical-optical) boundary. The innovative architecture does not require a traditional backplane but is built on an efficient modular design where low-power individual components are interconnected using an Ethernet virtual backplane for data communications and where optical fiber is used to connect the signal path through the modules. Each site is deployed with the footprint that matches its required capacity without limiting the future scalability. Figure 1. The Common Photonic Layer concept OADM/ROADM site Metro 200 km Regional 600 km Long haul 2,000 km CPL uses the same set of building blocks that can be deployed in applications requiring anywhere between 10s of km up to 2,000-km reach between terminal points, without Raman amplification. It is the DWDM platform of choice for metro, regional and long haul applications, providing common spares, documentation, training and user interface across the network. CPL allows a seamless evolution to 40-Gbps based networking over existing 10 Gbps lines on any fiber type (new/old, clean/dirty) without network re-engineering or the deployment of dispersion compensating modules or Polarization Mode Dispersion (PMD) compensators. Operational simplicity CPL has been designed from the start with the goal of introducing new levels of operational simplicity into the market. The platform provides highly automated functions for the following network deployment activities: Common Photonic Layer Pre-deployment network planning: The Optical Modeler tool helps determine the appropriate placement of components in the network in order to guarantee integrity of the signal transmission through the end of life of the product. The resulting design is captured in pre-configuration download files that can be exported to the EMS (Element Management System) to accelerate the provisioning of the system upon deployment. Initial system turn-up and incremental wavelength additions: Upon system turn-up or in-service addition of new wavelengths, the embedded Domain Optical Control or DOC software performs a series of automated processes for equipment provisioning. Combined with in-skin electronic Variable Optical Attenuators (VOAs), rapid initialization and adjustment of system components is achieved for a complete deploy-andforget process. Fault-tolerant distributed control architecture: CPL offers a dynamic and continuous system optimization to ensure optimal performance of the wavelengths transported end-to-end. This autonomous process alerts the operations center of any degradation warning signs that cannot be corrected automatically. Since the DOC software is fully distributed throughout the system, any failure or disruption of any part of the communications network will not affect the rest of the system. 2.5G 10G 40G λ s Any service from 16 Mbps to 10 Gbps Service-enabling Network Elements Multiservice switches SONET/SDH ADMs Optical switches DWDM terminals Network flexibility CPL provides an eroadm (Enhanced Reconfigurable Optical Add/Drop Multiplexer) architecture that delivers any wavelength, anywhere, anytime, without impact to the existing traffic. The eroadm is a CPL functional module that enables dynamic on the 2
fly optical branching to up to five different optical paths in addition to facilitating basic add/drop of individual wavelengths. Unlike first-generation ROADMs with colored ports, eroadms are colorless, which means any wavelength (color) can be added/dropped on any port. With the eroadm: Service providers and cable operators can redirect wavelengths to any span, using CPL s unconstrained optical switch architecture Optical branching at strategic fiber junctions is fully enabled with the eroadm agility by enabling the rerouting of light paths without requiring conversion back to electrical signals Wavelengths are managed optically through the eroadms, thus limiting the need for fiber interconnections, while helping to reduce the chance of causing outages due to incorrect manipulation of equipment The flexibility offered with CPL s eroadm solution provides efficient management of transiting wavelengths at add/drop and branching locations where previously more costly OEO bandwidth management was required. Wavelengths can be managed at the single channel level, eliminating stranded bandwidth, thereby increasing network utilization and efficiency. The DOC software provides continual network optimization during reconfigurations and network expansions for a fully automated process. Architectural advantages The main individual components that make up the architecture of CPL are detailed as follows: Channel mux/demux (CMD) The CMD is a 4-port or 8-port mux/demux filter that feeds into one of the nine ports on the GMD. Both types of CMDs can coexist on the same line to offer anywhere between 36 and 72 wavelengths on the DWDM system. Any DWDM source that is ITU gridcompliant can be transported, providing an open photonic interworking solution. With the CMD architecture, wavelengths with different reach requirements can be carried concurrently on the DWDM system. For example, regional reach wavelengths and long haul reach wavelengths can be deployed to enable an application such as the one described in Figure 1. Group mux/demux (GMD) The GMD provides a second stage mux/demux capability and supports nine CMD filters capable of offering a total of up to 72 ITU-compliant wavelengths in the C band. This architecture allows capacity to be added incrementally for a smooth evolution path. The GMD, in its capacity as the Virtual Shelf Processor (VSP), provides a communications infrastructure in order for the CPL node to interface with other nodes, elements within the node, and the outside world. Figure 2. Common Photonic Layer architecture Service Layer Optical Metro 5200 Optical Metro 3500 Optical Multiservice Edge 6500 Ethernet Routing Switch 8600 λ 1 CMD GMD Common Photonic Layer eroadm/ WSS Routers Amplifier sites Amplifier sites Vendor X Optical Cross Connect DX/HDX/HDXc λ n Channel access site 3
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. Wavelength Selective Switch (WSS) The WSS is the key enabler for eroadm solutions for the termination or rerouting of any wavelength to any port across the network. Single or multiple wavelengths that are dropped at one site can be re-inserted with new traffic and rerouted to a different location, eliminating bandwidth stranding. The WSS can connect up to five different nodes at an eroadm site while supporting local add/drop traffic. Amplifier The Amplifier is a low-noise, highoutput power module with fast transient control and self-provisioned variable gain control that delivers enhanced reach capabilities to ensure each wavelength is amplified equitably. Various amplifier modules are offered with CPL to provide cost-optimized metro, regional and long haul/ultra long haul applications. Domain Optical Control (DOC) The DOC software resides on each of the modules described above and performs continuous background check, evoa and optical output power optimization, fault isolation functions to ensure that the network runs at optimal state with the least human intervention and time consumption. With this feature, the requirement for expensive test equipment and time to perform system optimization is significantly lowered. Network management for CPL CPL is fully integrated into the Optical Network Manager (formerly known as Preside). Comprehensive screen layouts provide the Network Elements health at a glance, pull-down menus for simple access to nodal management functions, and all relevant nodal management information. Faults are centralized on the Optical Network Manager and inventory, provisioning and performance management can all be controlled via a common Graphical User Interface. Through the Optical Network Manager, the user can drill down onto the Craft Interface of the Network Element for full management options. The Optical Network Manager provides a proven interface to manage CPL and all the subtending service layer optical equipment to offer a centralized, integrated solution at the Network Operation Center. Summary CPL dramatically simplifies DWDM line systems to enable significant Capex/Opex savings and exploit this simplicity to drastically reduce the time to deploy value-rich services. In support of these objectives, the platform provides the smallest initial/final footprint solution with significantly lower power consumption, delivering seamless scalability and in-service capacity expansion from 2 to 72 wavelengths and beyond. Its building blocks are optimized to offer cost-efficient metro, regional and long haul reach configurations. The automated tools and intelligent software perform network optimization and accelerate the end-toend provisioning/addition of wavelengths. The flexible architecture allows these wavelengths to be delivered anywhere, anytime. CPL integrates with a proven network management platform and easy-to-use optical planning tools. CPL is truly the platform of choice for all DWDM network applications. 4
CPL system features Wavelengths supported (2.5G, 10G, 40G-ready) 36 (100GHz), 72 (50GHz) or any combination to deliver between 36 and 72 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 Optical control Supported configurations From 10s of km to 2000 km and beyond depending on service platform connected to CPL Auto wavelength discovery, continuous dynamic system optimization, fault isolation 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 Management SNMP, TL1, craft interface, Optical Network Manager, 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 revenuegenerating opportunities or capacity exhaust drive expansion of the network. 5
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