As a result, the number of fibers and network elements in the metro is multiplying and connectivity is playing an increasingly critical role as a foundation for operational efficiency an
Trang 1white paper
Creating a Foundation
for Profitability
Today service providers are challenged to satisfy cost-conscious, yet broadband-savvy customers demanding high network reliability and feature-rich service offerings, all at economical prices To meet this challenge, service providers must strive to be efficient, reliable, and scalable while rolling out new revenue-generating services With capital expense under scrutiny, most service providers are finding an evolutionary approach to be the most viable strategy for maximizing the value of embedded equipment while migrating to next-generation services As a result, legacy platforms such as SONET/SDH and DWDM, originally optimized for traditional circuit-switched voice services, now are leveraged to handle a wide array of data services Yet as new services such as bandwidth-on-demand, IP VPN, and others gain popularity, service providers are building the metro to more efficiently carry these new, as well as legacy, services As a result, the number
of fibers and network elements in the metro is multiplying and connectivity is playing an
increasingly critical role as a foundation for operational efficiency and ultimately, profitability Given the variety of services and technologies deployed in the metro, no single technology will likely prevail as a sole platform so multiple technologies will co-exist Traditional circuit-switched platforms will share the central office and remote terminal with new packet-switched platforms The network will continually evolve to accommodate new services and technologies The key to managing this ever-changing and increasingly complex network architecture is to install flexibility
in the face of uncertainty With a well-planned network foundation, service providers can support key services with carrier-class quality and reliability, while controlling costs for network management and operations
The solution is simple By migrating carrier-class connectivity products and practices to the metro edge, the physical layer becomes easier to manage throughout network evolution A well-planned connectivity infrastructure provides critical rerouting options, enables network
monitoring and troubleshooting, and lays the foundation for a future-proof infrastructure that accommodates change and growth without disrupting service
Strategies for Operational Efficiency
at the Metro Edge
“Within the metro will be the need to install, test, and reconfigure all types of
equipment with the same fundamental operational procedures and principles used
in large, carrier-class networks historically Any other approach is inherently risky.”
— Michael Day, CTO
Trang 2Simplicity within a complex network
While equipment vendors often display clean and simple network diagrams showing the deployment of network elements, the reality is that integrating new-world network elements into legacy networks and scaling to accommodate growth is complicated at best
New multi-service platforms with optical interfaces are entering the metro network, offering the promise
of greater bandwidth and greater revenue opportunity However service providers are now challenged to manage unprecedented amounts of fiber in the metro Simple factors such as managing the proliferation
of fiber cables, defining procedures for upgrading and expanding modular network elements, and selecting among the vast array of optical connectors are now critical to keeping operational costs down and minimizing risk
As network elements increase capacity and accept more incoming and outgoing fibers, a greater need for high-density cable management within and around active equipment elements is evident Proper fiber cable management remains critical to preserving signal integrity and becomes increasingly vital as fiber counts multiply The four critical elements of fiber cable
management – bend radius protection, cable routing paths, cable access, and physical protection – all directly impact the reliability, functionality, and operational cost of the network Simply put, poorly managed and unprotected fibers are more likely to bend and break, cause service failures, and increase network operational costs Proper protection within and around equipment elements not only enhances the long-term reliability of the fiber cables, but also reduces signal attenuation and enables service providers to realize fiber’s competitive advantage
Most new-world equipment platforms feature modular line cards designed to ease upgrades and growth while minimizing initial capital expense While this modularity can increase flexibility, it can also increase complexity at the physical layer These devices require significant interoffice communication between network elements, leading to a complex connection scheme that can become a burdensome operational expense if not properly managed with a foundation of physical layer connectivity
Each time a new line card is added or upgraded, it is not uncommon to require substantial connectivity changes For example, to upgrade a line card, as many as 8 to 16 connections may need to be recabled When deploying hundreds of new lines per month, service providers can quickly face a time-consuming, labor-intensive challenge With a well-designed connectivity foundation, technicians can add or upgrade the same cards with minimal time and effort using the
functionality of optical cross-connect frames or panels
for network reconfiguration This long-term operational
efficiency quickly offsets the one-time capital investment
made in connectivity gear, which is typically less than
10% of the cost of network element deployment
Another factor contributing to complexity in today’s
metro network is the proliferation of optical connector
styles While a constantly increasing and divergent array
of connectors offers service providers many choices, it
can also lead to increased costs for managing an
extensive fiber jumper inventory with various lengths
and hybrids A simple solution can be to standardize on
one connector style for all connectivity gear, which can
serve as an interface point to various network elements
Through this approach, service providers can reduce the
varieties of fiber jumpers in inventory dramatically,
reducing overhead and administrative costs
“In spite of everyone’s best wishes to simplify the network, the reality is that valuable equipment is already deployed and delivering service to customers This equipment will continue to add value while new platforms are integrated into the network We will have to live in a mixed environment of legacy and next-generation equipment for the
foreseeable future and will be challenged
to manage risk during this transition.”
— Michael Day, CTO
Trang 3Migrating proven craft practices
Today’s technicians face many new challenges: installing and
maintaining new-world equipment elements, handling more and
more optical fiber, understanding an expanding portfolio of
technologies, all while meeting customers’ increasing
expectations for provisioning and maintenance responsiveness
As complexity and challenges mount, carriers are finding that
standard central office practices are now instrumental for
operational efficiency in the metro
Typically, high-volume central offices centralize craft
practices around common connectivity interfaces that
remain constant regardless of changing technologies
Technicians become accustomed to a common work
interface and, as a result, can accomplish
day-to-day tasks faster and with fewer training hours
required to keep pace with evolving network
technologies In the metro edge, a connectivity
foundation offers similar benefits Technicians can
conduct day-to-day provisioning and maintenance
activities at a centralized connection point using
common craft practices, enabling speed and
efficiency Likewise, a centralized termination
point isolates day-to-day work from highly
sensitive equipment backplanes and minimizes
risk of inadvertent damage to expensive
equipment elements or disruption of adjacent circuits
As smart network architects plan for network design, it is critical to take into account these real world craft practice implications The three methods of connecting equipment – direct connect, interconnect, and cross connect – are critical to compare and evaluate for operational efficiency
The direct connect method (figure 1), sometimes called “hard wiring,” involves directly joining network elements without a central intermediary point Initially, this option seems ideal given its low upfront cost Yet as service is deployed and additional equipment is added to the network, hard-wired connections quickly prove to be unscalable and operationally unmanageable This approach to connectivity is often implemented without the realization of the operational impact – new services take longer to add, new network elements are difficult to integrate into the network, and network operations are ultimately more cumbersome and expensive
Comparatively, the interconnect method (figure 2) provides a common termination point between equipment elements and is often provisioned with some means of slack storage for fiber cables Because each network element is connected to a central termination point, technicians can more efficiently conduct day-to-day testing and maintenance operations If minimal network reconfiguration is
anticipated, an interconnect architecture can work, but the more a network changes, the more desirable a cross-connect architecture becomes
A cross-connect architecture (figure 3) provides the greatest flexibility for future network reconfiguration and greatest efficiency in craft practice All fibers are connected to a central termination point with semi-permanent cross-connect jumpers routed between ports of the fiber distribution frame or panel This makes accessing the network elements easier, enhances technician efficiency, and improves the long-term reliability of the fiber network A cross-connect system with strong, flexible slack storage provisions will significantly minimize long-term operational costs in an ever-evolving metro network
Careful choices in network design can support growth and change as the metro network evolves By selecting flexible, craft-friendly architecture, service providers can maintain a sound balance of capital and operational expenses while enhancing efficiency in the metro
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Trang 4Minimizing operational risk
Network upgrades and improvements often result in
more functionality in network elements and more
bandwidth on facilities and local loops As these new
technologies concentrate and accelerate the delivery of
revenue-generating services, the risk of outages,
downtime, and decreased performance is amplified The
selection of network connectivity elements and practices
is paramount to mitigating this risk
As greater amounts of fiber move into the metro, for
example, field-termination of fiber connectors may no
longer be the best practice To improve craft efficiency
and enhance network reliability, factory-terminated
connectors may be the best choice to relieve technicians
of the requirement to field-terminate an ever-increasing
number of fibers Since field connectorization requires a
skilled technician pool, labor costs can accrue quickly and
reliability can be jeopardized as technicians attempt to quickly terminate a large volume of singlemode and multimode fibers Field connectorization may seem less expensive at the time of purchase, but extraneous expenses encountered in the field increase cost and risk rapidly
Factory connectorization, on the other hand, minimizes installation expenses and risk by ensuring that connectors are polished, terminated, and inspected in a factory-controlled environment Likewise, factory termination enables high-quality, rapid connector installation by less experienced craft personnel and minimizes labor costs While factory-terminated cables may not necessarily be the right lengths for every equipment connection, network designers can accommodate by arranging for slack storage within the network infrastructure plan
Multi-fiber ribbon cables are gaining popularity as a valuable way to increase density per line card Without the ability to break out individual fibers from a multi-fiber ribbon cable, service providers risk disrupting high-volume, high-value traffic carried over the entire cable rather than simply addressing the issues related to traffic on a single optical fiber Operational efficiency and network reliability can be impaired if these multi-fiber ribbon cables are not deployed with a connectivity interface that enables technicians to break out individual fibers for testing and reconfiguration
Addressing the need for test access is critical to assess network operations at multiple points for
troubleshooting, repair, basic monitoring, and to ensure quality of service Physical test points should be positioned between electronic devices and at demarcation points where signal handoff occurs between carriers or to an enterprise network Through these access points, technicians can monitor signal integrity
to isolate faults to a particular equipment element or segment of the network This approach not only speeds troubleshooting time, but also minimizes “fingerpointing” between various carriers when a technician can identify which network is the source of a failure
The risks inherent in joining diverse equipment, building new infrastructure to support metro traffic, and ensuring quality of service are real but manageable with a solid connectivity foundation The time to think
of connectivity is now – while a majority of the metro is under construction and real operational
efficiencies can be designed into the network infrastructure
“Though many network elements feature integrated test points, carriers should position passive test points independently
to minimize risk of disrupting adjacent fibers or damaging expensive line cards and electronics When the test interface
is the same for each application and network element, craft practices can be simplified and risk can be minimized.”
— Tom Kampf, Program Manager, Fiber Products
ADC Telecommunications, Inc., P.O Box 1101, Minneapolis, Minnesota USA 55440-1101
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