WAN Network Connections From Copper to Fiber

By: John Shepler

LAN, MAN and WAN speeds continue to rise as content demands more and more bandwidth. This is increasing pressure on both copper and fiber based telecommunication networks for more frequent speed upgrades. Let’s take a look at what the options are for both traditional TDM (Time division Multiplexing) and IP (Internet Protocol) networks.

The Legacy of Copper Telecom Lines
Copper has been the mainstay of electronic communications, starting with the telegraph and then the telephone networks. The telegraph, of course, is long gone. The telephone is undergoing a technology shift where voice is becoming a converged network service. With the implementation of 4G LTE wireless, even cellular phone will soon move away from voice only channels to integration with data.

Clearly, analog POTS (Plain Old Telephone Service) is in its twilight years. What will remain for decades to come is its installed base of twisted pair copper lines that connect to nearly every building, commercial and residential. That copper still has value because it can transport digital signals as well as analog.

Digital T1 Lines
The oldest digital protocol for data transmission on twisted pair copper (not including telegraph) is still going strong. It’s the T1 line used for telephone trunking, point to point data, and dedicated Internet connections. T1’s history is that it was developed to transport multiple phone conversations digitally using existing telephone cabling. T1 can transport service over wide areas using signal regenerators to clean up the signal every 6,000 ft. You can get T1 nearly anywhere you can get landline phone service. The one limitation is its 1.5 Mbps bandwidth.

While 1.5 Mbps used to be considered broadband, it’s no longer adequate except for PBX telephony, casual Web access, email and point of sale credit card verification. This bandwidth is similar to 3G wireless. Wireless is rapidly moving to 4G wireless, with speeds an order of magnitude higher. Wired services are also moving to 10 or 15 Mbps as a minimal requirement.

Bonding T1 Lines & Ethernet over Copper
T1 is enjoying continued usefulness by bonding the bandwidth of multiple T1 lines to make one larger service level. This is practical up to 10 or 12 Mbps, but gets too expensive and hard to find available bundles of unused copper pair above that. What’s needed is a different technology that gets more bandwidth out of the same copper.

That technology is now available and called Ethernet over Copper or EoC. Ethernet is a departure from T1 in the way the bits are organized on the line, but serves the same purpose. It uses exactly the same copper pair cabling with multiple pairs bonded to increase bandwidth. The differences are that EoC is available in increments from about 3 to 45 Mbps and it is distance limited. Near the central offices, high speeds are available. A few miles away there may be no EoC service at all. In between, there are different service levels possible.

There have been some major advances in transmission of data over copper pair wiring, with some installations supporting bandwidths as high as 100 or 200 Mbps. These are uncommon. Another copper technology, Cable broadband using coaxial copper cables and a modulation scheme called DOCSIS 3, can reliably deliver 100 Mbps or more bandwidth. Even 1 Gbps is not unheard of, although not that widely available. Another service called DS3 or T3 offers 45 Mbps over a pair of coaxial lines where available.

Fiber Optic Services for Unlimited Bandwidth
What really gets the job done at higher bandwidths is fiber optic cabling. Fiber bandwidth is nearly unlimited, especially when wavelengths are bonded to create very large services. Like, copper, fiber also has a legacy history and a newer technical approach.

Traditional fiber optic service is based on a telephony standard called SONET (Synchronous Optical NETwork). Familiar service levels are OC-3 at 155 Mbps, OC-12 at 622 Mbps and OC-48 at 2.4 Gbps. Higher levels include 10 Gbps and 40 Gbps.

Ethernet over Fiber (EoF) is a Carrier Ethernet service like EoC, but using fiber rather than copper transmission. Fiber Ethernet is highly cost competitive and readily available from 10 Mbps on up to 10 Gbps. Today’s most popular service levels are 100 Mbps Fast Ethernet and 1,000 Mbps Gigabit Ethernet (GigE). In some areas, 100 Gbps service is available to businesses.

Wavelengths Options
Fiber enjoys another advantage over copper in that it supports multiple 10 Gbps wavelengths through a process called WDM or Wavelength Division Multiplexing. This means you can run different protocols on completely separate wavelengths within the same fiber strand. This provides a high degree of flexibility for financial institutions and others with demanding applications.

As you can see, there are a wide variety of options on both copper and fiber transmissionall currently available. What works best for your organization is a function of application requirements, scale and budget. You’ll likely have multiple technologies and multiple vendors to choose from.

Fiber Optic Service FAQ, Part 3

Here are more frequently asked questions and answers about fiber optic service for your business You may also be interested in the first and second lists of fiber FAQs.

Q: What is a lit building?

A: This is a building that already has fiber installed and “lit” for service. Usually only a single carrier lights each building. If your building is lit, you can easily get bandwidth services from that carrier.

Q: What are wavelength services?

A: A wavelength or Lambda is a particular color of laser light that carries the signal through the optical fiber. Early fiber systems used only a single light beam. Today, multiple beams travel the same fiber strand using a process called WDM or Wavelength Division Multiplexing. You can lease an entire wavelength for your exclusive use if you wish.

Q: Why would you lease a wavelength rather than just buying bandwidth?

A: Leasing a wavelength gives you high bandwidth dedicated to your use. Typically each wavelength supports 10 Gbps. You can decide whether to use SONET, Ethernet or some other protocol over the wavelength because the service does not share traffic with other users.

Q: What is dark fiber?

A: This refers to fiber strands that have been installed but not lit for service. Most fiber optic cable has dozens or hundreds of fiber strands all bundled together. Carriers that have extra strands they aren’t using will often lease them to other carriers or businesses that need the capacity.

Q: What’s the advantage of dark fiber?

A: Bandwidth is nearly unlimited and security is high because there is no traffic on the fiber strand other that what you provide.

Q: What protocols does dark fiber support?

A: Anything you can generate, including SONET, Ethernet, Fibre Channel and others. By using Wavelength Division Multiplexing, you can assign a different protocol to each wavelength and they won’t interact.

Q: Why wouldn’t you select dark fiber?

A: You’ll need to provide the termination equipment at each end, which can be rather expensive. On wavelength and other bandwidth services the carrier does this. Also, there may not be any dark fiber available on the route you have in mind.

Q: How does fiber support cloud services?

A: Cloud communications are bandwidth intensive. All the traffic that used to run to your in-house data center now goes over a WAN (Wide Area Network) connection to the cloud. You need high bandwidth and low latency connections for this to work properly, just what fiber is good at.

Is fiber bandwidth service the right solution to your business needs? Compare costs and service options for the fiber optic service options available for your business locations.


You may also be interested in reading Fiber Optic Service FAQs, Part 1 and Part 2.

Next Stop 100 Gbps WAN Bandwidth

Big data, cloud computing and HD video are pushing the limits of what we once considered high bandwidth private line and MPLS network connections. Gigabit Ethernet is now popular with companies that have high bandwidth demands. Some firms are moving to 10 GigE, as 1000 Mbps is no longer adequate. If 10 Gigabits per second is also a limiting factor for your business, the time has come to consider 100 Gbps bandwidth.

Most of the larger fiber optic carriers have been busy upgrading their core networks to 100 Gbps. They need this kind of backbone bandwidth to avoid having to install new fiber to meet demand. Few, however, have offered this capacity to their customers.

Zayo is changing the game. They are now offering 100 Gbps as a wavelength service between major cities. The 100 Gbps connections are located in key traffic aggregation points and IP nodes throughout the U.S. This makes the service especially attractive to content producers and large ISPs (Internet Service Providers) who have inherently high bandwidth demands.

Why choose wavelength service versus SONET or Ethernet transport? High bandwidth options is one reason. Another is the ability to specify protocols and security measures. Leasing a wavelength is the next best thing to leasing an entire fiber strand or deploying your own fiber optic cabling. Unless you are in the business of operating a regional or national fiber optic network, the cost of creating all this infrastructure is prohibitive. However, leasing a wavelength may well be within reason.

Wavelength services are created by a process called WDM or Wavelength Division Multiplexing. The idea is that each fiber strand can support much higher bandwidths if fed by multiple lasers instead of just one. Each laser is tuned to operate on a particular frequency or wavelength according to a standard international grid plan. The wavelengths all shine through the fiber simultaneously, but they do not interact. You can think of each wavelength as a separate fiber for most purposes.

How much bandwidth can a wavelength carry? By using simple on-off keying of the beam, a wavelength can transport up to 10 Gbps. For 100 Gbps you would have to combine or aggregate multiple beams or use a more advanced modulation scheme such as CP-DQPSK (Coherent Polarization-Multiplex Differential Quadrature Phase Shift Key) to transmit multiple bits per symbol. With a plug-in card such as the CIsco CRS 1-Port 100 Gigabit Ethernet Coherent DWDM Interface Module, a single wavelength can now transport 100 Gbps. There is standards work underway to extend that to 400 Gbps and eventually 1 Tbps.

Zayo offers wavelength services at 1 Gbps, 2.5 Gbps, 40 Gbps or 100 Gbps. Diversity and sub-50 msec protection switching is available to improve reliability to carrier standards.you can order single or multiple waves as needed to support your applications. Zayo has the ability to scale bandwidth capacity along their routes to 8 Tbps when such a need arises.

Companies interested in high bandwidth wavelength services are also often interested in low latency. Zayo offers low latency routs with up to 100 Gbps of bandwidth between Seattle, Chicago, New York City, and Philadelphia to key data centers and financial and enterprise locations. Their low latency routes also include a hop to London as well.

Zayo will continue to deploy their 100G wavelength service across major markets for through the first half of 2013. Their entire network includes 67,000 route miles serving 45 states and Washington D.C. with 10,530 on-net buildings that include 535 data centers, 515 carrier PoPs (points of presence) and 2,743 cell towers. They also offer colocation facilities with over 141,000 square feet under management.

Does your company need higher levels of bandwidth to maintain or improve productivity or support demanding applications? If so, there are fiber optic service options available for 100 Mbps up to 100 Gbps at attractive prices. Competitive quotes are available at no charge.

New Low Latency Fiber Optic Services For Atlanta

Atlanta, Georgia is a major hub for fiber optic traffic serving the United States and International destinations. It’s also the home of many Fortune 500 companies and thousands of enterprises in need of high performance bandwidth services. AboveNet has recognized a growing need in the Atlanta metro market and is making a major expansion of its low latency fiber optic routes for downtown Atlanta, Alpharetta, Buckhead and Norcross.

AboveNet is a highly competitive carrier that focuses on high bandwidth connectivity. They operate about 2.3 million fiber miles in top US and European markets feeding more than 2,800 optically-enabled commercial buildings. Their major hubs in the SouthEast are Atlanta and Miami, with others in Houston, Austin, Dallas, Phoenix, Los Angeles, San Francisco / San Jose, Portland, Seattle, Denver, Chicago, Boston Philadelphia, Baltimore, The New York Metro Area and the Washington DC Corridor. In addition, AboveNet connects to Asia in Tokyo, Japan and to Europe in London, Amsterdam, Frankfurt and Paris.

These AboveNet hubs are connected by DWDM (Dense Wavelength Division Multiplexing) equipment that terminates the fiber runs. Most backbone trunks offer 10 Gbps, with individual city locations providing up to 40 Gbps connectivity for carriers and companies that need this capacity.

AboveNet is making its complete suite of high performance bandwidth services available to businesses in the Atlanta metropolitan area. These include both Metro Area Network (MAN) and Wide Area Network (WAN), plus WDM Wavelength Services, Metro Ethernet, WAN Ethernet and IP Transit.

Few providers can offer wavelength services for MAN users. These include standardized Carrier Ethernet services that have the MEF 9 and MEF 14 certificates. Single wavelength service offers a 40 Gbps, 10 Gbps, 2.5 Gbps or 1 Gbps wave service to extend your corporate LAN/WAN to multiple metro area locations. Data mirroring can be done with a Fiber Channel, ESCON or FICON wave. Both protected and unprotected options are available.

Metro WDM applications include virtualization and the serverless office, real time transactions backup and high speed business continuity, streaming multimedia, Storage Area Network (SAN), delivering mission critical enterprise data and applications, and e-commerce transactions. There are basic, enhanced and custom wave solutions to meet any business requirement up to 40 Gbps.

WAN services allow you to reach beyond your metro area to connect with other metro locations are around the world. eXpressWave long haul optical transport is a point to point inter-city connection service that supports voice, data and video between more than 78 city pair combinations. Bandwidth options include 1 Gbps, 2.5 Gbps and 10 Gbps going from POP to POP. Metro connectivity is available in top US and European cities for companies with national and international business locations.

Do you have a business in the Atlanta metro area or other major city in the US that needs very high performance connectivity for metropolitan, national or international business needs? If so, get pricing and features for the fiber optic bandwidth solutions you need from AboveNet and other high performance carriers.




Note: Photo of downtown Atlanta at twilight courtesy of Wikimedia Commons.

Wavelength Services vs Dark Fiber

Fiber optic services are popular for high bandwidth metro and long haul connections. They typically start about 100 Mbps and go on up to 10 Gbps, 40 Gbps and occasionally 100 Gbps bandwidths. But what if you find that fiber optic bandwidth services are too restrictive for your needs? There are a couple of alternatives. One is leasing dark fiber routes and the other is wavelength services. Let’s see how they compare and why you might find one more attractive than the other.

Fiber optic bandwidth services are standardized, packaged services that offer either SONET or Ethernet connectivity from point to point. You may think of them as private line services, but chances are that you are not the only customer riding on the fiber strand. At lower bandwidths, such as OC3, you are probably being electrically multiplexed with other users to create a much larger bandwidth signal that is more cost effective to transport. If you are using a 10 Gbps or 40 Gbps service, you are still sharing the strand with other users but optically multiplexed using wavelengths.

One problem with these pre-packaged fiber optic services is that they generally limit you to a particular protocol and speed. If you change your mind, it can be time consuming and costly to change or upgrade your service. For this reason, some companies have decided to become their own bandwidth providers by leasing dark fiber and lighting it up with equipment they own. This gives you the ability to have multiple protocols running on the same fiber at whatever bandwidth makes sense. When you want something different, your own engineering staff reconfigures or changes out the equipment one each end. There’s no waiting around for carrier personnel because you are the carrier. The dark fiber is just an empty pipe, as the name implies.

The trick to having multiple protocols on one fiber is called WDM or Wavelength Division Multiplexing. It’s somewhat akin to the idea of electrical multiplexing in that many different signals can share the same transport mechanism. However, technically it is quite different. WDM uses multiple wavelengths or colors of laser light that are separate enough in frequency to be distinct. All of these colors, also called lambdas, exist in the infrared portion of the light spectrum that is seen as nearly transparent through glass fiber.

Think of WDM as shining a whole rainbow of laser beams down a fiber optic cable where they are detected separately at the other end. Each beam is independent of the others. One color doesn’t care that it is running Ethernet and the next color up is carrying SONET or ESCON. They don’t see each other and don’t interfere.

Since WDM is an established technology running on just about all carrier fiber optic networks, there is no reason why you can’t just lease an entire wavelength instead of a service running on that wavelength. That’s fairly easy to do these days because many networks have excess wavelength capacity available. You can have your own wavelength running a high bandwidth Ethernet service (10 GigE) or 10 Gbps or 40 Gbps SONET.

Why lease a wavelength instead of dark fiber? For one thing, you may not need the entire capacity of the fiber or all those wavelengths you can create yourself. There’s considerable capital cost in purchasing the WDM systems for each end of the fiber that you can avoid by just leasing the wavelengths you need by the month. Capital expense and network management then become the service provider’s problem.

Dark fiber may not be available for the entire route you have in mind or you may be planning to install your own fiber in a particular area. Until it is ready, you can make good use of existing capability by leasing wavelength services as long as needed.

Dark fiber, wavelength services, Gigabit Ethernet or OCx SONET. Which is right for your needs? Get comparative pricing and availability of fiber optic services now to do a good trade off analysis.



Note: Photo courtesy of Sandia National Labratories.

New Data Center Networking Solutions

Data management and storage requirements for enterprise level organizations continue to increase. In addition, a majority of enterprise IT departments now replicate data between data centers. This has created a need for new and more cost effective bandwidth services, especially at 10 Gbps and above. Level 3 is addressing these needs with an enhancement of its existing data center networking solutions.

What’s different about data center connectivity compared to other business requirements? Data centers are far more concentrated than other computing resources. This is especially true for storage, a prime driver for offsite data centers in the first place. What this does is increase the need for high bandwidth connections between the concentration of storage and the concentration of users. It also influences the connectivity required.

What you need for last mile connections to an MPLS network or private lines to link business locations can usually be handled by T-Carrier, SONET/SDH or Carrier Ethernet line services. Data centers need higher bandwidth connections, but may also need special SAN protocols including Fibre Channel, Infiniband, ESCON and FICON.

SAN stands for Storage Area Networks. These are large collections of disk drives that connect directly to the application servers. SAN networks have traditionally been very localized, with the disk arrays physically near the servers. But what do you do when you need to duplicate data between data centers?

Many companies operate two or more data centers, sometimes a half-dozen or more. Some of this is due to mergers and acquisitions of formerly independent organizations with their own IT infrastructures. Much is driven by a need for disaster protection and recovery. When your business is critically dependent on its electronic data, normal backup processes aren’t adequate. You can have multiple copies of your files locked up locally and still be put out of business by a fire, tornado, flood, earthquake, hurricane or other disaster that destroys whole buildings and everything in them.

This means that you want to have copies of your critical data dispersed geographically. Establishing independent data centers in two or more cities far apart means than a disaster that takes out one center probably won’t knock out everything. There’s also an advantage to content providers in having the servers and data content located close to the customers. Latency is reduced and performance is increased due to less network congestion. A challenge is how to make sure the data is replicated exactly at all locations.

This is where long distance SAN networking comes into play. You need high levels of bandwidth but also support for SAN protocols to keep everything synchronized. FCoE or Fiber Channel over Ethernet is a popular protocol for transmitting Fibre Channel frames over 10 Gbps Ethernet connections. WDM or Wavelength Division Multiplexing avoids having to layer protocols to connect facilities. Each wavelength in a fiber optic link can be assigned its own protocol, regardless of what is running on other wavelengths in the same beam.

Level 3 Communications has expanded its data center networking portfolio to include SAN fiber channel protocol, dark fiber and managed fiber solutions. This is in addition to dedicated bandwidth services from 1 Gbps to more than 40 Gbps, including 10 Gbps EVPL or Ethernet Virtual Private Line service. They offer low latency route guarantees and an international service footprint, including a presence at key public exchange facilities.

Are you concerned with managing multiple high performance data centers? Would you like to have more options and/or better pricing for all your telecom connectivity needs? If so, get complementary consulting help and pricing and availability for high bandwidth networking services.



Note: Photo of data center servers courtesy of WikimediaCommons

WDM Wavelength Services Offer Expandability

If your need is for high bandwidth, security and flexibility, you should take a look at wavelength services. This is more than the typical fiber optic bandwidth service. It’s almost like owning the network facilities yourself.

The thing about fiber optic transmission is that it offers almost limitless bandwidth. That’s a foreign concept to anyone who’s been tied to copper wireline services. It’s also an odd notion for those who pick a fiber optic service level and sign a contract for it. If you order OC3 SONET service, what you get is a line that runs at 155.52 Mbps with a payload of 148.608 Mbps. You don’t have to fill the pipe continuously, but the capacity is there all the time. If you need more bandwidth, you only recourse is to add an additional service or upgrade to something like OC12 or Gigabit Ethernet.

What you are using with fiber optic services is not the entire bandwidth of the fiber. In fact, you may be totally unaware that your signals are multiplexed with lots of others all traveling on the same fiber strand. If there is only one laser beam with a single color or wavelength shining through that fiber, it likely has a capacity of at least 10 Gbps. Chances are, though, that there are many different color beams all riding simultaneously down the fiber. They don’t interfere because they are different colors of light, called Lambdas, all in the infrared region of the spectrum. Each Lambda or wavelength has a carrying capacity as high as 10 Gbps. You can think of these as equivalent to individual high capacity lines. If the fiber optic strand were made of copper, each wavelength would be a separate pair of wires.

What if you could lease a wavelength instead of a copper wireline or a fixed bandwidth service on a fiber optic cable? The wavelength doesn’t care what modulation or data pattern you use. It’s just a pure light beam of one wavelength. There’s no fancy footwork required to convert between one protocol and another just to be compatible with what’s running on the line. That opens some interesting possibilities. You could use your leased wavelength to carry Gigabit Ethernet or Fast Ethernet, SONET OC3, OC12 or OC48, Fibre Channel, or ESCON.

Need to transport a variety of high bandwidth protocols? OK. Just lease multiple wavelengths and give each protocol its own Lambda. The won’t interfere. In fact, they won’t even known the other wavelengths exist.

This type of network transport is no longer a pipe dream. All you need to do is lease WDM Wavelength Services from a fiber optic network carrier such as AboveNet. What AboveNet has done is install a base of dark fiber in many metropolitan areas. It’s called dark because it hasn’t already be put into service with a particular fiber optic service in mind. It’s like a blank canvas ready to become any work of art. AboveNet “lights” the fiber as needed using WDM equipment to create their wavelength services.

WDM stands for Wavelength Division Multiplexing. It’s the technology that creates multiple wavelengths on a single fiber strand. This is a standardized process that ensures there is enough separation between the wavelengths that they won’t interfere and that different brands of networking equipment will work together. There are two flavors of WDM: CWDM or Coarse Wavelength Division Multiplexing and DWDM or Dense Wavelength Division Multiplexing. The difference is that DWDM squeezes more wavelengths, up to 160, onto a given fiber but at a higher cost than CWDM.

Is this affordable? AboveNet says that their CWDM service becomes competitive at the OC-3 service bit-rate. If you can use more bandwidth than that, you’ll save money with CWDM. Typical applications include connecting corporate headquarters with branch offices and data centers, or connecting multiple hospitals and medical centers for exchange of medical images and other health service records.

Has your business or organization become limited by the network services available? Perhaps it’s time to move up to wavelength services. Find out by getting prices and availability of fiber optic wavelength services for your locations. Complementary consulting by bandwidth experts is also available for serious applications.



Note: Image of light spectrum from prisms courtesy of Marcellus Wallace on Wikimedia Commons.

Metro Fiber Network Bandwidth For Denver

Bandwidth is booming in the Mile High City, or soon will be. AboveNet is installing nearly 100 route miles of dark and lit fiber to meet the mile-high bandwidth needs of Denver’s telecommunications, media, financial services, health care, retail and government users.

This could be a sign of things to come for nearly all metropolitan areas. The fact is that our productivity and economic growth is becoming more and more dependent on high levels of bandwidth to connect businesses, supplier, customers and remotely located employees. Copper can take us just so far. Then it’s time to connect with the nearly unlimited resources of glass fiber cables.

How much bandwidth are we talking about? AboveNet has fiber optic networks in cities nationwide that offer single wavelength service of 40 Gbps, 10 Gbps, 2.5 Gbps or 1 Gbps to extend a corporate LAN/WAN to multiple, metro area locations. You can have 40 Gbps fiber connectivity via an OC-768 handoff at your premises. That’s a level of bandwidth that was available only to carriers themselves not so long ago.

It should also be noted that each fiber strand can support more than one wavelength using a process called WDM or Wavelength Division Multiplexing. Each wavelength, or Lambda, is a slightly different color of laser light. Dozens or hundreds of wavelengths can travel through the same fiber without interfering. Each of those wavelengths can support up to 40 Gbps of bandwidth.

But is even this enough for the demands of major corporate or government users in a city the size of Denver? Well, those fiber cables that AboveNet is installing don’t just have one strand of fiber inside. These cables bundle 432 or 216 separate fibers within a large cable assembly. Multiply all those fiber strands times the number of wavelengths each fiber can support times the Gbps that each wavelength can carry and you’ve got some serious bandwidth. It’s more than is needed right now, so some fibers won’t be activated. These are the dark fiber that’s held in reserve for future needs or sold to organizations that want to have complete control over their communication resources by lighting their own fiber.

Do you have a need for metro or long haul fiber optic services from 40 Mbps to 40 Gbps? There are dark fiber and lit fiber optic services available now in most metropolitan areas from AboveNet and other high bandwidth competitive carriers. Prices are lower than they’ve ever been, thanks to improved technology and increased competition. You may be able to afford more bandwidth than you imagine. Find out with a competitive pricing quote and complementary consulting support from our Telarus bandwidth experts.

Wavelength Services For The Enterprise

Once needed only by telecom carriers, wavelength services are now available for enterprise users. These higher bandwidth fiber optic services are needed by hospitals, medical centers, banks, financial institutions, service providers to government, video production and distribution houses, content delivery networks and research facilities. Every day more applications cross that threshold of needing faster pipes to transfer data. Should those faster pipes be wavelength services?

A wavelength or lambda is light at a particular frequency or color. This characteristic is generally expressed in terms of wavelength in nanometers rather than frequency in terabits per second. Just as frequencies can be multiplexed to create a broadband wireline service, wavelengths can be multiplexed to offer multiple paths through a single fiber strand.

The multiplexing process at the physical level for fiber optics is called WDM or Wavelength Division Multiplexing. There are two technologies available. CWDM or Coarse Wavelength Division Multiplexing creates anywhere from 2 to 20 independent wavelengths, with 16 being a standard. DWDM or Dense Wavelength Division Multiplexing requires more precise equipment to create from 40 to 128 or more independent wavelengths.

As you can imagine, having dozens of independent wavelengths per fiber optic core and perhaps 100 cores in a cable, the amount of available bandwidth is truly staggering. So much so, that carriers are leasing out entire wavelengths to companies and organizations that need high bandwidth conduits. Wavelength services are similar to point to point T1 lines in that you have exclusive use of the wavelength. While the wavelengths in any particular core may be leased by dozens of different users, any multiplexing on the particular wavelength you are leasing is up to you. It's a private line service, with the line being a particular wavelength of light.

What bandwidths are available on these wavelength services? Commonly available speeds are 2.5 Gbps and 10 Gbps. Other increments of 1 Gbps and 5 Gbps are also increasingly available. Need more than 10 Gbps? It's possible to get as much as 40 Gbps in some areas. Can 100 Gbps be far behind?

Another advantage of wavelength services is that they are not locked into a particular protocol. You can use your wavelengths to transport Fast Ethernet (100 Mbps), Gigabit Ethernet, SONET OC-3, OC-12, OC-48, Fibre Channel, ESCON and Frame Relay.

Who's offering wavelength services suitable for large enterprise and other organizational use? Major competitive carriers such as Level 3, XO Communications and AboveNet have these and other fiber optic bandwidth services available right now. If you have a serious application that needs connectivity at this level, find out what wavelength services are available for your business locations.

Bandwidth Multiplication to the Rescue

If you think that you feel constrained by your WAN or Internet connection bandwidth, imagine the dilemma the service providers are in. Just when they thought that they'd invested enough in trenching fiber, expanding network capability and upgrading router speeds, along comes a killer app like video. In this case "killer" means bandwidth killer. When you've found that your bandwidth margin is much less than you expected, what can you do besides start over? How about speeding up what you've got?

Comcast and Cisco are testing a way to do just that. They've managed to multiply Comcast's fiber infrastructure by a factor of x10 using the latest in DWDM (Dense Wavelength Division Multiplexing) transmission equipment. That's 100 Gigabit Ethernet, 100 GigE.

What's important about this is that the setup used Comcast's existing fiber optic backbone that runs between Philadelphia, PA and McLean, VA. No new fiber was trenched. Instead, fibers already in the ground simply carried more data per wavelength.

Simply might be an understatement. The terminal equipment is Cisco's CRS-1 Carrier Routing System. It's part of Cisco's IP Next Generation Network architecture that scales to... are you ready for this ...92 Tbps of switching capacity. Yes, 92 Terabits per second of traffic. All of a sudden 100 Gigabits per second seems like the slow lane. But for long haul network operators 100 GigE will do just fine for now, thank you. It should be awhile before users start demanding Terabit connections. At least that's what everyone hopes.

Video streaming and downloads are now the majority of packets on the Internet. The Internet may have started as an information service envisioned as primarily text or text plus graphics. But the definition of information content has expanded to include voice, data acquisition, and high definition video. Video over IP is no longer the coming thing. It's here. From YouTube to TV program segments, to full length television programs and movies, video is sopping up as much bandwidth as it can get. In that context 100 GigE delivery networks are no longer an extravagance. They're the next benchmark.

Wavelength Division Multiplexing (WDM) advancements offer a means to increase network capacity by upgrading terminal equipment and using the same fiber strands. It comes down to more densely packing individual wavelengths using more accurate and stable lasers. Beyond that, network operators will have to press more dark fiber strands into service to multiply their available bandwidth.

Transmission efficiency improvements haven't been limited to fiber optic networks. The buried asset of twisted pair copper is also being asked to transport higher bitrates by upgrading terminal equipment to improved modulation techniques and active interference cancellation. It's common now to be able to get 10 Mbps and even 100 Mbps Ethernet services delivered over copper from nearby carrier POPs (Points of Presence) using lines once thought to be limited to T1 levels of 1.5 Mbps.

Bandwidth multiplication on both fiber and copper transmission lines has lead to the availability of higher bandwidths at lower prices for business users, and residential customers as well.

Many Wavelengths to Serve You

What happens when you max out the capacity of your network but still need more bandwidth? You have to go with a faster network, right? You may have to go with faster NIC (Network Interface Cards) and Ethernet switches for every node. What you don't want to do is run out of capacity on your lines. When you've got all you are going to get out of your structured wiring system, it gets expensive, really expensive, to upgrade that network. But what if you could just add some more signals into those same cables and multiply the bandwidth 32 or even 160 times? If your network is fiber optic based, you can do just that.

The magic is in a process called WDM or Wavelength Division Multiplexing. We think of fiber optic networks as having a beam of light at one end and a receiver at the other. The transmission electronics modulates a laser beam with our data stream and a photodiode at the other end converts the modulated light back into electrical pulses. What WDM does is send multiple beams down the same fiber optic cable in parallel. Two beams gives you 2x the capacity, four beams gives 4x, and so on. This process is so well developed that you can send 16 to 160 separate beams simultaneously to support enormous bandwidths.

Fiber optic networks are much faster than copper-based networks to begin with. Gigabit Ethernet over copper can be a challenge within an office environment. Forget long haul. T3 is the highest of the copper T-Carrier systems at 45 Mbps and is usually only deployed over a few miles. T1 lines can reach out to just about any distance using regenerators, but the bandwidth is limited to 1.5 Mbps. Compare that to typical long haul fiber bandwidths of OC-48 at 2.5 Gbps or OC-192 at 10 Gbps. Some carriers are upgrading their core rates to the OC-768 level of 40 Gbps.

In the world of copper transmission lines, frequency division multiplexing (FDM) is the equivalent of fiber optic WDM. FDM is what Cable TV companies use. Each channel has its own carrier and occupies its own narrow band of frequencies in the spectrum. More than 100 standard TV channels of 6 MHz each can be carried on a typical cable system. Some of these channels are assigned to broadband Internet services rather than television transmissions.

Wavelengths are also different frequencies which, in the optical (including infrared) parts the spectrum, represent different colors. They are also called lambdas after the Greek letter representing wavelength. Light split from a prism demonstrates that many different colors can exist simultaneously in a single beam without interference.

There a two general categories of WDM. CWDM or Coarse Wavelength Division Multiplexing uses up to 16 different wavelengths within an individual single mode fiber strand. DWDM or Dense Wavelength Division Multiplexing uses up to 160 wavelengths in a fiber strand and requires more precisely controlled lasers. But at 10 Gbps capacity per wavelength, a system with 160 wavelengths offers well over a Terabit/second bandwidth.

WDM schemes are found in long haul carrier core networks where the cost of installing hundreds or thousands of miles of fiber optic cable far exceeds the cost of new electronics to increase capacity by adding more wavelengths on the same fiber. WDM or CWDM is also installed on dark fiber when customers need the extra capacity in metropolitan (MAN) networks.

Thanks to WDM and competitive carrier build-outs, fiber optic bandwidth is more affordable than ever. That's especially true for the new Ethernet over fiber services available to businesses in major metropolitan areas.