Dark Fiber Gives You Control

By: John Shepler

Higher and higher bandwidths are expected in business IT infrastructure. That includes the local networks and leased lines for metro and wide area bandwidth. It’s about more than that, though. Just as important are parameters such as latency, packet loss and jitter. Security is a major concern for all network operations. Finally, the ability to make changes, create workarounds and rapidly bring resources online are important to keeping network operations running smoothly.

Big Bandwidth Means Big Pipes
The need for increasing bandwidth has resulted in a mass migration from copper wirelines to fiber optic cables. Copper may still make sense to the desktop, but outside network connections need the capacity of fiber.

Fiber leased lines are available from 10 Mbps to at least 10 Gbps, with 100 Gbps service becoming more readily available. They can be configured as point to point dedicated lines or dedicated Internet access. Many companies need some combination of the two. The Internet is essential to communicating with customers and suppliers. Direct lines to cloud service providers and between company facilities provide more consistent performance, lower latency and higher security.

Wavelengths are Like a Private Fiber Link
Fiber optic cables are said to have unlimited bandwidth. While that might seem like an exaggeration, in practice it is pretty hard to run out of bandwidth. Each cable has multiple fibers, sometimes as many as 100 in a bundle. Each of those fibers can carry multiple streams of non-interfering data through a process of wavelength division multiplexing.

There are two schemes. Coarse Wavelength Division Multiplexing can divide the fiber into a dozen or more laser colors called Lambdas, all traveling the same time. Dense Wavelength Division Multiplexing ups that count to 80, 96 or more separate wavelengths using more sophisticated equipment.

Note that each wavelength acts like its own fiber. It is unaware of other wavelengths on the same strand. When you lease a wavelength your data is not multiplexed with anyone else’s. You have exclusive use of all the bandwidth on that wavelength, which might be as high as 10 Gbps. Need more bandwidth? Lease another wavelength. Until the fiber bundle is fully loaded, you’ll never have to run more cable.

Dark Fiber Gives You Ultimate Control
What’s better than a wavelength? Having the entire fiber to yourself. That sounds great until you think about the cost of running your own fiber. It makes total sense on your own property, but what about connections across town or across the country? Unless you are in the business of providing carrier services, you’ll find trenching your own fiber to be cost prohibitive.

There is a way to get pretty much your own fiber. Lease an unused strand from a service provider. That’s more doable than you might think. Remember that it doesn’t make sense to go to all the trouble of burying a single fiber strand when you can bury a multi strand cable or even multiple multi strand cables for not much more cost. That way, a carrier only has to lay in the fiber once and have capacity to spare for decades.

These unused strands are called “dark” fiber because there is no laser light illuminating them. It could be your job to light the fiber. The carrier will simply give you access at each end of the fiber and the rest is up to you.

Clearly this beyond the capability of smaller companies, but they are likely well served by lit fiber options already available. Larger and more sophisticated IT organizations may be able to make good use of dark fiber for research labs, medical campuses, video content creation and transport, engineering & manufacturing, and other demanding applications.

Benefits of Dark Fiber
Owning exclusive rights to use an entire fiber is the next best thing to building your own. You do need to provide the termination equipment at each end and manage those resources. That may include your own DWDM equipment to generate multiple wavelengths for all the bandwidth you can reasonably use.

Without competing customers, there is no need for multiplexers to add and drop connections along the route. The fiber serves your locations only. The lack of unnecessary equipment in the line minimizes latency. Unlike the Internet there is no need for routers every so often to direct traffic. You not only have minimal latency, there is no reason it should vary from common carrier routing decisions, and no congestion as long as you are not overloading the capacity of the fiber or individual wavelength.

Security is another big benefit of dark fiber. There is no sharing of bandwidth among customers. This is similar to the old “nailed up” copper private point to point line. You need to trust the operator of the fiber, but don’t have to worry about the other customers. Of course, encryption on top of dedicated fiber gives you the most security you’ll get in point to point transmission.

Dark Fiber Availability
As fiber is being extensively deployed for Internet, cable television, and cellular towers, dark fiber is also becoming more and more available. Competitive fiber network operators and some cable system operators have lots and lots of extra capacity installed. They are more than happy to lease out unused strands when there are dozens sitting dark.

Do your needs demand the capacity, flexibility, and security that dark fiber offers? Find out what dark fiber options are available for your business locations.

ISDN PRI For PABX

The Private Automatic Branch Exchange, PABX, also known as the PBX, is the telephone system of choice for medium and large companies. If your company is large enough to invest in a PABX, it’s got enough employees to require multiple outside phone lines. The question is what is the best technology to supply those phone lines?

Businesses that only need a handful of telephone lines usually start off with a few analog POTS (Plain Old Telephone Service) lines and add more, one at a time, as needed. At some point you start to wonder if a digital trunk makes more sense than a dozen separate POTS lines. You are likely right.

Digital trunks are a technology to transport multiple phone calls to a subscriber using fewer wires. Each analog line requires a separate pair of wires. A trunk may use one or two pair to carry 23 or 24 phone calls.

How is this accomplished? The most popular technique is digitizing each phone call and then multiplexing all those bits onto a serial data stream. The line is synchronized at both ends so that individual time slots can be separated into channels. Each channel holds one concurrent call. This technology was standardized by Bell Labs in the T-Carrier system. The most popular of the T-Carriers is T1, although T3 is still used but generally called DS3.

The basic T1 telephone line consists of 24 identical channels of 8 bits each sampled 8,000 per second. That adds up to a line speed of approximately 1.5 Mbps. T1 lines were the first deployed as digital telephone trunks. PABX systems often have T1 interface cards and connectors so you can just plug in a T1 line and have up to 24 outside lines available. Larger systems have multiple line interfaces for 48 or more outside telephone lines.

T1 telephone is still highly popular, but is generally deployed in the form of ISDN PRI. PRI means Primary Rate Interface which uses a channelized T1 line for transport. ISDN is another standard called Integrated Services Digital Network. ISDN uses 23 of the T1 time slots for telephone lines but reserves one channel for data and switching. You give up the capability of one telephone line but gain much faster call switching plus Caller ID and ANI (Automatic Number Identification) for the other 23 phone lines.

ISDN PRI is readily available, less expensive than ever before and compatible with most PABX systems. With the capability of handling up to 23 outside lines, it has the capacity to handle the needs of most small to medium size offices and contact centers. By adding additional interfaces, a PABX system can handle 46, 69, 92 or over 100 outside telephone lines.

The competition for ISDN PRI is a newer service called SIP Trunking. SIP is the switching system used for VoIP telephone systems. A SIP Trunk is basically a packet network line with the bandwidth to handle multiple simultaneous calls and perhaps data transfers as well. Voice packets are given priority on a SIP Trunk to prevent call distortion and dropping of phone calls. A T1 line can be used as a SIP Trunk as well as for ISDN PRI, depending on how it is connected at each end.

Many PABX systems can now directly connect to SIP Trunks as well as T1 telephone lines and ISDN PRI. Some are IP PBX systems that use IP telephones as well as standard analog desk phones. What threatens all of these trunks now is not a new design of PABX but dumping the PABX completely in favor of hosted telephone services.

Hosted voice or telephone in the cloud moves the PABX from your office to a cloud service provider hundreds or thousands of miles away. You swap our your phones with IP telephones and a SIP Trunk. At the far end, the service provider does all of your in-house and outside line switching. It’s the provider who contracts for ISDN PRI trunks or other connection to the public telephone system. You simply pay per phone per month for local and long distance service plus in-house call switching. Often that is one flat fee per “seat.”

Which type of telephone system and trunking arrangement is right for your company? Get competitive quotes for POTS, T1 telephone, ISDN PRI, SIP Trunking and Hosted Voice to help with your trade study and selection.

SONET Rings To Support Ethernet

The hot bandwidth service these days is Carrier Ethernet. Everybody wants it once they see the cost advantage over the WAN connection they have now. The big question is can they get it?

In most cases, the answer is yes for a couple of reasons. First, new competitive carriers are rapidly building out their fiber optic core networks based on IP from the start. These networks are tailor made for Carrier Ethernet services. It’s relatively easy to get a point to point Ethernet connection between two distant business locations and use it to link their respective LANs. The result is one larger bridged LAN that enables all employees to be on essentially the same corporate network.

The other reason that Ethernet WAN services are so readily available is that established SONET fiber optic networks are being pressed into service to deliver Ethernet to the customer. This is known as Ethernet over SONET or EoS. The core of the network is still SONET, but operations at that level are invisible to you. As far as you are concerned, your connection is Ethernet all the way.

There’s no reason that SONET can’t transport Ethernet, ATM or other protocols. It was designed as a transport technology and has been adapted over the years to carry whatever traffic required hauling. The origins of SONET, like T-Carrier, are with the telephone industry. The name is an acronym for Synchronous Optical NETwork. Note the term synchronous. That tells you SONET is set up to be a highly synchronized network. The designed is based on multiplexing thousands of small channels called DS0s that each hold one telephone call. These DS0 building blocks can be combined to create T1 and T3 lines or SONET services such as OC-3, OC-12 and OC-48.

The beauty of synchronization for circuit switched architectures based on time division multiplexing is that everything is orchestrated so tightly and you can easily multiplex and demultiplex channels and higher level services. The device that does this is called an ADM or Add/Drop Multiplexer. An ADM can drop off a T1 line, DS3, OC3 or other service at your door from a much higher speed fiber line that carries traffic for many customers.

How does Ethernet squeeze into those tiny telephone channels? It takes some doing, considering that each DS0 carries exactly 64 Kbps. That’s about the speed of an old dial-up modem. What the industry has done is replace the telephone oriented channels with large concatenated frames and various mapping techniques to more efficiently carry Ethernet packets. SONET networks can now readily carry Ethernet services from standard 10 Mbps Ethernet to 100 Mbps Fast Ethernet, 1000 Mbps Gigabit Ethernet (GigE), and 10 Gigabit Ethernet (10GigE).

A feature of most SONET networks that makes them highly reliable is their twin ring design. Two separate fiber strands are used simultaneously. Each carries the same traffic, but in opposite directions. If a fault occurs in the working ring, the network switches over to the protection ring within 50 mSec. This self-healing property works best when the two rings are widely separated so that a single backhoe cut or equipment fault doesn’t take out both rings at once.

Ethernet over SONET and native IP networks are making Carrier Ethernet services of all speeds readily available for businesses looking to upgrade their bandwidth connections at reasonable costs. How much are we talking? Find out with an instant online Ethernet Fiber quote for 10 Mbps to 1 Gbps service levels. Higher bandwidths and SONET services quotes need some manual effort but will be sent to you promptly.

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.

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.

AboveNet Core Wave Makes Dedicated Wavelength Bandwidth Available

What do you do when ordinary bandwidth is no longer up to the task? You go above and beyond with AboveNet’s Core Wave service. For demanding financial services, media, health care, retail and government applications, you really do have to get to the core of fiber optic transport. The very core.

Most telecom services are electrically multiplexed somewhere along the way. What multiplexing does is combine your bandwidth service with dozens, hundreds or thousands of others to fill the capacity of a fiber optic core network. But what if you have enough demand on your own to take all the bandwidth a service provider can deliver?

One answer is to become your own service provider. You do this buy building-out or buying fiber strands or even entire fiber optic cables. That’s what Cable TV MSOs do. So do major telecom service providers. But bandwidth is their business. It’s what they do to generate income. You aren’t really in the business of bandwidth. You simply want to use large amounts of bandwidth to enable your business processes. Does investing large amounts of capital in fiber infrastructure really make sense for your corporate mission?

Of course it doesn’t. What does make sense is to partner with a service provider that has already made the investment and has enough bandwidth capacity at their disposal to meet your current and future needs. AboveNet has that capability and now they are making it available to large organizations in major markets.

Let’s take a look at AboveNet Core Wave. It’s a high capacity bandwidth service for point to point connectivity in metro areas, like New York City. Right now you can get 1 Gbps, 2.5 Gbps and 10 Gbps service. The platform is scalable, so that when demand justifies it AboveNet can also offer 40 Gbps and 100 Gbps bandwidth services.

How are they doing this? The platform is built on a fiber optic network managed by ROADMs. A ROADM is a Reconfigurable Optical Add Drop Multiplexer. This is the cutting edge of fiber optic networking. What a ROADM does is manage the traffic on the network optically. Each fiber transports not one, but many different light beams known as Lambdas or wavelengths. Each wavelength is said to have a different color, although these are in the infrared spectrum and not visible like the colors from a prism. A ROADM can manage dozens or hundreds of wavelengths in a process known as DWDM or Dense Wavelength Division Multiplexing.

Normally wavelengths have such high carrying capacity that they transport traffic for many companies. But Core Wave gives you the option of having your own dedicated wavelength. The wavelength is like a blank slate to be written on, so you are not forced into the protocol of the core network. AboveNet gives you the choice of Ethernet, SONET/SDH, or Fibre Channel for storage networking.

Are your bandwidth needs pressing the limits of conventional telecom services? If so, perhaps it is time you moved up to fiber optic wavelength services, like AboveNet Core Wave. Why not check pricing and availability now? There is likely more capacity available than you think.