What's fiber to the x (FTTx)

Fiber to the x (FTTx) is a collective term for various optical fiber delivery topologies that are categorized according to where the fiber terminates.

 

Optical fiber is already used for long-distance parts of the network, but metal cabling has traditionally been used for the stretches from the telecom facilities to the customer. FTTx deployments cover varying amounts of that last distance.

 

In an FTTN (fiber to the node or fiber to the neighbourhood) deployment, the optical fiber terminates in a cabinet which may be as much as a few miles from the customer premises. The cabling from the street cabinet to customer premises is usually copper.

 

 

In an FTTC (fiber to the curb or fiber to the cabinet) deployment, optical cabling usually terminates within 300 yards of the customer premises.

 

 

In an FTTB (fiber to the building or fiber to the basement) deployment, optical cabling terminates at the building, which is typically multi-unit. Delivery of service to individual units from the terminus may be through any of a number of methods.

 

 

In an FTTH (fiber to the home) deployment, optical cabling terminates at the individual home or business.

 

 

FTTP (fiber to the premises) is used to encompass both FTTH and FTTB deployments or is sometimes used to indicate that a particular fiber network includes both homes and businesses.

The FTTH Councils of Europe, North America and Asia-Pacific have agreed upon definitions for FTTH and FTTB. Standard definitions of the other terms have not yet been established.

 

The table below provides a graphical comparison of the most common FTTx topologies:

 

 

The table above was created by Wikipedia user Riick and is published under the terms of a Creative Commons Attribution-Share Alike license.

Which Fiber Optic Connector should you use?

The network cabling industry’s fiber optic manufacturers over the last few decades have been on a constant mission to develop the better fiber connector. This means lower cost, lower dB losses, easier to terminate out in the field. There have been over 100 connectors developed over the years but a select few have stood the test of time and beat out their competition. Below we will talk about the most common.

 

A fiber optic connector terminates at the end of a fiber optic cable and is used when you need a means to connect and disconnect the fiber cable quickly. A fiber splice would be used in a more permanent application. The connectors provide a mechanical connection for the two fiber cables and align both cores precisely so the light can pass through with little loss. There are many different types of connectors but many share similar characteristics. Many connectors are spring loaded. This will push the fiber ends very close to each other so as to eliminate airspace between them, which would result in higher dB losses.

 

There are generally five main components to a fiber connector: the ferrule, the body, the coupling structure, the boot and the dust cap.

 

Ferrule-the ferrule is the small round cylinder that actually makes contact with the glass and holds it in place. These are commonly made of ceramic today but also are made of metal and plastic.

 

Body-This sub assembly holds the ferrule in place. It then fits into the connector housing.

 

Connector Housing-This holds all sub assembly parts in place and has the coupling that will connect to the customer’s equipment. The securing mechanism is usually bayonet, snap-in or a screw on type.

 

Boot-This will cover the transition from the connector to the fiber optic cable. Provides stress relief.

 

Dust Cap-Just as it implies will protect the connector from accumulating dust.

 

There are many types of connectors on the market. The major differences are the dimensions and the method of connection to equipment. Most companies will settle on one type of connector and keep that as a standard across the board. It makes sense because all equipment has to be ordered with that specific connector type and to have 2 or 3 different connector types can get messy. For typical network cabling projects today LC is fast becoming the shining star of fiber connectors. LC is a small form factor connector which means it requires a much smaller footprint in your IT closet. Thus you can fit many more LC connectors into you fiber panels then say ST or SC connectors.

 

ST Connector

 

 

The ST connector (or Straight Tip) was the first popular connector type to be used as a standard for many organizations in their fiber network applications. It was first developed by AT&T. Often called the “round connector” it has a spring loaded twist bayonet mount with a 2.5mm round ferrule and a round body. The ST connector is fast being replaced with the smaller, denser SFF connectors.

 

SC Connector

 

The SC connector is a push-in/pull-out type connector that also has a 2.5 mm ferrule. It is very popular for its excellent performance record. The SC connector was standardized in TIA-568-A, and has been very popular for the last 15 years or so. It took a while to surpass the ST because of price and the fact that users were comfortable with the ST. Now it’s much more competitive with pricing and it is a very easy install, only requiring a push in and pull out connection. This is very helpful in tight spaces. Simplex and duplex SC connectors are available. The SC was developed by the Japanese and some say stands for Standard Connector.

 

FDDI/ ESCON Connectors

 

You may see FDDI and ESCON(IBM) duplex fiber connectors in older installations. These connectors will mate to their own networks and usually will be seen at the wall outlet locations. These connectors use a squeeze tab coupling mechanism. The closet side of the fiber will usually have a standard ST or SC connector. The FDDI/ESCON connectors can be mated to SC or ST connectors since they both have a 2.5mm ferrule. An adaptor would be required in this case. The FDDI stands for Fiber Distributed Data Interface.

 

LC Connector

 

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The LC connector was developed by Lucent Technologies, hence the LC. It is a Single Form Factor Connector that has a 1.25mm ferrule. The attaching mechanism is similar to an RJ-45 connector with the retaining clip. It is a smaller square connector, similar to the SC. LC connectors are often held together with a duplex plastic retainer. They are also very common in single mode fiber applications.

 

MT-RJ Connector

 

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MTRJ stands for Mechanical-Transfer Registered Jack and was developed by Amp/Tyco and Corning. MTRJ is very similar to an RJ type modular plug. The connector is always found in duplex form. The body assembly of the connector is usually made from plastic and clips and locks  into place. There are small pins present that guide the fiber for correct alignment. MTRJ’s  also are available in male or female orientation. They are only used for multi-mode applications. They can also be difficult to test because many testers on the market do not accept a direct connection. You usually need to rig up a patch cord adapter kit to make testing possible.

 

FC Connector

 

The FC connector you may find in older single mode installations. It was a popular choice that has been replaced by mostly ST or SC type connectors. It also has a 2.5mm ferrule. They have a screw on retaining mechanism but you need to be sure the key and slot on the connector are aligned correctly. FC connectors can also be mated to ST & SC’s through the use of an adaptor.

 

Opti-Jack Connector

 

The Opti-Jack is a clean, tough duplex connector cleverly designed around two ST-type ferrules in a package the size of a RJ-45. It has male and female (plug and jack) versions.

 

 

LX-5 is like a LC but with a shutter over the end of the fiber.

 

MU Connector

 

MU looks a miniature SC with a 1.25 mm ferrule. It’s more popular in Japan.

 

MT Connector

 

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MT is a 12 fiber connector for ribbon cable. It’s main use is for preterminated cable assemblies and cabling systems. Here is a 12 fiber MT broken out into 12 STs.

This connector is sometimes called a MTP or MPO which are commercial names.

 

Hopefully this guide may help you get an idea of what options are out there for your fiber optic connector needs.

 

As always, for all your fiber optic needs go to http://www.fiber-mart.com

MTP/MPO Cables—An Ideal Solution for High-Density Cabling

MTP/MPO Cables—An Ideal Solution for High-Density Cabling

by Fiber-MART.COM

For various reasons, the data quantity transmitted worldwide is growing exponentially and the need for ever-greater bandwidths continues unabated. Though the current data volumes demanded in backbone cabling can still be handled with 10 GbE, the forecast trends will require the introduction of the next technologies, 40 GbE and 100 GbE (Figure 1). Therefore, data centers must respond early to provide sufficient capacities and plan for upcoming requirements. To meet this demand, 40G QSFP+ transceivers, MTP/MPO cables and other related products are springing up like mushrooms in the market. They are important roles in the ultra-high density cabling in data centers. This post will focus on MTP/MPO cables in the data center.

Why MTP/MPO Cables Are Used?

For the reasons mentioned above, the number of network connections in data centers is on the rise rapidly. And the use of traditional fiber cables may make the data center crowed and difficult to be managed. To solve this problem, data centers have to achieve ultra-high density in cabling to accommodate all this cabling in the first place. The MTP/MPO cables, which bring together 12 or 24 fibers in a single interface (Figure 2), have been proven to be a practical solution. Incorporating to meet the 40GBASE-SR4 and 100GBASE-SR10 standard, The MTP/MPO multi-fiber connector of MTP/MPO cables is about the same size as a SC connector but can accommodate 12 or 24 fibers. Thus, MTP/MPO cables provide up to 12 or 24 times the density and offer savings in circuit card and rack space.

 

Details of MTP/MPO Cables

MTP/MPO cables are composed of MTP/MPO connectors and fiber cables, other connectors such as LC may also be found in some kinds of MTP/MPO cables. And the fiber cables used are generally OM3 and OM4, which are laser optimized multi-mode optical fibers. Unlike traditional connectors, the MTP/MPO connector should be carefully used to ensure proper connections are made. Thus, it is important to have an overall understanding of MTP/MPO connectors.

 

As is shown in the following figure, each MTP/MPO connector has a key on one side of the connector body, and the key sitting on top referred to as the key up position. In this orientation, each of the fiber holes in the connector is numbered in sequence from left to right. People often refer to these connector holes as positions, or P1, P2, etc. In addition, there is a white dot on the connector body to designate the P1 side of the connector when it is plug in.

 

There are two types of MTP/MPO adapters based on the placement of the key: key up to key down and key up to key up. When you want to connect two MTP/MPO connectors, it is important to choose a right adapter with keying designed to hold the two facing ends of the MTPs incorrect alignment. The following figure shows the right connections of two MTP/MPO connectors within the adapter.

 

Common Types of MTP/MPO Cables

MTP/MPO trunk cable and MTP/MPO harness cable are two common kinds of MTP/MPO cables. MTP/MPO trunk cables serve as a permanent link connecting the MTP/MPO modules to each other. And they can offer flexibility in changing the connector style in the patch panels. MTP/MPO harness cables provide a transition from multi-fiber cables to individual fibers or duplex connectors. These cables are offered for various applications for all networking and device needs like 100G modules including CFP, CFP2 and CFP4 series.

Conclusion

There is no way around the migration to 40 and 100 GbE. As the figure shows above, 40 and 100 GbE will be broadly introduced in the near future. Therefore, Data center managers will have to lay the groundwork today and adapt their infrastructure to meet future requirements. MTP/MPO cables are inevitable the ideal solution to meet these needs. fiber-mart.com is now striving to be a leading supplier of MTP/MPO connection components. We manufacture and distribute a wide range of MTP/MPO connection components including the MTP/MPO connectors, adapters, cables, cassettes, adapter panels, loopback modules, etc.