Archive | June 2016

What Will Affect the Longevity of Your Fiber Network?

When deploying a fiber network, people nowadays not only appreciate the high-speed broadband services, but the maintenance of how long it will last. After all, optical fiber is a particular type of hair-thin glass with a typical tensile strength that is less than half that of copper. Even though the fiber looks fragile and brittle, but if correctly processed, tested and used, it has proven to be immensely durable. With this in mind, there are essentially factors that will affect the longevity of your fiber network.

fiber network

Installation Strains

Stress, on the other hand, is a major enemy of fiber longevity, so the protection task is passed to the cable installer, who will ensure that the use of suitable strength elements limits the stress applied to the cable to much less than the 1 per cent proof test level. The installer then needs to ensure that the deployment process does not overstrain the cable. Figure 2 below illustrates a typical crew deployment for a trunk installation. The whole process should be paid more attention to the stress.

Figure 2 below illustrates a typical crew deployment for a trunk installation

Of the three techniques commonly used—pulling, pushing and blowing, only pulling creates undesirable stretching (tensile stress). Unlike metal, glass does not suffer fatigue by being compressed, and so the mild compression caused during pushing causes no harm to the fiber.

Surface Flaws

Optical fiber typically consists of a silica-based core and cladding surrounded by one or two layers of polymeric material (see in Figure 3). Pristine silica glass that is free of defects is immensely resistant to degradation. However, all commercially produced optical fibers have surface flaws (small micro-cracks) that reduce the material’s longevity under certain conditions. The distribution of flaws on the surface of the silica-based portion of the fiber largely controls the mechanical strength of the fiber. FS.COM fiber optic cables are well tested to ensure less surface flaws, like LC to ST fiber cable.

standard opticla fiber

To conquer this, reputable fiber suppliers carry out proof testing, which stretches the fiber to a pre-set level (normally 1 per cent) for a specified duration to deliberately break the larger flaws. And the user is then left with a fiber containing fewer, smaller flaws that need to be protected from unnecessary degradation. This means primarily stopping the creation of new flaws by coating the fiber with a protective and durable material for its primary coating.

Environmental Factors

Once deployed, the local environment has a big impact on fiber life. Elevated temperatures can accelerate crack growth, but it is the presence of water that has been historically of most concern. The growth of cracks under stress is facilitated by water leading to “stress corrosion”. You can check what the tendency of a fiber to suffer stress corrosion is by reviewing its “stress corrosion susceptibility parameter”, much more conveniently referred to as “n”. A high n value (around 20) suggests a durable fiber and coating.

Calculating How Long Your Network Will Last

Bearing in mind the three factors above, how can you calculate the lifetime of your fiber network? In general, the chances of a fiber being damaged by manual intervention, such as digging, over the same time frame is about 1 in 1,000. Quality fiber, installed by benign techniques and by careful installers in acceptable conditions should, therefore, be extremely reliable – provided it is not disturbed.

It is also worth pointing out that cable lengths themselves have rarely failed intrinsically, but there have been failures at joints where the cable and joint type are not well matched, allowing the fibers to move – for example, due to temperature changes. This leads to over stress of the fiber and eventual fracture.

Conclusion

To tell the truth, the biggest enemies to the carefully engineered reliability of fiber jumper can be either humans or animals, rather than the fused silica itself. The provided fibers are stored and coiled correctly, it is quite possible that they turn out to be stronger than we at first thought and perhaps the original flaws begin to heal with time and exposure to water under low stress levels. FS.COM offers high quality fiber cable assemblies such as Patch Cords, Pigtails, MCPs, Breakout Cables etc. All of our products are well tested before shipment. If you are interested, you can have a look at it.

40GBASE-LR4 CWDM vs. 40GBASE-LR4 PSM QSFP+ Transceiver

In response to the increasing bandwidth demands, the IEEE certificated 802.3ba Ethernet standard paving the way for the introduction of 40G and 100G Ethernet operations. Whether you believe it or not, the era of 40G Ethernet is upon us. 40GBASE QSFP+ (quad small form factor pluggable) portfolio offers customers a wide variety of high-density and low-power 40 Gigabit Ethernet connectivity options for data center, high-performance computing networks, enterprise core and distribution layers, etc. For instance, 40GBASE-SR4 and 40GBASE-LR4 QSFP+ transceiver are the common 40 Gigabit Ethernet connectivity options. 40GBASE-SR4 transceiver usually uses multimode fiber for short-reach application, while 40GBASE-LR4 QSFP+ is mostly favored by users for long-hual application. However, there are two links for 40GBASE-LR4 standards. One is coarse wavelength division multiplexing (CWDM). The other is parallel single-mode fiber (PSM). What’s the difference between them? In this article, a brief contrast between them will be introduced to you.

40GBASE-LR4 CWDM QSFP+ Transceiver

The 40GBASE-LR4 CWDM QSFP+ transceiver is compliant to IEEE P802.3ba 40GBASE-LR4 standard. This QSFP module supports link lengths of up to 10km over single-mode fiber (SMF) with duplex LC connectors. This transceiver converts 4 inputs channels of 10G electrical data to 4 CWDM optical signals by a driven 4-wavelength distributed feedback (DFB) laser array, and then multiplexes them into a single channel for 40G optical transmission, propagating out of the transmitter module from the SMF. Reversely, the receiver module accepts the 40G CWDM optical signals input, and demultiplexes it into 4 individual 10G channels with different wavelengths. The central wavelengths of the 4 CWDM channels are 1271, 1291, 1311 and 1331 nm (defined as members of the CWDM wavelength grid in ITU-T G694.2). Each wavelength channel is collected by a discrete photo diode and output as electric data after being amplified by a transimpedance amplifier (TIA).

CWDM-QSFP

40GBASE-LR4 PSM QSFP+ Transceiver

Unlike CWDM QSFP+ transceiver using a LC connector, PSM QSFP+ is a parallel single-mode optical transceiver with an MTP/MPO fiber ribbon connector. It also offers 4 independent transmit and receive channels, each capable of 10G operation for an aggregate data rate of 40G on 10km of single-mode fiber. Proper alignment is ensured by the guide pins inside the receptacle. The cable usually cannot be twisted for proper channel to channel alignment. In terms of a PSM QSFP+, the transmitter module accepts electrical input signals compatible with common mode logic (CML) levels. All input data signals are differential and internally terminated. The receiver module converts parallel optical input signals via a photo detector array into parallel electrical output signals. The receiver module outputs electrical signals are also voltage compatible with CML levels. All data signals are differential and support a data rates up to 10.3G per channel.

40G-PSM-QSFP

40GBASE-LR4 QSFP+—CWDM vs. PSM 

As noted before, 40GBASE-LR4 CWDM QSFP+ transceivers use a duplex LC connector via 2 optical single-mode fibers to achieve 40G without making any changes to the previous 10G fiber cable plant. However, 40GBASE-LR4 PSM QSFP+ transceivers use an MTP/MPO fiber ribbon connector via 8 optical single-mode fibers to reach 40G. Obviously, CWDM QSFP+ is a more cost-effective solution for 40G connectivity.

What’s more, in terms of the inner structure of an optical transceiver module, PSM QSFP+ uses a single uncooled CW laser that splits its output power into four integrated silicon modulators, which is much inexpensive than CWDM QSFP+. Besides, its array-fiber coupling to an MTP connector is relatively simple. A picture comparing the key differences between CWDM and PSM is shown below:

two links of QSFP+ 40GBASE-LR4

Additionally, the caveat is that the entire optical fiber infrastructure within a data center, including patch panels, has to be changed to accommodate MTP connectors and ribbon cables, which are more expensive than conventional LC connectors and regular SMF cables. Not to mention that cleaning MTP connectors is not a straightforward task.

Summary

To sum up, PSM and CWDM are the two links of 40GBASE-LR4 QSFP+ transceivers. Both of them can support a link distance of 10km. However, 40GBASE-LR4 CWDM QSFP+ are more common than 40GBASE-LR4 PSM QSFP+ because of its performance and low cost. Fiberstore offers a wide brand compatible 40G CWDM QSFP+ transceivers. Each of our fiber optic transceivers has been tested to ensure its compatibility and interoperability. For more information or quotation, please contact us directly.

How to Reduce the Cost of FTTH Architecture

In our digital world, people increasingly require higher bandwidth to facilitate daily life, whether for leisure, work, education or keeping in contact with friends and family. The presence and speed of internet are regarded as the key factor that subscribers would take into account when buying a new house. Recently there are a growing number of independent companies offering full fiber to the home (FTTH) services, ranging from local cooperatives and community groups to new operators. Today’s article will pay special attention to the reasons why we should implement FTTH network and the methods to reduce the cost of FTTH network.

Why Should We Deploy FTTH Network?

FTTH logo

No denying that the world is changing rapidly and becoming increasingly digital. People nowadays are knowledgeable workers who rely on fast connections to information stored in the cloud to do their jobs. Therefore, installing superfast FTTH broadband is an investment in equipping communities with the infrastructure they need to not just adapt to the present life, but to thrive in the future.

What’s more, the economic benefits of FTTH, for residents, businesses and the wider community are potentially enormous. While there are upfront costs in FTTH deployments, particularly around the last drop, equipment and methodologies are evolving to reduce these significantly. Fiber to the home is proven to increase customer satisfaction, and enables operators to offer new services, such as video on demand, 4K TV and smart home connectivity.

As well as bringing in economic benefits, FTTH broadband provides local businesses with the ability to expand, invest and seek new opportunities by providing rapid connections to major markets. All of this leads to increased investment in the rural economy, providing residents with more choice and stimulating growth.

What to Do?

Although deploying FTTH network might be similar cost as deploying copper network, there are some methods that you should know about reducing the costs of FTTH architecture. Adopting the following three principles helps achieve FTTH deployment, maximizing return on investment and dramatically reducing deployment times.

1. Reuse the Existing Equipment

Time and the total cost of FTTH deployment are typically relevant with the civil engineering side of the project, such as digging a new trench and burying a new duct within it. Where possible, crews should look to reuse existing infrastructure—often there are ducts or routes already in place that can be used for FTTH and in building deployments. These could be carrying other telecommunication cables, power lines, or gas/water/sewerage. Installing within these routes requires careful planning and use of cables and ducts that are small enough to fit through potentially crowded pathways. Figure 2 shows a generic point-multipoint architecture that fiber jumper plays an important part in it.

FTTH architecture

Additionally utilizing the push and pull cables in FTTH infrastructure simply reduce costs and install time as network installers can easily complete FTTH deployment by using pushing or pulling cables: pushing can be aided by simple, cost-effective handheld blowing machines, or pulled through the duct using a pre-attached pull cord. Even for more complex and longer environment, FTTH deployment can be quickly completed other than requiring expensive blowing equipment to propel the cable through duct.

2. Choose the Right Construction Techniques

If it is time to start digging, always make sure you use appropriate construction methods. The appropriate method will minimize cost and time by making construction work as fast and concentrated as possible, avoiding major disruption to customers or the local area. And remember to make sure you follow best practice and use the right fiber cable and duct that can fit into tight spaces and withstand the high temperatures of the sealant used to make roadways good.

FTTH deployment

The cable and duct used within FTTH implementations is crucial. Ensure that it meets the specific needs of deployments, and is tough, reliable and has a bend radius. It should be lightweight to aid installation and small enough to fit into small gaps and spaces in ducts. Also look to speed up installations with pre-connectorized cables that avoid the need to field fit or splice.

3. Minimize the Skills Required

Staff costs are one of the biggest elements of the implementation budget. Additionally, there are shortages of many fiber skills, such as splicing, which can delay the rate at which rollouts are completed. Operators, therefore, need to look at deskilling installations where possible, while increasing productivity and ensuring reliability. Using pre-connectorized fiber is central to this—it doesn’t require splicing and is proven to reduce the skill levels needed within implementations.

Conclusion

To cope with the digital world, the network is in constant need of enhancements and the increasingly stressed bandwidth and performance requires ongoing adjustment. Regardless of the FTTH architecture and the technology to the curb, the pressure is on for the network installer to deploy FTTH quickly and cost-effectively, while still ensuring a high quality, reliable installation that causes minimal disruption to customers and the local area. Fiberstore offers a variety of optical equipment that are suitable in telecom field. Our fiber optic cables are available in different optical connector, single-mode and multimode fiber as well as indoor or outdoor cables. For example, patch cord LC-LC are also provided.