What is a Fiber Optic Attenuator and what is it used for?

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The Fiber Optic Networks are the fastest networks today. They provide high bandwidth, long distance, reliable network solution. The two main components of a stable Fiber Optic Network are optical transceivers and optical cables. The whole solution is based on an electrical signal converted into optical light and then being transmitted by the optical transceiver down an optical cable. This light travels down the cable through one or multiple optical fiber strands. Depending on the type of transceivers and cables, the bandwidth and distance of the connection may vary.
The ability of the optical transceivers to transmit the optical light down the cable depends on their optical power. One major characteristic of the optical power of transceivers is the optical data link bit error rate. Having too much, or too little power can result in high data link bit error rates causing an intermittent connection. When having too little power the noise inside the cable is starting to become a problem because it interferes with the optical light. Having too much power will cause the receiver amplifier to saturate beyond the limit. This is mainly happening in Single-mode systems with laser transmitters. This is known as optical fiber attenuation. Optical fiber attenuation refers to the loss of optical energy of the optical light which happens while the optical light travels through the cable.
Generally only Single-mode systems, and short distance particular, have the need for attenuators. Multi-mode attenuators don’t have the need for attenuators because their transmitters, even VCSELS, don’t have enough power to saturate receivers.
In the past when people ran into these kinds of problems their solution was to wrap the cable around a round object like a pen, until the power is evened out and the desired attenuation is met. However, as the fiber optic cable is subjected to various stress including banding, today we can easily avoid these problems with the help of the Fiber Optic Attenuator. The Fiber Optic Attenuator is a device that is used to lower down the optical power so the receiver doesn’t get saturated. In today’s attenuators the reducing of power is mostly done by absorbing the extra optical light. Today’s attenuators are ultra-precise in reducing the power to a fixed or adjustable amount. They are also used for testing of the dynamic range of photo sensors and detectors.
Fiber Optic Attenuators exist in various shapes and sizes, however the most known and used are:
Fixed Power Attenuators- These attenuators are a compact size attenuators designed to reduce the power to a certain amount. As the signal approaches the communication device the power of the signal is reduced. Because of the way they function they are reducing the signal reflection effect and provide a more accurate transmission of the data. These attenuators are available with either multi-mode or single-mode fibers. They are mainly used for single-mode solutions in the LAN, CATV and Service Providers.
Variable Power Attenuators- These attenuators are slightly bigger than the fixed attenuators. They are mainly used for testing or equalizing the power between two signals. Unlike the fixed attenuators, these attenuators can offer a wider range of adjustable power values. Their main function consists of directly blocking the optical light and as a consequence they are insensitive to polarization. They are also available for multi-mode and single-mode fibers.
All BlueOptics© Attenuators are developed for ultra-sensitive power adjustments. They are available with different connectors: LC-APC (SFA21BAXX), LC-PC (SFA21BKXX for Single-mode and, SFA21EKXX for Multi-mode) SC-PC (SFA22BKXX), SC-APC (SFA22BAXX) and ST-PC (SFA23BKXX). All BlueOptics© Attenuators have a ceramic ferrule guaranteeing the best attenuation values and working in temperatures between -40°C and +75°C. All BlueOptics© Attenuators are manufactured by the leading manufacturers for connectors like Amphenol, Diamond and Nissin Kasei. All BlueOptics© Attenuators are tested after their manufacturing process with a highly precise interferometer and Optical-Time-Domain-Reflectometry to ensure only the highest quality attenuators are offered on the market. All BlueOptics© Attenuators are standardized and they all meet the IEC-61034, IEC-754-1, IEC 60332-1, IEC 60332-3, IEC/EN 60950 and RoHS standards. They offer a lifetime of 1500 mating cycles, 25 years warranty and a lifetime support.

How to use a Fiber Patch Cord

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Fiber optic patch cables are a very important part of any network. They are used to connect different network devices of various types with each other. These cables are produced in many different colors so they are easily distinguished and combined. Generally they are used for short range connections and usually they are no longer than 2 meters in length. Every patch cord is fitted with a specific connector at each end. When installing patch cords there are some key steps and things to note:
Be careful with the bending. The bending of a cable is measured as bending radius. There are 2 relevant minimum bending radii, one is for patch cord installation and one is for the patch cord once it’s installed. During the installation of the patch cord the minimum permited bend radius is greater than it is when the cable is placed in its final position. This is mainly because during the installation there is a lot of pulling and tension over the cable.
Make sure not to go beyond the maximum pulling forces during its installation. This will ensure the cable is not damaged and its performance impaired during installation.
Minimize the twisting and bending of the patch cord during its installation.
During patch cord installation, cable management precautions that should be observed include the elimination of cable stress caused by excessive tension, tightly bunched cords and sharp bends.
Always make sure not to exceed the temperature variations because more than often attenuation increases with temperature, typically 0.4% per oC for Cat 5e cables. The temperature variations can be found in the table below.
It is highly advisable to keep the cables in place using zip ties or other kind of patch management systems. For easier cable management and identification always keep the groups of cables as small as possible.
Always label the cables for easier identification. In a professional network infrastructure the cable labeling is covered by the latest labeling standard, ANSI/TIA/EIA 606A. This standard recommends that a printed self-laminated wrap around label should be used whenever possible.
Keep in mind that Alien crosstalk (AXT) may occur and it should be minimized if possible. The Alien crosstalk is an electromagnetic noise that can occur in a cable that runs alongside one or more other signal-carrying cables. This is most commonly found with 10G cables. This crosstalk is especially important because it can cause a lot of problems and it can’t be eliminated by the conventional phase cancellation techniques. The Alien crosstalk degrades the performance of the connection by reducing the signal to noise ratio (SNR). Alien crosstalk can be minimized by avoiding installation in which cables are bundled together or run parallel to one another in close distance. The use of patch panels that leave additional space between the racks is recommended. Another way of reducing the Alien crosstalk is by using shielded patch leads.
Avoid mixing cable types and bundling them into groups. If there is no other choice but mixing them, leaving at least 15mm space between them is a must for a stable performance.
Keep in mind that beforehand planning and designing is the initial and critical step in installing patch cords. Properly designing the whole cable infrastructure and properly labeling it will eventually save a lot of time and finances. The practices mentioned above will ensure a stable network and a solid ground for future network upgrades.

The difference between OM3 and OM4 fibers

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A fiber-optic is made of glass or plastic and transmits signals in the form of light. Optical fibers use reflection to propagate the light through a channel. A high dense glass or plastic core is surrounded by a less dense glass or plastic cladding respectively. The difference in density of the two materials must be enough to reflect the beam of moving light back into the core, instead of being refracted into cladding. This phenomenon is called total internal reflection.
A fiber-optic is made of glass or plastic and transmits signals in the form of light. Optical fibers use reflection to propagate the light through a channel. A high dense glass or plastic core is surrounded by a less dense glass or plastic cladding respectively. The difference in density of the two materials must be enough to reflect the beam of moving light back into the core, instead of being refracted into cladding. This phenomena is called total internal reflection.
Optical fiber can be used as a medium for communication. It is particularly beneficial for long-distance communications, since the light propagates inside the fiber with very little attenuation as related to copper cables.
The benefits of optical fiber with deference to copper systems are:
Wider bandwidth, a single optical fiber can support many voice calls or TV channels as compared to copper wire.
Electrical insulator, optical fibers are non-conductive, so optical fibers can be looped on electric poles alongside high voltage power cables. Resistance to electromagnetic interference, light transmitted through the optical fiber is not affected by nearby electromagnetic radiation; therefore the information transmitted through the optical fiber is protected from electromagnetic interference.
Low attenuation loss over long distances, power loss can be as low as 0.2 dB per km in optical fiber, which allows transmission for greater distances without the need for frequent repeaters.
Based on light propagation method, optical fibers can be classified into two main types that are Multi-mode and single mode. Multi-mode can be implemented in two forms: step-index and graded-index.
Multi-mode Fibers
Multi-mode is so named because multiple beams from a light source move through the core in different paths. How these beams move within the cable, depends on the structure of the core. The word “index” here refers to the index of refraction. In Multi-mode step-index fiber, the density of the core remains the same from the center to the edges. The term step index refers to the suddenness of this change, which contributes to the distortion of the signal as it passes through the fiber. Another type of Multi-mode fiber is called Multi-mode graded-index fiber. As discussed above, the index of refraction is related to density. A graded-index fiber is one with changing densities. Density is much higher at the center of the core and decreases slowly to its lowest at the edge.
Single-mode Fibers
Single-Mode uses step-index fiber and an extremely focused source of light that bound the beams to a small range of angles. The single mode fiber is manufactured with a far smaller diameter than that of Multi-mode fiber, and with significantly lower density.
OM3 and OM4 Fibers compared
Multi-mode fibers are identified by the OM (optical mode) label. Before we discuss the difference between OM3 and OM4 fiber types, these are few thing to know which are common in both types. The connectors used for both types are same, the transceivers used in both fibers are the same, since both operate on 850nm VCSELS (Vertical-Cavity Surface-Emitting Lasers), and the fiber size is same 50/125µ. Also be noted that OM3 is fully compatible with OM4.
Nowadays OM3 and OM4 have been everywhere for years, even if OM4 cable has been in production for about 10 years. However, it was standardized in 2009 and is called OM4 cable since then. Previously it was identified by several names such as OM3+ or Enhanced OM3.
There is just construction difference between both fiber cables. The difference in internal construction of OM4 cable within 50/125µ size allows the OM4 cable to operate on higher bandwidth. When measured at 850nm, OM3 operates at a bandwidth of 2500 megahertz, while OM4 has a bandwidth of 4700 megahertz.
Range of OM3 and OM4 fibers
An OM3 can support 10 gigabit at 300 meters, whereas an OM4 can support 10 gigabit for a distance of 550 meters. As far as 40 gigabit and 100 gigabit are concerned, OM3 will achieve 100 meters, on the other hand OM4 is capable to reach up to 150 meters.
Summary
As stated earlier, the only variance among an OM3 and an OM4 is the actual fiber cable. The cost for OM4 is higher due to the manufacturing. The wider bandwidth available in OM4 cabling allows longer link lengths for 10 gigabit, 40 gigabit and 100 gigabit systems.
Costs vary depending on the construction type of the cable. However, OM4 cable is much expensive as of OM3 cable. There are several factors at here which are used to figure out whether OM3 or OM4 is needed. But the origin is the cost versus what distances needed. In the perfect example, if someone had abundant resources, they would just use single mode fiber. Since single mode has all the bandwidth one need, so one can go quite of distance but it is very expensive. As most of all data centers have their premises under 100 meters so it really just comes down to a costing issue right there.

Should I use compatible SFP or SFP+?

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SFP – Small Form-Factor Pluggable Module
SFP, small form-factor pluggable for short, is a compact, hot-pluggable transceiver module used for both telecommunication and data communications applications. SFP transceiver can be regarded as the upgrade version of GBIC module. SFP most often used for Fast Ethernet of Gigabit Ethernet applications. They are efficiently supporting speeds up to 4.25 Gbps.
The SFP transceiver is not standardized by any official standards body, but rather is specified by a multi-source agreement (MSA) among competing manufacturers.
SFP + – Small Form-Factor Pluggable Module
SFP+ is an enhanced version of the SFP that supports data rates up to 16 Gbps. SFP+ supports 8 Gbit/s Fibre Channel, 10 Gigabit Ethernet and Optical Transport Network standard OTU2. It is a popular industry format supported by many network component vendors. Although the SFP+ standard does not include mention of 16G Fibre Channel it can be used at this speed. Besides the data rate, the big difference between 8G Fibre Channel and 16G Fibre Channel is the encoding method. 64b/66b encoding used for 16G is a more efficient encoding mechanism than 8b/10b used for 8G, and allows for the data rate to double without doubling the line rate. The result is the 14.025 Gbit/s line rate for 16G Fibre Channel.
Should I use compatible SFP or SFP+ ? YES ! Why not ?
Many manufacturers restrict their devices to accept only original SFP modules of the same brand, as identified by their vendor ID. Due to sometimes significant price differences between original and generic or compatible modules, there is a large market of “compatible” or “third party” modules that are programmed to show the appropriate vendor.  Third-party SFP manufacturers have introduced SFPs with “blank” programmable EEPROMs which may be reprogrammed to match any vendor ID. When it is plugged into a Catalyst’s SFP port the first time, the Catalyst queries this chip for its credentials. If it’s not Cisco, your Cisco Catalyst switches would be configured by default not to work with the 3rd party (non-Cisco) SFPs, so the Catalyst would automatically shut the port down entirely.
Cisco wants their customers buying only Cisco hardware, which is -to say the least- more expensive than anyone else on the market. They make their own optical transceivers, and try very hard to convince buyers that only official Cisco hardware will work. Since SFPs aren’t overseen by a central standards body -unlike WiFi, for example- there’s no one around to tell Cisco not to do it. The primary benefit is the cost savings. The difference in price often exceeds 80 percent or more. Because transceiver costs are a significant part of the total system cost, it is important for designers to minimize these costs.
Warranty period
Of course, the other concern is the warranty. Most manufacturers offer short-term warranties, but consider buying from a vendor that throws longer service and support terms into the deal. A quality third party SFP should be able to provide years of performance, and be able to move across several pieces of hardware as your needs change over the years
Testing & Verification
There are methods to test and verify the 3rd-party transceiver modules, but it’s not always as easy as it seems. We can conduct some of the following tests.
Test for an Acceptable Bit-Error Ratio
Test to Determine Interoperability With a Worst-Case Transmitter
Determine the Minimal Power Level & Jitter Level
Try Performing the Optical Eye-Mask Tests
Verify Compliance With Multiple Samples
Know About Instrumentation Effects
BlueOptics high availability SFP+ Transceivers meet or exceed industrial standards, such as CE and RoHS as well as the regulations of the FCC. Through continuous monitoring before, during and after the production process, according to ISO9001, CBO reaches a steady quality of each BlueOptics SFP+ Transceiver.  Another feature available when purchasing from CBO-TEchnology is the telephone support call. If you run into trouble with your unit, you can get in touch with our support center for help.
If you’re still hesitant about trying compatible optics from a third party manufacturer, the best way to ensure that you’re getting a reliable product at a good deal is to choose us as a vendor you trust, as we have  a proven track record of quality products and great customer service. Ask us to send you samples to test to your specifications to find out whether the units live up to your standards, and get your network running without unnecessarily straining your budget.

What Ethernet Standards can be used with SFP+ ?

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The enhanced small form-factor pluggable (SFP+) is an enhanced version of the SFP that supports data rates up to 16 Gbit/s.
The SFP+ specification was first published on May 9, 2006, and version 4.1 published on July 6, 2009. SFP+ supports 8 Gbit/s Fibre Channel, 10 Gigabit Ethernet and Optical Transport Network standard OTU2. It is a popular industry format supported by many network component vendors.
SFP+ connectivity are the most flexible and scalable Ethernet adapters for today’s demanding data center environments. The escalating deployments of servers with multi-core processors and demanding applications such as high performance computing (HPC), database clusters, and video-on-demand are the types of applications driving the need for 10-gigabit connections.
10 Gbit/s SFP+ modules are exactly the same dimensions as regular SFPs, allowing the equipment manufacturer to re-use existing physical designs for 24 and 48-port switches and modular line cards.
Although the SFP+ standard does not include mention of 16G Fibre Channel it can be used at this speed. Besides the data rate, the big difference between 8G Fibre Channel and 16G Fibre Channel is the encoding method. 64b/66b encoding used for 16G is a more efficient encoding mechanism than 8b/10b used for 8G, and allows for the data rate to double without doubling the line rate. The result is the 14.025 Gbit/s line rate for 16G Fibre Channel.
Like previous versions of Ethernet, 10GbE medium can be either copper or optical fiber cabling.  However, because of its bandwidth requirements, higher-grade copper cables are required: category 6a or Class F/Category 7 cables for lengths up to 100 meters. The 10 Gigabit Ethernet standard encompasses a number of different physical layer (PHY) standards.
SFP+ modules do only optical to electrical conversion, no clock and data recovery, putting a higher burden on the host’s channel equalization. SFP+ modules share a common physical form factor with legacy SFP modules,
Select the appropriate transceiver to provide the required reach. Depending on the product, you can obtain SFP+ transceivers for cable distances of up to 15 meters (m), 400 m, 10 kilometers (km), 40 km, and 70 km. Alternatively, you can use a direct attach cable.
PHY TYPE
REACH
10GBASE-SR
Up to 300m link length with 2000 MHz*km MMF (OM3). Optical interoperability with 10GBASE-SRL
10GBASE-SRL
Up to 100m link length with 2000 MHz*km MMF (OM3). Optical interoperability with 10GBASE-SR
10GBASE-LRM
Up to 220m link length with 50 μm or 62.5 μm MMF links
10GBASE-LR
Up to 10km link length on standard single-mode fiber (SMF, G.652)
10GBASE-CR
Pre-terminated twin-ax copper cables with link lengths of 1m, 2m, 3m and 5m (SFP+ to SFP+ or QSFP to 4 x SFP+)
Bi-Directional Single Strand
Unlike previous Ethernet standards, 10 Gigabit Ethernet defines only full duplex point-to-point links which are generally connected by network switches; shared-medium CSMA/CD operation has not been carried over from the previous generations Ethernet standards. Half duplex operation and repeater hubs do not exist in 10GbE.
Multiple vendors have introduced single strand, bi-directional 10 Gbit/s optics capable of a single-mode fiber connection functionally equivalent to 10GBASE-LR or -ER, but using a single strand of fiber optic cable. Analogous to 1000BASE-BX10, this is accomplished using a passive prism inside each optical transceiver and a matched pair of transceivers, using a pair of wavelengths such as 1310 nm / 1490 nm or 1490 nm / 1550 nm. Modules are available in varying transmit powers and reach distances ranging from 10 to 80 km.

The Application of 100BASE-X SFPs Transceiver

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In computer networking, Fast Ethernet is a collective term for a number of Ethernet standards that carry traffic at the nominal rate of 100 Mbit/s (the original Ethernet speed was 10 Mbit/s). Fast Ethernet is sometimes referred to as 100BASE-X, where “X” is a placeholder for the FX and TX variants. The standard specifies the use of CSMA/CD for media access control. A full-duplex mode is also specified and in practice all modern networks use Ethernet switches and operate in full-duplex mode.
The “100” in the media type designation refers to the transmission speed of 100 Mbit/s, while the “BASE” refers to baseband signalling. The letter following the dash (“T” or “F”) refers to the physical medium that carries the signal (twisted pair or fiber, respectively), while the last character (“X”) refers to the used encoding method.
Small Formfactor Pluggable (SFP)
The small form-factor pluggable (SFP) is a compact, hot-pluggable transceiver used for both telecommunication and data communications applications. The form factor and electrical interface are specified by a multi-source agreement (MSA) under the auspices of the SFF Committee. It is a popular industry format jointly developed and supported by many network component vendors. The SFP interfaces a network device (a switch, router, media converter or similar device) to a fiber optic or copper networking cable.
100BASE-TX SFP Transceiver
100BASE-TX is the predominant form of Fast Ethernet, and runs over two wire-pairs inside a category 5 or above cable. Like 10BASE-T, the active pairs in a standard connection are terminated on pins 1, 2, 3 and 6. Since a typical category 5 twisted pair cable contains 4 pairs, it can support two 100BASE-TX links with a wiring adaptor. Each network segment can have a maximum cabling distance of 100 metres (328 ft). In its typical configuration, 100BASE-TX uses one pair of twisted wires in each direction, providing 100 Mbit/s of throughput in each direction (full-duplex). BlueOptics© SFP 1000BASE-T, 100M, Copper Transceiver is one option for this category with RJ45 connector from CBO is designed for Gigabit Ethernet (GbE) high-speed applications of up to 1.25 gigabits per second over Cat5 Twisted Pair Cable.
100BASE-FX is a version of Fast Ethernet over optical fiber. This application uses a 1310nm near-infrared (NIR) light wavelength transmitted via two strands of optical fiber, one for receive (RX) and the other for transmit (TX). Maximum length is 412 metres. The BlueOptics© BO05A13602 SFP transceiver with LC duplex connector from CBO is designed for short-range multi-mode Fast Ethernet (FE), Fibre Channel over Ethernet (FCoE) or OC-3/STM1 SDH/SONET applications of up to 155 megabits per second.