Author: Fiber-MART.COM

by http://www.fiber-mart.comFiber optic networks evolved in late 20th century to cater the increasing demands of bandwidth and to allow faster communication networks. Fiber optic Transceivers use a laser as light source which transfer signals through one or more glass strands (fibers). Optical Transceivers have several advantages over the copper/electrical wire communication such as increased communication distance, more bandwidth and higher data rates. Apart from the enormous advantages that optical Transceivers offers, a few extra measures need to be taken as well, to ensure a reliable and robust network, which includes taking care of fiber bends, coupling, splicing and the use of appropriate Transceivers to communicate over the fiber optic network. Fiber optic Transceivers are available in various types and form-factors and evolved from the Gigabit Interface Converter, commonly referred to as GBIC, over Small Form-Factor Pluggable, commonly referred to as SFP up to the C Form-Factor Pluggable, commonly referred to as CFP. 

All of the above mentioned Transceivers provide the interface for the fiber optic to be terminated on the communication equipment (like a switch or router). The choice of the Transceiver depends on various factors which include: • Length of the communication link• Type of fiber optic cable being used, i.e., single-mode or multi-mode• Type of slot on the communication equipment• Bandwidth of the communication link Let us dig deeper into the evolution of the fiber optic Transceivers in the sections ahead. GIGABIT INTERFACE CONVERTER (GBIC) TRANSCEIVERThe GBIC Transceiver was first introduced and standardized in 1990 by the Small Form-Factor Committee (SFF Committee). The primary reason to develop such a Transceiver was to enable the use of fiber optic cables to connect two or more communication devices and allow more bandwidth and longer distance direct links. GBIC Transceivers usually provide up to 1Gbps duplex bandwidth over a single link, although it has been tested for speeds up to 2.5Gbps. GBIC Transceivers commonly use the SC connector to terminate the fiber optic cable.

GBIC Transceivers are also available for 1000BASE-T to terminate the common twisted pair copper cables. One of the main features of GBIC is that it is hot-swappable, i.e., one does not need to power off the communication equipment to insert or remove the GBIC. This allows the communication network to be always-on despite new links being added on it. The dimensions of the GBIC Transceiver as defined by the SFF Committee standard document are 57.15mm x 12.01mm x 30.48mm (L x H x W). The GBIC slot in the communication equipment is also designed keeping the mentioned dimensions in view. SMALL FORM-FACTOR PLUGGABLE (SFP) TRANSCEIVERSFP Transceivers were the next step in the development of fiber optic Transceivers, this one was also developed as a standard by the SFF Committee in 2001. A SFP Transceiver is much smaller in size as compared to its predecessor.

The size of the SFP slot in a communication equipment is somewhat comparable to the normal electrical Ethernet port. Dimensions given in the SFF Committee standard document are given in the following table: Transceiver width, front 13.7 mmTransceiver height, front 8.6 mmTransceiver width, rear 13,4 mmTransceiver height, rear 8,5 mmTransceiver overall length 56,5 mm It is necessary to mention here that several variants of SFPs have been developed to support higher bandwidth using the similar form-factor. In between SFP+, XFP, XENPAK, X2 are Transceivers that supports 10Gbps duplex link, QSFP Transceivers support up to 40Gbps links with a little larger size than the SFP and SFP+. C FORM-FACTOR PLUGGABLE (CFP) TRANSCEIVERTo meet the ever-growing demand for higher speed communications, engineers started working on developing a Transceiver that could support 100Gbps and higher bandwidths. In 2009, CFP MSA came out with a new standardized Transceiver called CFP which could support 100Gbps traffic. A CFP module has the dimensions of 144.8mm x 82mm x 13.6mm (LxWxH). 

A CFP Transceiver supports up to 10km link length on single-mode optical fiber cables and up to 150m on laser optimized multi-mode optical fiber cables. Variants of CFP Transceivers have also been developed as standards, CFP2 supports up to 100Gbps with a smaller form-factor and CFP4 supports up to 100Gbps with form-factor similar to QSFP Transceivers. CONCLUSIONIn light of the above mentioned details about the advancement and development of the fiber optic Transceivers, it is imperative that the trend of faster communication speeds and smaller form-factors will continue in future. Today, every other person has a smart-phone, a tablet PC, a laptop and a desktop computer which all connect to some kind of network, even the wrist watches and televisions connect to internet these days. This enormous growth in the internet’s traffic has produced the need for this development which we are seeing today in fiber optic networks. It is in near future that the current technology we have might not be enough to support the demands of the next generation smart devices, so the development and research is continuing at an even faster pace to cope up with the advancement in technology.

by http://www.fiber-mart.comCommonly, optical networks rely on Transceivers that utilize one optical fiber to transmit data and another optical fiber to receive data to and from the networking devices. Generally, this kind of data transmission raises the costs of the network deployment, however with use of the bidirectional optical WDM BIDI Transceiver, and its capability to send and receive data over one optical fiber, we can create a much more cost-effective optical networks. 

The Bidirectional Optical Transceiver or BIDI, is a type of an optical Transceiver which uses the Wavelength Division Multiplexing technology or widely known as WDM technology. The BIDI Transceiver manages to do this with the help of the integral bidirectional coupler which transmits and receives signals. The main difference that differentiates BIDI Transceivers from standard, two fiber Transceivers, is the possibility of the BIDI Transceiver to send and receive optical light data through a single fiber. This is easily illustrated in the pictures below which offer a side to side comparison between these two types of Transceivers.

The other key difference between the standard and BIDI Transceiver is the introduction of Wavelength Division Multiplexing technology incorporated into BIDI Transceivers. This technology separates the data sent and received over the same fiber based on the wavelengths of the light. However, to work at maximum level, the BIDI Transceiver must be deployed in matched pairs and tuned to match the expected wavelength of the transmitter and receiver they are transmitting and receiving data from and to. To put things in perspective, if one Transceiver is transmitting wavelengths of 1310 nm, the other side must have a receiving wavelength of 1310 nm and vice-versa. The common types of BIDI Transceivers used in today’s networks are: Bidirectional optical X2 Transceiver – Firstly designed for 10GB serial data communications. This transceiver is made of two sections with the transmitter part using a multiple quantum 1330/1270 nm Distributed Feedback Laser. The receiving part of the transceiver uses an integrated detector with preamplifier for 1270/1330 nm. This optical transceiver is mainly used in Ethernet solutions. Primarily used in older networking equipment. 

Bidirectional optical SFP Transceiver – this transceiver is most commonly deployed in high speed duplex data links over a single optical fiber. The most common optical wavelengths for this transceiver is 1310/1490 nm, 1490/1550 nm and 1310/1550 nm. Today this type of transceivers is used in optical communication for optical gigabit telecommunications and optical data bidirectional applications as follower of the GBIC Transceiver. Bidirectional optical SFP+ Transceiver – This type of transceiver is a more advanced version of the BIDI SFP Transceivers. SFP transceiver. It is designed for 10 GB deployment and distances up to 80 kilometers. Bidi variants are also available for the form factor XFP. Bidirectional optical QSFP Transceiver – This transceiver most commonly has two 20 GB/s channels with each transmitted and received at the same time over a single Multi-mode strand (OM3 or OM4). The obvious advantage of using Bidirectional Transceivers is simple. Reducing the fiber optic cable infrastructure, reducing the number of patch cords and panels and thus reducing the overall cost of the Network Solution. Even though Bidirectional Optical Transceivers cost more to purchase them, deploying them will eventually result in cutting down half of the amount of fiber per distance needed for a certain project. 

Today the Bidirectional Optical Transceivers are mainly used in FTTH/FTTB active Ethernet point-to-point connections. These connections consist of a central office, or premises equipment (PE), connecting to the CPE or widely known as Customer Premises Equipment. Active Ethernet solution uses the point-to-point technology in which each customer is connected to the PE on a dedicated fiber. In this case the use of BIDI Transceivers is essential because it provides a bidirectional communication over a single fiber by using the WDM technology making the connection simpler to deploy, troubleshoot and configure.

by http://www.fiber-mart.comIn data center environment there are many interconnections needed from regular large numbers of ports of access switches to the large bandwidth capacity ports of backbone routers with particular cases of ports facing the connections towards storage access networks. All these ports need reliable connections implementations in form of connection cables on short distances. There are two main forms of interconnection patches: AOC – Active Optical Cables and DAC – Twinax Direct Attach Cables. The target application is interconnection of top-of-rack switches with application servers and storage devices in a rack or across adjacent racks. 

Active Optical Cable (AOC) – The optical Solution AOC – Cables are constructed using optical fibers and have attached on the ends active optical components in form of optical transceivers. Their advantage consists in protection to electromagnetic perturbations, greater bandwidth capabilities and management functions embedded in the end active parts. All these features come with a proportional higher price than twinax cables. Direct Attach Cable (DAC) – The Twinax Copper Solution DAC – Cables use the twinax copper wires to transmit signals. Twinax cable is almost similar with CATV coaxial cable but not the same having two conducting wires inside covered by protective shield. They are suitable up to 10 Gbps data rates and distances up to 15 meters. At the end also a transceiver is used as a plug connector.

 The Comparison: Twinax versus Cat5 or Cat6 Ethernet Cables The advantage of twinax over short distance consists in lower transmission delay 0.1μs versus 1.5 to 2.5μs for current implementations of SFP+ DAC cables vs 10GBASE-T. The power draw of Twinax with SFP+ is around 0.1 watts, which is also much better than 4–8 watts for 10GBASE-T. Cables must not be bent below their minimum bend radius, which depends upon cable size as expressed in AWG – American Wire Gauge. What is the difference between Active and Passive DAC Cables? There are some versions of DAC which have some active modules at the respective ends. The active 10G SFP+ CU/CR DAC link utilizes a receive equalizer in the host PHY/SerDes in order to compensate for the Inter Symbol Interference (ISI), performing signal re-shaping and amplification introduced by the cable making them suitable for longer distances.

The usual distance to reach of passive DAC cables is within 7 meters for data center connectivity. The active components are available for data rates of up to 40G, passive types up to 100G. Passive cables are much less costly but require the host to do the work of driving it properly.  The new Generation: 100G Direct Attach Cables The 40GBASE-CR4 and 100GBASE-CR10 physical layers using 7 m twin-axial cable are being developed as part of 100 G Ethernet specifications by IEEE 802.3bj workgroup. IEEE 802.3bj define a 4-lane 100Gbit/s backplane PHY for operation over links consistent with copper traces on with lengths up to at least 1 Meter and a 4-lane 100 Gbit/s PHY for operation over links consistent with copper twinax cables with lengths up to at least 5 Meter. The SC282801LXM30 – BlueLAN© 100GBASE-CR4 QSFP28 Direct Attach Cable (passive), 1 to 2 Meter, AWG 30 – This item is currently the DAC solution with the highest bandwidth with a total throughput of 100 gigabits per second.

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In the modern and ultra-high tech Datacenters of today, more bandwidth is needed and used to support the latest demands in the Networking world especially the server-virtualization environment where multiple virtual machines are being combined on a single physical host server. To be able to accommodate the growing number of operating systems and applications and at the same time providing scalability and reliability, virtualization requires noticeable increased data transmission rates between the servers and the switches in the Datacenter.

At the same time the networking devices, and the pure Internet day to day use, have dramatically increased the data that has to be transmitted throughout the Datacenter including the Storage Area Network (SAN) and Network Attached Storage (NAS) environment. According to some researches done in the past couple of years, the amount of data transmission in the world is growing astoundingly, more than 20% in only 5 years. Accordingly the leading IT managers are looking for ways to reduce the cost of implementing the newest technology and at the same time provide the stable Network of tomorrow. With these thoughts in mind the leading manufacturers started developing the new technology that would be able to meet these requirements and this is the Direct Attach Cables or DACs. This is a high density and low power consumption technology that would allow to create an in-rack 10GB/s solutions between servers and switches. Today these Direct Attach Cables are used to transmit the huge data transmissions in Datacenters mainly between switches, servers and storage devices. Because of the way they are designed, using the same ports as the Optical transceivers use, they have become hugely popular with Datacenters. 

Direct Attach Cables are cables that have an Optical Transceiver type of ending connectors. They use the same ports as the Optical transceivers and they provide Ethernet, fiber channel and Infiniband solutions. These cables are mainly divided in three separate types that are most commonly used. Direct Attach Passive Copper Cables- Because these cables are passive and they lack in an active circuitry component they can provide 10GB/s speeds up to 7 meters.Direct Attach Active Copper Cables- With the help of the active circuitry component these cables can reach up to 15 meters providing 10GB/s or 40GB/s solution. Other than the active circuitry component this cables are designed in the same way as the Direct Attach Passive Copper Cables. Active Optical Cables- These cables incorporate active optical and electrical components which can reach up to 150 meters on Multi-mode fibers.

These cables can also be used as active direct attach breakout cables satisfying the various needs of Datacenters. These cables are most commonly used for a short reach direct connection applications. They are used in the Equipment Distribution Areas where the racks are the home of the end servers and where the cabling is terminated at patch panels. For interconnection between racks these cables are used to connect servers to switches, switches to switches or storages to switches. They use an electrical to optical conversion on the cable’s ends which provides higher speed and low latency without sacrificing compatibility with the most standard optical transceivers. With the fast growing 10GB/s Ethernet solutions these cables are mainly used in the SFP Form-factor for interconnection between switches and storages in the same rack.

However in the near future the 25GB/s Direct Attach Cables will start substituting the 10GB/s Direct Attach Cables making room for more bandwidth for spine switches. These 40GB/s Direct Attach Cables are already available on the market. CBO BlueLan© offers different variants of, cost-effective, Twinax Direct Attach Cables, active or passive, with various connectors capable of providing the very latest in high speed network demands, QSFP, QSFP28, SFP, SFP+, QSFP Breakout and IB4X. All cables have a 5 year warranty and a lifetime support.

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High-density data center is becoming the direction of the next generation data center. Today density is the key factor that determines the capacity of the facility. Parallel optics technology has become the transmission option of choice in many data centres as it is able to support 10G, 40G, and 100G transmission. For parallel optics to work effectively, it requires the right choice of cable and connector. 

An optical fiber connector terminates the end of an optical fiber, and enables quicker connection and disconnection than splicing. The connectors mechanically couple and align the cores of fibers so light can pass. Better connectors lose very little light due to reflection or misalignment of the fibers. In all, about 100 fiber optic connectors have been introduced to the market. MPO/MTP® connector – “multi-fiber push on” technology with multi-fiber connectors offers ideal conditions for setting up high-performance data networks in data centers to handle future requirements. 

MTP/MPO cabling assemblies, as an excellent solution for quick and reliable multi-mode fiber connectivity, provide an effective way for 40GbE and 100GbE network solutions, ensuring a high-performance and high-speed network The MTP® connector is a registered trademark and design of UsConnec. It is also a kind of MPO connector but with a higher performance which provides some advantages over a generic MPO connector. Compared to generic MPO connector, MTP® is designed with multiple engineered product enhancements to improve optical and mechanical performance. MT stands for mechanical transfer and an MT ferrule is a multi-fibre (usually 12 fibres) ferrule. The performance of the connector is determined by the fibre alignment and how this alignment is maintained after connection. Ultimately, the alignment is determined by the eccentricity and pitch of the fibre and how accurately the guide pins keep the fibres together during mating.

The performance of any MPO connector can be improved if the tolerances of the pins and the moulding processes are reduced during manufacture. Nowadays, a MPO/MTP® connector can support 2, 4, 8, 12 or 24 fibers, and even up to 72 fibers in the tiniest of spaces. MTP/MPO fiber cables fall on MTP/MPO trunk cables and MTP/MPO harness cables. As terminated with MTP/MPO connectors on one end and standard LC/FC/SC/ST/MTRJ connectors (generally MTP to LC) on the other end, these cable assemblies can meet a variety of fiber cabling requirements. MTP/MPO CASSETTESMTP/MPO cassettes are utilized to interconnect MTP/MPO backbones with LC/SC/ST/FC patching, and reduce installation time and cost for optical networking environments. They are able to provide secure transition between MTP/MPO and LC/SC/ST/FC connector. The standard MTP/MPO cassettes can accommodate 12 and 24 port configurations.

 MTP/MPO CASSETTES FEATURESHigh density easy-plug cassette modulesSimple to use, convenient installation: Pre-installed with fiber MTP/MPO adapters at the rear, and LC adapters in the front panel. Reduces cable load in raised floors to existing active server/switch/storage equipment with LC Duplex interface.Field terminations Elimination: reduces labour cost and improves cabling manageability.Available in 12 fiber and 24 fiber configurations, up to 36 duplex ports or up to 72 single-mode fibers. For example, a 10G system would utilise a single MPO / MTP (12 Fibre) connector between the 2 switches.High performance zirconia sleeve adaptors.Reliability -100% tested factory tested in a controlled environment.The gender can be changed after assembly or even in the field giving flexibility at point of use.The MTP connector has a metal pin clamp with features for centering the push spring eliminates lost pinscenters the spring forceeliminates fibre damage from the spring mechanism 

APPLICATIONS

Data centre infrastructureStorage area networkFibre channelParallel opticsUltra High Density Fiber ManagementTelecommunications networks and Broadband CATV networks.LAN/WAN PremisesTherefore, parallel optics and MTP cabling have proven to be an excellent solution for delivering 10G, 40G and 100G transmission especially within a data centre environment. It provides a flexible, high density option for quickly connecting services and is a reliable high speed solution for many data networks.

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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 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 multimode and single mode.  Multimode can be implemented in two forms: step-index and graded-index. Multimode 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 multimode step-index fiber, the density of the core remains 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 multimode fiber, called multimode 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 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 multimode fiber, and with significantly lower density. Multimode 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 50/125. 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 50/125 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. 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.   

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.