Category: Fiber Transceivers

by http://www.fiber-mart.comIn 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. fiber-mart.com 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.

by http://www.fiber-mart.comCurrently the data, voice, and video networks are becoming more complex and demanding more bandwidth and faster transfer rates far greater distances. To achieve these demands network executives are relying more about fiber optics. However, the actuality that many providers, enterprise corporations, and government entities are facing is the point that when their existing fiber infrastructure is overwhelmed, placing more fiber is not in fact an inexpensive or viable option. Hence, what now one should do! 

Many entities are opting Wave Division Multiplexing (WDM) technology in order to increase the capacity of their available infrastructure. WDM carry multiple optical signals of different wavelength onto a single fiber by multiplexing. By using WDM technology network executives can achieve a multiplication effect inside their existing fiber capacity. WDM is a protocol and bit rate independent. WDM based networks can transmit data in IP, SONET/SDH, ATM, MPLS, Ethernet and support bit rates from 100 Mbps to 40 Gbps. Consequently, WDM based networks can hold several varieties of traffic at different data rates over an optical channel.

This makes a less costly method to rapid response to customers’ bandwidth needs and protocol changes. To regulate bandwidth and increase the capacity of existing fiber optic infrastructure, WDW based networks, by simultaneously multiplexing and transmitting various signals at different wavelengths within the same fiber. As division and distributing business services tend to be more extensive, WDM optical technologies are becoming an appreciated tool for cable operators. Using just two different wavelength, WDM technology can increase the service capacity by twice with in the same amount of fibers. For quite some time, there have also been some limited methods using more complex WDM systems that may carry four or still more optical signals on same fiber. Lately, cable equipment makers have released revolutions using WDM that transmit multiple broadcast optical signals on the single fiber, making node division more cost effective and operationally friendly. WDM significantly increase the capacity of system.

You will find variations which can be popular: Coarse WDM (CWDM) and Dense WDM (DWDM). Each signal is at a different wavelength and each variation had different capabilities, cost, and operative friendliness, used in different WDM Multiplexer (or de-multiplexer) devices. Multiplexer merges several data signals into one signal for transporting on the single fiber while de-multiplexer separate the signals equally. CWDM technologies have only been produced for HFC (Hybrid fiber-coaxial) networks within the return-path up to recently. About return-path, almost eight transmitters at different CWDM wavelength can be multiplexed on to a single fiber using a CWDM Mux. This could be beneficial when return-path has lot more bandwidth contention related to the forward-path, so 24×7 node segmentation may be sufficient. 

DWDM technologies delivers much flexibility for node breakdown, yes it is more expensive and more operationally challenging ac compared to CWDM. The method to fragment the nodes using DWDM within the forward-path is known as broadcast/narrowcast DWDM overlay. It utilize two fibers within the downstream: one fiber having an optical signal with all the broadcast content, and other fiber with multiple optical signals on DWDM wavelengths, each containing unique narrowcast content to obtain a segment.

On the node, the narrowcast DWDM wavelengths are separated onto their unique fibers. The narrowcast content will then be overlaid with the broadcast content at the node in a choice of the RF domain or perhaps the optical domain.

by http://www.fiber-mart.comFiber optic transceivers are modular, pluggable and interchangeable optoelectronic devices. You can find a transceiver at the heart of any fiber optic communication system.

Everything from a local university to a large corporation utilizes data centers and transceivers. These devices convert an electrical signal to optical signal on one end and back again on the other. Tomorrow’s data centers, local area networks and digital communication systems will require faster data transmission rates. This “need for speed” stems from an increasing dependence on online communications. We use transmitters for almost everything we do online. Online shopping, educational programs and social media are just a few ways we have increased the need for faster transmitters. 

Transceivers also provide an essential path for upgrading a fiber optic link to the next generation of data transmission speeds. Because transceivers are interchangeable, the ability to upgrade the transceiver without upgrading the entire data center is a remarkably low-cost solution. Transceivers are currently capable of transferring data at speeds from 10 to 40 to 100 Gigabits per second. However, many experts expect transfer speed to continue increase over the next few decades.   Did you know? • Fiber optic transceivers have built-in intelligence! The built-in memory chips can be “programed” to work with specific switch gears, routers and transmission equipment.

This programmability enables data centers to use transceivers from a variety of providers! 

• Transceivers can use different schemes. For example; the PAM4 scheme is able to increase the modulation of the light containing the encoded data. You can also increase the transmission throughput by adding more fibers (parallel optical transmission) or adding more wavelengths on a single fiber (WDM). 

• Transceivers come in different formats and in a variety of shapes and sizes (form factors). This enables the transceiver to fit into the switch equipment “slots”. In some cases it can be quite confusing to figure out what products you actually need to use. Luckily C2G has all the resources you need to make the correct selection!   

What about MSA or MMWA? It is a common misconception that transceivers are not interchangeable (Read more about transceiver warranties) . There are many different manufacturers that work under an MSA, or Multi –Source Agreement, which has been established in the industry by transceiver suppliers. It assures standardized and compatible mechanical and electrical interfaces. The US government also protects transmission equipment warranties with the Magnuson-Moss Warranty Act (MMWA). This legislation, passed in 1975, ensures that equipment manufactures cannot require the data center to use only their brand of transceivers to retain the warranty. This means that you are free to use whatever transceiver you would like. How do you select your transceiver then? The transceiver selection process can be tricky. There are a variety of options and specifications.

But we have a few suggestion for helping you find the perfect transceiver: To begin, determine the three major application requirements for your fiber switch gear and transmission equipment. This would include finding the transmission data rates you need now and will need in the future (migration). Next, detail the protocols and data formats required.

Finally discover the type of fiber optic cabling you plan to use or may already have installed (standard multimode, wide band multimode, single mode, cable constructions and fiber counts). Once you answer all of these questions you can select a transceiver that will be compatible with your data center or network. The next step is to consult your manufacturer’s specification sheets for important technical information such as optical power transmitted and required at the receiver, as well as insertion fiber losses, wavelengths of operation and polarity requirements for all components. Always make sure your transceiver’s requirements match up with your switch and your cable’s fiber and connector types. 

In some cases C2G can provide a “Universal Transceiver” that works with some or all of your network equipment. This universal option allows you to reduce the inventory of spare transmitters required. C2G’s transceiver offering spans a wide range of equipment from popular manufacturers such as Arista, Brocade, Cisco, Finisar, HP, Juniper, and more. All of C2G’s transceivers are competitively priced, TAA compliant and guaranteed to meet all OEM specifications.

by http://www.fiber-mart.comMultimode optical fiber is the most common media choice for both backbone and horizontal distribution within the local area network (LAN) including campuses, buildings, and data centers. Let’s take a closer look at the types of multimode fiber options based on bandwidth and distance needs. 

1 GB/S NETWORKSThe majority of enterprise fiber networks today still run 1000BASE-SX, delivering up to 1 Gb/s over multimode. OM1 cable will support 1000BASE-SX out to 275 meters, and that distance jumps to 550 meters with OM2 cable. OM3 and OM4 came after the 1000BASE-SX standard was written, so the distances up to 860 meters listed in the chart below are based on the gigabit Fibre Channel values. When IT managers require distances upwards of 860 meters, they will likely want to consider single-mode cable instead of multimode. 

10 GB/S NETWORKSMany enterprise networks are moving beyond 1000BASE-SX and transitioning to 10 gigabit networks, such as 10GBASE-SR. This is where distance considerations really come into play. A network using OM1 has a maximum distance of 275 meters for 1000BASE-SX, but it would see a distance limit of only 33 meters for 10GBASE-SR. Similarly, OM2 fiber for 1000BASE-SX has a 550 meter limit, but drops down to 82 meters for 10GBASE-SR. The introduction of OM3 increased that distance to a more usable 300 meters in the enterprise. 

The distance limit for 10 Gb/s over OM4 is listed at 400 meters in the above chart. This limit is set by TIA and IEEE standards based on worse case assumptions. However, these distances can likely extend out to 500 or 550 meters. The 400-meter limit is based on the transceiver having a spectral width of 0.65 nanometers, but most of these transceivers today are 0.47 nanometers, so you can typically extend farther than 400 meters. That’s a conversation you need to have with the cabling manufacturer. 

40 AND 100 GB/S NETWORKSWhen considering multimode for 40 gigabit Ethernet — namely 40GBASE-SR4 using four transmitters and four receivers — you will need an MPO-style connector, and you can’t use older OM1 or OM2 fiber. Also, the distance limits will drop to 100 meters for OM3 and 150 meters for OM4. The original intent of 40GASE-SR4 was for the data center, with the vast majority of the links in data centers under 100 meters. But enterprise links are typically much longer than 100 meters. These networks will likely deploy 10GBASE-SR throughout the campus, and then 40GBASE-SR4 in server rooms or communications rooms. 

Moving to 100GBASE-SR4 reduces the supported length further to 70 meters over OM3 and 100 meters over OM4, which is why we are seeing an increase in the deployment of OM4 fiber and the consideration of single-mode, as it is not so distance limited.

by http://www.fiber-mart.comWith more than 100 fiber optic connector styles and types available today, the right choice for a particular application can often be difficult to figure out. Design and performance of both the optical fibers and connectors has become more sophisticated over the years.

Today’s fiber connectors provide end-to-end solutions that cover a wide range of applications and, in many cases, can be easily terminated in the field. Some early fiber optic connectors, used in telephone central offices, such as AT&T’s single mode Biconic and D4 style connectors were terminated with heat-cured epoxy adhesive and polished, at the factory, onto single mode optical fibers. They were used to connect high speed digital outside plant (OSP) fiber links.alt These connectors have threaded nuts that tighten onto threaded equipment port receptacles.

In the case of the D4 and FC, built-in keys provide repeatable optical coupling when mated to other FC/PC and FC/UPC bulkhead mounted connectors or to single mode laser equipment receptacles. In addition, the SMA and AMP Optimate style connectors were some of the key industry fiber connector solutions for digital communications data links at the time. Those were soon followed up by the popular ST bayonet-style connector that is still often used today. And, this is now… The LC (SFF – Small Form Factor) and MPO connector are popular today for applications in data centers and building networks because of their small size and ability to provide high density patching and connectivity.

Optical transceivers for most switches either have LC duplex ports, or use 12 or 24-Fiber MPO ports when employing parallel optical links for 40gbps or 100gbps speeds.  So, how do we determine the right connector? First – define the application. It is important to determine where the connectors are being used. Figure out what type of communication equipment is being connected at each end of the link, and what the data rates, distances and numbers of connections are for the network. That will determine the optical signal power loss budget , and the loss performance the fiber connectors need to meet. Consult the standards requirements which can also help define the cable and connector types.

For instance, connectors in the data center should meet the requirements of ANSI/TIA, and also meet the FOCIS standard defining the approved connector footprint(s) and ensuring intermatability. The standards can often point to a particular connector design and help quantify the key parameters of maximum Insertion loss and minimum return loss performance. Standards can also provide insights into the type of equipment necessary for the application: Once the application is defined, the active equipment’s optical transceiver modules and bulkhead receptacles are also determined. This selection usually sets the types of adapters and connectors that will be selected for connecting the transceivers and the backbone and patching fiber cables and harnesses. At this point, it will become evident whether or not pre-terminated cables can be used. For example, in some instances if MPO connectors are specified, a pre-terminated cable can be selected. For splicing applications, connectors do not need to be installed the field, since factory terminated pigtails, and the splice connector, are fusion spliced directly onto the fiber cables. Second – Describe the operating environment – How can the connectors be applied to the cable? There are a number of ways a fiber optic connector can be terminated to fiber optic cables. Take a look at the type of fiber and cable construction you are planning to work with in the application. The best way to select a particular connector is by looking at the operating environment where it is going to be used. Harsher environments usually make field termination more difficult and demand the use of heat-cured epoxy. Factory terminated fiber patch cords are polished, for instance. What is the connector life and performance expectancy?

 Epoxy terminated fiber connectors provide a lifetime of performance and are backed by manufacturer’s warranties. The gel in pre-polished connectors has been used for years in telecommunications splicing for a 40-year life. The ferrule end-face polish and finishes dictate the type of performance that a connector can achieve. The higher loss and reflections encountered with the SMA connector flat polish is virtually eliminated today with PC radius polishes.  

Choosing the right fiber optic connector requires proper planning and attention to detail to achieve the best possible fiber link performance in the field. Careful consideration and definition of the application and the environment for the connector will help to determine the best connector solution for the application.

Today’s networks require higher performance from the network cabling, as well as cost effective connectivity. Direct attach copper and fiber cables provide both of these with their factory terminated performance and reduction in costs associated with field terminations. Let’s begin with the types of direct attach cables on the market today, advantages and disadvantages to each, and which cables are best for various applications. 

What is a high speed direct attach cable? A high speed direct attach cable is a type of factory terminated cable assembly used in data centers for point-to-point connections of active network equipment. These cable assemblies consist of fixed lengths of shielded copper coaxial or fiber optic cable with pluggable transceivers factory terminated on either end. Direct attach cables are available in popular transceiver form factors, including SFP, SFP+ and QSFP .

You will typically find high speed interconnect cables in data centers, storage area networks and high performance computing centers (HPC) due to the requirement for high bandwidth, connection density and low latency. There are three common types of direct attach cables: Passive DAC – Direct Attach CopperActive DAC – Active Direct Attach CopperAOC – Active Optical Cable Passive DACs DACs are the most basic form of direct attach cabling. DACs are constructed using shielded twin-axial copper cable in varying gauges from 24 to 30AWG. The length of the cable affects the signal attenuation which requires a specific gauge for the conductors. Longer cables require larger gauges in order to reduce the signal transmission loss through the cables. DACs are passive assemblies since they do not amplify or condition the signal in any way. Instead, signals are passed through and regenerated by the host network equipment.

The length limit for passive DACs (without amplification) is 7m.Although DACs are passive, the connectors in DACs do contain an “Electrically Erasable Programmable Read-Only Memory”, or EEPROM, that is used to store and provide information to host network equipment such as manufacturer name, serial number, part number, and date of manufacture. Technically, this EEPROM does consume a very small amount of power, around 0.15 W. Active DACs Active DACs, or Active Copper Cables (ACCs), are similar in construction to passive DACs but contain a microprocessor and other circuitry in the transceiver connectors to extend signal reach. The distance limit of an ACC is about 15m, which is a 2x improvement over a passive DACs limit. Also, the additional circuitry of the ACC does increase its power consumption to around 0.5-1.0 W, on average.

 AOCs – Active Optical Cable AOCs are similar to the active DACs in that they consist of a duplex fiber optic cable terminated with pluggable transceiver connectors on either end. The cable used in an AOC is either multi-mode or single-mode optical fiber which provides advantages over DACs or DCCs, such as longer transmission distances, isolation from signal interference and crosstalk and higher signal transmission capacities (bandwidths). The connectors in AOCs are actually optical transceivers making them a bit more complex and expensive than passive or active DACs. The optical fiber and technology used in AOCs give them a reach of up to 100m or more. Of the three types of direct attach cables, AOCs consume the most power at around 1-2W. Advantages and Disadvantages of Using High Speed Direct Attach Cabling Over Transceivers When considering the use of direct attach cabling for a particular cabling infrastructure application, one must weigh the advantages and disadvantages.

The following list below highlights some of the advantages and disadvantages of using direct attach cabling over discreet transceivers attached with field-connected structured cabling. Advantages

 • Lower Price – Direct attach cables are less costly than using discreet transceivers with field-connected structure cabling, because the interconnection is simplified. There aren’t as many connectors, adapters, patch panels, and other infrastructure elements along the path of communication channel.

 • Lower Power Consumption – Particularly with passive DAC cables, power consumption is less when compared to the use of transceivers because they are “self contained” components and not bound by transmission specifications as transceivers. For example, transceivers designed to work with copper twisted pair structured cabling must have a maximum reach of 100m whereas an active DAC only needs to reach a maximum of 15m. As a result, the required internal circuitry and signal power can be simplified and reduced. 

• Plug and Play Simplicity – DACs and AOCs are only one component to manage rather than multiple components that must be interconnected together. In addition, the installer does not have to be concerned with cleaning and inspecting optical fibers in the field before plugging the cables into the transceivers. 

• Factory Terminated Performance – DACs and AOCs are terminated and 100% tested at the factory. This provides consistent and expected transmission performance levels for the channel. Disadvantages • Reduced Cable Flexibility – Passive and active copper DACs have a larger bend radius and weight than traditional structured cabling or AOCs, which can sometimes place additional demands on the cable management and airflow management within a rack or cabinet. 

• Reduced Modularity – Structured cabling provides improved modularity through the use of patch panels and other components to make moves, adds and changes quicker and easier. DACs and AOCs are point-to-point cabling that require some additional labor since they need to be completely pulled out of racks, cable managers, cable tray, and other infrastructure elements.

 • Limited Distance – Transceivers and structured cabling are designed to work together in a universal and cohesive system. Therefore, pluggable transceivers are required to reach 100m or beyond, while DACs and AOCs are not. Applications for Direct Attach Cables Direct attach cables can be used in a variety of applications and locations in a data center. In general, this pre-terminated solution is particularly effective for the following applications:

 • Top of Rack/Adjacent Rack – Passive or active DACs are ideal for shorter ToR or rack-to-rack runs with cost-conscious budgets. AOCs will certainly work at shorter lengths (typically 5 feet), but the performance/cost trade-off may not be as compelling. 

• Middle of Row – Active DACs may be a perfect solution in this application, as long as the runs are less than 15m. AOCs would also make a good solution for MoR deployments. 

• End of Row – AOCs are most likely the best option for EoR configurations since the applicability of the active DACs reach their limit at around 15 meters in length.

 • Zone-to-Zone – AOCs are the clear solution for longer zone-to-zone runs due to the advantages of using fiber optic cables as mentioned previously. DACs vs. AOCs vs. Transceivers & Structured Cabling The following shows a table summarizing the key differences between the use of DACs, AOCs and Transceivers: Conclusions Direct Attach Cables provide an excellent pre-terminated and factory assembled & tested solution for both copper and fiber optic cabling in data centers. Performance advantages and cost savings can be realized over field installed cabling by avoiding testing and inspection of individual connectors and cabling components in the link.