Author: Fiber-MART.COM

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.

With the communication industry consistently growing, it is best to be prepared for any environmental factors. From direct sunlight factors to wet locations, a reliable connection cannot afford to be overlooked.

For those locations; the industry’s original water resistant, water blocking low-voltage cable- Aquaseal cable, has become the recognized name for indoor/outdoor applications.

What is considered a Wet Location?

Wet locations occur in areas where direct burial in the ground, in conduit that is located below grade or any time the cable is passing through the concrete slab. These are areas where water, humidity or liquid saturation is possible- regions that are regularly exposed to the elements.

So how does it work?

Aquaseal low-voltage cable consists of a 2-ply tape on the inner shielded pairs which is virtually impenetrable. As well as a .025 inch sunlight resistant and moisture resistant jacket. Aquaseal contains this material, so when the water penetrates the cable, the 2-ply tape expands to protect the cables and connections.

Advantage of West Penn Wire’s Aquaseal cable versus the competitor:

2-ply tape material immediately expands to absorb any type of moisture to 10 mm within the first minute
Expands to 12 mm after ten minutes
Each cable contains the maximum amount of tapes.
Competitors: 1-sided ply tape allows for water to immerse through the cable and won’t flush it out.
Why is Aquaseal the better choice?

A single ply tape has the potential to wash away, while 2-ply tape contains and maintains the absorption rate at a particular point and the communications will not be interrupted.

What is the difference between In-conduit (AQC) and Direct Burial (AQ):

In-conduit (AQC): Any low-voltage cable with a gauge size of less than 18 will not pass the UL crush test, therefore these types of cables are required to be put into conduit if they will be installed in the ground.
Direct Burial (AQ): A nylon coating is extruded (not hydroscopic) over the PVC compound. This makes the conductors abrasive and resistant to water passing through it. Most PVCs are hydroscopic and will let water filter through it to help with other electrical and mechanical factors. The nylon also acts as a stiffening agent and will not allow the conductors to crush one another during the crush test procedure (Direct Burial test).

by http://www.fiber-mart.comIn some situations, where moisture or direct sunlight may be an issue, you need more than a standard Low Voltage Cable. Those situations are tailor made for West Penn Wire’s line of Aquaseal cables. Aquaseal has a strong history of use for applications where you need to run cable from one building to another either via direct burial or in-condiut and with Aquaseal there is no need to transition once you go back inside as they are suitable for both outdoor and indoor applications. As with all of the quality cables from West Penn Wire; the Aquaseal line maintains the full host of applicable UL ratings.  1) How do I use these cables? Good Question. Aquaseal Low voltage cables can be run from one building to another or inside of the same building whenever there is the potential for a wet environment. Aquaseal can be run via either direct burial (AQ Line) or inside conduit (AQC Line) – to suit the particulars of your installation.  2. What are the benefit to these cables? Aquaseal cables have a water blocking 2-ply tape and a jacket that resists sunlight and moisture. This allows the cables to expand within the jacket with an exceptional swell height, making the cable ideally suited for any type of wet location signal transmission.  They hold a (SAP) Super Absorbent Polymer to soak up and trap any type of water that could affect the cable and have maximum tape for more protection.   3. What can these cables be used for? Aquseal cables are available in more than 40 constructions to meet any specific requirements.  Access controlAudioCommunicationsFire Alarm Systems IntercomVideo 4) What is the difference between AQC and AQ cables? AQ products are for direct burial applications while AQC cables are used for any in-conduit application.