2018年6月18日星期一

What splitter structure you should have in FTTH network centralized or cascading

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FTTH currently developed very fast in South America and Africa, however, many new comers are curioused about how many splitters should i have in FTTH network.
 
PON is the basic structure for FTTH network, PON is short for Passive Optical Network. It consists of OLT, ODN (Splitter) and ONT. From the structure, splitter placement in ODN is very crucial. there are generally two types of splitter placement in ODN network, centralized splitting and cascading splitting. The centralized splitter uses single-stage splitter located in a central office in a star topology. The cascading splitter approach uses multi-layer splitters in a point to multi point topology.
 
The centrlized splitting structure generally uses a 1×32 splitters in the central office. . The central office CO may be located anywhere in the network. The splitter input port is directly connected via a single fiber to a GPON/GEPON optical line terminal (OLT) in the central office. On the other side of the splitter, 32 fibers are routed through distribution panels, splice ports and/or access point connectors to 32 customers’ homes, where it is connected to an optical network terminal (ONT). Thus, the PON network connects one OLT port to 32 ONTs.
 
A cascading splitting structure approach may use a 1×4/1×8 splitter residing in an outside plant enclosure/terminal box. This is directly connected to an OLT port in the central office. Each of the four fibers leaving this stage 1 splitter is routed to an access terminal that houses a 1×8/1×4, stage 2 splitter. In this scenario, there would be a total of 32 fibers (4×8) reaching 32 homes. It is possible to have more than two splitting stages in a cascaded system, and the overall split ratio may vary (1×16 = 4 x 4,  1×32 = 4 x 8, 1×64 = 4 x 16, 1×64 = 8 x 8).
 
A centralized architecture typically offers greater flexibility, lower operational costs and easier access for technicians. A cascaded approach may yield a faster return-on-investment with lower first-in and fiber costs. When deciding on the best approach, it’s important to understand these architectures in detail and weigh the trade-offs. The cascading type of splitting is the most commonly used in the FTTH ODN structures.
 

Comparing Passive Optical Networks and Passive Optical LANs

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The Basics of Passive Optical Networks (PONs)
A PON is a point-to-multipoint network using optical splitters and loose tube singlemode fiber for outdoor network deployments.
 
Passive optical network technology has been around for a long time. Outside plant carrier networks (fiber-to-the-home, or FTTH) providers have been using passive optical network technology for over a decade.
 
PONs work well because their providers have lots of experience with passive optical networks; they know how much bandwidth a customer (one home, or one dwelling unit) typically consumes, so they can set up their split ratios very efficiently. There is a demonstrated blueprint for where to locate splitters, and what ratios are needed. This has been developed through trial and error over time.
 
The Basics of Passive Optical LANs
A traditional LAN manages signal distribution with numerous routers and switch aggregators. Passive optical LANs use passive optical splitters, just like PONs, but are adapted to indoor network architectures. As an alternative to traditional LAN, passive optical LAN is also a point-to-multipoint network that sends its signals on a strand of singlemode fiber. POLAN (or POL) utilizes the optical splitters to divide the high bandwidth signal for multiple users, and makes use of wavelength division multiplexing (WDM) technology to allow for bi-directional upstream and downstream communication. A passive optical LAN consists of an optical line terminal (OLT) in the main equipment room and optical network terminals (ONTs) located near end-users.
 
Because of this setup, passive optical LAN can decrease the amount of cable and equipment required to deploy a network. Compared to traditional copper cabling systems and active optical systems, passive optical LAN streamlines the amount of cabling required within a network. Also, because the splitters are passive (requiring no power and emitting no heat), the power and cooling requirements for traditional intermediate distribution frames (IDFs) or telecommunications rooms (TRs) is drastically reduced or eliminated.
 
Passive Optical LAN Offers Many Benefits
The waters are a bit uncharted when it comes to passive optical LAN, however – especially compared to outdoor PON. As of right now, there are no established POLAN standards; each vendor works from its own platform (ONTs from one vendor are not compatible with the OLTs of another, for example). Also, there is a much shorter history for POLAN deployments; split ratios are generally not as well understood (how much bandwidth does your engineering department really need?). In the past, passive optical LAN deployments were also completed without following a structured approach, so they often lacked interconnection points for future moves, adds and changes (MACs) and repairs.

How Multiplexing Techniques Enable Higher Speeds on Fiber Optic Cabling

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Different multiplexing technologies are enabling the evolution of network speeds on fiber optic cabling. Such technologies include time division, space division and wavelength division multiplexing.
 
Wavelength Division Multiplexing
 
Wavelength division multiplexing is signaling simultaneously across multiple lanes segregated by different wavelengths (colors) of light that are multiplexed into and out of a single fiber. As the name implies, the wavelength band available for transmission is divided into segments each of which can be used as a channel for communication. It is possible to squeeze many channels into a small spectrum. The common versions used for long haul, single mode systems are called dense wave division multiplexing or coarse wave division multiplexing. In multimode systems, short wavelength division multiplexing techniques are appearing.
 
Space Division Multiplexing
 
Space division multiplexing, more commonly known as parallel optics or parallel fibers, is a way of adding one or more lanes simply by adding one or more optical fibers into the composite link. A lane in this scenario is physically another fiber strand. It’s an alternative to time division multiplexing lanes described above, where signals merged each in time on the same fiber. There are a number of examples of this technique being used in the industry. For example, 40G SR4 delivers 40Gbps over multi-mode fiber using four lanes or fibers. That’s four lanes in one direction and four lanes in the other direction. That’s also what the four on the end of ‘SR4’ means, four lanes of 10Gbps each.
 
Time Division Multiplexing
 
Time division multiplexing is simply a way of transmitting more data by using smaller and smaller increments of time, and multiplexing lower data rate signals into a higher speed composite signal. With time division multiplexing, lower speed electrical signals are interleaved in time and transmitted out on a faster composite lane. So, the higher resultant data rate would be multiple times the individual rates going in.
 
There are examples used today where Ethernet rates are achieved using such parallel electrical signals, combined in a multiplexer and serialized over fiber. For instance, 10Gbps Ethernet has four lane options where each of the lanes is at a quarter rate of 2.5Gbps.
 
Today’s top speed per lane is 25Gbps for Ethernet. If we look into the future, 50Gbps lane rates are being developed.
 
With the higher rates, more complex multi-level code schemes are used to get more bits through with each symbol. This is an indication that maximum speed limits are being reached and so alternative techniques are used to increase the composite lane speed.
 
 
Space Division Multiplexing
 
The standard for the 100Gbps solution uses 10 lanes of 10Gbps called SR10. There is also a second generation of 100G that has increased the lane rate to 25Gbps and that delivers 100G using four lanes, so mixing the improvements in time division multiplexing and parallel optic techniques to achieve the goal of higher speeds.
 
Taking this further from four lanes in each direction up to 16 or 24 lanes, speeds of 200Gbps, 400Gbps and beyond are made possible; however there are pragmatic limits. If you can get away with it, then clearly a four lane solution is more practical than a 24 lane solution. Going above 16 or 24 lanes is a diminishing return because it drives more cost into the cabling system. That’s where the third multiplexing technique, wave division multiplexing, comes in.
 
 
With short wavelength division multiplexing, wavelengths are used in the lower cost short wavelength range around 850nm to add lanes within a single strand of optical fiber. An example of this on the market today is Cisco’s 40G BD, or Bi-Di. Bi-Di stands for bidirectional and the signals are transmitting in both directions in each optical fiber strand, using two different wavelengths to discriminate between the reflections that might happen. This technique uses 20Gbps per wavelength in each of two fibers and that way they can get 40Gbps through the 2 core fiber channel using a duplex LC connector.
 
for more details about optical fiber cables, pls visit www.fiber-mart.com

2018年6月14日星期四

What is QSFP+ Optics Transceiver

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Definition and Application of QSFP
QSFP also called QSFP+, it stands for Quad (4-channel) Small Form-factor Pluggable Optics Transceiver. It is a compact, hot-pluggable fiber optical transceiver used for 40 Gigabit Ethernet (40GbE) data communications applications. It’s designed according to QSFP+ Multi-source agreement and IEEE802.3ab, they are usually for the application of Data center, 40G Ethernet, Infiniband, and other communications standards.
 
It interfaces a network device (switch, router, media converter or similar device) to a fiber optic or copper cable. It is an industry standard format defined by the Small Form Factor Committee (SFF-8436, Rev 3.4, Nov. 12, 2009—Specification for QSFP+ Copper and The CFP MSA was formally launched at OFC/NFOEC 2009 in March by founding members Finisar, Opnext, and Sumitomo/ ExceLight. The format specification is evolving to enable higher data rates; as of May 2013, the highest supported rate is 4x28Gbps (112Gbps) defined in the SFF-8665 document (commonly known as QSFP28) which will support 100GE.
 
The QSFP MSA specification supports Ethernet, Fibre Channel, InfiniBand and SONET/SDH standards with different data rate options. The QSFP Multi Source Agreement (MSA) document specifies a QSFP optic transceiver mechanical form factor with the latching mechanism, host-board electrical edge connector and cage. QSFP+ optic transceivers are designed to support Serial Attached SCSI, 40G Ethernet, 20G/40G Infiniband, and other fiber optic communications standards as well as copper cable media. The QSFP optic modules highly increase the port-density by 4x compared to SFP+ optic modules.
 
Types of QSFP+ Optics Transceiver
Optcore provides a full range of both copper cables, active optical cables and optical transceivers for 40GbE, compliant to the IEEE standards.
40G QSFP+ Transceiver Optics
40G QSFP+ Copper Cables
40G QSFP+ to 4xSFP+ Breakout Copper Cables
QSFP+ to CX4 Copper Cables
QSFP to MiniSAS(SFF-8088) DDR Cable
40G QSFP+ to QSFP+ Active Optical Cables (AOC )
40G QSFP+ to 8xLC Optical Cables
 

10G to 40G / 100G MPO Optical Link Testing Technology

by www.fiber-mart.com
Objective
Technology changes the life, informatization is the trend of the development of the world today. Networking, cloud computing, large data and other emerging network information technology innovation and application, and in mobile interconnection technology, the 3G network is maturing, 4G LTE network from the beginning of last year in the national pilot run, mobile interconnection speed will be a new step. In this era of information industrialization, we work and live in the city is also in the transformation of the Intelligent city, a variety of network applications are closely related to us. Whether it is the application of new technology or the construction of the Intelligent city, the application cannot be separated from the basic network. The construction of the basic network is based on the site, the active terminals, and interconnecting devices, as well as the basic interconnection channel-cabling system. Cabling system needs to be installed on the site, easy to be affected by environment, product quality, installation process and other factors, is the most important link to determine the quality of network transmission. The reliability of Cabling system depends not only on the quality supervision in the project but also on the final  field acceptance test.
 
The urgency of test technology development
At present, most of the small and medium-sized cabling projects still use 10 Gigabit as the backbone to achieving Gigabit to the desktop network architecture. However, with the rapid development of 3G / 4G and Internet services, bandwidth cannot meet the needs of applications. The main link uses 40G / 100G to become a large-scale wiring project, especially the inevitable trend of enterprise data center and Internet IDC data center project construction. According to IDC market report, after 2015, 40G / 100G will gradually become the mainstream port rate.
 
Since the IEEE released the 802.3ba 40G / 100G standard in June 2010, the 40G / 100G network has mainly been based on experimental networks and has fewer requirements for on-site testing. After more than two years of systematic research and development testing, the current 40G / 100G transmission technology is maturing, major manufacturers have introduced 40G / 100G switching routing equipment, carrier-class long-distance backbone link using single-mode optical fiber systems, and buildings and data centers The integrated cabling system is mainly based on multimode OM3 / OM4 optical fiber system transmitting over short distances. It adopts 12-pin MPO connector and four-channel / ten-channel pre-connected optical cable. Pre-connected optical cable greatly reduces installation time and labor costs, but how to quickly identify the polarity of the fiber, fast and accurate test of the link attenuation has become the primary problem of field testing.
 
Traditional optical fiber testing technology
First of all, let us first review the original Gigabit, 10 Gigabit optical fiber link test technology. In 2003, TIA-526-14-A multi-mode optical cable installation light intensity loss test standard formally defines the CPR (CoupledPowerRatio) optical coupling rate detection method, the light source is divided into five levels (as shown below), LED light source is level 1 Light source, VCSEL The vertical cavity surface emits a laser light source at a level between level 3 and level 4, and the FP laser light source corresponds to a level 5 light source. At the same time, the test limits of optical loss are further increased. The maximum loss value of 1000BASE-SX applied to OM1 optical fiber is 2.6dB. The maximum loss value of 10GBASE-SR applied to optical fiber OM3 is 2.6dB. This standard, as a common standard for optical fiber link testing, is not aimed at specific network applications. It emphasizes the normal state of optical signal transmission. It is recommended to use LED light sources to test multimode fiber links. This method can detect the worst fiber link Happening. The laser-optimized VCSEL light source is used to detect the link for a specific network application. For example, if the active device uses a VCSEL light source or the current network is to be upgraded to use a VCSEL light source, the measured fiber loss value is relatively close to the real loss in the network application value.
 
850NM CPR Categories
 
The TIA-526-14-A standard is referenced by several related test standards such as ANSI / TIA / EIA-568-B, ISO / IEC11801, ISO / IEC14763-3 and others. And ANSI / TIA / EIA568-B.1.7.1 and ISO / IEC14763-36.22 also specify the size and use of 50 / 62.5um multimode fiber spools. The reel is modeled as a mode filter by means of a coiled optical fiber to reduce the high mode generated by the light source in the optical cable and reduce the difference of test results caused by different light sources and improve the stability and repeatability of multimode optical fiber testing.
 
10G MPO multi-core fiber test solution
Compared with traditional dual-core fiber optic connectors such as LC, SC, and ST, MPO connectors can support at least 12-core optical fibers. The MPO connector is mainly used for pre-attached optical fiber cables. Because MPO optic fiber has 12 core channels, TIA-568-C.0-2009B.4 has analyzed the channel polarity in detail, for the duplex transmission, there are mainly three kinds of polarities A, B, C connections. All three methods are for a common goal —- to create an end to end optical transceiver channel, but the three ways cannot be compatible, respectively, using different polarity connectors and adapters. For the entire link compatibility and consistency, as far as possible to consider the use of the same polarity connectors and adapters, such as the use of the jumper polarity are AB, adapter types are KEYUP-KEYUP, or the polarity will cause different Confusion, easy to install error, resulting in link failure. Therefore, in the 10G Fiber Channel, the MPO main link polarity mainly adopts Class C (see below). The two ports are internally interoperable according to the corresponding numbers. The optical channels are connected in groups of two or more, such as 1- – 2, 2 — 1, forming a full-duplex transceiver channel. The left and right ends are converted into the LC interface through the MPO to LC module box and then connected to the device through the LC jumper. This situation is mainly used in the data center high-density cabling system.

Application of MPO Cabling in High-Density Data Center

by www.fiber-mart.com
Fiber optic jumper applications in the data center are very extensive, and in recent years the data center fiber optic transmission system bandwidth demand shows a high growth trend, so the use of a new generation of fiber and optical modules can continue to explore the potential of fiber-optic network bandwidth growth. As the multimode fiber jumper in the cost of a great advantage, to promote its application in the data center.
 
With the continuous drive of the application and popularization of the network media in the cloud computing environment, the multimode fiber jumper is also developing, from OM1 to OM2, and from OM3 to OM4 to use the VCSEL laser optimization technology, the bandwidth demand is increasing. New OM4 Multi-mode jumper fiber standard EIA/TIA492AAAD is introduced, which provides a better transmission mode for multimode fiber in the future wide application. This article provides an ideal communication solution for your data center, servers, network switches, telecentres, and many other embedded applications that require high-speed data transmission.
 
In a transport port connection device in a 40G / 100G data transmission application, such as QSFP optical modules, regardless of Fiber Channel connections using several fiber connections, and regardless of the type of fiber connection, they are connected directly to the MTP / MPO connector. Because the 40G / 100G data transmission application channel and the device connection between the equipment need to form a special mode, so that the device’s transmitter and receiver channels corresponding to each other, which requires MTP / MPO connector to complete the connection.
 
The MPO/MTP fiber jumper can provide a wide range of applications for all networks and devices that require 100G modules. They use the high-density multimode fiber optic connector system MT series of casing design, MPO / MTP fiber jumper with UPC and APC polished end, and also supports multimode and single-mode applications. The 10G OM3 / OM4 MPO / MTP fiber jumpers provide 10 Gbps of data transfer rates in high-bandwidth applications, which are five times faster than the standard 50 μm fiber jumper.
 
At the same time, multi-mode MPO / MTP fiber jumpers are also the most economical choice for most of common optical fiber communication systems. Single-mode MPO / MTP fiber jumper is mainly used for long-distance data transmission system. The MPO / MTP trunk cable is designed for data center applications. Typically, single-mode and multi-mode MPO / MTP fiber jumpers are designed to be 3mm or 4.5mm round cable, and connectors at both ends of the cable are also referred to as MPO / MTP connectors.
 
The MPO / MTP high-density push-pull fiber jumpers are currently used in three areas: high-density cabling data centers, fiber-to-the-home, and connection applications with a splitter, 40G QSFP+ / 100G QSFP28, 10G SFP+ and other optical modules. Today, there are already a series of high-density parallel optical interconnect products that can accommodate optical fiber transmission in modern data centers, such as custom MPO / MTP fiber jumpers, multimode fiber loopers, and QSFP+ high-speed cable assemblies.
 
Server virtualization and the development of cloud computing, as well as the development trend of network convergence, bringing a faster and more efficient data center network development needs. At present, 48x 10G channel composed of 10G switches, mainly limited to the use of SFP+ module to achieve the connection. In order to meet the higher bandwidth requirements, users can use a high-density QSFP+ high-speed cable to complete the connection, by increasing the data transmission rate of each channel and increase the port density to meet customer’s high bandwidth requirements.

2018年6月12日星期二

11 Common Networking Cable Mistakes

by www.fiber-mart.com
Network cabling is one of those things that seems easy on paper but ends up being hard once you apply it in the real world. Most people tend to ignore it but do not realize how much it will cost them in the long run. You could find yourself paying extra costs that were unnecessary in the first place, wasting time on running maintenance tests that never needed to be performed if the job was done right, poor network performance, and much more.
 
Close up of network cables connected to switch
 
The most surprising thing about networking cable mistakes is that there aren’t thousands of little mistakes that are being made. Many IT professionals agree only a few fundamental mistakes are responsible for the majority of the problems.
 
Here is a short list of the 11 most common networking cable mistakes that are seen in the IT industry: 
 
1) No cable management. This is where it all starts. Forget testing and other things – you can’t expect solid network performance if you are not properly managing your cables. This means that you will have to do the necessary work of properly labeling your cables and organizing them in a way that they can be easily accessed. Whether you use a rack or some other means, it is important to get this crucial mistake out of the way. It will be far easier to manage the cables, and maintenance will take up less of your valuable time.
 
2) Failing to plan. Before you even begin to take your cables and start connecting them to every port in sight, you need to know how everything is going to be laid out. Planning out your cable organization in advance is the first step to properly setting up your network.
 
Network cable bundle
 
3) Ignoring the rules. The best cable setup in the world is meaningless if you are breaking the rules! There are certain laws, standards, and codes that you have to abide by at the local, state, and federal level. Read up on the standards that pertain to you and your company. It’s one thing to have a safety hazard because you ignored the rules and another thing to pay hefty fines! 
 
4) Failing to control atmospheric temperature. The environment in which you set up your cables makes a huge difference. If the cables heat up too much, it could lead to the failure of the entire network. Likewise, moisture can also lead to network failure and compromise the safety of nearby workers. You need a system in place to keep all of your cables cool and dry. Cooling systems, air conditioning – whatever it takes to get the job done: Do it.
 
5) Ignoring distance limits. In general, 100 meters is the limit for the length of a cable. Keep in mind that this distance also includes path leads. Each cabling has its own limits, however, so you need to mindful of the cabling that is being used for your network.
 
6) Running cables near interference-causing devices. Believe it or not, there are many ways for interference to mess up your cabling setup. There are several types of interference (magnetic, electrical, etc.) that can be caused by seemingly harmless things like motors and fluorescent lighting. The pathway you set up for your cables should be free of these types of hazards.
 
7) No space for cable removal. The IT environment is dynamic in nature, and changes are going to be happening all the time. Adapting rapidly to change means that you should be able to easily remove cables at any time. If not, you are paving the way for operational hazards. When in doubt, always leave a little more space than you think is necessary.
 
8) Using separate cabling for data and voice. The traditional way of designing a cable network was to use separate set-ups for data and voice. Due to the different needs of the end user, this is no longer a viable option. Your best bet is to use twisted pair cabling.
 
9) Running cable parallel to electrical cables. This is a common mistake that usually leads to interference in data transmission from one point to the other. This can be remedied by crossing them in perpendicular instead of parallel.
 
10) Failing to test your network before activating it. Once everything has been set up, and you are happy with your layout, don’t forget to test your network before activating it. This will help you catch any errors you may have missed and address problems regarding data transmission and safety. Make sure to use the appropriate tools.
 
A bunch of network cables in a data center
 
11) Failing to ask for help. Sometimes, when all else fails, and you don’t know what to do, you need a second pair of eyes to look at what you have done. Call a licensed, experienced professional to help you set up your networking cable in a way that is safe and helps to transmit data efficiently.
 
Those are the 11 most common mistakes that you are going to see with networking cable. As long as you are aware of them and pay extra attention during the setup, you should be good to go on the first try! If not, look back at each mistake individually and check to make sure that you did not miss anything.