Author: sueyue

DWDM Solutions for Arista 7500E Series Switches

Nowadays, the deployment of DWDM solution has been hotly debated in many enterprise networks, especially in the new Lay2 and Lay3 equipment like Arista 7500E series switches. For many enterprises, DWDM network solutions are undoubtedly the best choices of action, because they can provide a scalable and elastic solution for the enterprise that offered high bandwidth and data separation. This article will demonstrate DWDM solutions to Arista 7500E switches which are the foundation of two-tier open networking solutions for cloud data centers.

Analysis of DWDM System

DWDM (Dense Wavelength Division Multiplexing) is a technology allowing high throughput capacity over longer distances commonly ranging between 44-88 channels and transferring data rates from 100 Mbps up to 100 Gbps per wavelength. For intra-datacenter solutions, an endpoint connection often uses multimode (850 nm) for short ranges and single mode (1310 nm) for longer ranges. The DWDM node converts this local connection to a channelized frequency or wavelength, which is then multiplexed with other wavelength and transmitted over a single fiber connection.

A key advantage of DWDM is that it’s bitrate independent. DWDM-based networks can transmit data in IP, ATM, SONET, SDH and Ethernet. Therefore, DWDM systems can carry different types of traffic at different speeds over an optical channel. Voice transmission, email, video and multimedia data are just some examples of services which can be simultaneously transmitted in DWDM systems.

DWDM multi-channel Mux/Demux

Arista 7500E 100G DWDM Line Card

With full support for Layer2 and Layer3 protocols, Arista 7500E series switch is the ideal option for the network spine for two tier data centers applications. Arista 7500E especially provides the perfect resolution for high bandwidth Metro and long-haul DCI solutions with the 6-port DWDM line card. It has great advantage to migrate from existing 10G DWDM to 100G coherent line side modules. The 7500E series DWDM line card provides six 100G ports with coherent 100G tunable optics, which enables customers to connect directly into existing WDM MUX module without the need to add transceivers, which can save cost and space to a large extent. The coherent optics use C-band region wavelengths and offer a cost efficient solution for up to 96 channels of 100Gb over a single dark fiber pair.

Use Cases for Arista 7500E DWDM Card
    • Less Than 80 km Dark Fiber Connection
      For distance less than 80 km, Arista 7500E switch with DWDM line cards can directly terminate a dark fiber connection with a pair of passive DWDM Mux, thus achieving a point-to-point connection between two locations.

Dark Fiber Connection

  • Between 80 km and 150 km Connection
    For distance greater than 80 km but less than 150 km, losses occurred during the process of transmission should be considered. In order to boost the power level, an EDFA (Erbium Doped Fiber Amplifier) is used to gain flatness, noise level, and output power, which is typically capable of gains of 30 dB or more and output power of +17 dB or more. With the use of EDFA, the signal can be boosted into a certain power level, thus achieving distances of up to 150 km.
Conclusion

The Arista 7500E series DWDM solution offers a cost-effective solution for transporting scalable and massive volumes of traffic, and enhances the 7500E system by providing high performance 100G DWDM port density with the same rich features and dedicated secure encryption in compact and power-efficient systems. Enterprises can easily migrate existing metro and long-haul DWDM networks to add new 100G capacities, thus expanding Layer2 and Layer3 services.

Originally published at http://www.china-cable-suppliers.com/dwdm-solutions-arista-7500e-series-switches.html

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Difference Between AON and PON

AON (Active Optical Networks) and PON (Passive Optical Network) serve as the two main methods of building CWDM and DWDM backbone network. Each of them has their own merits and demerits. This article will compare them according to their different features and applications.

AON

An active optical system uses electrically powered switching equipment, such as a router or a switch aggregator, to manage signal distribution and direction signals to specific customers. This switch directs the incoming and outgoing signals to the proper place by opening and closing in various ways. In such a system, a customer may have a dedicated fiber running to his or her house. The reliance of AON on Ethernet technology makes interoperability among vendors easy. Subscribers can select hardware that delivers an appropriate data transmission rate and scale up as their needs increase without having to restructure the network. However, AON require at least one switch aggregator for every 48 subscribes. Since it requires power, an active optical network inherently is less reliable than a passive optical network.

PON

A PON is made up of an optical line termination (OLT) at the service provider’s central office and a number of optical network units (ONUs) near end users. Typically, up to 32 ONUs can be connected to an OLT. The passive optical network simply describes the fact that optical transmission has no power requirements or active electronic parts once the signal is going through the network.

A PON system makes it possible to share expensive components for FTTH. A PON splitter takes one input and splits it to broadcast to many users, which can lower the cost of the links substantially by sharing, for example, one expensive laser with up to 32 homes. PON splitters are bi-directional, that is signals can be sent downstream from the central office, broadcast to all users, and signals from the users can be sent upstream and combined into one fiber to communicate with the central office.

PON

A passive optical network does not include electrically powered switching equipment. It uses optical splitters to separate and collect optical signals as they move through the network. A PON shares fiber optic strands for portions of the network. Powered equipment is required only at the source and receiving ends of the signal. PONs are efficient since each fiber optic strand can serve up to 32 users. Besides, PONs have a low building cost compared with active optical networks along with lower maintenance cost. However, PONs also have some demerits. They have less range than an AON, which means subscribes must be geographically closer to the central source of the data. When a failure occurs, it is rather difficult to isolate it in a PONs. Moreover, because the bandwidth in a PON is not dedicated to individual subscribers, data transmission speed may slow down during peak usage times in an effect known as latency. And latency would quickly degrade services such as audio and video, which need a smooth rate to maintain quality.

AON vs. PON

As early as the year 2009, PONs began appearing in corporate networks. Users were adopting these networks because they were cheaper, faster, lower in power consumption, easier to provision for voice, data and video, and easier to manage, since they were originally designed to connect millions of homes for telephone, Internet and TV services.

Passive Optical Networks (PON) provide high-speed, high-bandwidth and secure voice, video and data service delivery over a combined fiber network. The main benefits of PON are listed below:

  • Lower network operational costs
  • Elimination of Ethernet switches in the network
  • Elimination of recurring costs associated with a fabric of Ethernet switches in the network
  • Lower installation (CapEx) costs for a new or upgraded network (min 200 users)
  • Lower network energy (OpEx) costs
  • Less network infrastructure
  • You can reclaim wiring closet (IDF) real estate
  • Large bundles of copper cable are replaced with small single mode optical fiber cable
  • PON provides increased distance between data center and desktop (>20 kilometers)
  • Network maintenance is easier and less expensive
  • Fiber is more secured than copper. It is harder to tap. There is no available sniffer port on a passive optical splitter. Data is encrypted between the OLT and the ONT.
Conclusion

To sum up, the PON network’s predefined topology makes individual changes more difficult. By terminating all the fiber optics at the OLT, i.e. the same fiber optic topology as in the AON (point-to-point), this disadvantage can be overcome. Therefore, for future-proof infrastructure investment, reliable point-to-point fiber optics technology should always be considered.

Using EDFA Amplifier for Long-Haul CATV Systems

With Laser technology combining with fiber optic technology, CATV systems in the field of optical communication have demonstrated unprecedented and irreplaceable achievements in the past few decades. When transmitting optical signals with fibers, fiber attenuation is the main factor that limits the transmission distance. EDFA (Erbium-Doped Fiber Amplifier) designed for CATV long-haul transmission avoids the conversion of optic-electric-optic in CATV long-haul transmission. It amplifies low signal power into high signal power, thus extending transmission distance. This post analyzes EDFA configurations and the utilization in long-haul CATV systems.

EDFA Leading Position in CATV Systems

EDFA is one of the most prominent achievements in fiber optic transmission technology over the past decade. Because it cleverly combined the laser technology and optical fiber manufacturing technology in the CATV systems and its applications were then rapidly expanded. Originally PDFA and EDFA amplifiers were equally used for CATV systems, but today, EDFA has completely replaced PDFA and become the primary device for fiber optic transmission systems. Why EDFA has leading position on CATV systems? Because EDFA noise and distortion characteristics are better, and its superior characteristics can be clearly seen in the following:

  • Operates at wavelength of 1550nm, consistent with C-band where fiber has the lowest loss
  • Has higher saturation output power, useful in systems requiring transmission up to 100 km or systems requiring the optical signal to be split to multiple fiber optic receivers
  • The signal gain spectrum is wide up to 30nm or more, can be used for broadband signal amplification, especially for WDM (wavelength division multiplexing) system, ideal for radio and data services networks
  • Has user friendly interface RS232, easy to control and monitor with computers
  • Low noise figure with high stability
EDFA Configurations

The configuration of a co-propagating EDFA is shown in Figure 1. The optical pump is combined with the optical signal into the erbium-doped fiber with a wavelength division multiplexer. A second multiplexer removes residual pump light from the fiber. An in-line optical filter provides additional insurance that pump light does not reach the output of the optical amplifier. An optical isolator is used to prevent reflected light from other portions of the optical system from entering the amplifier.

EDFA Configuration-1

An EDFA with a counter propagating pump is pictured in Figure 2. The copropagating geometry produces an amplifier with less noise and less output power. The counter propagating geometry produces a noisier amplifier with high output power. A compromise can be made by combining the co- and counter-propagating geometries in a bi-directional configuration.

EDFA Configuration-2

A Typical CATV System Using EDFA

Figure 3 illustrates a basic long-haul CATV transmission system designed to carry 77 channels of CATV signals for 100 km in a basic point-to-point configuration.

CATV EDFA

As you can see in Figure 3, the local CATV provider sends 77 channels of CATV signals at the transmitting side. After processing and RF combining, those multiple signals are combined into one channel of CATV signal with the wavelengths of 1550 nm. It transmits over a single-mode optical fiber to 50 km. An EDFA amplifier is used at the middle point to amplify the signals to a certain power level, continuing to transmit over a single mode fiber to 100 km. At the receiving side, the 1550nm CATV channel is split into multiple channels of 1550nm CATV signals, serving multiple hotel cable TV users.

FS.COM CATV EDFA Optical Amplifiers List

EDFA has undoubtedly received wide interest for CATV applications because of its high output power, low distortion and low noise capability. FS.COM supplies optical amplifiers including CATV EDFA, SDH EDFA, DWDM amplifier, etc. The following table lists FS.COM CATV EDFA amplifiers which are available with range of output power from 13 dBm to 24 dBm to meet the requirements of a high-density solution for the large-scale distribution of broadband CATV video and data signals to video overlay receivers in a FTTH/FTTP or PON system.

Product ID Part Number Description
17467 CEDFA-O13 New 13dBm 1550nm CATV EDFA Fiber Optic Amplifier
17489 CEDFA-O17 New 17dBm 1550nm CATV EDFA Fiber Optic Amplifier
17495 CEDFA-O23 New 23dBm 1550nm CATV EDFA Fiber Optic Amplifier
36458 CEDFA-BA Customized 1550nm CATV EDFA Fiber Optic Amplifierr

Originally published at http://www.china-cable-suppliers.com/using-edfa-amplifier-long-haul-catv-systems.html

CWDM and DWDM Network Solutions

Growing demands of the internet users is one of the reasons that lead using wavelength division multiplexing (WDM) networks to transmit optical data. So, what is WDM? WDM is a technology that multiplexes various optical signals through a single optical fiber by taking advantage of different wavelengths of laser light. And the ITU-T recommendation specifies the wavelengths used in CWDM/DWDM or OADM. All the passive fiber optic components are made of filters that only allow specific wavelength to pass through a fiber port and then the others to be reflected to another fiber ports.

WDM Network Overview

A WDM network uses a multiplexer at the transmitter to join the several signals together, and a demultiplexer at the receiver to split them apart. With the increasing demand of data, video and mobile usage on many networks, WDM technology has proved to be the most reliable and cost-effective in transporting large amount of data in telecom. And by utilizing CWDM and DWDM network systems to scale the bandwidth, the operators enable to transmit service from 2Mbps up to 100Gbps of data. Now WDMs are very popular in field of CATV, Internet, VoIP, audio and video solutions, and even bring FTTX solutions to the people’s daily life.

CWDM Network Solutions

CWDM stands for Course Wavelength Division Multiplexer. “Course” means the channel spacing is 20nm with a working channel pass band (±6.5nm or ±7.5nm) from the wavelengths center. CWDM MUX DEMUX Modules take advantage of conventional thin-film filter (TFFS) technology and that allow various channels within ITU G.694 Grid (1270nm~1610nm,1271nm~1611nm), to realize multiplexing or demultiplexing wavelengths over one fiber. Due to the use of cheaper CWDM uncooled laser or lower-quality multiplexer and demultiplexers without fiber amplifiers. The CWDM works at a 60 or 80 km transmission with the wavelength of 1550nm. So CWDM is a very attractive options in metro networks.

DWDM Network Solutions

DWDM stands for Dense Wavelength Division Multiplexer. The word “Dense” is referring to the very narrow channel spacing measured in Gigahertz (GHz) as opposed to nanometer (nm). DWDM us typically use channel spacing measured in GHz (100G or 200G, C-Band 1525nm~1565nm). Now an optical fiber inter-leaver or optic fiber chip is used to double the channel of 100GHz or 200GHz spacing, that’s 50GHz or 100GHz AWG. Just like CWDM MUX DEMUX, DWDM MUX DEMUX also takes the advantage of thin-film filters and are used to increase the amount of data capacity that can be transmitted over a single fiber. The DWDM will be with more channels with much tighter channel spacing. Typical DWDM MUX DEMUX modules only have 32, 40, 44 channels but today’s 50Ghz 100Ghz DWDM MUX DEMUX doubles the channel spacing and can reach up to 64, 80, 88 and even 90 channels.

40 channel Mux Demux

DWDM is the most suitable technology for long-haul transmission because of its ability to allow EDFA amplification. Given the growing need for bandwidth driven by data-hungry applications (smartphones, video streaming, etc.), DWDM has now found its way into metro networks, and is even being used in some cellular back-haul deployments.

Conclusion

WDM systems have become one of the major solutions to meet the growing demand for increased network bandwidth brought about by the rapid growth of Internet and data services. CWDM and DWDM network solutions have their own suitable applications. If you want to get more details for these solutions, kindly visit http://www.fs.com.

Necessary Components in DWDM Systems

DWDM (Dense Wavelength Division Multiplexing) is used to increase the amount of information or systems that can be transmitted over a single fiber, thus allowing allow for more channels with much tighter channel spacing. In DWDM systems, DWDM devices combine the output from several optical transmitters for transmission across a single optical fiber. At the receiving end, another DWDM device separates the combined optical signals and passes each channel to an optical receiver. This article covers DWDM system components that combine (multiplex) and separate (demultiplex) multiple optical signals of different wavelengths in a single fiber.

Optical Transmitters/Receivers

As the light sources in a DWDM system, the optical transmitters are of great importance to the whole system design. In DWDM systems, multiple transmitters are used to provide the source signals which are then multiplexed. Incoming electrical data bits (0 or 1) trigger the modulation of a light stream (e.g., a flash of light = 1, the absence of light = 0). Lasers create pulses of light, each with an exact wavelength. In an optical-carrier-based system, a stream of digital information is delivered to a physical layer device, whose output is a light source (an LED or a laser) that interfaces a fiber optic cable. Then the device converts the incoming electrical signals to optical form signals. Electrical ones and zeroes trigger a light source that flashes light into the core of an optical fiber. The format of the underlying digital signal is not changed. Pulses of light propagate across the optical fiber by total internal reflection. At the receiving end, another optical sensor (photodiode) detects light pulses and converts the incoming optical signals back to electrical signals. Two fibers are used in this process, one for transmitting and the other for receiving.

DWDM Mux/DeMux Modules

The DWDM Mux combines multiple wavelengths created by multiple transmitters and operating on different fibers. The output signal of an multiplexer is referred to as a composite signal. At the receiving end, the DeMux (demultiplexer) separates all of the individual wavelengths of the composite signal out to individual fibers. The individual fibers pass the demultiplexed wavelengths to as many optical receivers. Generally, Mux and DeMux components are contained in a single enclosure. Optical Mux/DeMux devices can be passive. Component signals are multiplexed and demultiplexed optically, not electronically, therefore no external power source is required.

DWDM MUX DEMUX Mux/Demux 40 Channels over Dual Fiber

Optical Add/Drop Multiplexers (OADM)

In a DWDM system, the optical add/drop multiplexers (OADM) can add or drop DWDM channels into an existing backbone ring. It provides the ability to drop one DWDM channel from the network fiber, while allowing all other channels to continue pass to other nodes. Similarly, the drop/insert module removes an individual channel from the network fiber, however, it also provides the ability to add that same channel back onto the network fiber.

Optical Fiber Amplifiers

Optical fiber amplifiers boost the amplitude or add gain to optical signals passing on a fiber by directly stimulating the photons of the signal with extra energy. Optical fiber amplifiers amplify optical signals across a broad range of wavelengths. They can provide flat gain over a large dynamic gain range, have a high saturated output power, low noise, and effective transient suppression. Erbium-doped fiber amplifier (EDFA) is the most widely used fiber amplifier which has received great attention over the past 10 years. EDFA is generally used for very long fiber links such as undersea cabling. It uses a fiber that has been treated or “doped” with erbium, and this is used as the amplification medium.

Transponders (OEO)

Transponders are also referred to as optical-electrical-optical (O-E-O) wavelength converters. They can convert optical signals from one incoming wavelength to another outgoing wavelength suitable for DWDM applications. A transponder performs an O-E-O operation to convert wavelengths of light. Within the DWDM system, a transponder converts the client optical signal back to an electrical signal (O-E) and then performs either 2R (reamplify, reshape) or 3R (reamplify, reshape and retime) functions.

DWDM System with Transponders

Conclusion

With all the necessary components, DWDM-based networks can transmit data in IP, ATM, SONET, SDH and Ethernet. Therefore, DWDM-based networks can carry different types of traffic at different speeds over an optical channel. If you want to learn more about all these components for DWDM system, kind visit http://www.fs.com for more details.

Passive DWDM vs. Active DWDM

To keep pace with the rapidly growing volumes of data-network traffic driven by the growth of the Internet, service providers are always looking to increase the fiber capacity and wavelength spectral efficiency in their networks. DWDW (dense wavelength division multiplexing) is an optical multiplexing technology used to increase bandwidth over existing fiber networks. DWDM works by combining and transmitting multiple signals simultaneously at different wavelengths on the same fiber. It has revolutionized the transmission of information over long distances. DWDM can be divided into passive DWDM and active DWDM which will be illustrated in this article.

Passive DWDM

“Passive” refers to the passive DWDM MUX/DEMUX element which is an unpowered, pure optical equipment. Passive DWDM systems have no active components, which means that no optical signal amplifiers and dispersion compensation modules (DCM) are used. The DWDM passive link is only determined by the optical budget of transceivers used. Passive DWDM system has a high channel capacity and potential for expansion, but the transmission distance is limited to the optical transceivers used. The main application of passive DWDM system is metro networks and high speed communication lines with a high channel capacity.

Active DWDM

Active DWDM system is built from transponders, providing full optical demarcation point agnostic to the routers, switches and ADMs within the network. Active DWDM offers a way to transport large amounts of data between sites in a data center interconnect setting. The transponder takes the outputs of the SAN or IP switch format, usually in a short wave 850nm or long wave 1310nm format, and converts them through an optical-electrical-optical (OEO) DWDM conversion. In long-haul DWDM networks, several EDFAs are installed sequentially in the line. The number of amplifiers in one section is determined by the fiber cable type, channel count, data transmission rate of each channel, and permissible OSNR value.

active DWDM

Besides, the maximum transmission distance of the active DWDM system also depends on the influence of chromatic dispersion—the distortion of transmitted signal impulses. When designing a DWDM network project, permissible values of chromatic dispersion for the transceivers should be considered, and, if necessary, chromatic dispersion compensation modules are included in the line. DCM fixes the form of optical signals that are deformed by chromatic dispersion and compensates for chromatic dispersion in fibers.

Choosing passive or active DWDM system depends on your requirements and current setup. Because both of them have pros and cons.

Passive DWDM
Pros:
1. Inexpensive – As mentioned above, less components are required, and less engineering time is required.

2. INITIAL Setup – Because of the colored optics there isn’t a need to tune wavelengths for all of your connections. It’s a matter of matching your colored optics and plugging it.

Cons:
1. Scalability – you are limited to colored optics, and less wavelengths on the transport fiber. As you grow, you would be required to have more passive devices. Furthermore, with the more passive devices, you have more difficulty to manage. And you will have to start managing the same wavelength on multiple passive devices and they could be serving different purposes on each depending on your setup.

2. Control – If you need to change a wavelength or connection for whatever reason, your option is limited to taking it out of service and disconnecting the physical cabling as the wavelength is tied to the optic.

Active DWDM
Pros:

1. Active can fit a lot more wavelengths (colors) onto a single fiber pair. The composite signal that is sent over a single fiber pair can carry more bandwidth than a passive of the same size, in turn you don’t need as much physical fiber between your two sites (this really only applies if you require that much bandwidth). This is advantageous when distance is a problem because it allows you to get more out of a single leased fiber pair as opposed to passive.

2. Active setups grant you more control over your optical network, you can dynamically re-tune wavelengths without dropping connections (it’s transparent to whatever is riding on that wavelength).

3. Scalability – Active can be easier to scale as your network grows (you can fit more wavelengths on the fiber, see above), but again – we’re talking seriously big iron. I’ll dig into it a bit more below.

Cons:
1. EXPENSIVE – Active DWDM setups are much more expensive compared to passive DWDM. If you don’t have long-distance requirements, don’t choose active DWDM.

2. Configuration – Depending on your vendor, configuration can be a serious undertaking, and require a solid understanding of optical networks. There are many more components in active builds.

Conclusion

Most of the time, DWDM operates with powered component like transponders. Further, after multiplexing the signals, they typically need active amplification to have any preferred reach. Without this, you’re only going with a relatively short distance, which is not a good value for the expense of DWDM.

Installation Guide to CWDM MUX/DEMUX System

CWDM MUX/DEMUX System Overview

Coarse Wavelength Division Multiplexing (CWDM) is a wavelength multiplexing technology for access networks. It is designed to increase fiber optic network capacity without adding additional fibers. The wavelengths of CWDM channels range from 1270nm to 1610nm with 20nm spacing, which allows the use of cost-effective lasers. CWDM MUX/DEMUX system is a passive, optical solution to increase the flexibility and capacity of existing fiber lines in high-speed networks. By adding more channels into available fibers, the CWDM MUX/DEMUX system enables greater versatility for data communications in ring, point-to-point, and multipoint topologies for both enterprise and metro applications.

CWDM MUX/DEMUX System Components

All CWDM system components are passive and require no power supplies. They consist of the rack mount chassis, a set of CWDM MUX/DEMUX and CWDM OADM (Optical Add/Drop Multiplexing) modules with color-coded ports. The CWDM MUX/DEMUX takes 4 or 8 different wavelength channels and multiplexes them onto one common fiber cable for transmission to the network. Then it demultiplexes the channels it receives from the network and sends each channel to a different device. Multiple modules may be chained through the expansion port on the four-channel modules. Thus it increases flexibility and enables growth for evolving networks.

The CWDM OADM module can add or drop CWDM channels into an existing backbone ring. It provides the ability to drop one CWDM channel from the network fiber, while allowing all other channels to continue pass to other nodes. Similarly, the drop/insert module removes an individual channel from the network fiber, however, it also provides the ability to add that same channel back onto the network fiber. The drop/insert module supports two paths (east and west) for dropping and adding, so that network viability is maintained in a ring topology, even if a break occurs in the ring.

CWDM MUX/DEMUX System Installation Guide

Step1: Mount the system chassis on the rack. The CWDM rack-mount chassis can be mounted in a standard 19-inch cabinet or rack. Make sure that you install the rack-mount chassis in the same rack or an adjacent rack to your system so that you can connect all the cables between your CWDM MUX/DEMUX modules and the CWDM SFP transceivers.

mounting-system-chassis

Step2: Install the CWDM MUX/DEMUX modules. First loose the captive screws on the blank of module panel and remove the panel. Then align the module with the slot of the chassis shelf and gently push the module into the slot. Finally, ensure that you line up the captive screws on the module with the screw holes on the shelf and tighten them up.

installing-CWDM-MuxDemux-modules

Step3: Install CWDM SFP transceivers. Since each channel has a specific wavelength, transceivers must comply with the right wavelengths. Each wavelength must not appear more than once in the system. Device pairs must carry transceivers with the same wavelength.

Step4: Install the CWDM MUX/DEMUX to the switch. After inserting the CWDM SFP transceiver into the switch, single-mode patch cables are used to connect the transceiver to the CWDM MUX/DEMUX module.

Connect-the-CWDM-Mux-Demux-to-Switch

Step5: Connect the CWDM MUX/DEMUX pairs. In a CWDM MUX/DEMUX system, multiplexer and demultiplexer must work in pairs. Two strands of single-mode patch cables are needed in the duplex MUX/DEMUX module and one strand for the simplex one. Simply insert single-mode cables from your system equipment to the appropriate port on the CWDM MUX/DEMUX or OADM module.

Conclusion

CWDM MUX/DEMUX system is an attractive solution for carriers who need to upgrade their networks to accommodate current or future traffic needs while minimizing the use of valuable fiber strands. With CWDM technology, you can accommodate Ethernet and SONET on a single fiber that enables converged circuit/packet networks at high demand access sites. Besides, CWDM MUX/DEMUX can work seamlessly with transceivers to optimize link length, signal integrity and network cost, thus becoming a single rack-mount solution for enhanced design, power and space efficiency.

 Source: http://www.china-cable-suppliers.com/

Identify Various Ports on WDM Mux/Demux

In today’s world of intensive communication needs and requirements, fiber optic cabling has become increasingly popular. But considering the physical fiber optic cabling is expensive to implement for each individual service, using a Wavelength Division Multiplexing (WDM) for expanding the capacity of the fiber to carry multiple client interfaces is a highly advisable. WDM MUX/DEMUX (Multiplexer/De-Multiplexer) is one of the most important components in WDM systems. But there are so many types of ports which are not so easy to identify. This article will illustrate various ports with different functions on WDM Mux/Demux.

Common Ports on WDM Mux/Demux

For WDM Mux/Demux, channel port and line port are the most common and necessary ports for normal operation of the WDM Mux/Demux.

Channel Port
CWDM uses 18 wavelengths ranging from 1270nm to 1610nm with channel intervals of 20nm. Channel ports on CWDM MUX/DEMUX is usually ranging from 2 to 18. DWDM uses the wavelength ranging from 1470nm to 1625nm usually with the channel port ranging from 4 to 96. Since DWDM Mux/Demux has a more dense channel spacing of 0.8 nm (100 GHz) or 0.4 nm (50 GHz), it is more suitable for high-density networks.

CWDM Channels

Line Port
There are two types of line port available for CWDM and DWDM MUX/DEMUX. One is dual fiber line port, and the other is single fiber line port. The wavelengths order and the applications of them are totally different. Dual-fiber line port is used for bidirectional transmission, which means the TX port and RX port of every duplex channel port supporting the same wavelength. The WDM MUX/DEMUXs with dual fiber line ports installed on the two ends of the network could be the same. Single-fiber line port only support one direction data flow. If you choose a single-fiber WDM MUX/DEMUX on one side of the network, there should be a single-fiber WDM MUX/DEMUX which supports the same wavelengths but has the reverse order on the TX port and RX port of every duplex channel port.

Special Ports on WDM Mux/Demux

1310nm Port and 1550nm Port
1310nm and 1550nm ports are wavelength ports of WDM MUX/DEMUX. Since a lot of optical transceivers use these two wavelengths for long-haul network, adding these two ports when the device does not include these wavelengths is very important. CWDM Mux/Demux can add either type of wavelength ports, but the wavelengths which are 0 to 40 nm higher or lower than 1310 nm or 1550 nm cannot be added to the device. However, DWDM Mux/Demux can only add 1310nm port.

Expansion Port
Expansion port which can be added on both CWDM and DWDM Mux/Demux is a special port to increase the number of available channels carried in the network. It means that when a WDM Mux/Demux can not meet all the wavelength needs, it is necessary to use the expansion port to add different wavelengths by connecting to another WDM Mux/Demux’s line port.

Monitor Port
This port is used to monitor or test the power signal coming out of a Muxed CWDM or before it gets demuxed from the signal coming through the fiber network usually at a 5% or less power level. Generally, it can be connected with measurement or monitoring equipment, such as power meters or network analyzers.

No matter the common ports or the special ports on WDM Mux/Demux have their own features and application. FS.COM WDM products designed for easy and fast implementation take up minimal space and use least power, thus providing the highest integration level of CWDM and DWDM networks. They can also provide complete solutions for CWDM and DWDM. Kindly contact sales@fs.com for more details if you are interested.

Why Is Fiber Optic Technology ‘Faster’ than Copper?

The deployment of fiber optics in telecommunications and wide area networking has been common for many years, but more recently fiber optics have become increasingly prevalent in industrial data communications systems as well. Fiber optic technology uses pulses of light to carry data along strands of glass or plastic. It’s the technology of choice for the government’s National Broadband Network (NBN) and data centers, which promises to deliver next-generation 200G and 400G Ethernet speeds.

fiber optic technology

When talking about ‘speed’, we were actually talking about throughput (or capacity) — the amount of data you can transfer per unit time, says Associate Professor Robert Malaney from the University of New South Wales, School of Electrical Engineering and Telecommunications.

And fiber optics can definitely transfer more data at higher throughput over longer distances than copper wire. For example, a local area network using modern copper lines can carry 3000 telephone calls all at once, while a similar system using fiber optics can carry over 31,000.

So what gives it the technical edge over copper wires? Traditional copper wires transmit electrical currents, while fiber optic technology sends pulses of light generated by a light emitting diode or laser along optical fibers.

In both cases you’re detecting changes in energy, and that’s how you encode data. With copper wires you’re looking at changes in the electromagnetic field, the intensity of that field and perhaps the phase of the wave being sent down a wire. With fiber optics, a transmitter converts electronic information into pulses of light — a pulse equates to a one, while no pulse is zero. When the signal reaches the other end, an optical receiver converts the light signal back into electronic information.

The throughput of the data is determined by the frequency range that a cable will carry — the higher the frequency range, the greater the bandwidth and the more data that can be put through per unit time. And this is the key difference — fiber optic cables have much higher bandwidths than copper cables (eg. cat5e copper cable).

“Optical fiber can carry much higher frequency ranges — note that light is a very high frequency signal — while copper wire attenuates or loses signal strength at higher frequencies,” says Malaney.

Also, fiber optic technology is far less susceptible to noise and electromagnetic interference than electricity along a copper wire.

“You can send the signal for over 200 km without any real loss of quality while a copper cable signal suffers a lot of degradation over that distance,” says Malaney.

As well as a significant increase in connection speed, fiber optic networks offer a tremendous capacity to keep up with any new technological advances. Once the basic fiber optic infrastructure is in place, it can be rearranged and the end point electronics upgraded when necessary, to deliver even higher capacity. It can do this far more effectively than existing wireless or copper based systems.

In terms of its serviceable lifetime, glass (from which fiber optic cable is made) is long lasting, stronger than copper and more able to retain its transmission properties after physical stress such as weight strain, or even attack by rats and cockatoos. We install fiber differently from copper: in good quality coatings, inside ducts, or in the case of newer systems, encased entirely by electrical transmission wires.

For applications where signal security is a concern, fiber optic technology is an excellent solution. Fiber optic cables do not generate electromagnetic fields that could be picked up by external sensors. It is also more difficult to ‘steal’ signals by spicing into optical fibers than it might be with conventional copper wiring.

Shielded vs. Unshielded Twisted-Pair Cable

As we all know, the advantages and disadvantages of shielded and unshielded twisted-pair cable are under debate for a long time. Advocates of STP cable, which includes screened twisted-pair and foil twisted-pair cables, claim that it is superior to UTP cable. Shielded versus unshielded twisted-pair cable, which is the winner? This post will give you the answer.

STP and UTP cable differ in design and manufacture. But their purpose should be the same–to provide reliable connectivity of electronic equipment. In theory, both types of cable should do this equally well. The true test comes when you look at how each of these cable types performs that task within its respective end-to-end system.

Shielded vs. Unshielded Twisted-Pair Cable

Shielded Twisted-Pair Cable

Shielded twisted-pair cable encases the signal-carrying wires in a conducting shield as a means of reducing the potential for electromagnetic interference. How effective the shielding is depends on the material used for the shield–its thickness and frequency, the type of electromagnetic noise field, the distance from the noise source to the shield, any shield discontinuity and the grounding practices. Also, crosstalk and signal noise can increase if the effects of the shield are not compensated for.

Some STP cables, for example, use a thick braided shield that makes a cable heavier, thicker and more difficult to install than its UTP counterpart. Other STP cables use only a thin outer foil shield. These cables, known as screened twisted-pair cables or foil twisted-pair cables, are thinner and less expensive than braided STP cable; however, they are not any easier to install. Unless the minimum bend radius and maximum pulling tension are rigidly observed when these cables are installed, the shield can be torn.

Unshielded Twisted-Pair Cable

Unshielded twisted-pair cable does not rely on physical shielding to block interference. It relies instead on balancing and filtering techniques using media filters, baluns or both. Noise is induced equally on two conductors and is canceled out at the receiver. With properly designed, manufactured and installed UTP cable (like CAT6 UTP cable), the network is easier to maintain than one in an STP cable plant, with its shielding continuity and grounding issues.

UTP cable has evolved during the years, and different types are available for different needs. Basic telephone cable, also known as direct-inside wire, is still available. Improvements over the years–variations in the twists or in individual wire sheaths or overall cable jackets–have led to the development of Cat3 cable that is compliant with the Electronic Industries Association/ Telecommunications Industry Association-568 standard for transmission rates up to 16 megahertz. Cat 4 UTP cable is specified for signal bandwidths to 20 MHz, and Cat5e UTP cable for specifications to 100 MHz–and possibly higher.

Shielded vs. Unshielded Twisted-Pair Cable

Since UTP cable is lightweight, thin and flexible, as well as versatile, reliable and inexpensive, millions of nodes have been, and continue to be, wired with this cabling medium. This is especially true for high-data-rate applications. For best performance, this UTP cable should be used as part of a well-engineered structured cabling system.

If STP cable is combined with improperly shielded connectors, connecting hardware or outlets, or if the foil shield itself is damaged, overall signal quality will be degraded. This, in turn, can result in degraded emission and immunity performance. Therefore, for a shielded cabling system to totally reduce interference, every component within that system must be fully and seamlessly shielded, as well as properly installed and maintained.

An STP cabling system also requires good grounding and earthing practices because of the presence of the shield. An improperly grounded system can be a primary source of emissions and interference. Whether this ground is at one end or both ends of the cable run depends on the frequency at which a given application is running. For high-frequency signals, an STP cabling system must be grounded, at minimum, at both ends of the cable run, and it must be continuous. A shield grounded at only one end is not effective against magnetic-field interference.

The length of the ground conductor itself can also cause problems. If it is too long, it no longer acts as a ground. Therefore, because specific grounding requirements depend on the application, a general grounding policy that ensures the best results for an STP cabling system is not possible.

UTP cabling doesn’t have this problem. While an STP cabling system is dependent on such factors as physical continuity of the cable shield or installation with adequately shielded and grounded components, a UTP cabling system inherently has fewer potential trouble spots and is much easier to install.