1. Ddm Futures Quote

In the future, DWDM technology will continue to provide the bandwidth for large amounts of data. The truth is that with the development of technology, closer spacing of wavelengths will be possible, thus increasing the capacity of systems. But DWDM is also moving beyond transport to become the basis of all-optical networking with wavelength. Future DWDM terminals will carry up to 80 wavelengths of OC–48, a total of 200 Gbps, or up to 40 wavelengths of OC–192, a total of 400 Gbps—which is enough capacity to transmit 90,000 volumes of an encyclopedia in one second.

CWDM and DWDM explainedThe two key WDM technologies are coarse wavelength division multiplexing, CWDM and dense wavelength division multiplexing, DWDM. Which solution is best suited to a given environment depends on the network and user requirements.CWDM supports up to 18 wavelength channels transmitted through a fiber at the same time. To achieve this, the different wavelengths of each channel are 20nm apart.

DWDM, supports up to 80 simultaneous wavelength channels, with each of the channels only 0.8nm apart. CWDM technology offers a convenient and cost-efficient solution for shorter distances of up to 70 kilometers. For distances between 40 and 70 kilometers, CWDM tends to be limited to supporting eight channels. Unlike CWDM, DWDM connections can be amplified and can therefore be used for transmitting data much longer distances. The sweet spot for CWDM is up to 10 Gigabit Ethernet and 16G Fibre Channel. And it is quite unlikely capacities with increase beyond this in the future.

DWDM however, is able to handle higher speed protocols up to 100Gbps per channel making it a more suitabletechnology for higher speed protocols.Traditionally CWDM components have been lower in cost making it more popular than DWDM. Now the price for both solutions is comparable. With higher speeds, more channel capacity, longer distances and passive networking, DWDM is the technology of choice for green field installations. Active or passive systems – what’s the difference?Both CWDM and DWDM solutions are available as active or passive systems.In a passive, unpowered solution the xWDM transceiver resides directly in the data switch. The output from the xWDM transceiver connects to an unpowered multiplexer that combines and redistributes, multiplexes and demultiplexes, the various signals. As the xWDM transceiver resides in the data switch, it means that all xWDM functionality is embedded in the data switch.Active xWDM solutions are stand-alone AC or DC powered systems separated from the switch.

The task of the stand-alone system is to take the short-range optical output signal of the fiber or IP switch and convert it to a long-range xWDM signal. This OEO, (optical to electrical to optical), conversion is handled by a transponder. The converted xWDM signal is then transmitted with the help of transceivers and multiplexers.

Due to the separation of the xWDM transport solution from the actual switch, active systems also tend to be more complex than passive, embedded solutions.

FS Official 2016-11-29It has been over 20 years since DWDM technology first came on the scene, and in the last two decades it has revolutionised the transmission of information over long distances. At present, DWDM technology is so widely applied that we almost forget that there was a time when it did not exist and when accessing information from the other side of the globe was expensive and slow. DWDM Technology: Data in a Rainbowstands for Dense Wavelength Division Multiplexing, an optical technology used in fibre optics to increase bandwidth over existing fibre optic backbones. The “dense” here means that the wavelength channels are very close to each other. PrincipleThe data from various different sources is put together on optical fibre in which each signal travels at same speed on its own light wavelength. At the receiver end, every channel is demultiplexed into original source, therefore different data formats with different data rates such as Internet data, Synchronous Optical Network data (SONET), and asynchronous transfer mode (ATM) data can be transmitted together at the same time through one optical fibre.

Thus DWDM technology increases the network capacity and makes efficient use of bandwidth. The capability of transmission of DWDM is 4 to 8 times of TDM (Time Domain Multiplexing) and here EDFAs (Erbium doped optical amplifier) are deployed because these amplifiers can boost the strength of signal so that the signals need not be regenerated again and again. The signal can be transmitted to more than 300 km before regeneration.Figure 1: The principle of DWDM technology Applications. DWDM has capability to expand capacity and can serve as backup bandwidth without a need to install new fibres, thus it is ready made for long distance telecommunication services. DWDM can also be used in various networks like sensor networks, remote radar networks, tele spectroscopic process control network and many more networks.

By the use of only two fibres, 100% protected ring with 16 separate communication signals can be constructed deploying DWDM terminals as these are self healing rings. In order to meet the demand in fast growing industrial base, DWDM system can be used for existing thin fibre plants as these plants cannot support high bit rates. Transparency—Because DWDM is a physical layer architecture, it can transparently support both TDM and data formats such as ATM, Gigabit Ethernet, ESCON, and Fibre Channel with open interfaces over a common physical layer. Scalability—DWDM can leverage the abundance of dark fibre in many metropolitan area and enterprise networks to quickly meet demand for capacity on point-to-point links and on spans of existing SONET/SDH rings. Dynamic provisioning—Fast, simple, and dynamic provisioning of network connections give providers the ability to provide high-bandwidth services in days rather than months. DWDM Backbone NetworksThe DWDM-based network structures can be divided into three classes, which are simple point to point DWDM link, DWDM wavelength routing with electronic TDM and switching/routing backbone network and all optical DWDM network.

Simple Point to Point DWDM LinkIn this architecture, the electronic nodes can be SONET/SDH switches, Internet routers, ATM switches, or any other type network nodes. The DWDM node consists of typically a pair of wavelength multiplexer / de-multiplexer (lightwave grating devices) and a pair of optical-electrical/ electrical-optical converters. Each wavelength channel is used to transmit one stream of data individually.

The DWDM wavelength multiplexer combines all of the lightwave channels into one light beam and pumps it into one single fibre. The combined light of multiple wavelengths is separated by the demultiplexer at the receiving end. The signals carried by each wavelength channel are then converted back to the electrical domain through the O/E converters (photo detectors). In this way, one wavelength channel can be equivalent to a traditional fibre in which one light beam is used to carry information.

It is worth noting that the wavelength channels in one fibre can be used for both directions or two fibres are used with each for one direction.Figure 2: Point to Point DWDM Link 2. Wavelength Routing With Electronic TDMIn this structure, wavelength routers are used to configure or reconfigure the network topology within the optical domain and the TDM network nodes are used to perform multiplexing and switching in the electrical domain.

This combined optical and electrical network architecture can be applied in SONET/SDH in which the electrical TDM network nodes would be SONET switches, or in the Internet in which the electrical TDM network nodes would be the Internet routers. The architecture can also be used in an ATM network where the electrical TDM network nodes would be ATM switches.Figure 3: Wavelength Routing with Electronic TDM 3. All Optical DWDM NetworkAs it is seen that the electrical TDM/switching nodes can be of any kind, such as SONET/SDH switches, Internet routers, and ATM switches.

Ddm Futures Quote

This indicates that the all-optical TDM nodes in the all-optical architecture can be optical SONET/SDH switches, or all-optical ATM switches, or all-optical Internet routers. Different types of all-optical TDM/switch nodes can also be in one network, provided the protocol conversions are implemented. In fact, the optical TDM/switch node and the wavelength router in one routing site can be combined into one all-optical switching node that not only forwards packets through time domain multiplexing but also selects the light path intelligently according to the availability and traffic loads of the links.Figure 4: All Optical DWDM Network Deploy DWDM Over CWDM NetworkIn the previous text, we have fully discussed DWDM technology and network. And is used to be a more popular low cost entry point for many customers. However, As the need for capacity grows and service rate increases, there is a demand to increase the capacity of existing CWDM networks. The principle of deploying DWDM over CWDM lies in the fact that DWDM wavelengths are actually within the CWDM wavelengths range as shown in the Figure 5.

Thus, the DWDM network can be connected to CWDM network via the CWDM channels of 1470 nm, 1490 nm, 1510 nm, 1530 nm, 1550 nm, 1570 nm, 1590 nm, and 1610 nm. In most cases, the 1530nm and 1550nm channels are suggested for the combination of CWDM and DWDM system to increase the capacity of the existing CWDM fibre optic network.Figure 5: DWDM and CWDM WavelengthsTo combine the DWDM wavelengths with CWDM wavelengths, both CWDM MUX/DEMUX and DWDM MUX/DEMUXs should be used. The following picture shows the connection methods for hybrid CWDM and DWDM by using 1550nm channel. On both ends of the fibre link, a CWDM MUX/DEMUX and a DWDM MUX/DEMUX with corresponding wavelengths are deployed. Connect the line port of the DWDM MUX/DEMUX to the 1530nm/1550nm channel port of the CWDM MUX/DEMUX, the DWDM wavelengths can be added to the existing CWDM network.Figure 6: Build DWDM over CWDM NetworkThe wavelengths should be carefully considered during the selection of the CWDM MUX/DEMUX and DWDM MUX/DEMUX. As above mentioned, wavelengths of 1530 nm and 1550 nm are suggested to be used for CWDM and DWDM hybrid. The following picture shows the suggested wavelengths for CWDM and DWDM hybrid.

If the 1530nm port is to be used, the DWDM MUX/DEMUX channel ports are suggested to range from 1529.55 nm to 1536.61 nm. For 1550nm port, the channel ports of the DWDM MUX/DEMUX is suggested to range from 1545.32 nm to 1557.36 nm.Figure 7: Suggested Wavelengths for CWDM and DWDM Hybrid Practical Considerations in Deploying DWDM NetworkWhen deploying a DWDM-based network, customers may encounter some questions which will affect their choices of vendor, equipment type, design, and so on. Some of these questions are as follows. What is my strategy for protection and restoration?Designing a protection strategy is a complex process that many considerations should be taken into account. There are both hard failures and soft failures. The former must be addressed through redundancy at the device, component, or fibre level. The latter must be addressed by the system through intelligent wavelength monitoring and management.

Protection and survivability strategies depend upon service type, system, and network architectures. In many networks, they also depend on the transport protocol. The Historical Evolution and Future Trend of DWDM TechnologyAs the Figure 8 shows, by the mid-1990s, dense (DWDM) systems were emerging with 16 to 40 channels and spacing from 100 to 200 GHz. By the late 1990s, DWDM systems had evolved to the point where they were capable of 64 to 160 parallel channels, densely packed at 50 or even 25 GHz intervals. It can be seen that as technologies advance, there is an increase in the number of wavelengths accompanied by a decrease in the spacing of the wavelengths.