9 TBit/s – this peak value was recorded at the beginning of March by the world's largest internet node, the German Commercial Internet Exchange (DE-CIX).The new world record shows once again the strong increase in data traffic and the high demands on the cabling infrastructure.In order for the networks to be able to meet current and future digitalization requirements, companies and institutions need forward-looking and investment-safe migration options for high-speed transmissions up to 400G and beyond.You don't need to look into the crystal ball for this: the transmission rates will continue to increase at ever shorter intervals.The Ethernet Roadmap predicts transmission speeds of 800 Gbps and 1.6 Tbps by 2030.Transmission rates of up to 400G can currently be achieved.Possible types of optical transmission are standard transmission, transmission via WDM (Wavelength Division Multiplexing) - in which several signals run over one channel - and parallel optical transmission.Combined parallel optical and WDM transmissionParallel optical transmissions of 400 Gbit/s via multimode are standardized in the IEEE 802.3bs standard.It provides 16 parallel channels (SR16) each with 25 GBit/s per channel (400GBase-SR16).Adopted in December 2017, this standard requires a 32-fiber MPO connector.Although this has been available on the market since 2018, there is still no transceiver on the active component side that supports this type of transmission.Two other standards are currently being standardized: With the 400GBase-SR8 specification, the IEEE 802.3cm working group is developing a new standard for the transmission of 400 Gbit/s over eight channels, each with 50 Gbit/s per channel.In contrast to 400GBase-SR16, the industry has already developed suitable transceiver technology for 400GBase-SR8 transmission.A 16-fiber MPO is being standardized, which transmits 50 GBit/s per channel over eight channels using the PAM4 modulation method.A 24-fiber MPO connector with selective pin assignment is also provided for in the MSA transceiver specifications (Multi-Source-Agreement).Corresponding products are available on the market.As a completely new technology, a new standard has emerged with the SR4.2 transmission type since the beginning of the year: it combines parallel optical and WDM transmission for the first time and transmits the 400 GBit/s parallel optically over four channels (eight fibers) and over two at the same time Wavelengths via multiplexing.This allows the transmission performance to be increased.CS, SN and MDC In addition to the well-known 12-fiber MPO, the new single-fiber connectors MDC (US Conec) and the SN connector (Senko) specified in the IEEE 803.2cm standard are optionally available for SR4.2 transmission.Together with the CS connector (Senko), which has also been available since 2019, they form alternatives to the multi-fiber connector.All three are characterized by their compact design based on the 1.25 mm LC ferrule - but are significantly narrower than an LC duplex connector.The CS connector has a form factor that is approximately 40 percent smaller and is standardized for the OSFP (Octal Small Form Factor Pluggable) transceiver device interface.In conjunction with suitable cabling systems, network technicians can use it to terminate up to 256 fibers in one height unit.The SN and MDC connectors, which are also very slim, are designed for the new generation of high-density transceivers SFP DD (Small Form Factor Pluggable Double Density) and QSFP DD (Quad Small Form Factor Pluggable Double Density).Both have space for up to 384 fibers in one height unit.Depending on the type of transmission, the individual fiber connectors can be combined en bloc in groups of two or four and plugged into the transceiver.With four connectors, eight fibers are available – or the eight channels required for BiDi transmission (bidirectional) – for the transmission of 50 GBit/s per channel and thus 400G.The CS, SN and MDC connectors thus offer the option of realizing high transmission rates even with few fibers and thus fuel current developments that superficially make the MPO connector superfluous.Because one thing is clear: In the rear, single-fiber connectors are not an option due to their lack of packing density.Also in terms of price for the active components, it is expected that the transceivers for the CS, SN and MDC single-fiber connector faces will be significantly more expensive than for the MPO connector.And last, but not least: Even if a lot is possible with the new single-fiber connector faces and few fibers, companies beyond the 400G cannot avoid MPO connectors and channel bundling.Because with the transmission rates that will continue to increase in the future, companies need flexibility and investment protection.Both can only be achieved with plug-and-play cabling solutions with MPO connection technology in the rear.For this it is important to have the highest possible number of fibers available, with which flexible use is possible depending on the type of transmission.System platforms such as the TDE Modular Link System (tML), for example, work with MPO 12 fiber, MPO 24 fiber or MPO 32 fiber connection technology in the rear area and offer companies the option of using the installed and such continue to use the equipped trunk cable.The use of the new single-fiber connectors in the patch area, on the other hand, opens up new perspectives in terms of packing density and energy efficiency: scalable cabling systems already bind the CS connectors with two fibers, which are significantly more compact than the LC duplex connector, or the SN and MDC connectors with two to eight fibers each.This is made possible by the special design of the tML modules, which are open to all common and future connector faces.In combination with the tML platform, the packing efficiency of the cabling system can be significantly increased: With the CS connector, up to 256 fibers can be found modularly and with the MDC connector even up to 384 fibers, twice as many as when using LC -Duplex connectors and a four-fold increase in the number of ports in one height unit.This guarantees data centers drastic savings in expensive space, which also does not have to be air-conditioned.The first projects, including one at a leading German research institute, are already being used successfully.The use of multi-fiber technology in the rear offers companies another decisive advantage: while only two fibers can be connected at the same time with single-fiber connectors such as the CS, SN or MDC, with plug-and-play connectivity it is at least twelve to currently 32, depending on the application fibers.This reduces installation and connection times to a minimum and in many cases even saves the installer.Read the latest news from the world of LANline regularly in our LANline newsletterDRAKA Comteq Germany GmbH & Co. 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