Gigabit Ethernet and Class six cabling

In September 1997, the ISO/IEC JTC1 SC25 WG3 Standard Committee decided to develop two new types of cables for the next edition of ISO 11801, which are divided into six class/e and seven class/F for the performance of the two new cables. This decision has aroused the great interest of the wiring industry and some standard committees (especially the American Tia/eia organization and the European CENELEC).
In addition to the work carried out by the wiring Standards Board, the LAN Standards Committee is also developing technologies for gigabit transmission on existing structured cable systems. The IEEE802.3 Gigabit Ethernet, which was studied in 1996, has attracted wide attention from the network industry as a special LAN technology. The most challenging task facing the IEEE802.3 committee is the development of a reliable and robust gigabit Ethernet technology capable of operating on the existing five-class/D-level systems.
As we all know, Ethernet technology is closely related to cabling technology, so how Gigabit Ethernet technology is developed to support a new generation of cables, especially the proposed category six line/e cable?
　　
IEEE 802.3 Gigabit Ethernet
The Gigabit Ethernet project, which began in 1996, has done a lot of work now. The primary goal of the Gigabit Ethernet project is to provide 1Gbps of bandwidth to backbone networks and to provide natural upgrades to existing Fast Ethernet networks, while leveraging existing network management tools and training as much as possible.
In order to maintain the maximum collision area of 200 meters in diameter, the minimum CSMA/CD carrier time, the Ethernet time slice extends from the current 512 bits to 512 bytes (4096 bits), and the minimum packet size is still 64 bytes. The carrier extension property solves the CSMA/CD inherent timing problem without modifying the minimum packet size. Although these changes may affect the performance of small packets, this effect has been offset by the characteristics of the CSM/CD algorithm known as packet burst delivery.
In order to reduce the time that Gigabit Ethernet products Enter the market, the standard 1000BASE-SX,-LX and-CX versions can adapt to the current time-tested Fiber channel technology. That is, the 8B10 NRZ (no Return to zero) encoding mode, to provide 1.25Gbaud effective baud rate, so can provide full speed 1Gbps data rate.
The 1000BASE-SX series uses low-cost shortwave CDs (compact disc, optical disc lasers) or Vcsel (Vertical cavity Surface emitting laser, vertical cavity surface light-emitting lasers) transmitter, The 1000BASE-LX series uses a relatively expensive long-wave laser. The 1000BASE-CX series is intended to connect high-performance servers and high-speed peripherals with short jumper cables between wiring.
The 1000BASE-T series is a new design that supports a large number of installed five-class cabling systems. A complex digital signal processing (DSP) technique is used to overcome the defects of line 5. 1000BASE-T uses all 4 pairs of twisted pairs in the transmission and works in Full-duplex mode, so new parameters such as echo loss and remote crosstalk power and (Fext) are important. This design uses PAM-5 (5-level pulse amplification modulation) encoding to transmit a Mbps on each pair of pairs. Bidirectional transmission requires that all four wires must use a hybrid magnetic field line for the transceiver port, because the perfect hybrid magnetic field line is not available, so the transmit and receive circuits cannot be completely isolated. Any sending or receiving line will echo the device. Therefore, to achieve the required error rate of 10-10 (BER) must offset the echo. 1000BASE-T cannot filter on frequencies that are concentrated above 125MHz, but uses the frequency-scrambling technique and grid coding to filter the frequency bands after 80MHz. In order to solve the limitations of the five types of lines in such a high frequency range due to near-end crosstalk (in the case of psnext), appropriate schemes should be used to counteract crosstalk. The use of grid coding can enhance the ability to resist interference, this conclusion is applicable to all the above.
End users may be confused about what cables to use to support 1000base-t. Although this technical support has been installed on the 5-Class line system, it is important to note that the newly added cabling parameters must also be satisfactory. These parameters include echo loss, hierarchical distal crosstalk (elfext), propagation delay and delay distortion. Therefore, if the cable meets the requirements of Line 5 (1998) or Super 5, then it will support 1000BASE-T. If the installed cable meets only the 5 line standard (1995), the cabling system should be measured and certified in accordance with the newly added wiring parameters prior to connecting the 1000BASE-T device. (Computer science)
　　
Do you need 6 types of wiring?
The current wiring industry in the need for six types of wiring is a lot of controversy (even in the current draft stage) in order to correctly analyze, let us look back to 1992 years 3 types of wiring prevalence, and 5 types of wiring only just proposed when the situation. The inexpensive 10Mbps is developed on the basis of three types of cabling for running Ethernet (BASE-T) and Mbps ATM LANs. As the bit rate of Ethernet increases to Mbps and ATM LAN grows to 155.5 Mbps, electronic devices have to increase their complexity and cost in order to support these LAN technologies on the basis of three types of cabling. 100BASE-T4, 100base-t2 and 155.5 Mbps CAP64 ATM LAN require sophisticated DSP technology to overcome the limitations of three types of cabling. With 5 types of cabling being adopted by many end users, inexpensive 100Mbps (100BASE-TX) Ethernet and 155.5Mbps NRZ ATM LANs have been developed and better performance has been achieved on the basis of five types of cabling.
The actual situation shows that: the full cost of each user's connection when running 100BASE-T4 with three kinds of wiring (for example, from router to network card, including cable) is 164 pounds, while the implementation of 100BASE-TX on the basis of five types of cabling costs £ 132, by contrast, Average per-user connection cost savings of 24%.
No doubt, the same development will happen again in 1000base-t LAN technology, because the 1000BASE-TX design uses two pairs of lines to send, two to receive the working way, therefore does not need full duplex mode echo cancellation. In order to shorten the time to enter the market, will choose the MLT-3 encoding method used by 100BASE-TX, MLT-3 bandwidth efficiency of 4 bits per hertz, so the frequency width is 125MHz. This is well limited to the next and Psnext ranges of category six cabling, so crosstalk cancellation is unnecessary. The current level of semiconductor technology does not use the back-ripple crosstalk cancellation device will reduce at least 50% of the overall complexity of the 1000BASE-TX design (compared with the current 1000base-t design). The grid coding technology may also need to be improved to ensure compliance with EMC requirements.
By extension, this design can be used for 1.2 Gbps systems if the data ratios are raised from each to Mbps. As a result, class six cabling will not only reduce the cost of electronic devices that support gigabit Ethernet, but also provide infrastructure protection for future LAN technologies that may exceed 1Gbps.
Cabling infrastructure investments will be considered a long-term investment, and wiring facilities themselves should also be an asset. According to international wiring standard ISO 11801, a wiring system has a life expectancy of at least 10 years. During this time, PC technology will make great progress. For the time being, although the desktop system has not yet used 1Gbps requirements, this is mainly due to the current PC internal bus structure constraints, because the bus determines the processor and memory and other peripheral devices (such as network card) between the data exchange rate. The famous Moore's Law predicts that the number of transistors on a chip increases by one times every 18 months. This is often used to describe the growth rate of PC processor performance, that is, the performance of PCs will be increased by one times every 18 months. Based on these facts, there may be a PCI 2 bus in desktop PCs within three years. And so on, in the life cycle of cabling system, it is very possible for 1000BASE-TX technology to be applied to the desktop system.
　　
Possible applications
Let's think about the amount of throughput that these applications will require. Multimedia applications are becoming a basic requirement for desktop PCs. Intel has introduced MMX (multimedia Exchange, multimedia Exchange) technology, which will greatly drive multimedia applications. The advent of multimedia business and multimedia messaging has dramatically influenced the design of local area networks. Future multimedia business applications will inevitably require higher bandwidth and lower response times to achieve satisfactory performance. The future of computer commerce, according to Intel, will be the communication between screens, and business is built between the Intel-structured visual-Connection PC (visual Connected PC,VCPC). The AGP (Accelerated Graphics Interface) interface, launched in 1997, supports MMX technology for Low-cost, high-performance 3D graphics applications. With the advent of low-cost DVDs (Digital versatile disk, Digital universal disks), scanners and digital cameras will provide users with a new interactive, intuitive and living computer experience where users can take their own unique visual data-entry software. The size of the file will increase dramatically, with a large number of bitmap graphics and pictures used to boot the operation, making the files, documents more interesting and more user-friendly. Visual computing will require a higher bandwidth than the current LAN.
　　
Conclusion
The IT industry has made great strides in network technology over the past five years. An increasing number of end users are entering the network, which facilitates the development of complex and transactional application software. The enhancement of PC performance and the multiplication of digital signal processing ability, as well as the increase of silicon wafer storage capacity, have created new business opportunities for software developers to develop applications that require a large amount of bandwidth. The result is a rapid increase in file size. All of these trends put higher demands on the web. Cabling infrastructure is its central nervous system, which must be guaranteed to operate efficiently and avoid network paralysis. This allows the end user to select at least 5 classes of lines to ensure that the network is working properly, and a 6-class line is recommended for newly installed systems, which will ensure that Gigabit Ethernet technology is economically responsive to current and future needs.