Ten questions about twisted pair line ten answers

Ten questions about twisted pair line ten answers

While learning to write.   Personal level is limited, if there is falsehood please treatise. ：）
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Baishi<baishi54_at_126.com>
54baishi.126.com
2005-4-29
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1. Twisted pair RJ45 Interface line sequence label how to look. I don't get it.
A: The crystal Head has a metal contact on the side upward, plastic clips downward, inserted one end of the RJ-45 seat outward, the contact is labeled 1-8.

2. I often hear people say what 8p8c, that is what ah.
A: The RJ-45 crystal Head of the production line needs eight grooves, referred to as "8P" (position, position), the metal contacts in the Groove Total eight, referred to as "8C" (Contact, contacts), the industry has "8P8C" nickname.

Why is the

3.  twisted pair stranded in two insulated copper conductors instead of parallel? Parallel lines are not much easier to produce.
A: This is because the network is through the >10mhz high-frequency signal, the wire between the insulation line is equivalent to a dielectric plate, and the capacitance formed by the wire to the high-frequency signal by the bypass attenuation effect (signal phase is lagging), due to the high frequency of the signal becomes not negligible, So it is not possible for parallel lines to transmit high frequency network signals.
However, if we pair the parallel line, we will create a series inductance in the form of the capacitor, and the sketch is as follows:
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is known by the electronic circuit knowledge, the function of the inductor is just the opposite of the capacitance, it makes the signal phase ahead, as long as the wire to adjust the winding, so that the inductance and capacitance of the wire to the formation can just offset, And as the length of the line to increase the effect of both the same degree of increase, ideally, the signal can be non-attenuated in the twisted pair on the transmission.

4. The twisted pair transmits the analog signal or the digital signal. Can you pass the power supply?
A: The twisted pair can transmit analog signals and can transmit digital signals. It depends on the technology that it spreads and accepts. For example, Tsinghua Tongfang "four nets in one" technology the most core is the ability to use a super five type of twisted-pair linear analog signal, digital signal to the same network transmission. and the ordinary telephone line transmits is the analog signal. The typical transmission of a network cable is the analog signal (which transmits and receives the analog technology used. Although the information it transmits is digital).
Twisted pair can also transmit power, but you have to ensure that the transmission of power to meet the requirements of the equipment. If the equipment work power is 10-12VDC, the current is 50MA, twisted pair of internal resistance of 10ω/100 meters (the actual use to measure), if the transmission of power is 12VDC, to ensure the use of normal equipment, you have to transmit power within 200 meters. If the distance is closer (200-300 meters) and the low-voltage DC power is transmitted, it can be transmitted. In the distance (about 1500 meters) and the front-end is not good to take power, you can also use one of the two lines to transmit 220v50hz AC, but not recommended in the same twisted pair of both signal transmission and power supply, such as the need to go power, please use a dedicated power cord, and the twisted pair to maintain a certain distance.

5. What kinds of shielded twisted-pair wires are there?
A: According to the 568B standard shielded twisted-pair line only 7 lines, but there are manufacturers through their own technical innovation to produce 3 categories and 5 categories of shielded twisted pair.

6. Twisted pair is not all 4 to 8 lines.
A: The twisted pair is not all 4 to 8 lines, and the early 2 class lines are 2 to 4 lines. In the US cable standard (AWG), the 3, 4, five, and super five twisted pairs are defined as 4 pairs. Ethernet in the use of twisted-pair as a transmission medium only requires 2 pairs (4-wire) line to complete the signal transmission and reception. There are 3 standards in Fast Ethernet using twisted pair as a transmission medium: L00base-tx, 100base-t2 and 100base-t4. The 100BASE-T4 standard requires that all 4 pairs of wires be used for signal transmission, while the other two standards require only 2 pairs of wires. The most common in Fast Ethernet is the 100BASE-TX standard, so when buying a twisted pair used in a 100M network, some network vendors or companies provide only 2 pairs of twisted pair, on the grounds that Fast Ethernet requires only 2 pairs of wires to transmit information.

7. When making the straight line, is not sure to follow the 568B standard to do.
Answer: No. A pass-through line is a twisted pair used to connect a computer in a network to a hub (or switch). It is divided into one by one correspondence method and 100M connection method. One by one correspondence method, that is, twisted pair of two lines to correspond, the one foot, must be connected to the other end of a foot, although no order requirements, but to be consistent. 100M connection means that it can meet the communication rate of 100M bandwidth. Although it is also one by one correspondence, but the color of each foot is fixed, you need to follow the 568B standard to do the specific order: white orange/orange/White green/Blue/Bai Lan/Green/white brown/brown.

8. Super Five class can run thousands of megabytes. Can you run million-trillion?

A: Not all Super 5 cables can run Gigabit Ethernet, in fact by the Eia/tia 568B Standard, the scope of the five types of lines is 100mb/s 100base ethernet. The class six line is for Gigabit Ethernet. The quality of the Super five UTP can also achieve 1000M----1000base-t, quality is mainly reflected in the electrical performance to meet the needs of Gigabit Ethernet 4-core full-duplex transmission requirements, such as through 3COM/MOHAWK/CDT ' s 1000base-t Cabling-certified Ultra five UTP.

In fact, Super five unshielded twisted pair based on the Gigabit Ethernet solution is standard to follow, that is the 802.3AB standard. 802. 3AB defines the 1000BASE-T specification based on the five types of unshielded twisted pair, whose ultimate goal is to achieve an effective 1000Mbps Ethernet transmission of 100 meters on the five types of unshielded twisted-pair wires. 802. The main significance of 3AB is to protect a large number of users are now investing in the five types of cabling systems. Five types of cabling systems have been used in a large number of buildings built in recent years, and the information industry rapid, the new technology if not to consider the protection of the user's past investment, will certainly lose its vitality. The manufacturers also have solutions. such as 3com/mohawk/cdt ' s 1000base-t. Reference: 3COM/MOHAWK/CDT's 1000BASE-T technical white Paper: "1000BASE-T: Gigabit Ethernet on class fifth twisted-pair" http://www.3com.com.cn/solutions/whitepapers/ 2000/20000726.asp

Http://www3.it168.com/solution/20040805/200408053532.pdf

At this time, the Super five class with four pairs of lines, each pair of lines are two-way transmission, that is, full duplex. (six class run gigabit although also use four pairs of lines, but only two pairs of lines in the transmission of data, the other two pairs of data received, that is, single-work. Note: Super Five class and six class operating frequency is not the same, the encoding method is different, so they run gigabit when the device is not the same, ultra-five-class run Gigabit encoding method is relatively complex, equipment is relatively expensive. (Super Five class line running 1000Mbps, the flow of distribution to 8 copper wire, each copper also bear 125Mbps, but its frequency range only to 100MHz, which means 1Hz to produce 1.25bit, code modulation is more complex.) and six line with 1 to achieve 500Mbps, each line to assume 250Mbps, and its frequency range to 250mhz,1hz on the production of 1bit will be enough to use, so the coding is relatively simple.

The ultra five lines in the

Gigabit Ethernet operate in full duplex mode and are very sensitive to return loss. For example, if the switch receives a packet, it may be difficult to tell whether it is being sent to the correct or if it is being reflected back. Therefore, an active digital signal processor is required on the network device supporting 1000BASE-T to compensate for the return loss. )

B. 50% of the world's cabling is 5 types of cabling, 30% is 6 class cabling. For Wan Shaolai said, to be put into use as soon as possible, for the above two types of cabling system support is a must to consider the issue. But in some of the million trillion research plans there are still some different views, that gigabit run on the fiber is enough, do not consider the 5 Class 6 cabling system. The million trillion international standard 802.3ae was released as early as the end of 03. However, the development of million trillion is not as smooth as originally imagined. The biggest problem is how the million trillion technology and the existing network seamless connection, users think it is best not to change the existing network structure and cabling system, smooth upgrade to million trillion. In the actual application, the cabling for the access layer may not change, the use of existing cabling system is enough, but such a structure for the access layer of equipment, can only maintain the existing 100Mbps transmission rate, to be able to run the million-gigabit rate is not possible. Million trillion if only in the core layer to play a role in the access layer or the use of existing technology, that million trillion of large-scale application of the era is difficult to come soon. This is not the purpose of the million trillion development. Whether running 10G on Class 5 and Super 5 cables should be included in the 10GBASE-T standard that is being formed, a controversy that some companies have caused when defining next-generation physical layer chips. Many electronics and cable companies are sceptical about the ability of more than half of the 5-class cable cables used to complete the 10GBIT/S data Transfer task today. Currently, the IEEE 802.3an Task Force on draft standards has excluded the Super 5 type of cable, but this is not the final decision. Solarflare uses a custom transceiver and a 10G sampling 8-bit A/D converter to send a 10gbit/s signal over a 50 meter Ultra 5 line cable. The company says it will be able to transmit distances of 100 meters when its custom 9-bit A/D converter is launched. However, Solarflare could not launch the product until the 10GBASE-T standard was completed in early 2006. Its products may include a new A/d and a transceiver with 4 million transistors integrated on a 90-nanometer line width. The Ethernet router and switch manufacturer FORCE10 will also support 10G fiber connectivity, and it argues that, from a technical point of view, the Super 5 line will bring 10G into the enterprise and low price areas, because the use of fiber is too expensive. The end-User Alliance of Cisco, Intel, and the United States National Laboratory supports plans to include Super 5 line cables in the 10GBASE-T standard. Cable manufacturers, however, oppose the plan, which they believe will not meet the performance requirements of 10G transmissions. 100MHz is the specified bandwidth for Class 5 and Super 5 line cables, but some companies have tested the enhanced version of 350MHz. 802.3an Task Group now has the specified 10gbase-t bandwidth of 650MHz, but this number may be reduced to 500MHz. Solarflare and some other companies believe that the Super 5 line can reach 350 to 400MHz of bandwidth, and that the idea that 10G needs CAT7 is wrong. The 802.3an Task Group has set a target, specifying 10G to use 200MHz CAT6 cable at distances of 55 to 100 meters, or 600MHz CAT7 cable at 100 m distance. Some people think that the final version of the specification contains the Super 5 line cable is possible. Now, the Task Force has discussed two signal methods. Solarflare recommends the use of format code modulation based on the 10-way 833 msample/s Pam (pulse-amplitude modulation, pulse amplitude modulation), while Intel recommends low-density parity for 8-way msample/s Pam. Now most of the labs are super 5 lines, by the 2006 standard, half of the cable will also be Super 5 class line, if it can run 10G and low price, people certainly will not refuse it. Some users of the cable length of not more than 50 meters, in the future they may also be connected to 10G, but the redesign of the Super 5 line to implement this technology is not ideal, some types of super 5-class line at 450MHz performance is not as good as 250MHz.

9. How far Away is the twisted pair transmission distance.
A: Both the 10base-t and 100BASE-TX standards, or the 1000BASE-T standard, make it clear that the farthest transmission distance is 100 meters. In the comprehensive wiring specification, it is also clear that horizontal wiring must not exceed 90 meters, the total length of the link must not exceed 100 meters. In other words, 100 meters is a limit for wired Ethernet. This limit is the link length from the NIC to the hub device. In fact, we can use some methods to break the limit of 100 meters.
Quality cabling products, high-quality network equipment, reduce transmission rate. If you want to extend the network to a distance farther than 150 meters, only with dedicated network devices, such as using a network extension. Please refer to the article "Breakthrough Ethernet 100 m Limit" (http://chinabyte.chinese.com/ServerIndex/77131870382587904/20040906/1850661.shtml).

10. How do you increase the scope of the network?
For:
A. In 10base-t Ethernet, if you want to increase the scope of the network, in two twisted pair cable can be installed between the repeater (generally with the hub or switch-level connection), but can install up to 4 repeaters, so that the maximum network range to reach 500m. This connection method, also known as the Cascade.
B. If there are two cases in the 100BASE-T network.
1. When the connected device is a 100mbit/s hub: up to two hubs can be connected at the same time, and the longest distance between the hubs is only 5m, so that the maximum connection distance of the network is 205m;
2. When the connected device is a 100mbit/s switch: The connection condition is the same as the 10BASE-T network, i.e. the connection distance is 500m. This is because the switch works in swap mode.