Many people have always believed that 10 base-t 10m networks use 4 signal lines in the network cable, and 100 Base-T 100M uses all 8 signal lines (if so fast? ). However, when the author used a network cable that was previously used in the so-called 10M direct connection (1 and 3, 2 and 6 exclusive case mask), the Internet was accidentally discovered by 100m high-speed transmission. Solution, so on the Internet to consult a lot of information, plus several experimental verification, finally discovered the truth, that is, 100M twisted pair and 10m standard picks are complete!
Twisted pair joint (RJ45) pin number definition
NIC / HUB end jack
Cable crystal joint
The standard approach of 10M twisted pair joints, wire requirements CAT-3 (3 lines).
Number signal definition line pair color 1TX orange white 2TX-orange 3RX green white 4 unlock 5 unlock white 6RX-green 7 unused brown 8 unused brown
The standard approach of 100M twisted pair joint, the wire requires CAT-5 (5 cables), and the joint picking method is fully compatible with 10M.
Number signal definition line pair color 1TX orange white 2TX-orange 3RX green white 4 unlock 5 unlock white 6RX-green 7 unused brown 8 unused brown
Standard connection for 1000M twisted pair joint
The wire requires CAT-5E (5 types of enhancement lines, commonly known as super5), and joints are fully compatible with 10M / 100M.
The 1000 base-T bidirectionally uses all the signal lines in the RJ45 joint. Although the line 5 lines can work, it is recommended to use a 5-class enhancement line.
Number signal definition line pair color 1bi_da orange white 2bi_da-orange 3bi_db green white 4bi_dc blue 5bi_dc-blue white 6bi_db-green 7bi_dd brown white 8bi_dd-brown
Standards summary of all kinds of twisted pairs
In combination, 10M, 100M, 1000M various criteria, can be found that although the standard definitions are slightly different, the final joint is the same, as shown below:
The origin of the twisted pair
As shown in Figure 3, the standard pick up of the twisted pair is not a raystorm, but to keep the layout of the cable connector, in addition to the interference between the connector Mutual cancellation is minimized, and the differential signal value of the external interference is also equal to equal to the anti-interference circuit to be subtracted. Therefore, when we usually make a network line, if you do not work according to standards, although sometimes the line can also be turned on, the interference between the lines of the line cannot be effectively eliminated, so that the signal transmission error rate is increased, and ultimately leads to network performance. .
In fact, the network cable connection used in this article is the EIA / TIA 568B standard, as well as the standard of EIA / TIA 568A, it is just a position in the chart, the orange line is exchanged, and the green white -1, Green-2, Orange-3, Lan-4, Lan Bai-5, Orange-6, Brown-7, Brown-8), the layout of cable connector is still symmetrical.
Standard direct connection method of various twisted pairs
When connecting between 10M, 100M NIC, you can use Hub, then just intersect TX and RX two lines, that is, 1 and 3, 2 and 6 exchange. The 1000m lines are both bidirectional, so they do not need to cross, but in order to be compatible with them, they also use 1 and 3, 2 and 6 exchange to directly connect, so, due to the 1000m standards, the old Compatibility of standards, we can use the network cable according to the standard of 1000M, and can be used for various speeds. Below is the specific connection one of the straight lines (another head is taken by standard):
The alignment map and the standard pickup diagram can be found that the two is actually exchanged with the green line pair, and the careful person will find that it is just the EIA / TIA 568A standard, so it is said that the production of the twisted pair The standard approach is to press EIA / TIA 568A, and the other is in accordance with the EIA / TIA 568B pickup. Both heads are in line with international standards, which is the benefits of line according to standard lines. What is the difference between 3, 5, and super 5?
First of all, why do you want to use twisted pairs instead of parallel? Is the parallelline is not easier to produce?
This is because the network line passes the high frequency signal of> 10MHz, and the insulation line between the wires corresponds to a dielectric plate, which is bypassing the high frequency signal from the high frequency signal formed from the wire (signal phase). Lagged), due to the high signal frequency, it is not negligible, so the parallel line delivery high frequency network signal is not.
But if we put the parallel line twisted, it will form a series of inductors while forming the capacitance, and the sketch is as follows:
_____ // _____ | = | --------------------
Using electronic circuit knowledge, the action of inductance is just in contrast to the capacitor, which makes the signal phase advance, as long as the wire is adjusted, so that the inductance and capacitance formed by the wire can just cancel the line, and the length of the line is increased. The role is equal to the same degree of equivalent, and the signal can be transmitted on the twisted pair without attenuating no attenuation.
From this, we can know that there are three types, 5 categories, and the super five lines on the market are substantially similar from the appearance. The inside of its insulation is different: First, the insulation materials of the signal line are different, the better lines, it The smaller the dielectric constant, so that the smaller the resulting capacitance, the second is the width of the line pair may be different (determined according to the dielectric constant of the insulation).
Another point is that the better the size of the line, the better, this is the reason, indicating that the wire has a high copper content (because pure copper is very soft), its DC loss will be small, the other It indicates that the wire may be multi-strand rather than a single strand, because the multi-shaped line is strong for high frequency signal. This is related to another physical phenomenon (like a skin effect).
The wonderful use of the level on the HUB
Usually, it will leave a level between HUBs for HUB, which is to connect many HUBs together. In order to make full use of hardware resources in an inert-level, the interface is generally connected to it next to it ( Figure 5). Another situation is to set a function of a dial switch to change the function of the last network port (Fig. 6), then what is the difference in the network port as a level connected?
In fact, it is very simple. The level of the network is a standard two-machine connection, which is 1 and 3, 2 and 6, can't think of it.
Then we know this fact, you can: 1, Figure 5, you can also use two normal network cables to connect two computers when you have no electricity, just plug in a network cable, and then pick it next to it. The interface is in line.
2, for Hub without level, we can connect it with other HUB levels through a two-machine straight line (each inserted an ordinary network port).
3, insert the two-machine straight line into the HUB level, can connect the network as other HUB network like the ordinary network cable (1 and 3, 2 and 6 crossing twice, change again), so you go out Just take a two-machine straight wire, straight and interpolated HUB is incorrect, the door-to-door service personnel are very useful.
