What does telecom say about the number of megabytes of bandwidth and the download/upload speed you see?

Lee boss opened a small internet bar, in the telecommunications office 4M Telecom Broadband (ADSL access), but he returned home with IE browser test download speed but only 400kb/s about, and not too stable, to other people transfer file speed only more than 50 kb/s. But he asked his friend Zhang boss of 4M Telecom Broadband (fiber access) download and to other people file speed how many, Zhang Boss said, download has 450kb/s around, very stable, fast when there is 500kb/s, to other people send files speed also have 450~500 more kb/s.

So this Lee boss is very fire, think that telecom cheated him, said is 4M broadband, download only 400kb/s, and send file (upload) only more than 50 kb/s, that is actually so?

Conclusion: Telecommunications did not deceive him! Then why does Zhang boss handle the telecommunications broadband than the boss of the telecommunications fast belt speed and fast, and stable?

Question one: Why Li Boss's upload bandwidth is slower than download speed;

Lee boss Broadband is ADSL access, because ADSL is not equal bandwidth, upload speed only about 1/8 of the download speed. And Zhang boss is using fiber access, upload download speed is equivalent. So Lee boss Broadband upload speed than download slow is normal phenomenon.

Question two: Why is the upload speed of ADSL only 1/8 download speed?

ADSL (Asymmetric digital subscriber line, asymmetric subscriber loop) is a type of network access. It is called an asymmetric digital subscriber line loop because of an asymmetric uplink and downlink bandwidth. In the early days, telephone lines were used as ADSL line media. It uses the Frequency division multiplexing technology to divide the ordinary telephone line into the telephone, uplink and downlink three relatively independent channels, so as to avoid interference between each other. Even when the phone is on the internet, there will be no internet rate and the quality of the call decreased. Usually ADSL can provide up to 3.5Mbps upstream speed and up to 24Mbps downlink speed without affecting the normal telephone communication.

is constrained by this mechanism of the restrictions, the resulting ADSL line download fast, upload slow, and upload speed is the download speed of 1/8, can be said to be international standards. At the same time, because of this limitation, a single ADSL line in general, the maximum rate is only 10Mbps, very few 24Mbps ADSL.

Of course, with the development of the network, telephone line access ADSL generally less, most rural still use telephone line access, and urban areas are generally used LAN access, that is, the use of network cable access, although the transmission medium has changed, because some manufacturers still use the ADSL standard, so usually, as long as the ADSL, Whether the telephone line, or cable access, are still following the ADSL protocol specification, that is, the upload bandwidth is 1/8 of the download bandwidth. Only network cable transmission speed stability than the telephone line has improved, so we feel that LAN access to the ADSL speed is fast, and stable.

Optical fiber is a shorthand for optical fibers, a light conduction tool that is achieved by the principle of total reflection in a fiber made of glass or plastic. is to achieve upstream download symmetric network access mode. The tiny fiber is encapsulated in a plastic sheath, allowing it to bend without breaking. Typically, the transmitter at one end of the fiber uses a light emitting diode,led or a laser beam to transmit the optical pulses to the fiber, and the receiving device at the other end of the fiber uses a photosensitive element to detect pulses. In daily life, optical fiber is used as a long-distance information transmission because the conduction loss of light in optical fiber is much lower than that of electricity in wire conduction.

Question three: Then why 4M broadband, download speed only about 400kb/s?

First, Telecom says that the bandwidth is the "rate" unit, and when we download or upload data through a tool or IE, the "speed" unit is displayed. So what's the difference between the two? Please see below:

Bandwidth rate: That is the case, Telecom said 4M broadband:
Refers to the telecommunications, Unicom, CRC and other ISP providers to the Internet cafes, "bandwidth rate", in Mbps or Kbps units.

Bandwidth speed: That is, the case of the boss Lee saw the download and send file speed:
Refers to the "bandwidth speed" displayed by the tool when the user downloads or uploads data using the tool, in MB/s or kb/s.

Next, we explain the differences in turn:

What is ①g, M, K?
G, M, K is the number of means, and we usually say that the meaning of tens of thousands of, thousands of, hundreds of is the same, but the binary between them is 1024, not 100. For example:
1g=1024m,1m=1024k.

② What does uppercase B and lowercase b mean, what is the difference?
Large b:b (byte byte): is the basic unit of measure for storage space and is also used as the representation file size. Typically the user calculates the storage space or file size.
The small b:b (bit bit), which is the length unit of the binary number.
The conversion relationship between them is: 1 bytes = 8 bits binary number, namely: 1byte=8bit.

What do you mean, ③kbps?
K has said that the number of units, B (bit) has also been said, is the number of bits. What does p and s mean? P (per) is the meaning of each time. S (second) is the time unit, the second meaning. There are no case-sensitive points.
Therefore, the meaning in Kbps is: how many times per second can be passed 1024 bits number, generally as a bandwidth rate unit, at least telecommunications, unicom, such as the ISP vendors are such, routers will follow this standard.

What do you mean, ④kb/s?
K is the unit of quantity, B (Byte) byte, which is the most basic unit of storage space, S (second) is the time unit, the second meaning. There are no case-sensitive points.
The meaning of B/s is: How many bytes of data are passed per second.
The meaning of kb/s is how many kilobytes of data per second, that is, how many KB of data, the general Download tool shows that the download speed is this unit.

So looking back, let's look at the 4M broadband download speed for boss Lee only 400kb/s? How much theory should be correct?

We first calculate the theoretical speed, in order to facilitate the calculation, we convert the 4Mbps into kbps:4*1024=4096kbps, and then convert the rate unit into a speed unit: 4096kbps/8=512kb/s, so the boss Li 4M broadband theory download speed should have 512kb/s , and the actual only 400kb/s around is normal.

Look at the actual transmission speed, because the network transmission will have loss, while the download speed also to the other server can provide bandwidth, so 4M broadband, download speed has 400kb/s is normal.

So boss Lee's 4M broadband upload only 50kb/s normal? How much should the theory be?

Similarly, the theoretical speed of the first calculation of the theoretical velocity is 512kb/s, and previously said that ADSL broadband upload speed is the download speed of 1/8, so 512kb/s/8=64kb/s, in addition to network transmission loss, there is 50kb/s upload speed is very normal.

Attached: Bandwidth rate and theoretical transmission speed comparison table:

Special Instructions:
Theory, can be interpreted as ideal or expectations, but with the actual words, whether it is optical fiber or ADSL access, the actual speed is lower than the theoretical speed! If you go to test speed, but also by the other side of the server bandwidth and the degree of busy first, the actual test will actually see the speed is lower than the theory, general fluctuations in the 50~100kb/s around.
In some cities, there is also a phenomenon of insufficient bandwidth, such as the obvious 10Mbps fiber broadband, speed theory should have 1280kb/s, and the actual only 800~1000kb/s. You can only contact telecom or Unicom vendors if you encounter this problem.

What does telecom say about the number of megabytes of bandwidth and the download/upload speed you see?