What does uplink bandwidth and downlink bandwidth mean? What's the difference?

Upstream bandwidth and downlink bandwidth, or what does uplink speed and downlink speed mean? When setting the speed limit of the router, and the configuration of some other software often encountered upstream speed and downlink speed, many users simply do not know the two represents the consciousness, not to mention the configuration, the following will be a detailed introduction for you.

We have these two behaviors in the process of accessing the Internet: One is uploading data, and the other is downloading data. Uplink broadband (speed) refers to the speed of the upload, while the downlink broadband (speed) refers to the download data is several times.

Uplink broadband (speed) and downlink broadband (speed) is asymmetric, generally the downstream speed is greater than the speed of the upstream. We usually use the broadband to say how many M, are refers to the downlink broadband, because we are mainly on the Internet to download data from the Internet, and upload a lot less data.

In addition, many users also have such a question, that is found in the use of broadband in the process, found that the speed of the computer download is not up to the standard of their own processing of broadband, such as the processing of 10M broadband, the results download speed only 1m/s about the speed, this is why?

This is because the broadband operator is not the same as the unit of Downlink speed on the Windows computer, the unit of the Windows computer is Kbbs, and the unit of broadband operation is kbbs,1b=8b. For example, you have a broadband operation from the 10M of broadband, 10mbps=10240kbps/8=1280kbps, so you download data on the computer is, your maximum download speed is only 1280KBps, that is, only about 1m/s look. So don't say broadband company deceptive, handle the broadband buckle, this is only the unit of calculation caused by different.

Why the upstream rate is inconsistent with the downstream rate

Traditional telephone line systems use low-frequency portions of copper wire (bands below 4kHz). and ADSL uses DMT (discrete multi-audio) technology, the original telephone line 0kHz to 1.1MHz band divided into 256 bandwidth of 4.3khz sub-band. Among them, the band of 4khz for the transmission of POTS (traditional telephone service), the 20KhZ to 138KhZ frequency bands used to transmit uplink signals, 138KhZ to 1.1MHZ band used to transmit the downlink signal
We see that the frequency span of the downlink determines the large and upstream frequency spans! This is also due to the fact that we use the downlink more than the upstream for our daily use.

and ADSL theoretically up to 3.5Mbps upstream speed and up to 24Mbps downlink speed.

Links: http://www.zhihu.com/question/20609353/answer/15625836


Why is the upstream speed much lower than the downstream speed? Due to the limitations of ADSL technology, uplink channel 25, downlink channel 249. The upstream speed is generally only 512Kbps, the downlink can reach 8Mbps, the latest adsl2+ standard downlink can reach 21Mbps.

This explanation only shows that it is technically this way, but why is technology like this? Then there is the following question:

Why does ADSL have to do this technical restriction? Or, if there are so many protocols in xDSL, why is ADSL (a-asymmetric asymmetric, which is symmetrical to the upper and lower lines of the standard DSL) used by the telecom industry? Because of the needs of the telecommunications industry, ordinary people are most likely to download a lot of internet, upload very little, before the Web 2.0, upload is mainly TCP confirmation package bar.

Why is the upstream speed slower than the downstream speed after changing the fiber? Fiber is the same as twisted pair, is the use of the same two optical fiber respectively responsible for the upstream and downstream. Because the telecommunication terminal limits your speed, the upstream gives 2M speed.

Why does the Great Wall have higher broadband uplink speed? Because the Great Wall broadband is equivalent to a local area network, the equivalent of a city all long-width users with twisted-pair wire at 10Mbps speed to connect to a large network, and then in this network connected to the Internet's export to each user limit speed. So the long width is called download 2M Thunderbolt 8M, meaning you can download from the Internet up to 2 m, and then from the long-wide network is 10m-2m=8m. And the long width upload 1M, meaning that you upload to the Internet up to 1M, but upload to the long-wide network is 10M speed.

Why can't telecom give users a higher upload speed? The previous user does not need, now all use peer-to, the need for higher upload speed. Because telecommunications also has a computer room, many Web site servers to be placed in the engine room, these servers need upstream traffic. Telecom upstream traffic to be divided into the use of the computer room, in addition, telecommunications should also consider if the user does not put the server in the telecommunications room, but to build a machine room to pull the fiber. Therefore, in addition to limiting the uplink bandwidth, but also from two aspects of the restrictions, one is that ordinary users do not get a fixed IP address, and the second is to restrict access to ordinary users of the 80 port. What if you want the 10Mbps to go up and down the same fiber, plus a fixed IP address? Yes, the annual fee is 10 times times the average 10M fiber.

What does uplink bandwidth and downlink bandwidth mean? What's the difference?