Addiction point of view: don't make the download unhappy. Do you know that upload bandwidth traffic jam will also slow down download speed?

We all know that when we want to enjoy high-speed surfing, we need to apply for a broadband network with a relatively large bandwidth, but most consumers only know to choose a tariff scheme with a relatively high download bandwidth, but they don't pay attention to the upload bandwidth, and they don't know that when the upload bandwidth is exhausted, the download speed will actually slow down. What the hell is going on here? Let's first understand why upload and download transmission affect each other.

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Viewpoint 1: Why do you need higher upload bandwidth? Who needs higher upload bandwidth? In fact, you can judge whether your upload volume is heavy or not from your usual habit of using the internet.

For example, professional workers, such as live broadcasters, photographers, filmmakers, animation producers, art producers, music producers and other industries, often need to upload their works to the Internet or send them to customers. The upload bandwidth is likely to be blocked at this time. And if ordinary users like to upload photos, share videos or play live games at the same time, they also need higher upload bandwidth.

If you use NAS (Network Attached Storage Device) at home or at work, you need to pay more attention to the upload bandwidth, because when you need to download files in NAS, NAS needs to upload, so the upload bandwidth may be full at this time, resulting in no immediate response? Acknowledgment (Acknowledgment) package further affects the download speed and makes the network Kaka.

Wait! There is no way to send bACK ack packets, which will affect the download speed? Yes, that's what I want to tell you next. If your upload bandwidth is insufficient, it will not only affect the upload speed, but also affect the download speed.

▲ If you are a professional worker or often need to upload files, you can consider applying for a scheme with higher upload bandwidth.

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▲ In an environment where many people * * * use the Internet, a relatively high upload bandwidth is also needed to avoid traffic jams.

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Viewpoint 2: Relationship between TCP/IP connection and ACK packet TCP/IP (transmission control protocol over inter protocol) is the most widely used communication protocol in the development of Internet. Computers, mobile phones, tablets and other devices connected to the Internet need to transmit data according to TCP/IP protocol. The characteristics of TCP/IP can not only ensure the correct transmission of data, but also help the sender adjust the data transmission speed. To understand this principle, we should first look at the three-way handshake process of TCP/IP.

In the process of TCP/IP connection, the computer will send a SYN packet to the server, then the server will send back a SYN/ack packet agreeing to establish the connection, and finally the computer will send back an ACK packet indicating that it has received the information from the server. When the server receives this ACK packet, it completes the three-way handshake and enters the connection establishment state. So we can understand that in the process of transmitting data, every time the computer receives data, it will send it back? The ACK packet lets the server know that the data has been correctly received by the computer before sending the next packet.

▲TCP/IP connection needs to confirm the correctness of connection and data transmission through ACK packet.

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Viewpoint 3: the smooth return of ACK packets can ensure the download speed. When you download data, the server doesn't know how fast your download speed is at first, and it can transmit 1000 packets a second. Or 2000 or 3000? Therefore, TCP/IP definitions will be transmitted in small quantities first. If the ACK packet is received correctly, the next transmission will be doubled.

For example, the server will send two data packets first, and if the data download is normal, the computer will also send back an ack packet. Next time, it will send four packets, then eight packets, 16, 32, 64 ... and the transmission speed will increase exponentially.

However, as the download speed becomes faster and faster, which exceeds the maximum speed that the network bandwidth can bear, the data packet will be lost. At this time, because the computer has not received the data packet and will not send back the ack packet, the server will judge that the data transmission speed has exceeded the bandwidth limit. At this point, it will first halve the transmission speed, and then slowly increase it, and repeat the above automatic adjustment mechanism to achieve a stable network speed, which is the automatic congestion control mechanism of TCP/IP.

Therefore, when the response of the ACK packet is not smooth, even if the download bandwidth is still sufficient, TCP/IP will misjudge the network congestion, thus affecting the network transmission efficiency.

▲ Under normal conditions, when the computer downloads from the server, it will send back an ack packet to let the server know that the data transmission is correct.

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▲ When the data transmission speed of the server exceeds the broadband speed of the application and the bandwidth cannot be loaded, resulting in the loss of data packets, the computer will not send back the corresponding ack packets, so the server will slow down the data transmission speed to meet the broadband network speed of the application.

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Viewpoint 4: Upload traffic jam also affects download speed. The example mentioned above is that under normal circumstances, the download speed reaches the bandwidth limit, resulting in the server not receiving the ACK packet. But there is another situation that will also cause the server not to receive it? ACK packet, that is, the upload bandwidth is used up.

We can imagine the relationship between data packets and ack packets. A fruit and vegetable store (server) will send a truck to deliver the goods (data packets). When the customer receives fruits and vegetables, he will sign a receipt (ACK package) and the truck will return to the fruit and vegetable store with the receipt.

If the traffic is smooth, fruits, vegetables and receipts can arrive on time. If there is traffic jam on the road (insufficient bandwidth), if it happens on the road (downloading), customers will definitely not receive fruits and vegetables on time (downloading will be slow). If there is a traffic jam on the way back (uploading), the truck will not be able to send back the receipt on time, which will affect the next truck to leave from the fruit and vegetable store, resulting in customers not receiving the fruits and vegetables on time.

Therefore, if the upload bandwidth given by telecom operators is not enough, it will easily lead to full upload bandwidth, which will lead to the delayed arrival or loss of ACK packets that should be sent back to the server when downloading files. When the server receives the ACK packet late, it will misjudge that the current data transmission speed is greater than the download bandwidth of the computer, and the server will actively reduce the data transmission speed according to the design of TCP/IP connection protocol. At this time, users will obviously feel that the network speed is slowing down.

▲ If the upload bandwidth is blocked and the ACK packet cannot be returned normally, the server will misjudge and slow down the download speed.

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HiNet optical generation provides higher upload bandwidth. After reading the above explanation, you should be able to understand why sometimes when uploading files, the network will feel confused, and even the speed of downloading files will slow down. Therefore, if you often need to upload files, you can consider choosing a network tariff scheme with higher upload bandwidth to avoid traffic jams. When the network download speed is fast, the more ack packets need to be returned, so the higher the upload speed, the smoother the ACK packet response and the smoother the network usage.

Two years ago, engadget made an on-the-spot evaluation of speed measurement chaos in four broadband networks. At that time, the download speed of HiNet Optical Generation was 100m, which was better than other industries. At present, the optical download is at 100M, and the bandwidth of 40M or 100M upload is available, 300M download with 100M upload, 500M download with 250M upload. Take the tariff plan of Kaibo Broadband as an example. No matter whether it is 120M, 200M or 300M, it is uploaded with 30M, while when it is downloaded with 500M, it is uploaded with 50 m. In contrast, the upload speed is much lower than that of Optical Generation, so when the upload utilization rate is high, it may affect the download speed and cause network congestion.

▲ The download schemes of ▲HiNet Optical Generation 100M or above all provide the upload bandwidth of 100M or above, and the 1G scheme even provides it? 600M upload bandwidth.

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▲ Kaibo broadband download rate is less than 500M, and upload bandwidth is less than 50 m.

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▲ In the first two years of ▲HiNet Optical Generation, there was still a high-speed limited-time preferential scheme in 200 yuan every month. Take 300M/ 100M as an example, you only need to pay 1, 199 yuan every month, which is cheaper than 100M/ 100M!

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After reading this report, you should know why the download bandwidth of the network you applied for is very fast, but you still often feel that the Internet is not smooth. When choosing a suitable internet access scheme, netizens suggest that you can also consider the upload rate. After all, whether the upload bandwidth is sufficient also has a lot to do with the fluency of downloading!

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