Knowledge about the ADSL Network Connection Mode

Asypolicric Digital Subscriber Line (Asymmetric Digital user loop) is a new data transmission method. It is called because of asymmetry between upstream and downstream bandwidth. It uses the frequency division multiplexing technology to divide common telephone lines into three relatively independent channels: telephone, uplink and downlink, thus avoiding mutual interference. Currently, Ethernet (the main part of the Internet, the expansion of star networks) is based on ADSL and optical fiber (optical fiber can both reach the peak value up and down, without affecting each other, stable and secure, but expensive) this technology is generally used by families and offices. The channel mentioned above is the term of network engineering. From the perspective of physics, it is actually a specific frequency band (the frequency of the oscillating electrical signal is, from a frequency to a frequency, that is, the frequency band)
In this way, the uplink and downlink operations can be performed simultaneously after the frequency modulation (the network project is called the full duplex mode). The uplink is transmitted from your local network to the Internet, downloading is to download data from the Internet ). Of course, for servers, the uplink speed is the download speed that it can provide you, and your final download speed is determined by the minimum speed of your network. These two concepts are easy to confuse. For two computers, it is easy to understand. Your uplink is my downlink maximum value, and My uplink is your uplink maximum value.
In reality, the network still goes through many nodes, such as routers and switches.
 
As shown in the figure, host A actually reaches the downstream speed of 10 Mbps. These devices include the forwarding devices of telecom carriers and the ADSL speed limit. your internal network device starts from your computer Nic, the network adapter to the destination is terminated. MAC is the same for MAC, both upstream and downstream: data transmission, which is limited by the forwarding performance of each device during transmission. In addition, there are software restrictions, for example. days. chao.. min. sense. time consumed by the word filter program ...... ADSL is not symmetric, but asymmetry still has its provisions, the common standards are as follows: ITU-T G.992.1 (G. dmt) G. dmt: full speed, 8 Mbps downstream, up 1.5 Mbps ITU-T G.992.2 (G. lite) G. lite: downstream 1.5 Mbps, upstream 512 Kbps ITU-T G.994.1 (G. hs) Variable Bit Rate (VBR) ANSI T1.413 Issue #2 downlink 8 Mbps, upstream 896 Kbps and some faster update standards, but few telecom service providers currently use: ITU G.992.3/4 ADSL2 downstream 12 Mbps, upstream 1.0 Mbps ITU G.992.3/4 Annex J ADSL2 downstream 12 Mbps, upstream 3.5 Mbps ITU G.992.5 ADSL2 + downstream 24 Mbps, uplink 1.0 Mbps ITU G.992.5 Annex M ADSL2 + downlink 24 Mbps, uplink 3.5 Mbps like my office uses ITU G.992.3/4 Annex J ADSL2 standard, downlink 12 Mbps, based on these standards, you can develop an office traffic distribution plan for uplink traffic of Mbps:
Is the bandwidth setting of the enterprise gateway. I would like to describe the boss-level readers who use a finger to play the keyboard as follows: (I hope I can understand) the door to the pigsty is very big. I can use a few trucks to get in and out. 1. delivery in: How much is it? 2. delivery: You can only load 100 pig pigs at a time, regardless of how much traffic you need and how many trucks you want to transport.
There are two situations in your home: 1. If you have money, the door to your home is usually opened. buy pig: transport trucks come in directly, but you can only drive the trucks in one breath at a time (there is no problem with a 100-head push door) 2. pig selling: as long as it can be sold, it can be transported all the way out, but there is only one truck at most (only 100 heads can be loaded, although you can push 200 pig in turn) 2. Average, only one pig can be moved in and out at the same time. when buying pig, a truck delivers 100 heads and must be pushed forward. The truck finds that it is idle for too long, so it only ships one head at a time. sell pigs, push them one by one, drive the truck away, and pick up the second pig farm here as a server. Generally, the performance of the server is very powerful. The trucks are transmission equipment, unlike the trucks in reality, it doesn't take time for trucks to run here. It's your computer to arrive at your home in real time. A pig represents 1 Mbps or 1 m bits (8 bits = 1 byte)