Ps: The inspiration comes from a dropped line of LOL teammate, feeling a lot of emotion, so it is broken to read.

WLAN and WIFI

WLAN, which stands for Wireless Local Area Networks, is used to make up for the poor ductility of limited Local Area Networks and realize the purpose of network extension. WLAN uses the ISM radio broadcast frequency band for communication. There are three IEEE protocols involved: the 802.11b and 802.11g standards use the 2.4 GHz band, while 802.11a uses the 5 GHz band.

WIFI is an implementation of WLAN. WIFI stands for Wireless Fidelity, a Wireless local area network based on Wireless Fidelity technology. Because WIFI mainly uses 802.11b protocol, so people gradually used WIFI to call 802.11b protocol. With the evolution of technology, WIFI technology has reached the sixth generation.

WIPI technology has been proposed in China. Theoretically, WIPI has better security performance, but because of various interests, it has not been recognized by the international community, and has even been suppressed. Huawei, for example, was “temporarily” removed from the Wi-Fi Alliance, allowing WAPI to return to the public eye after years of hiatus.

What is the difference between WiFi5 and WiFi6? – zhihu (zhihu.com)

5G WIFI and 5G mobile?

Today’s routers offer WIFI connectivity in the 2.4ghz and 5ghz bands, commonly known as XXX and XXX_5G. 5G frequency band has higher wireless transmission rate, stronger anti-interference ability, stronger wireless signal and higher stability.

In recent years, the popular “5G” refers to the fifth Generation of mobile communication technology proposed by Huawei, ZTE, Ericsson and other companies, where G is the abbreviation of “Generation”. (FOR quite some time I thought the two 5G’s meant the same thing). 1G is analog technology; 2G is digital voice communication; 3G is multimedia communication. With the beginning of 4G, people officially entered the era of wireless broadband. Compared with 3G, THE communication speed of 4G has been improved by leaps and bounds. The short video creation platform, HD video platform and live broadcast platform which began to rise gradually around 2013 basically developed rapidly after the promotion of 4G technology.

5G communication is another evolution of 4G communication, with huge improvements in transmission rate, latency, connection number, connectivity and so on.

What exactly is WAPI? Why is it safer than Wi-Fi? – zhihu (zhihu.com)

Wireless network card

Today’s laptops and mobile phones come with WLAN connectivity, essentially because they have built-in wireless network cards and corresponding drivers (hardware must be driven by software to use, whether it is connected to a mouse, an external keyboard, or a connection or wireless headphones). The way to check for network drivers is to view all network drivers installed on your computer in device Manager -> Network Adapters.

Occasionally, the laptop fails to search the Internet. Note that “disconnection” is the ISP’s business, such as a construction team accidentally digging out a cable somewhere; There is a network but not connected is the thing of the device itself, which may be caused by the damage of the driver corresponding to the network card. Take the author’s meat machine as an example, the Wireless Network driver responsible for connecting WIFI is Killer Wireless-N/A/AC Wireless Network Adapter. For a while, when the computer was turned on, the driver reported an error and failed to search for WIFI signals (perhaps because it was not compatible with Windows 10 at the time).

Checking the status of the network driver in the network adapter item can often save a lot of effort, and the solution can be very “simple” – that is, to uninstall the damaged driver, and then download the new driver from the computer’s official website. The Windows device Manager is a very useful panel that can be used to check the drivers of all the hardware devices on the computer. When you encounter a hardware problem, first check whether the driver is normal, and then try to check whether the hardware itself is faulty. After all, the driver is broken can be reinstalled, hardware is broken need to go after sales.

In addition to the direct router, the desktop computer can also connect to WIFI through an external wireless card device. Hardcore gamers can get a PCI wireless card and install it themselves. For non-hardcore gamers, a USB wireless card is not only easy to use, it is not easy to break the computer, and the only drawback may be the perennial use of a USB port.

Under normal circumstances, when the chassis is plugged into the wireless network card through the USB port, it can install the driver software itself, and then the computer can recognize the wireless network and connect. Here to TP-link network card use tutorial as an example, very easy to understand.

How do I install and set a free – drive wireless card? – The tP-link service is supported

bandwidth

Bandwidth is actually the throughput of data transmission in bit per SEC (BPS). Obviously, in the unit time of 1 second, the more data transmission, we can say its throughput is greater.

We usually measure the speed of downloading files in bytes per second. Since 8 bits = 1 Byte, the theoretical maximum download speed is ≈ bandwidth throughput / 8 (1 Mbit = 1000 Kbit and 1 MB = 1024 KB, ignoring some computational errors). Of course, the question of “whether the download will be faster” also depends on “whether the various cloud disks or download software itself will limit the stream”, “whether the download is single-threaded or multi-threaded”, “P2P, P2SP, P2S” and other factors, and the computer’s wireless card hardware itself. The author handles 200M bandwidth service at home. In the actual test, the maximum downlink speed of the game with higher configuration is 91Mbps, but the maximum downlink speed of the business with general configuration is only 50 Mbps.

In addition to downloading, which users are more concerned about, uploading is also a frequent activity. Such as:

  1. Online games. The client needs to send the data packet to the server in real time, otherwise it will lose the “monster data”. This is a relatively small amount of data, and some game developers define a protocol for it. These packets are extremely compact binary streams (20-50 MB of data for a game of LOL in a hot spot, depending on whether it’s a bladders or 15 throws).
  2. Uploading a local file to a web disk or transferring a file to a peer in a chat tool.
  3. Background services regularly send log reports to the server (this amount of data should also be relatively small, if a background program all the time in a lot of bandwidth from your computer secretly upload data, then it may be a virus…….) .

Download speed depends on downstream bandwidth, while upload speed depends on upstream bandwidth. For the average home user, the demand for downloads is much higher than for uploads, so the downlink bandwidth provided by the carrier is much higher than the uplink bandwidth. Especially in the early use of ADSL asymmetric digital subscriber line dial-up Internet, up and down the speed difference ratio can be up to 20 ~ 30. Until the optical fiber network, the imbalance improved: in the author’s network environment, for example, the downstream speed/upstream speed is about 2:1.

When carriers use the word “bandwidth,” they generally mean downlink bandwidth, because consumers are more concerned about how long it takes them to download a Blu-ray movie.

The principle of thunderbolt download? – zhihu (zhihu.com)

Speed network – speedtest.cn

Network speed and network latency

The network doesn’t cause violence, it delays.

When we talk about “Internet speed” in our daily life, we actually mainly refer to network delay. If the latency is low, then we say “fast”. Instead, we complain that the Internet is too slow. Network latency is affected by many aspects, especially the logical network topology. Bandwidth is part of it, but it’s not the deciding factor.

Let’s say we’re driving on the freeway, so “high bandwidth” means more lanes at intersections, and “low latency” means less time to get from start to finish.

So “high bandwidth” means “must be low latency”? Not really. For example, we could have gotten from POINT A to Point B through only one stop, but on one day, because of temporary construction at that stop, we had to take A detour through 15 stops, each with different congestion conditions. In this case, when we “drive” online, we will see a significant increase in delay, and the delay range is large. In the case of fixed routes, “high bandwidth” means less traffic jams, in other words, lower latency.

As a rule of thumb, delays do increase slightly during peak hours in a community, which can be easily explained by a real-life example: the more traffic jams you get home from work, the slower you get home.

For example, my home download speed can break 20 MB/s, WIFI signal is no problem, bandwidth is also said to be the past, some international server games still have to hit the accelerator, because the machine is far away from the logical route of the game server, so latency is very high, and even often lost connection. The working principle of the accelerator is to choose the shortest logical network path from the host to the game server, so as to achieve the purpose of reducing game latency.

Network latency is also associated with network protocols. If we call our “back to back” communication with the server an RTT round trip, then a TCP connection needs 1.5 RTT and an HTTP 1.1 connection 2.5 RTT. An HTTPS connection with HTTP 1.1 + TLS V1.2 security authentication requires up to 4.5 RTT delays. This can be done in two ways: the protocol itself reduces the RTT multiple by taking shorter handshakes (but being shorter means sacrificing safety and reliability), and the accelerator approach reduces the RTT itself (but costs more).

“Cat” and routing

The “cat” in this context is the Chinese nickname for the Modem Modem, the device that converts analog signals to digital signals. We now all use fiber optic communication (the corresponding “cat” is also called “optical cat”, formally referred to as optical modem), which uses optical signals instead of traditional analog signals for data transmission over fiber optic channels. At one end of the fiber optic communication is the PON device provided by the operator, and at the other end is the ONT device used by the user.

Optical transceiver has two types of access, one is optical fiber access, and the other is connected to a router or network device through a crystal connector. It has two noteworthy indicators: pON and LOS. If the PON indicator is on, the optical transceiver is properly connected to the optical fiber. If the LOS indicator is on, the optical transceiver cannot receive optical signals. In normal operation, the PON light should be on, and the LOS light should be off.

(Figure source network, los light flashing, indicating that the light cat is having some problems)

Builders have buried optical fibers in the walls of houses since construction. So, theoretically, if you could bring your own naked cat, wouldn’t you be able to go straight to the Internet? Here comes the issue of “certification”. Generally speaking, the light cat is provided by the operators for free. For example, when I went to China Unicom for business when I was an undergraduate, a special person would bring the light cat to the dormitory to install it at the appointed time, and then access their own router. You can also purchase and configure a cat by yourself. However, you need to manually configure the OLT authentication of the service provider according to certain steps, which is very troublesome. And have a little bit careless, can because of authentication failure and cannot connect to the Internet, want to call again at this time please repair personnel, they also feel trouble……

When the network is disconnected, if the PON light automatically turns off shortly after the pON light is turned on, and the LOS light blinks once, there may be a certification problem. You need to consult the carrier whether the network service has expired. Another common occurrence is when the LOS lights are on and the PON lights are not — this is probably the work of the construction team (funny). If it can be confirmed that the fault is the line itself, you just need to wait patiently for the line to recover.

Next question. Why do we need to access the router? Some of the cats themselves provide WIFI, but this is usually only enabled temporarily for debugging purposes. For the simple reason that light cats are essentially modems.

Routers are network-layer devices that are more complex, intelligent and responsible than pure switches. For example, any network device needs at least one IP address to communicate with the LAN and even the public network. This IP address is automatically assigned by the router’s DHCP function. In a building, each household’s network environment should be isolated from each other, so each household’s network environment is an independent, dedicated LAN.

Therefore, it is not difficult to find that all the devices in the home have AN IP address between 192.168.0.1 and 192.168.255.255 (the router and the cat have to borrow an IP address from each of them), which is the range of class C private LAN IP addresses. At the same time, zhang SAN 192.168.3.1 and Li Si 192.168.3.1 have no connection, no conflict, also can not communicate directly (must go router), because these are two LOCAL area network IP addresses.

The ROUTER’s DHCP job assigns IP addresses dynamically. Means that other devices in different period of time, to get the IP address in this range, rather than fixed (this does not affect we play games, surf the Internet at ordinary times unless we itself is foreign to provide access to services), but the router can always ensure that under the same time, in a local area net to get the virtual IP is not conflict between different devices. The router itself uses a fixed low-order IP address to act as the default Gateway of the virtual network in the home. It is responsible for sending and receiving data from LAN devices to the public network and translating NAT addresses. The IP address should be marked on the body, but you can also view the IP address of the default gateway by running the ipconfig command on your computer (Windows).

Wireless LAN adapter WLAN: Connect to a specific DNS suffix....... : Local link to IPv6 address........ : 19 c4 fe80: : : 764 a: b37d: 19 IPv4 addresses four fad %............ : 192.168.0.108 subnet mask............ : The default gateway 255.255.255.0............. : 192.168.0.1 please router gateway address.Copy the code

You can enter the gateway address in the browser to go to the local configuration page of the router. After entering the password of the administrator admin, you can customize the device connection permission, connection number, upstream and downstream rate limiting of each device, WIFI password and name, and device connection management in the management panel. If the user forgets the password of the router, the user generally needs to press the reset button on the router with the pin to reset.

After all, many routers will label themselves as “gigabit” or “10-gigabit” (including any other “gigabit nic” on the market). The specific router to choose the throughput should be based on their actual bandwidth, otherwise it is a waste of budget and performance. For example, if your correspondent has a bandwidth of 200 Mbps at home, there is no obvious need to buy a 10 gigabit route.

Perhaps, many people seem to think that “the larger the number of routes” must be faster. Unless the bandwidth we handle is really up to the throughput of the router, it’s not much different from “100 MBPS routing”. In terms of bandwidth, I believe that the main factor affecting network speed (latency) is whether the electronic device can receive the WIFI signal smoothly, or conversely, whether the router can send a continuous, stable WIFI signal.

From life experience alone, we all know that the worse the signal, the greater the delay. TCP is partly to blame for this — the worse the signal, the more likely it is that packets will be distorted, wrong or lost. In the early days, bandwidth was a precious resource, and TCP’s designers assumed that the more packets were lost, the more congested the network must be. (Wireless networking was not yet available, so that’s an outdated idea in today’s eyes.) As a result, when packet loss occurs, TCP does not take radical flooding measures, but takes more conservative congestion control and timeout retransmission strategies. As wireless networks become more popular today, it leads to a strange phenomenon: the worse the signal, the more packets are lost, and TCP makes network transmission even more “timid”, thus creating a vicious circle.

If the WIFI signal is poor, you can consider buying a repeater, signal amplifier and other ways to solve. If there is a problem with excessive latency even when the signal is full, then it is time to consider whether the bandwidth is causing the bottleneck.