Basic networking
This article can help readers understand the basic knowledge required for networking, including equipment selection and basic configuration methods for general home networks, micro-enterprise networks, and networking of less than 20 people.
basic knowledge
Modem
We know that the information in the computer is a digital signal composed of "0" and "1", but what is transmitted on the telephone line can only be analog electrical signals (analog signals are continuous, digital signals are discontinuous of). Therefore, when two computers want to transmit data through a telephone line, a device is neededresponsible for digital-to-analog conversion. This digital-to-analog converter is the Modem we are going to discuss here.
When the computer sends data, the modem first converts the digital signal into the corresponding analog signal. This process is called "modulation", also known as D/A conversion.
Before the modulated signal is transmitted to another computer through the telephone carrier, it must also go through the receiver's Modem to restore the analog signal to a digital signal that the computer can recognize. This process is called "demodulation", also known as A/D conversion. .
It is through such a digital-to-analog conversion process of "modulation" and "demodulation" that remote communication between two computers is achieved.
Introduction to IPv4 addresses
1 What is an IP address?
IP addresses are used in networks toidentify a node (or the interface of a network device).
IP address is used for addressing of IP packets in the network.
An IP address is like a real-life address that identifies a node in the network through which data finds its destination.
2 IP address representation
An IPv4 address has 32 bits.
IPv4 addresses are usually expressed in "dotted decimal"
3 Private IP address
Public address: An IP address that is managed and allocated by a specialized organization, and can communicate directly on the Internet.
Private address: Organizations and individuals can use it at will and cannot communicate directly on the Internet. An IP address that can only be used on the intranet< /span>.
Some addresses in Class A, B, and C are reserved specifically as private IP addresses:
Class A: 10.0.0.0 ~ 10.255.255.255
Class B: 172.16.0.0 ~ 172.31.255.255
Class C: 192.168.0.0 ~ 192.168.255.255
For families with less than 20 people and micro-enterprise scenarios, Class C addresses are usually used.
NAT technology overview
With the development of the Internet and the increase in network applications,limited IPv4 public addresses have become a bottleneck restricting network development. To solve this problem, NAT (NetworkAddressTranslation) technology was born.
NAT technology is mainly used to enable hosts in the internal network to access external networks. Convert public address to private address. On the one hand, NAT alleviates the shortage of IPv4 addresses. On the other hand, NAT technology prevents the external network from communicating directly with the internal network using private addresses, improving the security of the internal network.
DHCP Service Overview
IETF released DHCP (Dynamic Host Configuration Protocol,Dynamic Host Configuration Protocol< in 1993 /span>).
The function of DHCP is to enable the host in the network environment to dynamically obtain IP address, Gateway address, DNS server address and other information, and can Improve address usage.
Wireless LAN
Wireless Local Area Network (WLAN) refers to the application ofwireless communication technology to interconnect computer devices to form a structure that can communicate with each other and realize Resource sharing network system. The essential characteristic of wireless LAN is that it no longer uses communication cables to connect computers to the network, but connects wirelessly, making network construction and terminal movement more flexible.
IEEE 802.11 standard
IEEE 802.11 is a common standard for wireless LANs today. It is a wireless network communication standard defined by the Institute of Electrical and Electronics Engineers (IEEE).
With the evolution of technology, the 802.11 standard has also evolved. From 802.11 to today's 802.11ax (that is, wifi6), the biggest change is the faster transmission speed. Commonly used frequencies are 2.4g and 5g.
802.11b supports 2.4g, the standard supported by early wireless routers, which is slower.
802.11n supports 2.4g and 5g. The first generation of routers that support both 2.4g and 5g adopts a standard that is much faster than the previous generation.
802.11ac supports 5g. The second generation standard used by routers that support both 2.4g and 5g. The 802.11n standard is used at the 2.4g frequency, and the 802.11ac standard is used at the 5g frequency. Because the 2.4g frequency uses the old standard, this generation The 5g speed of the router is faster than 2.4g. This generation of routers is also the most commonly used today.
802.11ax supports 2.4g and 5g. The third generation router that supports both 2.4g and 5g adopts the standard, which is often called WiFi6. Due to price factors, its popularity is currently slow.
Equipment knowledge
Modem (cat)
Modeming is what we often callModem, but it is actuallyModulator< /span>modem< /span>" based on the homophony of Modem. . Some people also affectionately call it "cat abbreviation, Chinese called Demodulator (demodulator) and
For the concept of modulation and demodulation, please see the description in the above basic knowledge.
The "cat" used at home in the past was to convert telephone signals into Ethernet messages, that is, convert analog signals into digital signals. Nowadays, with the vigorous development of fiber optic network infrastructure, the "cat" in the past has also been upgraded to"optical cat", that is,< a i=3>Optical signal conversion into Ethernet packets.
Note: Today's optical modems also have NAT technology and DHCP services. Sometimes operators also open wireless LAN functions. If the number of users is 1-2 people, you can consult the operator when applying for a package. You can choose not to buy a router and use optical modems. Both can meet the needs.
router
The router has many functions, the most important of which is the ability to runNAT technology, DHCP service , for usage scenarios with less than 20 people, wireless LAN is also a very important function.
According to application scenarios, they can generally be divided into home routers and enterprise routers.
According to the management method, it can generally be divided into web management and command line management.
For usage scenarios with less than 20 people, web-managed home wireless routers are usually used.
Choice of carrier and package
Common operators include China Telecom, China Unicom, China Railcom, China Mobile, etc. The situation in different places is different. It is recommended that you ask your neighbors and search the Internet.Select a local with a better reputation. Good operator.
Package selection, with the development of network communication infrastructure, home broadband has begun to popularize 300M, 500M, and Gigabit. Due to the current demand for networks in life, entertainment and work,It is recommended that you choose a Gigabit family package if possible.
Equipment selection
Optical modem: Usually, the optical modem is installed when the operator comes to install the home network.
Router selection
Brand selection: For usage scenarios with less than 20 people, it is generally recommended to choose routers from more well-known brands, such as Pulian, Huawei, H3C, Xunjie, etc., the price range is recommended to be 200-500 yuan, and the price depends on the number of people, for example, if there are more people, choose 400-500.
Determination of the type and quantity of routers: It depends on the actual area. Generally, the signal coverage of wireless routers is about 30-50 square meters (it is recommended not to listen to the 100-150 square meters of coverage advertised by the merchants), The signal will be attenuated behind partition wall. If there are a large number of rooms, or if there are partitions and the signal attenuation is large, it is recommended to choose wireless Mesh Router.
Purchasing channels: It is recommended to choose channels with better after-sales service, such as the brand’s JD.com, Tmall self-operated flagship stores, or offline specialty stores.
Device configuration
Optical modem: Usually the optical modem will be configured when the operator comes to install the home network.
Router configuration
1 Enter the management platform
The mobile phone can connect to the wireless signal that comes with the router, then log in to the browser and enter the default management address provided by the manufacturer to register a username and password dedicated to routing management, and then enter the configuration interface. The computer can be directly connected to the LAN port of the router, then enter the default management address provided by the manufacturer to register a username and password dedicated to routing management, and then enter the configuration interface.
Different manufacturers have different management platform pages, but the functions are similar.
Note: Some manufacturers have special APPs on mobile phones for managing routers.
2 First, choose how to access the Internet
Usually there are three common ways of accessing the Internet: static, dynamic, and PPPOE dial-up. The names in management platforms of different manufacturers are different, but the principles are the same.
Static: This method requires you to manually enter the public network address provided by the operator. This method of accessing the Internet is relatively stable and suitable for small and above enterprises. Usually, only those who purchase the enterprise dedicated line package will provide a dedicated static address. This type of enterprise dedicated line The package price is relatively high, so there is no need for families and micro-enterprises to purchase it.
Dynamic: Automatically obtain a temporary public network address through the DHCP service provided by the operator (optical modem). This method of Internet access has weak network stability. By default, this method will be used if the user does not actively request it.
PPPOE dial-up Internet access: Connect to the operator's server through the account and password provided by the operator, and obtain a temporary public network address. This method of Internet access is more stable than dynamic, but requiresusers to actively contact the operator to change the Internet access method and contact the operator to obtain the account number and password.
3 Configure the router management address
Different manufacturers will have different default management addresses. Users can also specify them manually. This is usually used in the case of multiple routers.If the sub-router is connected to the main router, insert LAN port, then the user needs to manually specify an address in the main routing network segment.
4 Configure DHCP service
By default, DHCP is enabled on the router. In the case of multiple routers, if the sub-router is connected to the main router with a LAN port, then the DHCP service of the sub-router must be turned off to avoid a There are multiple DHCP service providers in the network, resulting in network instability.
5. Configure wireless network
Enter the relevant page and enter the wireless network name and password. If it is a router that supports both 2.4g and 5g, there is an option to combine multiple frequencies into one during configuration, that is, set the 2.4g and 5g frequencies to the same name. Usually the 2.4g speed of second-generation routers is slow, but the signal penetrates the wall. The ability is strong, but 5g is the opposite. If there is a wall, the 2.4g signal will be stronger than 5g. However, in the case of dual-band integration, if there is a wall, sometimes the 2.4g signal will still be good. Sometimes it is connected to 5g, but the signal strength is not good. When the names are the same, we don't know whether it is connected to 2.4g or 5g. Sometimes we also hope to actively choose 2.4g to obtain better network stability. ThereforeFor stability reasons, it is recommended to disable dual-band integration and configure it with a different name.
