Foreword As one of the necessities of modern life, WiFi is increasingly inseparable from it. In use, we often encounter many problems, such as: the signal is not good; the signal is good, but the network is still stuck; want to extend the wireless coverage, and did not lay the network cable in advance and so on. The landlord took the opportunity to extend the WiFi coverage of the home and talked about how to properly establish a home network and related knowledge. Of course, because it is not a professional person, the inadequacies of the questions should be given to you. Talk about my environment The structure of the house where I live is roughly as follows: Because the place of residence is the old community, naturally there is no weak electricity box. The telecommunications fiber-optic cable is from the door to the door and barely put the light cat (it is also the location of the main route, because the old house did not lay the network cable in advance, and naturally put the main route and the light cat together). In the living room, and I live The room and the main router are directly separated by two walls. The attenuation of the signal after 5 GHz penetration is very serious. There are many 2.4 GHz routes around, and the 2.4 GHz band has serious interference. It does have a certain distance, and the packet loss is very severe. Is in an unusable state. How to improve the coverage of wireless signals without laying cables is imperative! For the solution, I think there are roughly the following ways: 1, to strengthen the wireless signal itself output power This method is the simplest, the cost is almost zero, and the wireless output power of the router can be adjusted. However, there are too many partitions for me, so it can be said to be a glass of water. Give up naturally. 2, increase the gain, change the antenna The antenna of the router has a fixed gain. Different antennas have different gain effects on the signal. Simply put, the actual wireless signal transmission distance of the 5 dB antenna is far more than 1 dB. However, it should be noted that the effect of increasing the gain is to transmit farther, not to increase the signal strength. I need to pass signals through the wall instead of transmitting signals over long distances, and switching antennas is certainly not feasible. 3, install antenna reflection The direct way is to remove a can, and use signal reflection to enhance the signal in a certain direction. The biggest drawback of this approach is that it enhances the directionality of signals, sacrificing signals in other directions, and enhancing signals in a certain direction, but there are still many uncertainties. Because I still need to use wireless in the living room, this method still gives up. 3, wireless bridging Also referred to as WDS, wireless router 2 is wirelessly connected to wireless router 1 . Other devices directly connect to the wireless router 2 to access the Internet. However, because of this mode, the wireless router 2 needs to meet two sets of data exchange requirements at the same time, and the wireless network speed will be halved. And because of the serious wireless interference around my location, I still prefer not to have more equipment to interfere with it, so the plan is also abandoned. 4, using electricity cats to do network cable, use AP to connect equipment This is the last resort used by the landlord. The electricity cat converts the internal wires of the room into a network cable, and then uses a wireless router as an AP. This can add no extra construction, and it can make the equipment access from my bedroom connect to a device that directly accesses the main route. In the network hierarchy. I think that at this time someone may ask, what is the AP, what is the power cat. In the following sections, I mainly talk about some basic network equipment related knowledge. If you are not interested, you can skip it. What are routers, switches, cats, power cats, APs, MBs and Mbs, 2.4GHz and 5GHz? Because the current equipment is often a multi-purpose, highly functional integration. This really brings us a lot of convenience, but in further applications (such as setting up a slightly more complex home network), we are often overwhelmed or even unable to start. In the following, I will specifically talk about the specific roles of various devices in a home network. With some understanding, this will greatly help us build a reasonable home network. "Cat" The original name is Modem or Modem. Because this is just the beginning of the popularity of the time when the graphical operating system (such as Windows, Mac OS) has just begun to spread, the mouse became a new computer peripherals at that time. The modems are really mouthfuls, and the people of the country match their English homophonic sounds with the mouse, namely cats and mice. The modem is gradually called "cat". The cat is an indispensable device for accessing a wide area network. The main function of the cat is actually simple. The data transmitted to other devices on the wide area network is packaged, and the received data is unpacked, and nothing more. router The routers mentioned here are not what we generally call routers. Wireless routers used in ordinary homes are actually a combination of routers, switches, and APs. Strictly speaking, the function of the router is to accurately transfer the data obtained on the WAN and the Internet to specific devices on the local area network. Based on this function, the router must know the difference between the devices, so the router separates the devices linked to it by means of IP address allocation. For example, if you use cell phone A to download a file, the router assigns you an IP address on your mobile phone link, which is the address from which it finally delivered the file. When the file arrives at your route, the router The file is forwarded to the IP address of the mobile phone A, so the mobile phone A receives the file instead of the mobile phone B that is connected to the router at the same time. In general, the router has at least two interfaces, the LNA is connected to the switch, and the other LNA is connected to the "cat" switch The switch device sounds very big, the actual function is very simple, its English name switch can explain its function. It is to connect the equipment A and equipment B in our home network, local area network and then disconnect the two equipments as required, and indirectly conduct A and C. A switch is a device that facilitates data exchange with devices that access it. Its role was that of the former operator (the machine on the right was the early telephone exchange, picture from Baidu). The switch has a special feature. All the interfaces it provides are LNA interfaces. In the past, the connection between devices needed to be manually connected between the two devices through a cable, and the switch was able to establish a device that disconnected numerous virtual connections in an instant. AP That is, Access Point, access point. AP is actually a generic name for a large group of network devices. It often uses a hub to make APs. A hub is a device that provides equipment access to a switch, both wireless and wired. Compared to an interactive machine that can establish a large number of virtual connections, an AP can only connect a device connected to it to its superior device (often a switch). An AP cannot allow data exchange between devices connected to it. Therefore, a device that occupies a large amount of bandwidth is not recommended to access the AP because it will make the other devices accessing the AP unable to obtain the required bandwidth reduction speed. At the same time, the hub's upstream speed will also limit the maximum speed that the device connected to it can achieve. Incidentally, the connection port between the AP and the upper-level device is the WAN port, and the device directly connected to it is connected through the LNA interface. Electricity "cat" The electric "cat" is a new device introduced in recent years, and its specific functions are very similar to the traditional "cat". It is to carry on the modulation and demodulation of the electric signal in the home circuit. It directly solves some situations where the network cable must be used without pre-laying the cable. Pure power cats generally have only one cable interface, the LNA port. MB and Mb I think this may be the most confusing thing for people who are the first to contact the Internet and computers, as if the two words are the same, but it always feels that promotion and actual use are not the same thing. The full name of MB is directly translated by Mega Byte is megabytes. Mb is called Mega bit or megabit. Bits are actually data units that are one level smaller than bytes. 8bit = 1Byte, this is why you think that marked a very high speed, and the actual transmission is still so slow (a typical example is 100MB broadband, listening to scary, the actual speed is 12.8MB per second only). 2.4GHz and 5GHz This group of nouns is the frequency used by wireless signals and is gradually becoming widely known as 5G wireless routers are sold. Simply put, 2.4G wireless signal is more suitable for bypassing obstructers (such as walls) to transmit signals, and is also easier to achieve long-distance transmission, but its signals are easily interfered with and it is not easy to achieve higher transmission bandwidth; 5G wireless signals Poor bypassing of obstacles is often done at the expense of signal strength, and the transmission distance is also relatively short, but its signal is easy to achieve high-bandwidth transmission. At present, most wireless routers can send and receive signals of these two frequency bands, but when selecting a wireless router, it is necessary to pay attention to the fact that manufacturers generally add the fastest speed that can be achieved in both frequency bands, making people feel that the router can provide very fast speed. The actual need to analyze the main use of the band to buy, for example, you only need 2.4G large coverage, buy a 5G 1200Mb plus 2.4G 300Mb wireless routing and no less than a 5G 600Mb, 2.4G 400Mb wireless routing utility. Some preparation before networking With the above knowledge, I think I can now apply the above basic knowledge to further understand the actual equipment and home network structure. I will first put a complete network topology. The equipment involved in this diagram is the equipment I mentioned above, not the highly integrated devices that we actually use every day. For this picture, I will first explain that in actual use, only devices that are within the black dashed line can be used for direct data exchange, and the AP, as mentioned above, is just a medium for connecting the device to the switch. A new network layer is created, so there are APs that do not affect the data exchange and do not affect the IP address acquisition (the main factor affecting the equipment connected to the switch through the AP is the bandwidth of the AP and the switch). The devices within the dotted line are all in the same network segment. So for example, the router and the wired and wireless devices connected through it are all in one network segment. However, devices in the same area as the secondary router and devices in the same area as the main route are absolutely not possible within a network segment, and direct data exchange is not possible. Knowing this content is helpful for the following networking, and it can also prevent you from making many mistakes. Analyzing the home network requires the purchase of suitable equipment Different people have different needs for home networks. Some need wireless coverage in large areas, and some need to be able to achieve high-speed data transmission within the home network. Some people actually only need to access the Internet in one or several fixed locations. However, there are numerous wireless routers on the market, and there are a lot of devices such as enterprise-class switches and wireless APs that beckon to you. Not knowing your own needs often takes a lot of money. So I made the following table for your reference: Below I will talk about the more worthwhile purchase in the equipment in the table, you only need to compare and buy according to the equipment introduction, and the combination will be fine. If you have a variety of needs, then in addition to overlapping devices, you only need to follow a better purchase for each requirement. You must first purchase the required item directly according to the required item. You do not need to purchase other optional items. For example, you need to play online games on the one hand requires low latency, while the location of the computer can not be covered by a wireless router, then you need to combine the needs of low delay and fixed-point coverage, at least buy a hundred mega-class router in advance need to lay a good cable is Must, and then with the AP or secondary router can be. 1, buy gigabit router The gigabit routers mentioned here are actually the combination of routers with gigabit switches and gigabit wireless APs. Most of the wireless routers in the market can only achieve the 887Mb wireless transmission speed in the 5G band, and the wired transmission has only a hundred megabits. For the data distribution and transit center as a home core network, such devices are unqualified. In general, wireless routers with more than 200 yuan will only provide Gigabit LNA interfaces if the manufacturer has specifically specified that their devices support wired gigabit. There are few full-gigabit wireless routers with a size below 200. For this kind of router I recommend two: one Asus RT-AC 66U B1, one mesh R6220. ASUS is more suitable as the main router, and its attached USB3.0 interface can achieve basic NAS functions. Netgear this, may be the lowest full-Gigabit wireless router, and its file sharing is also very powerful, SMB sharing, DLNA, iTunes server features. Only its USB interface is 2.0, and the transfer speed of the mounted mobile hard disk is generally only 20MB/S. 2, buy ordinary fast wireless router For users who generally only use the Internet, they do not require a high level of intranet transmission, and users who do not need a particularly large amount of coverage directly purchase such ordinary 100-megabit routers. I personally recommend millet's. The price is more cost-effective, generally about 100 yuan, in addition to millet routers does bring us some ease of use. The initialization configuration is unusually simple, and there are also some functions such as storage sharing and automatic backup. If there is a meter device, it is more handy. However, I do not recommend buying Millet Router Pro. Although it is the standard for all Gigabit routers mentioned above, it also has a built-in hard disk. However, there are few network interface interfaces, and it may be necessary to buy devices such as switches and hard disks (millet routers are hard to replace hard disks). Not worth it. 3, AP I don't think it necessary to buy high-end APs such as UBNT's commercial-grade applications. If you do not have a large bandwidth requirement, you can even use the above-mentioned Fast Forward Routing as an AP. If the equipment connected to the AP needs a large bandwidth, it is recommended to directly purchase the netware mentioned in the gigabit routing. The specific setting method varies depending on the router, but the connection method is similar. First enter the router settings interface, find settings such as wireless access points, wireless relay and other settings, change the wireless router work mode to AP mode, save the restart route with a network cable to the upper switch LNA port and just set the wireless The Wan port of the route can be connected. Here are some common branding setup methods (ASUS routers and brushing Merlin's routing setup are similar): The Wan interface is generally placed independently. In the following figure, the blue interface is marked as the Wan interface, and the right row of yellow interfaces is the Lan interface: ASUS (Merlin firmware router): Netware: 4, network cable Network cable is actually a device that is very important in network construction but is often ignored or over-emphasized by Xiao Bai. In general, Cat5E and above category network cables are sufficient to meet the needs of Gigabit transmission, if you do not want to purchase 10GbE network equipment later. Lay Cat 5E or Cat6E cable. For short-distance connection between equipment and equipment, directly buy a super-five or Category 6 cable. For the pre-paved network cable during the renovation, purchase the wholesale cable and the wall panel. Crystal head like this kind of thing does not need to be too mythical, in the fly channel to buy a dollar or so a model can be, but now need to use the crystal head is really not much. 5, buy a cat. At present, electric cats are actually divided into two types. One is the first card of the following type, and it has only a simple function of using electric wires as a network cable. One is the wireless or wired extension class. This type of cat is actually integrated by a router, a switch, or even a wireless AP. According to the above topology diagram, devices connected via this type of cat will not be connected to other types of devices. Equipment in a network segment, there is a corresponding need to carefully purchase such cats. When using a power cat as an AP or directly connected to a network cable, pay attention to the maximum speed it can provide. If your home has a network device such as a NAS, or if your AP is connected to a device that requires large bandwidth (such as a home Data sharing within the network, watching the hard disk movie hanging on the router, etc.). Then you need a Gigabit Power Cat to use with a Gigabit AP (the following card). 6, the secondary router Secondary routers and APs have similarities in their use, and home networks often use a wireless router for their use, but they are used in specific ways. I will speak later. Formal networking So much nonsense, finally talked about here. Let me first explain how to extend wireless coverage based on my situation. I belong to a fixed-point coverage (mainly in the bedroom for extended coverage) that has large bandwidth requirements (a mobile hard disk is hung on the main route, and the NAS will be moved over time). At the same time, renting a house can't lay a network cable. Specifically, I put all network devices in a hierarchy (for data exchange within the home network). That is, my network has only cats, routers, switches, APs, some wired devices, and some wireless devices. First, the wireless signals of the main route satisfy the coverage of the living room and the bedroom 1, and the wireless devices and wired devices in these areas are connected. At the same time, the hard disk/NAS direct and indirect main path is moved, and the data of the above device can be directly transmitted to any device in the home network. Then use the power cat to convert the wire into a network cable to connect the AP in my bedroom with the main router, so that the device in my bedroom is directly connected to the main router so as to obtain the data of the mobile hard disk connected to the main route. To sum up, the establishment of a home network is based on the needs of the above analysis to purchase the appropriate equipment. Just you need to understand the role of each device, as well as to understand the following considerations: AP or secondary route Both the AP and the secondary router allow access to his device for network access and Internet access. Looks very similar, but in actual situations the difference will be very large. As I mentioned in the previous network topology diagram, "In practice, only devices within the black dashed line can be used for direct data exchange, and the AP, as mentioned above, is just a medium to connect the device to the switch. A new network layer will not be generated. Therefore, APs do not affect data exchange and do not affect IP address acquisition. The main factor affecting APs and switches through APs is the bandwidth of APs and switches. The secondary routers do not The data exchange between connecting to his device brings too much bottleneck. Why is this? In fact, devices connected to the same AP share the bandwidth of this AP and the higher-level switch. At the same time, devices that connect to the same AP want to exchange data can only be performed at the switch. Because AP only plays a role in merging a bundle of network cables into one! Assume that an AP is full-duplex (that is, data can be transmitted while receiving data), and the connection speed to the switch is 1000 Mb. There are three devices connected to the switch through the AP. Internet access usually means that even if the three devices are fully fired and your home has Gigabit broadband, the gigabit bandwidth between the AP and the switch is just enough to meet the demand, and this will not lead to a situation where the line speed is not enough. However, if you put a NAS, a desktop PC with a Gigabit Ethernet card, and a mobile phone through the AP, it will access the switch. You use a desktop computer to copy a file on the NAS. The NAS needs to transfer the file to the switch through the AP uplink. The switch uses the downlink data to the desktop. At this time, the AP uses all the file transfer bandwidth of the upstream and downstream bandwidths of the AP. At this point you want to use the mobile Internet? The line bandwidth of the AP is already insufficient. Even if the wireless signal is very busy, it will get an anomaly! Of course, in practice, the AP will also adjust the bandwidth allocation of each device, but in any case your external network needs always conflict with the internal needs of the home network, and is limited to the bandwidth of the AP and the switch. And if it is a secondary router (ie, highly functional integrated router)? In other words, there is a superior network that distributes data from the WAN to a secondary router. The bandwidth of the switch connected to the router is all Gigabit, so limiting the speed of each device indirectly to the WAN is just how big your home broadband is. The situation at this time is the same as using an AP. But if you need to copy files from the NAS to your computer again. At this point, the file exchange between the NAS and the computer is performed directly at the switch without using a common line. Your other devices need external network data to exchange data directly with the router. The exchange of data exchange carrying capacity of the exchanger is arbitrarily reached the terabyte level, even if all equipments of the access switch are exchanging data, there is no pressure. 5G or 2.4G The characteristics of the two I have already mentioned above, for the family generally use only one wireless router for 5G settings is more important than 2.4. The 5G network signal cannot be transmitted over a long distance. Therefore, it is necessary to set the transmission strength so that it is not as easy as to use 2.4G directly to allow him to rush through a wall and bring intermittent networks. My suggestion is that 5G should be controlled in a room in the transmission of large bandwidth. Generally, one wall can be used to block traffic. More distant obstacles suggest using 2.4G, or use with AP/secondary route. to sum up It seems simple to set up a home network, but there are often problems when you come across some slightly more complex applications. At this point we should be clear about the network level of each device in the network, the role of the device. Draw a network topology diagram further, in general, the problem can be solved. In the end, thank you for reading so many things. I wrote the tutorial for the first time and I have to work hard! PS. I hope that all of you friends in Chengdu will join our group of friends. 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