Knowledge points of wireless network coverage system

1. What is AP?

Answer: AP - Wireless Access Point (Wireless Access Point) AP is the HUB in the traditional wired network and is also the most commonly used device when building a small wireless LAN. AP is equivalent to a bridge connecting the wired network and the wireless network. Its main function is to connect various wireless network clients together and then connect the wireless network to the Ethernet to achieve the purpose of wireless network coverage.

2. Are APs divided into “thin” and “fat”?

(1) Thin AP (FITAP):

• Also known as wireless bridge, wireless gateway, or so-called "thin" AP.
• A simple understanding of thin AP: it cannot be configured by itself and requires a dedicated device (wireless controller) for centralized control, management and configuration.
• The "controller + thin AP + router architecture" is generally used for wireless network coverage, because when there are a large number of APs, managing the configuration only through the controller will greatly simplify the workload.

(2) Fat AP (FATAP)

The so-called fat AP in the industry is also called wireless router by some people. Wireless router is different from pure AP. In addition to wireless access function, it generally has two interfaces, WAN and LAN, supports address translation (NAT) function, and often supports DHCP server, DNS and MAC address cloning, as well as VPN access, firewall and other security functions.

3. What is AC?

A: A wireless controller (Wireless Access Point Controller) is a network device used to centrally control controllable wireless APs in a local area network. It is the core of a wireless network and is responsible for managing all wireless APs in a wireless network. AP management includes: issuing configurations, modifying related configuration parameters, RF intelligent management, access security control, etc. (Currently, all ACs and APs on the market are from the same manufacturer to manage each other)

4. What is POE power supply and what is a POE switch?

A: POE (PowerOver Ethernet) POE is also known as the power supply system based on LAN (PoL, Powerover LAN) or Active Ethernet (Active Ethernet), sometimes referred to as Power over Ethernet. It refers to the technology that can provide DC power to some IP-based terminals (such as IP phones, wireless LAN access points AP, network cameras, etc.) while transmitting data signals without any changes to the existing Ethernet Cat.5 wiring infrastructure. POE technology can ensure the normal operation of the existing network while ensuring the safety of the existing structured wiring, minimizing costs.

Mass market application - POE switch: POE switch can not only provide the transmission function of ordinary switches, but also provide power supply to the device at the other end of the network cable. Power supply + data transmission are integrated, and there is no need for additional power supply modules or POE power supply modules to power the device. One Cat.5 cable can complete all the work.

5. Differences between 'standard' and 'non-standard' POE power supply

• Standard PoE: In accordance with the IEEE802.3af/at specification, it is necessary to detect the 25K characteristic resistance of the receiving end first and perform handshake. Only when the handshake is successful will power be supplied; otherwise, only data will be passed.
• For example: plugging a POE power supply into a computer network card will not burn out the computer network card, but will allow normal Internet access because data can pass through.
• Non-standard POE: Also called forced power supply, it supplies power as soon as the AC power is connected; it does not detect the receiving end first, does not perform handshake, and directly supplies 48V or 54V.
• For example: If you plug a POE power supply into a computer network card, you can access the Internet normally, but if you directly supply 48 or 54V without negotiation, the device may be burned.

There are several output voltages (DC) on the market, including 48V, 24V and 12V.

6. What software and hardware are needed to deploy a wireless project?

Basic hardware: router POE switch AC controller wireless AP

High-end hardware: firewall router traffic and behavior management bypass main switch floor switch POE switch AC controller wireless AP

7. Is it true that the greater the AP power, the better?

Answer: No, the greater the power of the AP, the higher the signal strength. If you understand it literally, you will be misled. The stronger the signal, the better. However, a strong signal refers to the signal itself. The signal transmission in the entire wireless network is two-way. The transmitter and the receiver will transmit data to each other. If the signal at the sending end is too strong, it will inevitably affect the data returned by the receiving end, which will cause network transmission delays or packet loss.

Simple understanding: In a space, you and another person are talking at the same time. If the other person's voice is too loud and yours is too soft, the other person will not be able to hear what you are saying, thus affecting the quality of the call.

In a large wireless project, what are the key points and areas that need the most attention?

8. Key points from the engineering perspective:

(1) Design

The actual construction drawings determine the direction and location of the wiring, and need to consider factors such as concealment, damage to buildings (structural characteristics), avoiding power lines and other lines while utilizing existing space, and the necessary and effective protection needs for cables under on-site conditions.

(2) Router location

The router is generally placed in an underground weak-current room (away from the strong-current room to avoid strong electromagnetic interference). Pay attention to ventilation and keep it dry. It is best to have a cabinet and place it together with the core switch.

(3) Location of the POE power supply switch

The POE switch should be reasonably located in the middle of the AP point to reduce the wiring cost and shorten the distance from the switch to the AP.

(4) AP location selection

The AP points should be placed in the center of the scene and radially outward. The coverage of AP parts should overlap to reduce signal blind spots. The distance between AP and POE switch should not exceed 80 meters (for example, genuine AMP network cable)

(5) Laying of network cables

As the transmission carrier of network signals, network cables should be protected during laying to avoid breakage or dead corners. If necessary, they should be placed in iron pipes or on roof bridges. Special attention should be paid to the principle of high-voltage wires to reduce interference with signals.

Notes on practical debugging and post-maintenance:

a. External network and routing: The external network cable is connected in place to ensure the normal Internet access conditions of the line, and the routing is connected to ensure that the routing itself can communicate normally on the Internet. During construction, the main exchange and the construction floor exchange are connected to ensure normal communication of the backbone network.

b. Debugging the intercom: During the debugging stage, it is necessary to borrow a set of intercom equipment from the shopping mall to facilitate the debugging work.

c. During the construction and debugging phase, sufficient spare parts must be reserved for APs, switches, network cables, and other construction and debugging hardware.

d. Construction drawings: Before each construction, please ask the contractor to provide us with two copies of the construction drawings.

• Construction network topology diagram: requirements, detailed floor switches, routing information and locations, number of APs and other hardware on each floor and connection methods.
• Construction equipment connection line identification diagram: requirements, routing, switch and AP connection information, corresponding ports, etc., theoretical approximate network cable length of all connection lines (including between routers, switches and APs).

e. Construction wiring and line marking planning:

• Information identification record: AP point Mac information record: When the construction party places the AP position, it is necessary to record the floor number and position number of the AP and the corresponding Mac information (note the corresponding floor map AP number, for example: the mac information format of No. 1 on the 1st floor is 1F-1: AC:11:22:33:44:AP). This information is uniformly recorded in the Word document floor mall construction drawing according to the floor distribution or directly recorded manually in the empty space on the side of the construction drawing for later maintenance and use.

Line marking record:

• On the input and output cables at the switch end: it is necessary to indicate which floor and location number the cable connector is connected to (note the AP number corresponding to the floor map, for example: No. 1 on the 1st floor is in the format of 1F-1). Cables coming in from the external network must also have cable labels: they need to be marked with "External Network Access".
• Interconnection between switches on all floors: The source of the wiring head must be marked with the identification or serial number at the end of the switch line interconnection line. (Please note the floor and switch marking, for example: switch No. 1 on the 1st floor, the format is 1F-1 SW)

Check on-site whether the installed AP is powered on and working properly:

After the construction workers completed the construction, they checked on site that all APs were powered on normally. When powered on, the green indicator light on the AP was on. If the router was in place and running, the software could be used to detect whether the AP was emitting signals and accessing the Internet normally.

If the above information is completely clear, there is no need for construction personnel to be on site. If the above information is completely unclear, construction personnel will be required to cooperate on site for each debugging.