How to distinguish between LAN, WAN, WLAN, VLAN and VPN?


Local area network (LAN)A computer group that is interconnected by multiple computers in a certain area. Generally it is within a few kilometers

. LANs enable file management, application sharing, printer sharing, scheduling within workgroups, email and fax communication services. The LAN is closed and can consist of two computers in the office or thousands of computers in a company.

Wide Area Network (WAN)It is a collection of large, regional computer networks. Usually spans provinces, cities, and even a country. The WAN includes different subnets of different sizes, and the subnet can be a local area network or a small WAN.

The difference between LAN and WANThe LAN is in a certain area, and the WAN has to cross a larger area.

 How do you define this area? For example, the head office of a large company is located in Beijing, and the branch offices are spread all over the country, if the company will Branches are connected through a network, then a branch is a local area network, and the entire head office network is a wide area network.

What is the difference between the WAN port and the LAN port of the router?The current broadband router is actually an integrated structure of routing + switch, we can think of it as two devices.

WAN: Used for external IP addresses, usually referred to as egress, forwarding IP packets from the internal LAN interface.LAN: Used for internal IP address, the LAN is a switch inside. We can use the router as a normal switch without connecting to the WAN port.

Wireless LAN (WLAN)WLAN uses electromagnetic waves to send and receive data in the air without the need for cable media.

 The data transmission rate of the WLAN can now reach 11Mbps, and the transmission distance can be as far as 20km or more. As an alternative or extension to traditional cabling networks, WLANs free individuals from their desks, enabling them to access information anytime, anywhere, and improve employee productivity.

WLAN uses ISM (Industrial, Scientific, Medical) radio broadcast band communication. The WLAN 802.11a standard uses the 5 GHz band and supports a maximum speed of 54 Mbps, while the 802.11b and 802.11g standards use the 2.4 GHz band to support speeds of up to 11 Mbps and 54 Mbps, respectively.

Then what is the WIFI we usually use online?WIFI is a protocol for implementing wireless networking (actually a handshake protocol), and WIFI is a standard for WLAN. The WIFI network works in the 2.4G or 5G frequency band.

 In addition, 3G/4G is also a wireless Internet, but the agreement is different, and the cost is very high!Virtual Local Area Network (VLAN)A virtual local area network (VLAN) refers to a network in which the network does not stick to the physical location and flexibly divides one of the different logical subnets according to needs.

For example, users located on different floors or users in different departments can join different virtual local area networks as needed: the 1st floor is divided into network segments, and the 2nd floor is divided into network segments.

Virtual Private Network (VPN)The virtual private network function is to establish a private network on the public network for encrypted communication. Widely used in enterprise networks.

The VPN gateway implements remote access by encrypting the packet and converting the destination address of the packet.In the traditional enterprise network configuration, the traditional method is to rent a DDN (Digital Data Network) leased line or frame relay. Such a communication scheme will inevitably lead to high network communication and maintenance costs.

 For mobile users (mobile workers) and remote individual users, they usually enter the LAN of the enterprise through the dial-up line (Internet), but this will inevitably bring security risks.

To allow foreign employees to access intranet resources, the solution to using VPN is to set up a VPN server in the internal network. After connecting to the Internet in the local area, the foreign employees connect to the VPN server through the Internet and then enter the intranet through the VPN server.

 In order to ensure data security, communication data between the VPN server and the client is encrypted. With data encryption, data can be considered to be securely transmitted over a dedicated data link, just as a dedicated network is set up, but in reality the VPN uses a public link on the Internet, so the VPN is called Virtual private network, which essentially uses encryption technology to encapsulate a data communication tunnel on the public network.

 With VPN technology, users can use the VPN to access intranet resources, whether they are on a business trip or at home, which is why VPN is widely used in enterprises.


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