Differences between LAN, WAN, WLAN, VLAN, and VPN

Differences between LAN, WAN, WLAN, VLAN, and VPN

Local Area Network (LAN)

A group of computers that are interconnected by multiple computers in a region. Generally, it is less than a few thousand meters. Local Area Network (LAN) Supports file management, application software sharing, printer sharing, scheduling within the Working Group, email and fax communication services, and other functions. A lan is closed and can be composed of two computers in the office or thousands of computers in the company.

Wide Area Network (WAN)

Is a collection of large, regional computer networks. It usually spans provinces, cities, and even countries. The Wan includes different subnets, large and small. The subnet can be a LAN or a small Wan.

Differences between LAN and WAN

The LAN is in a certain area, and the Wan must span a large area. How can we define this area? For example, if a large company is headquartered in Beijing and has branches all over the country, if the company connects all its branches through the network, a branch is a local area network, the entire corporate network is a wide area network.

What is the difference between the WAN port of the router and the LAN port?

The current Broadband Router is actually an integrated structure of the routing + switch. We can regard it as two devices.

WAN: used to connect to an external IP address. Generally, it refers to the egress. It forwards IP packets from the internal LAN interface.

LAN: used to connect to an internal IP address, and a switch is used to connect to the LAN. We can use a 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 cable media. The data transmission rate of WLAN has now reached 11 Mbps, and the transmission distance can be more than 20 km. As an alternative or extension of traditional cabling networks, wireless LAN frees individuals from their desks so that they can obtain information anytime and anywhere, improving the office efficiency of employees.

WLAN uses the ISM (Industrial, Scientific, and Medical) radio broadcast frequency band for communication. The WLAN 802.11a standard uses a 5 GHz band and supports a maximum speed of 54 Mbps. The 802.11b and 802.11g standard use a 2.4 GHz band, which supports a maximum speed of 11 Mbps and 54 Mbps respectively.

What is the WIFI we usually use for Internet access?

Wi-Fi is a protocol for achieving wireless networking (in fact a handshake protocol), and WIFI is a standard for WLAN. The Wi-Fi network works in the 2.4G or 5G frequency band. The other 3G/4G also belongs to wireless Internet access, but the protocols are different, the cost is very high!

Virtual Local Area Network (VLAN)

A virtual LAN (VLAN) is a network technology in which sites in a network are not confined to physical locations and can be flexibly divided into different logical subnets as needed.

For example, users of different floors or departments can add different virtual LAN as needed: the first floor is divided into 10.221.1.0, and the second floor is divided into 10.221.2.0.

Virtual Private Network (VPN)

The virtual private network function is to establish a private network on a public network for encrypted communication. It is widely used in enterprise networks. VPN gateway implements remote access through data packet encryption and Data Packet Destination Address conversion.

In the traditional enterprise network configuration, remote access is required. The traditional method is to lease 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 office staff) and remote individual users, generally access the enterprise's Lan through a dial-up line (Internet), but this will inevitably bring security risks.

To allow employees in other countries to access intranet resources, the solution of using VPN is to set up a VPN Server in the intranet. After a local employee connects to the Internet, the employee connects to the VPN Server over the Internet and then enters the Intranet through the VPN Server. To ensure data security, the communication data between the VPN Server and the client is encrypted. With data encryption, you can think that data is transmitted securely on a dedicated data link, just like a dedicated network, however, VPN uses public links on the Internet. Therefore, VPN is called a virtual private network. In essence, it uses encryption technology to encapsulate a data communication tunnel on the Internet. With the VPN technology, users can use VPN to access intranet resources as long as they are on a business trip or working at home. This is why VPN is widely used in enterprises.

Why can I access a foreign website through VPN in China?

Connect to the internet normally (wired or wireless), and VPN refers to the line you connect, but it is virtual. After connecting to the VPN Server, our computer will be connected directly to this server using a line. That is, when we connect the VPN Server in the United States, it is similar to connecting the computer with the server in the United States with a super-long network cable. After that, all the receiving/sending operations will go through this U.S. server, just like you are in the United States. But we have another question. Why are we so troublesome to go directly to a foreign website? Because many foreign websites are hosted by China's National firewall and cannot be accessed by us. However, most of these firewalls can only hold computers in China and foreign computers.