VLAN stands for Virtual Local Area Network. A virtual LAN is a virtual subdivision of a network used to connect the computers on the same floor or in the same department or to segregate servers for better performance. For some organizations, VLANs provide several advantages over a single large network.
A router is a network hardware device that routes packets to their destination by checking the content of each piece of data ("packets") sent on the network, while switches are network devices that direct packets based on by which port they are received. A switch can direct a packet much faster than a router since it doesn't spend time reading the content of the packet. Large networks rely on routers to group switches and connect them to on another, while VLANs allow the network administrator to direct data using only switches.
VLANs are easier to manage because they allow the network administrator to group IP address together. For example, the accounting department might use all of the addresses from 192.168.1.1 to 192.168.1.256, while the human resource department uses the addresses from 192.168.2.1 to 192.168.2.256. VLAN can also use specific switches for specific VLANs instead of having a department spread over several physical network devices. For example, an administrative team can label switch 1 as HR and switch 2 as accounting for easier management.
Physical Layer Independence
VLANs are independent of their location, meaning that two switches can be interconnected so they function on the same VLAN even if they are on different continents. This allows, for instance, an HR department in Tokyo to share the same VLAN as the HR in Los Angeles. VLAN makes the network transparent to the end user, allowing a user in Japan to print a report on a network printer in California.
VLANs are more secure because switches will send and receive information only to and from the VLAN on which they are designed to transmit, therefore it would only be possible for hackers to capture the information transmitted on a VLAN if they were physically connected to that VLAN. VLAN can also be configured to grant or restrict security privileges to certain users.
Routers require powerful processors to read and route packets on a network; this makes them more expensive and less efficient than switches. Switches use much smaller processors and therefore use less electricity.
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