VLAN (Virtual Local Area Network)

VLAN (Virtual Local Area Network) is a local area network equipment will be logically divided into one network segment to realize a virtual working group on emerging data exchange technology. This emerging technology is mainly used in switches and routers, but among the mainstream or in the switch. But not all switches have this feature, only the VLAN protocol before the third layer above the switch has this feature, this can view the manual switch can be learned.
IEEE 1999 standard was enacted to implement the program 802.1Q VLAN protocol draft standard. VLAN technologies, allows the administrator based on the actual application requirements, the same physical LAN logically different users into different broadcast domains, each VLAN contains a set of computer workstations have the same needs, and the physical form of the LAN have the same properties. Since it is logically divided, rather than from the physical division, so the same VLAN is no limit to individual workstations within the same physical range, that is, these workstations can be in different physical LAN segment. Shows the characteristics of the VLAN, a VLAN within the broadcast and unicast traffic is not forwarded to another VLAN, and thus help control traffic, reduce equipment investment, simplifying network management, improve network security.
 Exchange of technology development, but also accelerated the exchange of new technologies (VLAN) of the application speed. Into the corporate network through a virtual network VLAN segment, can be enhanced network management and network security, control unnecessary data broadcasting. In a shared network, a physical segment is a broadcast domain. In exchange network, broadcast domain can be arbitrarily selected a group of second tier network address (MAC address) consisting of a virtual network segment. In this way, the network division of the working group to share the network to break geographical constraints, and completely under management to divide. This grouping pattern based on work flow, greatly improving the network planning and restructuring of management functions. VLAN in the same workstation, regardless of their actual connection with which the switch, the communication between them as if as a separate switch. Broadcast in the same VLAN in the VLAN members only to hear, and not transmitted to other VLAN to go, so you can better control the generation of unnecessary broadcast storms. Also, if there is no route, then, between different VLAN can not communicate with each other, thus increasing the corporate network security between different departments. Network administrators can configure routing between the VLAN to the overall management of internal information between different management unit visits. Switch is based on user workstations by MAC address to VLAN's. Therefore, the user can freely move the office in a corporate network, no matter where he switched network access, he can be comfortable with other users within a VLAN communication.
 VLAN network can be a mixed composition of the type of network devices, such as: 10M Ethernet, 100M Ethernet, Token Ring, FDDI, CDDI, etc., can be workstations, servers, hubs, network uplink trunk and so on.
 In addition to the network VLAN can be divided into multiple broadcast domains, thus effectively control broadcast storms, as well as the topology of the network becomes a very flexible benefits, but also can be used to control network in the different departments, between different sites each visit.
 Ethernet VLAN is the broadcast address security issues and put forward a protocol based on Ethernet frame VLAN header added, with a VLAN ID to the user is divided into smaller working groups, different work restrictions exchange of visits between the two groups of users, each working group is a virtual LAN. Virtual local area network can limit the broadcast range of benefits, and can form a virtual working group dynamic management network.