Weak current College】 【switch virtual local area network VLAN 4 Division.

VLAN or VLAN (VirtualLocalAreaNetwork abbreviation), is a means of equipment within the LAN logically instead of physically divided into individual segments enabling virtual team skills.

VLAN is to deal with Ethernet broadcast queries and security made it in Ethernet frames to add the VLAN header, use the VLANID put the user into smaller working groups to limit the different working groups of users on the second floor, each working group is a virtual local area network. Virtual local area network has the advantage that you can limit the scope of broadcasting, and to form a virtual team, dynamic management network.

VLAN skills allows network managers to one physical LAN logically divided into different broadcast domain i.e. VLAN, each VLAN contains a set of identical requirements of workstation, and physical LAN has formed on the same property. But since it is logically instead of physically divided, so the same VLAN within the workstation does not have to be placed on the same physical space, that is, the workstation does not necessarily belong to the same physical LAN segments. A VLAN on the inside of the broadcast and unicast traffic will not be forwarded to a different VLAN, even if both computers have the same network segment, but they are not the same VLAN number, their respective broadcast stream will not be forwarded each other, thus contributing to the control flow, reduce equipment investment and simplify network management, improve network security.

1. on the basis of the dividing VLAN ports

Many manufacturers are using VLAN switch ports to the members of the Division of VLAN. The port is set in the same broadcast domain. For example, a switch of 1, 2, 3, 4, 5 port is interpreted as a virtual network of AAA, the same switch 6, 7, 8 ports virtual network BBB. doing so allows communication between the various ports, and allows shared-network upgrades. However, this Division mode virtual network is limited to a single switch.

Second generation port VLAN skills allowing spans multiple switch ports for multiple different VLAN, different switches on several ports to comprising the same virtual network.

To switch ports to divide the network members, the configuration process basic and straightforward. Therefore, from the current view, such a divided according to the port VLAN form remains the most commonly used forms.

2. on the basis of the dividing VLAN MAC address

This Division is based on the VLAN Essentials every host's MAC address to partition, that is, for each MAC address of the host to configure the group to which it belongs. This Division VLAN essentials the biggest advantage is that when users move the physical location, that is, from a switch to other switches, VLAN without reconfiguration, so you can think of this as the MAC address of essentials is the VLAN based on user, the main points of weakness is original, all users must perform configuration, if you have hundreds or even thousands of users, configuration is very tired. But the main points of this Division has also led to switch execution efficiency decreases, because each switch port that may exist in multiple VLAN groups of members, so you cannot limit the broadcast packets. In addition, for users with notebook computers, they can often replace the network card, so that the VLAN must be kept on the configuration.

3. on the basis of the dividing VLAN network layer

This Division is based on the VLAN Essentials every host on the network layer address or protocol type (if supports multi protocol) partition, although this division points are based on the network address, such as IP address, but it is not a routing, and network layer routing without contact.

The main points of advantage is the user's physical location changes, and do not need to reconfigure the VLAN, but which can be divided according to the protocol type, this network VLAN managers is key, that key does not have to attach to the frame label to identify the VLAN, which can reduce network traffic.

The essentials of drawback is inefficient, because examines each packet on the network layer address is required to consume processing time (relative to the preceding two points), the General switch chip can automatically check the network packets of Ethernet frame header, but to make the chip can check for an IP frame headers, to higher skills, but also more time-consuming. Of course, this is an implementation of the various manufacturers. key points

4. on the basis of the dividing VLAN IP multicast

IP multicast is in fact a VLAN's explanation that think a multicast group is a VLAN, this Division's main points of the VLAN to a wide area network essentials, so this gives you much more flexibility, but also very easy to extend through the router implementation, of course, this idea is not suitable for LAN, largely inefficient.