Static VLANs are also called port-based VLANs. This is to specify which port belongs to which VLAN ID. From the physical level, you can directly specify that the inserted LAN corresponds to the port directly.
When the VLAN administrator initially configures the corresponding relationship between the switch port and VLAN ID, the corresponding relationship has been fixed. That is, only one corresponding VLAN ID can be set for accessing a port and it cannot be changed later unless the administrator re configures.
When a device is connected to this port, how to determine whether the VLAN ID of the host corresponds to the port? This is determined according to the IP configuration. We know that each VLAN has a subnet number and which port corresponds to it. If the IP address required by the device does not match the subnet number of the VLAN corresponding to the port, the connection fails, and the device will not be able to communicate normally. Therefore, in addition to connecting to the correct port, the device must also be assigned an IP address belonging to the VLAN network segment, so that it can be added to the VLAN. To understand this, it is necessary to understand that the subnet consists of an IP and a subnet mask. Generally, only the last three bits of the subnet are used for final name recognition.
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To sum up, we need to configure the VLAN and the ports one by one. However, if more than one hundred ports in the network need to be configured, the resulting workload cannot be completed in a short time. And when the VLAN ID needs to be changed, it needs to be reset-this is obviously not suitable for those networks that need to change the topology structure frequently.
In order to solve these problems, the concept of dynamic VLAN has been introduced. What is a dynamic VLAN? Let’s take a closer look.
2. Dynamic VLAN: Dynamic VLAN can change the VLAN of the port at any time according to the computer connected to each port. This can avoid the above operations, such as changing settings. Dynamic VLANs can be roughly divided into three categories:
(1) VLAN with MAC address
VLAN based on MAC address determines the port ownership by querying and recording the MAC address of the computer network card connected to the port. Suppose a MAC address “B” is set as belonging to VLAN 10 by the switch, then no matter which port the computer with MAC address “A” is connected to, the port will be divided into VLAN 10. When the computer is connected to port 1, port 1 belongs to VLAN 10; when the computer is connected to port 2, port 2 belongs to VLAN 10. The identification process only looks at the MAC address, not the port. The port will be divided into the corresponding VLAN as the MAC address changes.
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However, for VLAN based on MAC address, the MAC addresses of all connected computers must be investigated and logged in during the setting. And if the computer exchanges the network card, you still need to change the setting because the MAC address matches the network card, which is equivalent to the hardware ID of the network card.
(2) VLAN based on IP
Subnet based VLAN determines the VLAN of the port through the IP address of the connected computer. Unlike the VLAN based on MAC address, even if the MAC address of the computer changes due to the exchange of network cards or for other reasons, as long as its IP address remains unchanged, it can still join the original VLAN.
Therefore, compared with VLANs based on MAC addresses, it is easier to change the network structure. An IP address is the information of the third layer in the OSI reference model, so we can understand that VLAN based on subnet is a method to set access links in the third layer of OSI.
(3) VLAN based on users
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User-based VLAN determines which VLAN the port belongs to according to the current login user on the computer connected to each port of the switch. The user identification information here is generally the user logged in by the computer operating system, such as the user name used in the Windows domain. The user name information belongs to the information above the fourth layer of OSI.
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The above is the explanation of the VLAN Implementation Principle brought to you by Shenzhen Haidiwei Optoelectronics Technology Co., Ltd. The Shenzhen Haidiwei Optoelectronics Technology Co., Ltd. is a manufacturer specializing in optical communication equipment products.