VLAN Principle Learning Notes

VLAN (virtual LAN), translated into Chinese is a "virtualized local area network". The physically connected network is divided into a plurality of logical independent virtual subnets, originally, the second layer switch can only build a single broadcast domain, but with the VLAN function, it can divide the network into multiple broadcast domains.

The switch allows the LAN to be divided into multiple VLANs, and in general, the default VLAN for the switch is VLAN1.

Why can't routers be used to separate broadcast domains? 1, the Router interface is limited, 2, the router can only divide the broadcast domain through the network interface unit.

Inter-VLAN communication: Routing technology required

The port of the switch can be divided into the following two kinds:
Access Link (accesslink)
Aggregation links (Trunklink)

The VLAN partitioning of a single switch is usually:
L Generate VLANs
L Set Access links (determine which VLAN each port belongs to)
The method of setting the access link can be fixed in advance, or it can be changed dynamically according to the connected computer. The former is called "Static VLAN", and the latter is naturally "dynamic VLAN".

A static VLAN, also known as a port-based VLAN (portbased VLAN). As the name implies, it is the setting that explicitly specifies which VLAN each port belongs to. 、

Dynamic VLANs Change the VLAN that the port belongs to at any time, depending on which computer is connected to each port. This avoids actions such as the above change setting. Dynamic VLANs can be broadly divided into 3 categories:
L MAC address-based VLAN (macbased VLAN)
L Subnet-based VLAN (subnetbased VLAN)
L User-based VLAN (userbased VLAN)

VLAN partitioning of multiple switches: The aggregation link method (trunk link), which attaches a VLAN attribute message to the V data frame, is capable of forwarding ports for communication of multiple different VLANs.

VLAN trunking makes it possible to connect a data frame between a switch and a switch or between a switch and a router through this trunk line.

VLAN trunking Protocol (VTP) is used to simplify the management of VLANs in large switched networks, according to VTP, switch operation mode is divided into: server, client, transparent three mode, server mode can create, delete, modify switch configuration, client mode is not allowed to create, delete, modify the switch, In transparent mode, configuration information cannot be transmitted to other switches.

VLAN Principle Learning notes