Chapter 1: Inter-VLAN routing through sub-interfaces
Technical background: VLAN is a broadcast domain. Usually, the two broadcast domains are connected by a router, and the data packets between the broadcast domains are all provided by the router to provide relay services. This is called: inter-VLAN routing.
A VLAN is a broadcast domain. Devices in the same VLAN can directly communicate at Layer 2, while devices in different VLANs cannot communicate directly. To achieve communication between VLANs, you need to use Layer 3 devices (devices with routing functions), such as routers or Layer 3 switches.
Inter-VLAN communication through router
Since the above model wastes router resources, it needs to be improved;
Each sub-interface can be set with an IP address and specify the sub-interface VLAN_id
The disadvantage of this model is that when transmitting data, the data passes between the switch and the router twice, which causes the load of this line to be too large. This problem can be improved using a firewall
Layer 3 switch:
The sub-interface just now is represented by vlanif (vlan interface), which can also be called (SVI (switched virtual interface)). You can use interface vlanif 10 to enter the interface for configuration.
