The main functions of the switch include physical addressing, network topology, error checking, frame sequence, and flow control. At present, the switch also has some new features, such as support for VLAN (Virtual Local Area Network), support for link aggregation, and even some have firewall functions.
Learning: The Ethernet switch knows the MAC address of the connected device on each port, and maps the address to the corresponding port and stores it in the MAC address table in the switch cache.
Forward/Filter: When the destination address of a data frame is mapped in the MAC address table, it is forwarded to the port connected to the destination node instead of all ports (if the data frame is a broadcast/multicast frame, it is forwarded to all ports) .
Eliminate loops: When the switch includes a redundant loop, the Ethernet switch avoids loop generation through the spanning tree protocol, while allowing the existence of a backup path.
In addition to being able to connect to the same type of network, switches can also interconnect between different types of networks, such as Ethernet and Fast Ethernet. Many switches today offer high-speed ports that support Fast Ethernet or FDDI to connect to other switches in the network or to provide additional bandwidth for critical servers with large bandwidth.
In general, each port of the switch is used to connect to a separate network segment, but sometimes in order to provide faster access speed, we can connect some important network computers directly to the ports of the switch. In this way, the network's key servers and important users have faster access speeds and support greater traffic.