L2 Switching Basics

L2 switching allows packets to be switched in the network based on their Media Access Control (MAC) address. When a packet arrives at the switch, the switch checks the packet's destination MAC address and, if known, sends the packet to the output port from which it learned the destination MAC.

The two fundamental elements in Ethernet L2 switching are the MAC address and the virtual LAN (VLAN). In the same way that IP routing references stations on the networks via an L3 IP address, Ethernet L2 switching references end stations via the MAC address. However, unlike IP, in which IP addresses are assigned by administrators and can be reused in different private networks, MAC addresses are supposed to be unique, because they are ...

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