Overview
Trunking allows a single cable to connect two switches (or a switch and a router) while maintaining the separation of VLAN traffic. Without trunking, a separate physical cable would be required for every VLAN.
How it Works
When a frame is sent over a trunk link, a VLAN Tag is added to the header to identify which VLAN the frame belongs to. The receiving device reads the tag and forwards the frame to the correct VLAN.
Protocols
- IEEE 802.1Q (Dot1q): The industry-standard trunking protocol.
- ISL (Inter-Switch Link): A legacy Cisco proprietary protocol.