Overview
IEEE 802.1Q (often called 'Dot1q') is the most common method for implementing VLAN trunking. It works by inserting a 4-byte tag into the original Ethernet frame header.
Key Concepts
- VLAN ID (VID): A 12-bit field in the tag that identifies the VLAN (supporting up to 4096 VLANs).
- Native VLAN: A specific VLAN on a trunk link that carries untagged traffic. Both ends of a trunk must agree on the Native VLAN to avoid security issues and traffic leaks.