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| 2.6 |  | VLAN Identification |
| 2.6.1 |  | VLAN frame identification |

VLAN identification logically identifies which packets belong to which VLAN group. Multiple trunking methods exist:

- Inter-Switch Link (ISL)
- IEEE 802.1Q
- IEEE 802.10
- ATM LAN Emulation (LANE)

ISL is a Cisco proprietary encapsulation protocol for trunking between switches. ISL prepends a 26-byte header and appends a 4-byte cyclic redundancy check (CRC) to each frame. ISL is supported in switches and routers.

The IEEE 802.1q protocol is an IEEE standard method for identifying VLANs by inserting a VLAN identifier into the frame header. This process is referred to as frame tagging or internal tagging.

The IEEE 802.10 standard is a method of transporting VLAN information inside the standard 802.10 frame (FDDI). The VLAN information is written to the Security Association Identifier (SAID) portion of the 802.10 frame. This method is typically used to transport VLANs across FDDI backbones.

LAN Emulation (LANE) is an ATM Forum standard that can be used for transporting VLANs over Asynchronous Transfer Mode (ATM) networks.