4.4 VLAN Identification
4.4.1 VLAN frame identification
VLAN identification logically identifies which packets belong to which VLAN group. Multiple trunking methodologies exist, as follows:
  • IEEE 802.1Q - This 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.
  • ISL - This protocol is a Cisco proprietary encapsulation protocol for interconnecting multiple switches; it is supported in switches as well as routers.
  • 802.10 - This standard is a Cisco proprietary 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) - LANE is an ATM Forum standard that can be used for transporting VLANs over Asynchronous Transfer Mode (ATM) networks.