Multiple VLANs Link Protocols

BD

The two link protocols used to carry multiple VLANs over a single link are 802.1q and ISL.

802.1q is a standard protocol used to implement VLAN tagging on Ethernet networks. It inserts a 4-byte tag into the Ethernet frame to identify the VLAN ID to which the frame belongs. The tag contains information about the priority, VLAN ID, and EtherType. This tag enables switches to forward frames between VLANs without the need for multiple physical links.

ISL (Inter-Switch Link) is a Cisco proprietary protocol that also adds a header to the Ethernet frame to identify the VLAN. ISL is not widely used today, as 802.1q is the industry-standard protocol for VLAN tagging.

VTP (VLAN Trunking Protocol) is a Cisco proprietary protocol used to manage VLAN configurations across a network. It is not a link protocol used to carry multiple VLANs over a single link.

IGP (Interior Gateway Protocol) is a class of protocols used by routers to exchange routing information within an autonomous system (AS). It is not a link protocol used to carry multiple VLANs over a single link.

802.3u is a standard that defines Fast Ethernet over twisted