Which encapsulation type is used for 802.1Q tunneling?

The encapsulation type used for 802.1Q tunneling is dot1q. This standard defines how VLAN information is carried within Ethernet frames. Specifically, when a frame is tagged using 802.1Q, it includes a VLAN identifier that allows switches to recognize which VLAN the frame belongs to as it travels through the network. This tagging is essential for maintaining VLAN separation and ensuring that traffic is appropriately segmented across the virtual networks.

In the context of 802.1Q tunneling, this encapsulation method enables the encapsulated frames to carry VLAN traffic transparently across a network backbone while preserving VLAN information. When one VLAN is tunneled through another, the outermost frame can be tagged with a specified VLAN identifier using dot1q encapsulation, ensuring that the inner VLAN remains intact.

The other encapsulation types listed, such as ISL (Inter-Switch Link), Ethernet, and PPP (Point-to-Point Protocol), are not applicable to 802.1Q tunneling. ISL, while it was an earlier Cisco proprietary method for VLAN tagging, has been largely superseded by the standardized dot1q. Ethernet, as a general term, refers to the layer 2 protocol used for transmitting data packets but does not specifically denote