L2TP operates at which layer of the OSI model as described?

L2TP operates at which layer of the OSI model as described?

• A. In Cisco products
• B. In data link layer
• C. In network layer
• D. In transport layer

Answer: (B)

L2TP stands for Layer 2 Tunneling Protocol, and its purpose is to carry Layer 2 frames (PPP frames) over an IP network by creating a tunnel at the data link layer. The tunneling encapsulates PPP data so it can traverse networks that use IP, but the function it serves is to transport data at the data link layer, not to operate primarily at the network or transport layers. The fact that the tunnel itself travels over UDP (a transport-layer protocol) doesn't change the layer at which L2TP encapsulates and forwards Layer 2 frames. So, the correct layer is the data link layer.

L2TP stands for Layer 2 Tunneling Protocol, and its purpose is to carry Layer 2 frames (PPP frames) over an IP network by creating a tunnel at the data link layer. The tunneling encapsulates PPP data so it can traverse networks that use IP, but the function it serves is to transport data at the data link layer, not to operate primarily at the network or transport layers. The fact that the tunnel itself travels over UDP (a transport-layer protocol) doesn't change the layer at which L2TP encapsulates and forwards Layer 2 frames. So, the correct layer is the data link layer.