Question

Which WAN technology is designed to work with a variety of commonly used layer-2 protocols and is sometimes called a layer-2.5 technology because it inserts a 4-byte header that contains its own information between the layer-2 frame and the layer-3 IP packet?

Answer 1

Answer: Multi protocol label switching(MPLS)

Explanation:

Multiprotocol Label Switching (MPLS) was designed with the main objective of shaping the traffic flow in term of how it can be speed up in a wide area network of an enterprise.

In MPLS each router can independently determine the next hop of a packet by looking at the destination IP address and after that it consults it routing table.  It is more efficient than traditional IP routing. The router receiving the first packet decides on the entire route of the packet throughout the network.

 MPLS is designed to work with a variety of commonly used layer-2 protocols and is sometimes called a layer-2.5 technology because it inserts a 4-byte header that contains its own information between the layer-2 frame and the layer-3 IP packet