Answer the following questions about layered protocol models.

(a) Consider a three-layer protocol. The layers from top to bottom are application, transport, and network. All layers use headers and the transport layer also uses a trailer. Sketch a packet showing headers and trailers for this protocol.

(b) Assume a protocol that uses variable length packets of maximum payload size 250 bytes. In addition to the payload, there are 25 bytes of header and 12 bytes of trailer in each packet. For a 600-byte message, what is the overhead (in %) for this protocol?