Consider a 4-layer protocol stack with the following layers (numbered 1 to 4 from bottom to top), physical, network, transport, and application. The physical layer uses one-byte flags to mark the start and the end of a packet. The other three layers all use four-byte headers.

1. Sketch the layered protocol model.

2. Sketch a packet for this system carefully showing and labeling all the fields.

3. The transport layer imposes that the maximum packet payload (data portion) for this layer must not exceed 100 bytes other layers have no such restriction. Calculate the percentage overhead assuming a message of 450 bytes is to be transmitted