(i) Noise on transmission link converts 0bit to 1bit

(ii) A packet is routed to wrong destination

(iii) A packet switching network delivers a data unit to a terminal attached to it out of sequence

(iv) A printer printing halfway through a line is suddenly commanded by mistake to return to the beginning of line.

(v) During half duplex mode session the transmitting user starts receiving data from the user at other end.

1. Physical Layer

• This layer deals with the transfer of bits over a communication channel, for example copper wire pairs, coaxial cable, optical fibre.
• This layer is concerned with the particular choice of system parameters such as voltage level and signal duration, also setup and release of physical connection as …