Q$1)[2$ pts$]$ A bit stuffing framing mechanism uses the sequence $01111110$ to mark frame

boundaries. Show how the following bit sequence is transmitted as a frame $($include the frame

boundary$).$ If you changed the contents of the frame, explain.

$00001111100001111110$

Q$2)[2$ pts$]$ A character stuffing framing method uses the pair of characters DLE STX and DLE

ETX to mark the start and end of a frame. How is the following sequence of characters transmitted

as a frame? Include the frame boundary and briefly explain any change in the contents of the frame.

a$,$ b$,$ c$,$ ETX, DLE, STX$,$ DLE, DLE, DLE

Q$3)[4$ pts$]$ You are given the $8$ bit sequence $10001101.$ Illustrate the steps needed to factor

the polynomial corresponding to this sequence by the divisor D$($x$)=$ x$3+1$ as dictated by the

CRC scheme illustrated in the lecture. What is the CRC sequence obtained? Show your work.

Q$4)[2$ pts$]$ The Alternating$-$Bit protocol is used to transfer a sequence of two data frames

labelled A and B$.$ Assume that the propagation delay $($signal travelling time$)$ in one direction is

one time unit, the time to transmit each data frame and the acknowledgment frames is negligible,

and the retransmission timers are set for $3$ time units. Draw the sequence diagram for the scenario

when data the sequence bit starts at $0$ and the acknowledgment with sequence bit $1$ is lost once.

Draw the diagram to scale and indicate the actions for each host on the diagram $($eg: frames are

dropped, delivered, etc.$).$ At what time is the last frame B delivered at the destination?