1 2 3 4 5 Consider the shared medium Ethernet LAN with four users as shown in the figure…

1 2 3 4 5 Consider the shared medium Ethernet LAN with four users as shown in the figure…

Question:

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Consider the shared medium Ethernet LAN with four users as shown in the figure below:
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U1
Time slot #
Shared Medium Ethernet
Prop del = t
In the above, assume that users U1, U2, U3 and U4 transmit packets P1,P2,P3,P4 of length 5T, 12T, 3T,
8T respectively, where T (51.2 us) is the end-to-end propagation delay. Assume for simplicity that
packet arrivals and transmissions at terminals occur at virtual slot boundaries t-T, 2T, 3T, 4T, …nT.
Also, assume that the shortest Ethernet packet (after collision) is T sec, and that backoff algorithms
delay by KT units of time, where k={0,1}, {0,1,2,3}, {0,1,2,3,4,5,6,7),…. as determined by the number
of collisions. Now suppose U1, U2, U3 and U4 have newly arriving packets in their transmit buffers at
tl=13=1 and t2=t4=4 respectively as shown in the table below. Specify the sequence of transmissions
and retransmissions on the channel from slot #1 to the time when all four packets P1, P2, P3, P4 have
been transmitted successfully assuming no other traffic on the LAN. Provide brief explanations for each
channel event and identify any random values used for backoff. Use the following tabular format to
give your results, and explain important entries with numbered footnotes.
U2
Station U1
CS/packet arrives
****
U2
Idle
Idle
Idle
CS/packet arrives
U3
CS/packet arrives
….
U3
****
****
U4
U4
Idle
Idle
Idle
CS/packet arrives
..continue until all packets are transmissions are complete; use the terms “transmit”, “CD/jam”, “collision”, “defer”,
“backoff”, in addition to others given in the table

Expert Answer:

Answer rating: 100% (QA)

To solve this problem we need to simulate the Carrier Sense Multiple Access with Collision Detection CSMA CD algorithm in a shared medium Ethernet Loc
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