Calculations

Question 1

How would you calculate Propagation delay? (Dprop)

Answer 1

Distance/propagation speed = propagation delay.

Example;
lets say two wireless diveces that are 100 meters apart.

Then its:
100 m / speed of ligth (300.000.000 m/s) = 333.3 ns.

Question 2

If we have a packet of size 1500 bytes (12,000 bits) and the transmission speed of the medium is 10 Mbps (10,000,000 bits per second), what is the transmission time?

Answer 2

Transmission time = Packet size / Transmission speed

Transmission time = 12,000 bits / 10,000,000 bits per second = 0.0012 seconds = 1.2 milliseconds

Question 3

what is propagation delay?

Answer 3

Propagation delay, on the other hand, refers to the amount of time it takes for a signal to travel from the sender to the receiver over the communication channel. It is influenced by the distance between the sender and the receiver, the type of transmission medium, and the speed at which the signal travels through the medium. The formula for calculating propagation delay is:

Propagation delay = Distance / Propagation speed

Question 4

What is Transmission time?

Answer 4

Transmission time refers to the amount of time it takes to transmit a message or data packet from one device to another over a communication channel. It is influenced by the size of the message, the transmission speed of the communication medium, and any overheads involved in the transmission process. The formula for calculating transmission time is:

Transmission time = Packet size / Transmission speed

Question 5

Ignoring processing and queuing delays, obtain an expression for the
end-to-end delay.

Answer 5

R1= Transmission rates between the sending host and the switch

R2= Transmission rates between the switch and the receiving host

L = Packet of length

L/R1 = Transmission delay from host to switch

L/R2 = Transmission delay from switch to receiver

Td = total end-to-end delay

Td = L/R1 + L/R2

Question 6

Suppose Host A begins to transmit the packet at time t = 0. At
time t = dtrans, where is the last bit of the packet?

Answer 6

With host B, the last bit of packets is transmitted at Dtrans

Transmission time = Packet size / Transmission speed

Question 7

Suppose dprop is greater than dtrans. At time t = dtrans, where is the first bit
of the packet?

Answer 7

Dprop is when the first packet arrives, Dtrans is when the last
bit of packet arrives. So the first bit of packet will be at host B.

Question 8

Suppose s = 2.5 . 108 m/s, L = 1500 bytes, and R = 20 Mbps, where M is
SI standard (base 10) 106 and not binary (base 2) 220 = 10242. Find the
distance m so that dprop equals dtrans

Answer 8

Dtrans = L/R
Dprop = m / s
m / s = L/R
m = Ls/R
m = 1500bytes* 2.5 . 108 m/s/(20Mbps) = 0,12 * 2500000 m =
300000 m