lecture 3

Question 1

bandwidth can be either

Answer 1

analog or digital

Question 2

analog bandwidth (3 points)

Answer 2

• represented in Hertz
• refers to the range of frequencies in a
  composite signal
• or the range of frequencies that a channel can pass

Question 3

digital bandwidth (2 points)

Answer 3

• represented in bps

- refers to the speed of bit transmission in a channel or link

Question 4

how to convert analog to digital

Answer 4

multiply analog signal (in Hz) by 14,000 to get bps

Question 5

performance metrics (8)

Answer 5

• utilization
• throughput
• response time
• delay
• latency
• goodput
• fairness
• QoS

Question 6

channel utilization is

Answer 6

the time a channel is busy/being used

Question 7

channel efficiency is

Answer 7

it is the same like utilization except overheads are excluded

Question 8

how to calculate utilization

Answer 8

actual output/expected output *(100)

Question 9

throughput is

Answer 9

• number of bits successfully transmitted/processed

- represented in bps

Question 10

delay is

Answer 10

the time to traverse from one end to the

other in a system

Question 11

4 types of delay

Answer 11

• propagation
• transmission
• processing
• queuing

Question 12

propagation delay (s) =

Answer 12

distance/speed (same unit)

Question 13

what will change propagation delay

Answer 13

the medium

Question 14

transmission delay (s) =

Answer 14

• packet length(bits)/transmission rate (bps)

- packet length(bits)/bandwidth (bps)

Question 15

processing delay is

Answer 15

time taken to process a packet at router or destination host

Question 16

steps to processing delay

Answer 16

1) receive packet
2) remove header
3) detect error
4) deliver packet to output port

Question 17

bandwidth (bps) * delay (s) =

Answer 17

number of bits that can fill the link (pipe)

Question 18

how to know which delay is more dominant

Answer 18

• calculate the delays

- delay with most amount of time taken is the dominant one

Question 19

what is propagation delay

Answer 19

the time taken for a packet to reach its destination (flight time)

Question 20

to analyze delay in a subnet (3)

Answer 20

1) exclude the hosts
2) assume the p2p delay is equal between the nodes
3) n = number of nodes, therefore, n-1=number of delays

Question 21

what is transmission delay

Answer 21

time taken to push the bits from one router to the other

Question 22

what is queueing delay

Answer 22

the time the packets wait at input and output queue

Question 23

queueing delay (s) =

Answer 23

number of packets * transmitting delay

Question 24

what is end-to-end packet delay and what are the steps (4)

Answer 24

• time to deliver from source host to destination host
  1) processing delay
  2) queueing delay
  3) transmission delay
  4) propagation delay

Question 25

link packet delay =

Answer 25

• proc + qd + trans + prop

Question 26

data rate is exchangeable with

Answer 26

throughput

Question 27

how to calculate end to end delay

Answer 27

• link delay * n -1

- sum of link delays

Question 28

what is latency

Answer 28

the minimum possible delay

Question 29

what is goodput

Answer 29

• numbers of bits successfully received