lecture 3 Flashcards
bandwidth can be either
analog or digital
analog bandwidth (3 points)
- represented in Hertz
- refers to the range of frequencies in a
composite signal - or the range of frequencies that a channel can pass
digital bandwidth (2 points)
- represented in bps
- refers to the speed of bit transmission in a channel or link
how to convert analog to digital
multiply analog signal (in Hz) by 14,000 to get bps
performance metrics (8)
- utilization
- throughput
- response time
- delay
- latency
- goodput
- fairness
- QoS
channel utilization is
the time a channel is busy/being used
channel efficiency is
it is the same like utilization except overheads are excluded
how to calculate utilization
actual output/expected output *(100)
throughput is
- number of bits successfully transmitted/processed
- represented in bps
delay is
the time to traverse from one end to the
other in a system
4 types of delay
- propagation
- transmission
- processing
- queuing
propagation delay (s) =
distance/speed (same unit)
what will change propagation delay
the medium
transmission delay (s) =
- packet length(bits)/transmission rate (bps)
- packet length(bits)/bandwidth (bps)
processing delay is
time taken to process a packet at router or destination host
steps to processing delay
1) receive packet
2) remove header
3) detect error
4) deliver packet to output port
bandwidth (bps) * delay (s) =
number of bits that can fill the link (pipe)
how to know which delay is more dominant
- calculate the delays
- delay with most amount of time taken is the dominant one
what is propagation delay
the time taken for a packet to reach its destination (flight time)
to analyze delay in a subnet (3)
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
what is transmission delay
time taken to push the bits from one router to the other
what is queueing delay
the time the packets wait at input and output queue
queueing delay (s) =
number of packets * transmitting delay
what is end-to-end packet delay and what are the steps (4)
- time to deliver from source host to destination host
1) processing delay
2) queueing delay
3) transmission delay
4) propagation delay
link packet delay =
- proc + qd + trans + prop
data rate is exchangeable with
throughput
how to calculate end to end delay
- link delay * n -1
- sum of link delays
what is latency
the minimum possible delay
what is goodput
- numbers of bits successfully received
