Propagation delay

 propagation delay, which is the time after full message has been sent from the sender, until it has reached the receiving node
 The propagation speed depends on the physical medium of the link (that is, fiber optics, twisted-pair copper wire, etc.) and is in the range of  meters/sec for copper wires and  for wireless communication, which is equal to the speed of light

 Propagation time = Distance / propagation speed

 Example: Ethernet communicaiton over a UTP copper cable with maximum distance of 100 meter between computer and switching node results in:
Maximum link propagation delay ˜ 100 m / (200 000 000 m/s) = 0.5 µs

http://en.wikipedia.org/wiki/Transmission_time

• Consider a network with a single 5 Mbps (megabits per second) link and a 15 ms (millisecond) propagation delay. 

The sender transmits a 3000-byte packet to a receiver.
Give all answers in units of milliseconds

What is the transmission delay for the packet?

 dtrans = L/R

 L = 3000 B = 24,000 b

 24,000 b * 1000 ms        24
           ----------   =  --- ms = 4.8 ms
           5,000,000 b      5
 
 
Assuming transmission begins at time 0, when will the first bit of the packet arrive at the receiver?

15 ms (this is the definition of propagation delay, which is given in the problem statement)

What is the total end-to-end delay for the packet, i.e., at what time does the entire packet reach the receiver?

 de2e = dtrans  + dprop
 de2e  = 4.8 ms + 15 ms = 19.8 ms

What is the total end-to-end delay for a 6000-byte packet?

 de2e = dtrans  + dprop

 dtrans = L/R

 L = 6000 B = 48,000 b

 48,000 b * 1000 ms        48
           ----------   =  --- ms = 9.6 ms
           5,000,000 b      5

 de2e = dtrans  + dprop
 de2e = 9.6 ms + 15 ms = 24.6 ms

 http://www.cs.odu.edu/~mweigle/CS312-F11/Quiz1