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signal coding | modulation | switching | delay | media | multiplexing | TDM | topology |


As a packet travels from a source over several routers to the destination, it suffers from several types of delay along its path through the network:

  • Processing delay:  the time to process the header fields and determine where to direct the packet
  • Queuing delay:  the time a packet has to wait in the queue for transmission across the link
  • Transmission Delay:  the amount of time required to push all the packet’s bits into the link (= L/R with L = Packet Length, R = Rate of the Link)
  • Propagation Delay:  the time required to propagate to the next router or host  (= D/S with D = distance between the two systems, S = propagation speed, which is equal to, or a little less than, the speed of light)

The application allows you to explore the difference between transmission delay and propagation delay. The transmission delay is a function of the packet’s length and the transmission rate of the link, but is has nothing to do with the distance between the two systems. The propagation delay, on the other hand, is a function of the distance between the two systems, but has nothing to do with the transmission rate and the packet’s length.

(idea and more details: J. F. Kurose, K. W. Ross: Computer Networking - ch.: delay and loss in packet-switched networks)