Things to Remember: 1. Nodal processing check bit errors determine output link Things to Remember: 2. Queueing Time waiting at output link for transmission Depends on congestion level of router Things to Remember: 3. Transmission delay: R= link bandwidth (bps) L= packet length (bits) Time to send bits into link = L/R Things to Remember: 4. Propagation delay: d = length of physical links propagation speed in medium (x m/sec) Propagation Delay = d/s GOTO TOP Comparing Transmission and Propagation Delay Newcomers to the field of computer networking sometimes have difficulty understanding the difference between transmission delay and propagation delay. The difference is subtle but important. The transmission delay is the amount of time required for the router to push out the packet it is a function of the packets length and the transmission rate of the link, but has nothing to do with the distance between the routers. The propagation delay, on the other hand, is the time it takes a bit to propagate from one router to the next it is a function of the distance between the two routers, but has nothing to do with the packet’s length or the transmission rate of the link. Computer Networking and Management Page 34 of 44
