Go Back N ARQ
- 1. GO- BACK N ARQTEAMS:BANDWIDTH BROTHERSDEADLOCKFOSTERSNEW CREATORSROTHMANS
- 2. INTRODUCTIONCONCEPT OF PIPELININGIMPROVING THE EFFICIENCY OF TRANSMISSIONWHY ITS CALLED GO- BACK N ARQCONCEPT OF SEQUENCE NUMBERS, SLIDING WINDOW, TIMERS ,ACKNOWLEDGEMENT AND RESENDING FRAME.
- 3. DISADVANTAGES OF STOP AND WAIT1) Efficiency is very less if channel is thick and long. Thick means channel has large bandwidth. Long means the round trip is delay product of these two is called bandwidth delay product...2) There is no pipelining because we need to wait for a frame to reach the destination and be acknowledged before the next frame can be sent.
- 4. PIPELININGIn networking if a task is often began before the previous task ended. This is known as PIPELINING.
- 5. SLIDING WINDOWSEND SLIDING WINDOW
- 6. RECEIVE SLIDING WINDOWSend window before slidingSfSn
- 7. Send window after slidingSfSn
- 8. Receive window before slidingRn
- 9. Receive window after slidingRn
- 10. Delay component in ARQTime to send frame and get ACK.
- 13. RECEIVER WINDOW
- 14. PIGGYBACKINGControl signal is attached with Data signal. Request Window Sender Window Arrival Window Both Window {Data, Control}Used to improve the efficiency of the Bidirectional Protocol.Carries control information about arrival or lost framesBoth Sender and the Receiver window use a timer and are involved in three types of events. Request. Arrival. Time-out.Both site must use the same Algorithm.
- 16. Go-Back-N Error RecoveryThe recovery of a corrupted Frame proceeds in three stages:First, the corrupted frame is discarded at the remote node's receiver.
- 17. Second, the remote node requests retransmission of the missing frame using a control frame (sometimes called a NACK or REJECT). The receiver discards all frame s which do not have the number of the requested frame.
- 18. The final stage consists of retransmission of the lost frame(s).ADVANTAGES OF GO-BACK NARQThe sender can send many frames at a time. Timer can be set for a group of frames. Only one ACK can acknowledge one or more frames. Efficiency is more. Waiting time is pretty low. We can alter the size of the sender window
- 19. DISADVANTAGES OF GO-BACK N ARQBuffer requirement:Transmitter needs to store the last N packetsScheme is inefficient when round-trip delay large and data transmission rate is highRetransmission of many error-free packets following an erroneous packetWhen RTT is large: for a high number of NACK, a lot of BW is wastedIf NACK is lost , a long time is wasted until re-transmission of all packets (until another NACK is sent).
- 20. Selective Repeat ARQTo overcome the disadvantages of GO BACK N ARQ, we use Selective Repeat ARQTo utilize more bandwidth
- 21. COMPARISON CHART
- 22. THANK YOU