Why the protocol name is Go-Back-N?
On the sender side for every packet send there is a time out timer which will expire for packet number 2. Now from the last transmitted packet 5 sender will go back to the packet number 2 in the current window and transmit all the packets till packet number 5. That’s why it is called Go Back N.
What is difference between Selective Repeat and Go-Back-N?
The main difference between these two protocols is that after finding the suspect or damage in sent frames go-back-n protocol re-transmits all the frames whereas selective repeat protocol re-transmits only that frame which is damaged.
What ARQ does TCP use?
TCP uses a variant of Go-Back-N ARQ to ensure reliable data transmission over the Internet protocol. However, it does not guarantee delivery of data packets. If TCP uses Selective Acknowledgement (SACK), Selective Repeat ARQ is used.
What is the efficiency of the Go-Back-N ARQ protocol?
In Go-Back-N ARQ, N is the sender window size, which we can see in the above example was 5. Now, here N should be greater than 1 in order to implement pipelining. If N=1, then our system reduces to Stop & Wait protocol. Now the efficiency of Go-Back-N ARQ = N/(1+2a), where a = tp/tt.
What is the difference between Go-Back-N protocol and Stop n Wait protocol?
In Stop and Wait protocol, no specific order is needed at receiver end. In GoBackN protocol, in-order delivery only are accepted at receiver end. In Selective Repeat protocol, out-of-order deliveries also can be accepted at receiver end.
What is the need of ARQ?
Automatic Repeat Request (ARQ) is an error-control mechanism for data transmission which uses acknowledgements (or negative acknowledgements) and timeouts to achieve reliable data transmission over an unreliable communication link.
Does TCP use Go-Back-N?
TCP standard doesn’t specify what to do, but most receiver implementations buffer out-of-order packets. GBN or Go-back-N (the sender resends the entire window of packets starting with “i”), or SR / Selective Repeat (sender retransmits only “i” and hopes other packets will reach).