Sliding window protocol

Question

Consider the 1 Mbps error free line.The maximum frame size is 1000 bits.New packets are generated about 1 seconds apart.The timeout interval is 10msec.If the ack timer is eliminated.How many times the average message be transmitted.

assume case 1: when one way propogation delay is 10 ms.

             case 2 : when one way propogation delay is 4 ms

Comments

After Tt = 1ms and Tp = 10 ms

2Tp will be 20, before 20 already packet will be retransmitted at 11th msec. but at 21st sec we got ack about the packet. and retransmitted packet will get rejected as duplicate but before rejecting and getting its ack another one will be sent. Hence I thought 2 retransmissions.

---

In Go back N, the first scenario will result in infinite retransmissions because a packet has exactly one unique identifier which is different for every retransmission hence Timeout will occur every time.

---

@Ashwin Kulkarni Will sender again sent 1st packet? 

Because after Ack's timeout sender doesn't recognize this frame.