rdt.0 has a fatal flaw! What happens if Handling duplicates ACK/NAK corrupted? o sender adds sequence o sender doesnt know what number to each pkt happened at receiver 0 sender retransmits current 口 san't just retransmit kt讦fAcK/ NAK garbled possible duplicate o receiver discards(doesn't deliver up)duplicate pkt What to do? o sender ACKS/NAKs receivers AcK/Nak What stop and wait if sender acK/NaK lost? Sender sends one packet then waits for receiver g retransmit, but this might cause retransmission of response correctly received pkt 3: Transport Layer 3a-183: Transport Layer 3a-18 rdt2.0 has a fatal flaw! What happens if ACK/NAK corrupted?  sender doesn’t know what happened at receiver!  san’t just retransmit: possible duplicate What to do?  sender ACKs/NAKs receiver’s ACK/NAK? What if sender ACK/NAK lost?  retransmit, but this might cause retransmission of correctly received pkt! Handling duplicates:  sender adds sequence number to each pkt  sender retransmits current pkt if ACK/NAK garbled  receiver discards (doesn’t deliver up) duplicate pkt Sender sends one packet, then waits for receiver response stop and wait