rdt2.1: discussion

Sender:

• seq # added to pkt

• two seq. #’s (0,1) will suffice. Why?

• must check if received ACK/NAK corrupted

• twice as many states

  • state must “remember” whether “current” pkt has 0 or 1 seq. #

Receiver:

• must check if received packet is duplicate

  • state indicates whether 0 or 1 is expected pkt seq #

• note: receiver can not know if its last ACK/NAK received OK at sender

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