self doubt Stop and wait protocol

Question

Consider a network topology using STOP and WAIT protocol  A---------R----------B   (here R is STORE and FORWARD ROUTER) Tp=1uS ,  Tx(data)=1000uS,  Tx(ack)=10uS File Size =10000bits, Packet size=1000bits. How long will it take for A to send whole file to B?

 

Dobut—here A will send packet to router R and router will send ack back to A then A will Transmit second packet 

                             OR

   here A will send packet toHost B and B will send ack back to A then A will send second packet 

Comments

@gourav94240 which would be a reliable one? 

Suppose you send to R and get acknowledgement , and further if the packets are lost would it be reliable?

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@prashant jha 1 in store and forward router packets are stored before sending . Geeksforgeeks/computernetworkpacketswitchingdelays

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how does it answer my question?

Answer 1

Since it is Stop and Wait Protocol, next packet will be sent only upon receipt of acknowledgement of previous packet from reciever/Host, not router.

Here total no. of packets = 10.

For 1 packet, total time taken to complete one cycle = TxAR + TpAR + TxRB + TpRB + TxackBR + TpackBR + TxackRA + TpackRA

(AR : A->R link, RB: R->B link, etc)

                                                                             =  1000us + 1us + 1000us + 1 us + 10us + 1 us + 10us + 1us = 2024us

For 10 packets, total time taken = 2024*10 us = 20240us = 20.24 ms.