multiple choice (data communicatons); 1. How can Nagle\'s solution to the silly

Question

multiple choice (data communicatons);

1.  How can Nagle's solution to the silly window syndrome affect negatively interactive TCP application protocols that normally send short packets ?

a. waiting for an ACK or for enough accumulated data (1 MSS) to send will cause large and variable delays, especially on a 'slow' network

b. delaying sending ACKs back to the client will create long delays, affecting Quality of Service

c. replying with a rwnd of 0 will cause long delays on the client side

d. the first packet will be delayed unnecessarily if it is too short

2. Consider the TCP FSM on slide 40 on the posted PDF slides for the TCP protocol. What must happens to the TCP server after it listens and receives a SYN packet for the connection to begin exchanging data packets ?

a. it can piggyback a SYN+ACK with the first data packet to the client

b. it must reply with a SYN+ACK packet then it waits in the SYN_RECEIVED state for an ACK from the client

c. it replies with an ACK packet, then moves to the SYN_RECEIVED state waiting for an ACK from the client before moving to the ESTABLISHED state

d. it sends a SYN packet and enters to the SYN_SENT state, where it waits for SYN+ACK from the client

3. 1.      A TCP receiver has a 1000 byte buffer. There are 300 bytes to be passed to the server process that consumes these data. What is the size of the TCP receive window rwnd ? (write just the number, expressed in bytes):

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Explanation / Answer

d) the first packet will be delayed unnecessarily if it is too short because using nagles algorithm in silly window says that wait utill the data becomes 1MSS if the data is too short we must wait for 1 RTT(Round trip time) until data becomes of some big size but less than 1MSS .this may delay the ist packet if it is very short. tcp can piggyback a SYN+ACK with the first data packet to the client.it is true because TCP send data and ack in the same packet that is what we call as piggybacking. As the minimum of 1000 and 300 is 300bytes so the rwnd size is 300.here we are taking the minimum in order to avoid the overwhelming of the reciever.min(1000,300) = 300bytes =300*8=2400bits=2GB +352bits=2^20+352bits

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