Unformatted text preview: In this chapter we transferred 32768 bytes in about 35 seconds (Figure
21.6) across a link with an RTT that averaged around 1.5 seconds (Figure 21.4). Calculate
how long TFTP would take for the same transfer.
21.4 In Section 21.7 we said that the receipt of a duplicate ACK is caused by a segment being
lost or reordered. In Section 21.5 we saw the generation of duplicate ACKs caused by a lost
segment. Draw a picture showing that a reordering of segments also generates duplicate
21.5 There is a noticeable blip in Figure 21.6 between times 28.8 and 29.8. Is this a
21.6 In Section 21.6 we said that the 4.3BSD Tahoe release only performed slow start if the file:///D|/Documents%20and%20Settings/bigini/Docu...homenet2run/tcpip/tcp-ip-illustrated/tcp_time.htm (28 of 29) [12/09/2001 14.47.27] Chapter 21. TCP Timeout and Retransmission destination was on a different network. How do you think "different network" was
determined? (Hint: Look at Appendix E.)
21.7 In Section 20.2 we said that TCP normally ACKs every other segment. But in Figure
21.2 we see the receiver ACK every segment. Why?
21.8 Are per-route metrics really useful, given the prevalence of default routes? file:///D|/Documents%20and%20Settings/bigini/Docu...homenet2run/tcpip/tcp-ip-illustrated/tcp_time.htm (29 of 29) [12/09/2001 14.47.27] Chapter 22. TCP Persist Timer TCP Persist Timer
We've seen that TCP has the receiver perform flow control by specifying the amount of
data it is willing to accept from the sender: the window size. What happens when the
window size goes to 0? This effectively stops the sender from transmitting data, until the
window becomes nonzero.
We saw this scenario in Figure 20.3. When the sender received segment 9, opening the
window that was shut down by segment 8, it immediately started sending data. TCP must
handle the case of this acknowledgment that opens the window (segment 9) being lost.
Acknowledgments are not reliably transmitted-that is, TCP does not ACK
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This test prep was uploaded on 04/04/2014 for the course ECE EL5373 taught by Professor Guoyang during the Spring '12 term at NYU Poly.
- Spring '12