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Unformatted text preview: tilization). What does the window size appear to be for both cases? (Assume a 500ms delay for the satellite link.) How big should the window be for the satellite link?
20.4 If the API provided a way for a sending application to tell its TCP to turn on the PUSH
flag, and a way for the receiver to tell if the PUSH flag was on in a received segment, could
the flag then be used as a record marker?
20.5 In Figure 20.3 why aren't segments 15 and 16 combined?
20.6 In Figure 20.13 we assume that the ACKs come back nicely spaced, corresponding to
the spacing of the data segments. What happens if the ACKs are queued somewhere on the
return path, causing a bunch of them to arrive at the same time at the sender? file:///D|/Documents%20and%20Settings/bigini/Docu...homenet2run/tcpip/tcp-ip-illustrated/tcp_bulk.htm (24 of 24) [12/09/2001 14.47.22] Chapter 21. TCP Timeout and Retransmission TCP Timeout and Retransmission
TCP provides a reliable transport layer. One of the ways it provides reliability is for each end
to acknowledge the data it receives from. the other end. But data segments and
acknowledgments can get lost. TCP handles this by setting a timeout when it sends data, and
if the data isn't acknowledged when the timeout expires, it retransmits the data. A critical
element of any implementation is the timeout and retransmission strategy. How is the timeout
interval determined, and how frequently does a retransmission occur?
We've already seen two examples of timeout and retransmission: (1) In the ICMP port
unreachable example in Section 6.5 we saw the TFTP client using UDP employing a simple
(and poor) timeout and retransmission strategy: it assumed 5 seconds was an adequate
timeout period and retransmitted every 5 seconds. (2) In the ARP example to a nonexistent
host (Section 4.5), we saw that when TCP tried to establish the connection it retransmitted its
SYN using a longer delay between each retransmission. TCP manages four different timers
for each connection.
1. A retran...
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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