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Unformatted text preview: occupied by the FIN flag. Chapter 23
23.1 It is usually simpler to invoke the keepalive option than explicitly coding application
probes; the keepalive probes take less network bandwidth than application probes (since
keepalive probes and answers contain no data); no probes are sent unless the connection
is idle. file:///D|/Documents%20and%20Settings/bigini/Doc...omenet2run/tcpip/tcp-ip-illustrated/append_d.htm (15 of 20) [12/09/2001 14.48.04] Appendix D: Solutions to Selected Exercises 23.2 The keepalive option can cause a perfectly good connection to be dropped because
of a temporary network outage; the probe interval (2 hours) is normally not configurable
on an application basis; Chapter 24
24.1 It means the sending TCP supports the window scale option, but doesn't need to
scale its window for this connection. The other end (that receives this SYN) can then
specify a window scale factor (that can be 0 or nonzero).
24.2 64000: the receive buffer size (128000) right shifted 1 bit. 55000: the receive buffer
size (220000) right shifted 2 bits.
24.3 No. The problem is that acknowledgments are not reliably delivered (unless they're
piggybacked with data) so a scale change appearing on an ACK could get lost.
24.4 232x8/120 equals 286 Mbits/sec, 2.86 times the FDDI data rate.
24.5 Each TCP would have to remember the last timestamp received on any connection
from each host. Read Appendix B.2 of RFC 1323 for additional details.
24.6 The application must set the size of the receive buffer before establishing the
connection with the other end, since the window scale option is sent in the initial SYN
24.7 If the receiver ACKs every second data segment, the throughput is 1,118,881
bytes/sec. Using a window of 62 segments, with an ACK for every 31 segments, the
value is 1,158,675.
24.8 With this option the timestamp echoed in the ACK is always from the segment that
caused the ACK. There is no ambiguity about which retransmitted segment the ACK is
for, but the other part of Karn's algorithm, dealing with the exponent...
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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