Chapter 22

22.1	In Figure 22.3 notice the times of all the acknowledgments (segments 5, 7, 9, 11, 13, 15, and 17): 0.170, 5.170, 10.170, 15.170, 15.370, 20.170, and 25.170. Also notice the time differences between sending the data and receiving the ACK: 164.9, 18.5, 18.7, 18.8, 198.3, 18.5, and 19.1 ms. Explain what's probably going on.
A:	The ACKs are probably all delayed on the host `bsdi,` because there is no reason to send them immediately. That's why the relative times have 0.170 and 0.370 as the fractional part. It also appears that the 200-ms timer on `bsdi` is running about 18 ms behind the same timer on `sun.`
22.2	In Figure 22.3 at time 25.174 a window of 767 is advertised, but 768 bytes are available in the receive buffer. Why the difference of 1 byte?
A:	The FIN flag, just like the SYN flag, occupies 1 byte in the sequence number space. The advertised window appears to be 1 byte smaller because TCP allows room for the 1 byte of sequence number space occupied by the FIN flag.