Solution#6.6

Deadlocks are possible. For example, a packet arrives at A out of blue, and A acknowledges it. The ack gets lost, but A is now open while B knows nothing at all about what has happened. Now the same thing happens to B, and both are open, but expecting different sequence numbers.

Solution#6.13

Even though each datagram arrives intact, it is possible that datagrams arrive in the wrong order, so TCP has to be prepared to reassemble the parts of a message properly.

Solution#6.15

The entire TCP segment must fit in 65,535-byte payload field of an IP packet. Since a TCP header is a minimun of 20 byte and IP header is also 20 bytes, only 65,495 bytes are left over for TCP data.

Solution#6.20

The successive estimates are 29.6, 29.84, 29.256.

Solution#6.23

No. IP packets contain IP addresses, which specify a destination machine. Once such a packet arrived, how would the network handler know which process to give it to. UDP packets contain a destination port. This information is essential so they can be delivered to the correct process.

Solution#6.34

It takes 2x6 = 12 instructions to copy 8 bytes. Twelve instructions takes 120 nsec. Thus each byte requires 15 nsec of CPU time for copying. The system is thus capable to handle 67 MB/sec or 533 Mbps. It falls far short of processing 1 Gbps.