Exercises for Module 4

1. In the following TCP connection establishment and data transfer scenario, fill in the spaces marked '?' with the appropriate Sequence and Ack number values.

2. (a) In the following UDP datagram (including a 20-byte IP header), what is the checksum value XXXX ?

4500 004a 6581 4000 4011 6eca c0a8 0065 Answer. ae3c

44a8 60a2 8206 0035 0036 XXX 79d0 0100

0001 0000 0000 0000 0331 3135 0331 3031

0331 3938 0331 3332 0769 6e2d 6164 6472

0461 7270 6100 000c 0001

(b) What is the length of application data in the above datagram ?

Total length (header + data ) is 0x0036= 54 bytes ; Since header is 8 bytes, the application data must be 46 bytes.

3. UDP Checksum is not mandatory. How do you know if a particular host's UDP implementation is calculating checksum?

If checksum field in a UDP datagram generated by this host is 0x0000, that means the UDP is not calculating checksum.

4. In the following TCP connection establishment and data transfer scenario, fill in the spaces marked '?' with the appropriate Sequence and Ack number values.