C6

Question 1

what OH fields are copied from IH

Answer 1

TOS, DF

Question 2

What fields of IH are not the same as original datagram

Answer 2

TTL, Checksum

Question 3

TTL inner header

Answer 3

at the start of tunnel, TTL is decreased by 1

if TTL is not 0, it is inserted into IH
checksum is re calculated

otherwise, if ttl is 0 no more ip in ip encapsulation and an ICMP message is sent back to the source

Question 4

what is flow control?

Answer 4

a faster sender will not congest a slower receiver

Question 5

What is the reliability of a protocol?

Answer 5

low error rate, retransmission in case of errors

Question 6

What is the TCP header length?

Answer 6

20 bytes - 60 bytes

Question 7

Source port TCP header

Answer 7

16 bit TSAP
source socket = source ip address + source port + communication descriptor

Question 8

Destination port TCP header

Answer 8

16 bit TSAP
destination socket = destination IP address + destination port + communication descriptor

Question 9

Sequence Number TCP header

Answer 9

32 bit, referes to the first data byte of the current TCP segment

Question 10

ACK number TCP header

Answer 10

piggybacking acknowledgement referring the next data byte expected