Question:

a) An application sends a message which is 3400 bytes long. It sends the data as one UDP datagram. The message is then transferred from a sender to a receiver over three hops. The first link has an MTU of 1500, the second has an MTU of 1000 bytes, and the third has an MTU of 1200 bytes. Assume that no PATH MTU discovery and that the IP header is without options. The four fragmentation fields in the IPv4 header are:
identification, don't-fragment flag (DF), more fragment flag (MF) and fragmentation offset.

i. How many fragments will arrive to the IP module at the receiving host and how large will each IP fragment be (headers included)?

ii. What will be the fragmentation field values of each fragment when they have arrived at the receiver?

b) Suppose you have an unsecured IP packet that enters an IPsec tunnel. Sketch on how a plain IP packet, as shown in the figure, looks inside the tunnel.

i. If the tunnel uses an AH security association
ii. If the tunnel uses an ESP security association
iii. If the tunnel uses AH+ESP security association

c) Three aspects of IPsec are integrity, authentication and privacy. Which aspect(s) can be dealt with through IPsec AH?

d) What does a mobile node do upon returning to its home network?

e) What is the inefficiency of MIP in forwarding packets or datagrams?

f) Does UDP provide any security feature for MIP?