+1 862 207 3288 HW3 TSM323 Summers 2015
*** Summary of chapters 5, 6 and Answer 6 out of 9 questions
1. Consider the following scenario. Node A is registered with a Home Agent (HA) in Austria under the IP address 1.0.0.10. Node B is registered with a HA 2.0.0.1 in Belgium under the IP address 2.0.0.10. Both nodes are initially in their home networks.
• Node B moves to a subnet in Switzerland controlled by a Foreign Agent (FA) 3.0.0.1.
• Node A initiates a TCP connection with node B (node A knows B’s domain name).
• Node A moves to the same Swiss subnet, and then continues using the same TCP connection.
2. Describe all relevant packets exchanged between all entities in this scenario, assuming that
nodes A and B use
a. Basic Mobile IP with a FA COA.
b. Basic Mobile IP with co-located COA.
c. Mobile IP with the reverse tunneling extension (FA COA or co-located COA). (Hint: You might want to look at RFC 3024 to get some details right.)
d. Mobile IP with the route optimization extension. Can both FA COAs and co-located COAs be used with this extension?
3. Describe the type of exchanged packets, and the IP addresses they contain.
4. Mobile IP
a) List the entities of mobile IP and describe data transfer from a mobile node to a fixed node and vice versa. Why and where is encapsulation needed?
b) Show the steps required for a handover from one foreign agent to another foreign agent.
c) Name the inefficiencies of mobile IP regarding data forwarding from a corresponding node to a mobile node. What optimizations are possible and what additional problems do they cause?
d) Explain packet flow if two mobile nodes communicate and both are in foreign networks. What additional routes do packets take if reverse tunneling is required?
e) Show the structure of the packets of each step (slides 9-10) between the original mobile user and the (now mobile) correspondent.
5. What are the problems with TCP over wireless network?
6. Snoop:
f) We described the snoop protocol when the MH is the TCP-receiver. What is the problem with snoop when the MH is the TCP-sender?
g) Describe a possible solution to this problem
7. According to RFC 2581 on TCP congestion control, a TCP receiver should use the delayed ACK algorithm. This algorithm gives the receiver the option to delay an ACK, if it is for an in-order segment, but must acknowledge every second full-sized segment. What are the main drawbacks of this algorithm in wireless networks?
8. Consider two mobile nodes in a foreign network having a foreign agent. Is it possible for the
two mobile nodes to use the same care-of-address? Explain your answer.
9. Consider a mobile node MN from network X. The user of MN wishes to communicate with a corresponding node CN in network Y. The node MN moves from X to a foreign network A.
• Describe the sequence of messages that are required in Mobile IPv4 so that MN and CN can continue
to communicate. Give the purpose of each message, where it is from, where it is to, and the path that it takes. Include both the user data messages and the Mobile IP control messages.
• Now, consider the case where CN moves to foreign network B while MN is still in the foreign network A. Can CN and MN still communicate? (Does Mobile IP support both endpoints moving?) Show the message flow to indicate how it will succeed or fail in this case.
