CS 6250 Midterm Exam Name Instructor Dr Clark October 19 2005 CS 6250 Fall 2005 Midterm Exam Problem Possible Score 1 20 2 10 3 16 4 18 5 16 6 20 Total 100 This test is closed book and closed notes Answer the questions in the space provided When answering questions please state any and all assumptions you are making 1 CS 6250 Midterm Exam Name Part 1 Protocol Layering 20 points List in order the five protocol layers we discussed For each layer provide the following 4 things 1 Name of the layer 2 Service s provided by this layer to the upper layer 3 A specific standard protocol that fits in this layer 4 Where on which devices this layer is implemented 2 CS 6250 Midterm Exam Name Part 2 IPv6 10 points What steps did the designers of IPv6 take to make packet header processing more efficient There are several things that were done List them all for full credit 3 CS 6250 Midterm Exam Name Part 3 Network Programming 16 points 1 8 pts I ve said that our TCP programs must perform all I O operations in a loop What is meant by this Explain why it is important 2 8 pts What is meant by the term byte ordering Explain why it is important in the context of network programming 4 CS 6250 Midterm Exam Name Part 4 Routing 18 points 1 6 pts What is meant by the term domain based routing 2 6 pts What mechanisms does BGP use to prevent routing loops 3 6 pts Why do the administrators of the Tier 1 networks restrict route advertisements to netmasks of no more than 22 bits 5 CS 6250 Midterm Exam Name Part 5 Network Address Translation 16 points 1 8 pts What specific problems does NAT solve What benefits does a NAT device provide As part of your answer give a specific example of a case where NAT is deployed 2 8 pts What problems are created by the use of NAT As part of your answer give a specific example of a case where a NAT devices creates such a problem 6 CS 6250 Midterm Exam Name Part 6 Mobile IP 20 points 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 1 10 pts 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 2 10 pts 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 7