“ping” is a well-known utility program to test the reachability of a destination machine. The results of a ping message printed on the screen are the measured round trip delays between the two machines. In the mobile IP network shown below, assume that the one-way delay between any two routers in the figure is 15 ms, and that the delay between two machines in a broadcast domain can be ignored. (a) Suppose indirect routing is used in the mobile IP network shown below. When user B sends a ping message to user A, what would be the measured round trip delay? (b) Repeat (a) if user B is also a mobile device and is now located in a foreign network.

 

home network User A User B wide area network visited network Y foreign agent