This problem refers to Figure 15.7. Suppose that LAN Z is the home network for host E and that D sends a block of data to E via IP.

a. Show the PDU structure, including the fields of the IP header and the lower-level headers (MAC, LLC) with the contents of address fields indicated for the case in which E is on its home network.

b. Repeat part a for the case in which E is on a foreign network reachable via the Internet through R3. Show formats for the MAC frame leaving D and the IP datagram leaving R3. Assume that IP-to-IP encapsulation is used.

c. Repeat part b for the IP datagram leaving R3, but now assume that minimal encapsulation is used.

LAN X R1 Internet LAN Y R3 R2 LAN Z Figure 15.7 A Simple Internetworking Example