1. This question is based on the figure shown below. The figure shows the topology of the network, and the assigned IP address and MAC address.

a. Consider sending an IP datagram from Host E to Host D. Will Host E ask router R1 to help forward the datagram? In the Ethernet frame containing the IP datagram sending by E, what are the source and destination IP and MAC addresses?

b. Suppose E would like to send an IP datagram to B, and assume that Es ARP cache does not contain Bs MAC address, will E perform an ARP query to find Bs MAC address? In the Ethernet frame (containing the IP datagram destined to B the current expected receiver is B), what are the source and destination IP and MAC addresses?

c. Suppose Host E would like to send an IP datagram to Host F, and neither Es ARP cache contains Fs MAC address nor does Fs ARP cache contain Es MAC address. Further suppose that the switch S1s forwarding table contains entries for Host F and router R1 only. Thus, E will broadcast an ARP request message. Once Host F receives this ARP request message, it will send back to Host E an ARP response message. But will it send an ARP query message to ask for Es MAC address? Why? In the Ethernet frame (containing the IP datagram destined to F the current expected receiver is B), what are the source and destination IP and MAC addresses?

d. Suppose now that the router1 is replaced by a switch 2. Suppose A would like to send an

IP datagram to D, and assume that As ARP cache does contain Ds MAC address. Will A perform an APR query to obtain Ds MAC address? In the Ethernet frame containing the IP datagram destined to D (the last hop communication with the next expected receiver is D), what are the source and destination IP and MAC addresses?

A 192.168.1.001 Fo 192.168.3.001 77-77-77-77-77-77 -00-00-00-00-00 L192.168.2.001 44-44-44-44-44-44 Router 1 LAN Switch 1 LAN LANG 192.168.2.002 92.168.1.002 22-22-22-22-22-22 33-33-33-33-33-33 192.168.3.005 88-88-88-88-88-88 192.168.2.004 B 192.168.1.003 D 66-66-66-66-66 192.168.3.003 F 99-99-99-99-99-99 A 192.168.1.001 Fo 192.168.3.001 77-77-77-77-77-77 -00-00-00-00-00 L192.168.2.001 44-44-44-44-44-44 Router 1 LAN Switch 1 LAN LANG 192.168.2.002 92.168.1.002 22-22-22-22-22-22 33-33-33-33-33-33 192.168.3.005 88-88-88-88-88-88 192.168.2.004 B 192.168.1.003 D 66-66-66-66-66 192.168.3.003 F 99-99-99-99-99-99