Consider the 3 LANs interconnected by 2 routers as shown in Figure 2 below. a. Assign IP addresses and MAC addresses for all the interfaces. Use address spaces 200.150.1.xxx for subnet 1, 200.150.2.xxx for subnet 2 and 200.150.3.xxx for subnet 3. b. Now consider the situation where host A is sending an IP datagram to host C. Give the source and destination MAC addresses (in the frame encapsulating this IP datagram) and the source and destination IP addresses of the IP datagram, as the frame is transmitted from node A to the left router, from left router to the right router and right router to node F. Now replace router between subnets 1 and 2 with a switch in Figure 2 below. Label that switch S1 and the router between subnets 2 and 3 R1. c. Consider sending an IP datagram from host F to host E. Will host E ask router R1 to help forward the datagram? Why? In the Ethernet frame containing the IP datagram, what are the source and destination IP and MAC addresses? d. Suppose F would like to send an IP datagram to A, and assume that Fs ARP cache does not contain As MAC address. Will F perform an ARP query to find As MAC address? Why? In the Ethernet frame (containing the IP datagram destined to A) that is delivered to router R1, what are the source and destination IP and MAC addresses? e. Suppose host A would like to send an IP datagram to host B, and neither As ARP cache contains Bs MAC address nor does Bs ARP cache As MAC address. Further suppose that the switch S1s forwarding table contains entries for host B and router R1 only. Thus A will broadcast an ARP request message. i. What actions will switch S1 perform once it receives the ARP request message? ii. Will router R1 also receive this ARP request message? If so, will R1 forward the message to subnet 3? iii. Once host B receives this ARP request message, it will send back to host and ARP response message. But will it send an ARP query message to ask for As MAC address? Why? iv. What will switch S1 do once it receives an ARP response message from host B?

Subnet 1 Subnet 2 Subnet 3