Consider Figure 6.33. Now we replace the router between subnets I and 2 with a switch SI, and label the router between subnets 2 and 3 as Rl.

Figure 6.33

a. Consider sending an IP data-gram from Host E to Host F. Will Host E ask router Rl to help forward the data-gram? Why? ¡n the Ethernet frame containing the IP data-gram, what are the source and destination IP and MAC addresses?

b. Suppose E would like to send an IP data-gram to B, and assume that E€™s ARP cache does not contain B€™s MAC address. Will E perform an ARP query to find B€™s MAC address? Why? In the Ethernet frame (containing the IP data-gram destined to B) that is delivered to router Rl, what are the source and destination IP and MAC addresses?

c. Suppose Host A would like to send an IP data-gram to Host B, and neither A€™s ARP cache contains B€™s MAC address nor does B€™s ARP cache contain Ks MAC address. Further suppose that the switch SI €˜s forwarding table contains entries for Host B and router R I only. Thus, A will broadcast an ARP request message. What actions will switch SI perform once it receives the ARP request message? Will router Rl also receive this ARP request message? If so. will R 1 forward the message lo Subnet 3? Once Host B receives this ARP request message, it will send hack to Host A an ARP response message. But will it send an ARP queiy message to ask for A€™s MAC address? Why? What will switch SI do once it receives an ARP response message from Host B?

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D Subnet 1 Subnet 3 Subnet 2