1. (25 Points) Consider three LANs interconnected by two routers, as shown in the Figure 1. Interfaces in Subnet 1 have

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1 25 Points Consider Three Lans Interconnected By Two Routers As Shown In The Figure 1 Interfaces In Subnet 1 Have 1 (123.04 KiB) Viewed 10 times

1. (25 Points) Consider three LANs interconnected by two routers, as shown in the Figure 1. Interfaces in Subnet 1 have addresses of the form 192.168.101/24; Interfaces in Subnet 2 uses addresses of the form 192.168.102/24; Interfaces in Subnet 3 use addresses of the form 192.168.103/24. Each adapter has also a MAC address. Subnet 1 Subnet 3 Subnet 2 Figure 1: Three LANs connected by two routers a. Show the appropriate IP and MAC addresses in the given network topology. b. Consider sending an IP datagram from Host E to Host B. Suppose all of the ARP tables are up to date. Enumerate all the steps. c. Repeat (c), now assuming that the ARP table in the sending host is empty (and the other tables are up to date). d. Replace the router between subnets 1 and 2 with a switch S1, and label the router between subnets 2 and 3 as R1. Suppose E would like to send an IP datagram 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 datagram destined to B) that is delivered to router R1, what are the source and destination IP and MAC addresses? e. Suppose now that the leftmost router in Figure 1 is replaced by a switch. Hosts A, B, C, and D and the right router are all star-connected into this switch. Give the source and destination MAC addresses in the frame encapsulating this IP datagram as the frame is transmitted (i) from A to the switch, (ii) from the switch to the right router, (iii) from the right router to F. Also give the source and destination IP addresses in the IP datagram encapsulated within the frame at each of these points in time.