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1. Host A wants to send a packet to Host B. What role does the Router S play in

ID: 3572061 • Letter: 1

Question

1. Host A wants to send a packet to Host B. What role does the Router S play in this transfer?

2. Now Host A wants to send a packet to Host D. What role does the Router S play in this transfer?

3. Let IP(a) be the IP address of Host A, network interface a. Let MAC(a) be the MAC address. Give the source and destination IP

and MAC addresses for the frame on each wire for the previous two scenarios:

1. A sending to B

2. A sending to D

4. Assuming all ARP tables are empty, describe the ARP message exchange for each of these scenarios:

1. A sending to B

2. A sending to D

Host A a Host B b Host C c Router R Host D

Explanation / Answer

For case 1 router will work as a repeater

For Case 2 router will check its routing table and using appropriate routing protocol will send the packet to next hop or destination.

For Case 3

1. MAC(a) sending to MAC(r) then MAC(r) sending to MAC(B) and IP(a) sending to IP(r) then IP(r) sending to IP(b)

2. MAC(a) sending to MAC(r) then MAC(r) sending to MAC(s) then MAC(s) sending to MAC(d) and  IP(a) sending to IP(r) then IP(r) sending to IP(s) then IP(s) sending to IP(d)

For Case 4

1. A will sent ARP message to router interfaces and it will broadcast the same message in its adjacent and next hop address . B will accept the message and will send a acknowledgement using the same path.

2. A will send ARP Message to router r interfaces then router broadcast in its adjacent network and pass it to it another interfaces s as broadcasting message and interface s pass it to its adjacent network. D will recieve the packet and will send acknowledgement using same path