(ARP and Switch Self-Learning) The following network has 9 hosts (A-F) and 4 swi
ID: 3597792 • Letter: #
Question
(ARP and Switch Self-Learning) The following network has 9 hosts (A-F) and 4 switches (S1-S4) marked with link numbers. Suppose that host A and D have completed DHCP and so they both know their own IP address. Also, the IP address of D is already known to A
a. Now, an application in Host A gives a small message to a UDP socket to deliver the message to host D. Explain which packets are sent by host A and which packets are sent by host D.
b. Now suppose that the application in host D generates a UDP response. Explain which packets are sent by Host D and which packets are sent by Host A.
c. Assuming all switch forwarding tables are initially empty, fill each switch's forwarding table after both operations described above are performed.
S2 2 S1 3 S3 S4 1 3Explanation / Answer
a) A prepares small message segment and gives to UDP socket.
Transport layer makes that segment into multiple packets based on network layers maximum capability packet size.
A already know D's IP. So, A's network layer will successfully make packets with D's IP as destination IP.
Then those packets will be delivered to DLL(here also segmentation will be done). Here to make frames, A should know D's MAC address. For that, A will make a ARP request with D's IP and broadcasts throughout the network. Now D will respond with it's MAC address in ARP reply(Because both A and D are in same network). Now A will know D's MAC address. So, prepare frames out of packets and sends through network. Because this message is delivering by UDP protocol, D will not reply with any ACK for that message.
b) Now D is replying with a UDP message to A. Now D can obviously know A's IP and MAC address. So, D will follow same process as A, but directly makes frames without consulting ARP protocol. So, D will send message frames and won't expect any reply from A. Because it is UDP protocol. In this process A will not send any packets to D.
c)
Switch S1:
Dest Port
B 2
C,D,E,F 3
A 1
Switch S2:
Dest Port
C,D 3
E,F 2
A 1
Switch S3:
Dest Port
C 1
D 3
A 2
Switch S4:
Dest Port
E 2
F 3
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.