Computer Networks Answers

Explain the difference between a MAC address and an IP address. You should relate your answer to the OSI model

Activity 3: Learning Unit 1‐3: ADDRESSING Q.3.1 Explain why devices on a network need addresses. (5) Q.3.2 Explain the difference between a MAC address and an IP address. You should relate your answer to the OSI model. (6) Q.3.3 Explain how devices get their MAC or IP address. (4) Q.3.4 Explain how a packet gets from one network to another. Your explanation should relate this movement to the IP address format. (5) Q.3.5 As the Internet has expanded, we have run out of IP addresses. Outline TWO ways how this problem has been overcome. 

802.11

Use the “wlan_packet_capture” file to answer the following questions. After opening the file, enter the string wlan in the filter field and then apply the filter. Find the first probe request message in the trace and use that to answer the following questions.

a. What are the MAC address fields in the 802.11 frame? [2]

b. Which MAC address in this frame corresponds to the wireless host (give the hexadecimal representation of the MAC address for the host)?

[1] i. To the access point? [1]

ii. To the first-hop router? [1]

Ethernet

Use the “ethernet_packet_capture” file to answer the following questions. After opening the file, find the first DHCP message in the trace and use that to answer the following questions

a. What is the 48-bit Ethernet source address of the frame? [1]

b. What is the 48-bit destination address of the Ethernet frame? [1]

c. Is this destination Ethernet address associated with the destination IP address? [1]

d. Give the hexadecimal value of the two-byte Frame type field. [1]

e. What upper layer protocol does this correspond to? [1]

IP

Using the “tcp_packet_capture” file and the first HTTP GET message, answer the following questions:

a. Within the IP packet header, what is the value in hex of the upper layer protocol field? b. Is the checksum Validation enabled for this datagram?

c. Explain your answer for b

d. Has this IP datagram been fragmented? [1]

e. Explain how you determined whether or not this datagram has been fragmented. [2] f. State one major disadvantage of IP fragmentation [2]