Now find the ARP reply that was sent in response to the ARP request. a) How many bytes from the very beginning of the Ethernet frame does the ARP opcode field begin? b) What is the value of the opcode field within the ARP-payload part of the Ethernet frame in which an ARP response is made? § Snippet: § c) Where in the ARP message does the “answer” to the earlier ARP request appear – the IP address of the machine having the Ethernet address whose corresponding IP address is being queried? 2. What are the hexadecimal values for the source and destination addresses in the Ethernet frame containing the ARP reply message?
Added by Thomas A.
Step 1
To answer the questions regarding the ARP reply, we will break down the process step by step. Show more…
Show all steps
Your feedback will help us improve your experience
Akash M and 88 other AP CS educators are ready to help you.
Ask a new question
Labs
Want to see this concept in action?
Explore this concept interactively to see how it behaves as you change inputs.
Key Concepts
Recommended Videos
Answer the following questions, based on the contents of the Ethernet frame containing the HTTP GET message. Whenever possible, when answering a question you should hand in a printout of the packet(s) within the trace that you used to answer the question asked. Annotate the printout to explain your answer. To print a packet, use File->Print, choose Selected packet only, choose Packet summary line, and select the minimum amount of packet detail that you need to answer the question. 1. What is the 48-bit Ethernet address of your computer? 2. What is the 48-bit destination address in the Ethernet frame? Is this the Ethernet address of gaia.cs.umass.edu? (Hint: the answer is no). What device has this as its Ethernet address? [Note: this is an important question, and one that students sometimes get wrong. Re-read pages 468-469 in the text and make sure you understand the answer here.] 3. Give the hexadecimal value for the two-byte Frame type field. What upper layer protocol does this correspond to? 4. How many bytes from the very start of the Ethernet frame does the ASCII "G" in "GET" appear in the Ethernet frame? Next, answer the following questions, based on the contents of the Ethernet frame containing the first byte of the HTTP response message. 5. What is the value of the Ethernet source address? Is this the address of your computer, or of gaia.cs.umass.edu (Hint: the answer is no). What device has this as its Ethernet address? 6. What is the destination address in the Ethernet frame? Is this the Ethernet address of your computer? 7. Give the hexadecimal value for the two-byte Frame type field. What upper layer protocol does this correspond to? 8. How many bytes from the very start of the Ethernet frame does the ASCII "O" in "OK" (i.e., the HTTP response code) appear in the Ethernet frame?
Akash M.
Problem 3: Data Framing ARP (2.5pts) Consider the following network topology. Assume that routing tables are properly configured, and the network just started (i.e., all caches are empty). Node C: - MAC Address: 00-00-00-00-00-05 - IP Address: 192.168.1.253 Node A: - MAC Address: 00-00-00-00-00-02 - IP Address: 192.168.0.2 Node B: - MAC Address: 00-00-00-00-00-03 - IP Address: 192.168.0.3 Router: - IP Address: 192.168.1.254 - MAC Address: 00-00-00-00-00-04 3.1. Sent by node C Node C sends a UDP packet [src=192.168.1.253, dst=192.168.0.3] (no IP level response). Show destination/source MAC addresses (in form -02, -03, -01, -04, or -05) of Ethernet frames that will result from this (received/sent). For each, highlight if it is ARP (request/response) or actual UDP packet. Only communication between node C and Router should be considered (both directions). Should be 3 frames. 3.2. Sent by the switch Now consider the same UDP packet, but packets received and sent by the switch. The switch has 3 ports and will be self-learning during the exchange (initially switching table is empty). Show MAC addresses for each from the switch received and which port(s) they were forwarded. Remember, switch can send to one or multiple ports, depending on if it has no information or self-learned information from previous exchanges.
Networking ARP/ICMP Scenario 1: H1 is trying to communicate with H4. They are on separate networks that are connected by R. All machines are running properly. H1's ARP table has been cleared out, so before sending any data, it must send out an ARP Request. It receives an ARP Reply back. For the ARP Reply: The operation field is set to _______ ______'s MAC address is set as the sender hardware address of the ARP Packet ______'s IP address is set as the sender protocol address of the ARP Packet ______'s MAC address is set as the target hardware address of the ARP Packet ______'s IP address is set as the target protocol address of the ARP Packet H1 sees ______'s MAC address set as the source address on the Ethernet Frame that encapsulates the ARP Reply it receives H1 sees ______'s MAC address set as the destination address on the Ethernet Frame that encapsulates the ARP Reply it receives Scenario 3: H3 is trying to ping H4. They are on separate networks that are connected by R1. H4 is currently shut down. What type of ICMP error message will be sent? (Give the name) Who will be the source IP address on the IP datagram that has the ICMP error message encapsulated? Who will be the destination IP address on the IP datagram that has the ICMP error message encapsulated? Scenario 4: H2 is trying to ping H5. They are on separate networks that are connected by R1 and R2. When sending the ping, H2 sets the TTL field to 2. What type of ICMP error message will be sent? (Give the name) Who will be the source IP address on the IP datagram that has the ICMP error message encapsulated? Who will be the destination IP address on the IP datagram that has the ICMP error message encapsulated? Scenario 5: H6 runs the traceroute program to find the route to H1. They are on separate networks that are connected by R2 and R1. For each ping request H6 sends out, what is the destination IP address set to in the IP datagram that encapsulates the Ping Request? For each ping request H6 sends out, who does H6 set as the destination MAC address in the Ethernet Frame that encapsulates the IP datagram that encapsulates the Ping Request? Which machine(s) will send Time Exceeded error message(s) to H6? Who will be the source IP address on the IP datagram that encapsulates the Ping Reply? When H6 receives the Ping Reply, who will be set as the source MAC address on the Ethernet Frame that has the IP datagram that encapsulates the Ping Reply?
Recommended Textbooks
Computer Science and Information Technology
Introduction to Programming Using Python
Computer Science - An Overview
Transcript
18,000,000+
Students on Numerade
Trusted by students at 8,000+ universities
Watch the video solution with this free unlock.
EMAIL
PASSWORD