IP LAB EXPERIMENT ‐ ARP
- Answer the following questions based on the contents of the Ethernet frame containing the HTTP GET message. =============================================================================================================
a. What is the 48-bit Ethernet address of your computer?
b. What is the 48-bit destination address in the Ethernet frame? Is this the Ethernet address of gaia.cs.umass.edu? What device has this as its Ethernet address?
The 48 bit destination address in the Ethernet frame is 00:06:25:da:af:73 which is also the address of the router/gateway.
No this is the address of the router/gateway to which the source computer is sending the request.From there it gets transferred to the destination computer.
c. Give the hexadecimal value for the two-byte Frame type field. What upper layer protocol does this correspond to?
The upper layer corresponds to the network layer as per the type field.
2.Answer the following questions based on the contents of the Ethernet frame containing the first byte of the HTTP response message.
a. What is the value of the Ethernet source address?
b. What is the destination address in the Ethernet frame? Is this the Ethernet address of your computer?
Yes it is the ethernet address of our computer.
c. Give the hexadecimal value for the two-byte Frame type field. What upper layer protocol does this correspond to?
- Answer the following questions based on the contents of the ARP Request packets. ==================================================================================
a. What are the hexadecimal values for the source and destination addresses in the Ethernet frame containing the ARP request message?
b. Give the hexadecimal value for the two-byte Ethernet Frame type field.
c. How many bytes from the very beginning of the Ethernet frame does the ARP opcode field begin?
The ARP opcode field begins 20 bytes from the very beginning of the Ethernet frame. On clicking the OPCODE field, we see the hex values 20-21.
d. What is the value of the opcode field within the ARP-payload part of the Ethernet frame in which an ARP request is made?
e. Does the ARP message contain the IP address of the sender?
f. Where in the ARP request does the “question” appear – the Ethernet address of the machine whose corresponding IP address is being queried?
- Answer the following questions based on the contents of the ARP Reply packets. ================================================================================ a. How many bytes from the very beginning of the Ethernet frame does the ARP opcode field begin?
It begins at 20-21 st field.
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?
The value of the OPCODE field within the arp payload in response packet is 2
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?
Yes because we can confirm that this packet contains the answer since it contains sender's IP field.
d. What are the hexadecimal values for the source and destination addresses in the Ethernet frame containing the ARP reply message?
e. There is yet another computer on this network, as indicated by packet 6 – another ARP request. Why is there no ARP reply (sent in response to the ARP request in packet 6) in the packet trace?
There is no response for the second ARP request packet because ARP request packet is a broadcast message and the arp response is unicast . So the system which has the ip that is queried by the server will send a unicast response packet back to the router. So since the traffic is captured from this system which has the ip .105,we are not able to see the reply arp packet which is sent back.
since our ip is .105 and the sender ip is .104 and .104 gets its reply only from .117 .