Question
12. A station running TCP/IP needs to transfer a file to a host. The file contains 2048 bytes. How many bytes, including all of the TCP/IP overhead, would be sent, assuming a payload size of 512 bytes and that both systems are running IPv4? (Also assume that the three-way handshake and window size negotiation have been completed and that no errors occur during transmission.)
a) What is the protocol overhead (stated as a percentage)?
b) Perform the same calculation, this time assuming both clients are using IPv6.
Answer
a)
Assuming IPv4 and a payload size of 512 bytes, then calculate the total number of bytes sent, including all TCP/IP overhead.
TCP/IP overhead consists of the IP header, TCP header, and any additional protocol-specific headers. Here is a breakdown of the overhead for IPv4:
- IP header: 20 bytes
- TCP header: 20 bytes
Total overhead = IP header + TCP header = 20 bytes + 20 bytes = 40 bytes
Payload size = 512 bytes
Total bytes sent = Payload size + Total overhead
= 512 bytes + 40 bytes
= 552 bytes
To calculate the protocol overhead as a percentage, divide the overhead by the total bytes sent and multiply by 100:
Protocol overhead = (Total overhead / Total bytes sent) * 100 Protocol overhead
= (40 bytes / 552 bytes) * 100 Protocol overhead
≈ 7.25%
Hence, the protocol overhead for the IPv4 transmission is approximately 7.25%.
b)
Now, let's perform the same calculation, assuming both clients are using IPv6.
For IPv6, the IP header size increases to 40 bytes, while the TCP header size remains the same at 20 bytes.
Total overhead = IP header + TCP header
= 40 bytes + 20 bytes = 60 bytes
Payload size = 512 bytes
Total bytes sent = Payload size + Total overhead
= 512 bytes + 60 bytes
= 572 bytes
Protocol overhead = (Total overhead / Total bytes sent) * 100 Protocol overhead
= (60 bytes / 572 bytes) * 100 Protocol overhead
≈ 10.49%
Hence, with IPv6, the protocol overhead for the transmission would be approximately 10.49%.