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POTCP after the handshake: seq ack homework
 

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    <p>Ok so I've got this question for homework, I'm given that 'Host X' sends 'Host Z' a packet and the Seq=46 and Ack=87 and the payload/data = 'Hello?' </p> <p>From there I am given: a packet sent from Host Z to Host X with payload='Go away' and the last packet sent from Host X to Host Z with the data='No!' </p> <p>The homework is to find out what the value of the Seq and Ack of the last two packets would be. I know the handshake is over so it's not just as simple as adding 1 to the Seq and putting it into the Ack of the next packet. I read somewhere that when a payload is received the recipient then issues an Ack equal to 1 + the length of the payload in bytes. If that is correct how would I go about turning those strings into bytes? And what happens with the Seq? Is that still grabbed straight form the prior packets Ack?</p> <p>Thank you all so much.</p> <p>Assuming each character is equal to one byte, I will go ahead and answer my question, and if I'm wrong hopefully someone will correct me.</p> <p>I am making the assumption that the Seq and Ack I'm given is the first transmission out of the handshake, so:</p> <pre><code>X-&gt;Z Seq=45 Ack=NULL X&lt;-Z Seq=86 Ack=46 X-&gt;Z Seq=46 Ack=87 X-&gt;Z Seq=46 Ack=87 data='Hello?' (6 bytes) X&lt;-Z Seq=87 Ack=52 data='Go away' (7 bytes) X-&gt;Z Seq=52 Ack=94 data='No!' (3 bytes) </code></pre> <p>I believe that is all and that what I have above is correct, but please let me know if I did something wrong. Thank you all again.</p>
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    1. COI guess the "correct" answer is to assume one character = one byte, but with unicode being commonly used that old rule cannot be trusted any more. Asking for the character encoding of the data is definitely a relevant question to send back to the teacher.
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    2. COThanks Anders, I was thinking it would be one byte per character but I was seeing different things online, I wasn't sure if ASCII was the correct way to go when measuring characters when dealing with tcp...
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    3. COI think for the case of homework, what you have written is almost certainly correct. If it makes you feel better, you can write that you are assuming 1 byte/character. If your textbook has examples, you can look at those to see if they make the same assumption.
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