8 bit block division -- University Level Intro Course: Networking

[SumDood_]

Homework Statement

Convert your ID to a bit stream. If the last block is not 8 bits, add 0s to the right. Convert each block to the polynomial. Find the remainders by dividing all the blocks on the divisor, 11010.

Relevant Equations

Assume ID = 173

What I think I should do:
1 = 0001
7 = 0111
3 = 0011
First block = 00010111
Second Block = 00110000

Now, I do binary division
00010111/11010 = find the answer
00110000/11010 = find the answer

This is what I think I should do, but I am not sure if this is correct. Is this basically CRC?
Any help is appreciated, thank you!

 

[Steve4Physics]

Hi @sumdood. (I typed SumDood but it renders as sumdood).

Edit: Hi @SumDood_

Since no one has yet replied, here are a few (non-expert) thoughts, so you don’t feel ignored!

The question seems incomplete. Have you posted it in full?

Let’s assume (as you have done) that you are meant to encode each decimal digit of the ID as a 4 bit unsigned binary integer.

Because four extra zeroes must be appended to your 2nd block, the problem then is that you can’t distinguish between ID=173 and ID=1730. You would be better to treat your ID as 0173 (assuming leading zeroes are acceptable in the ID.)

The question tells you to "Convert each block to the polynomial". But you haven't done this - you might be required to explicitly write each block's polynomial (e.g. x⁴ + x² etc. for the the first block as you currently have it.)

If you were being asked to do a CRC, with generator = 11010 (5 bits), then you would have to add (5-1=) 4 zeroes to each block before dividing by the generator. That’s not in the instructions so it doesn’t look like a CRC.

You might want to ask whoever set the question for clarification.

 

[SumDood_]

Hi @sumdood. (I typed SumDood but it renders as sumdood). Since no one has yet replied, here are a few (non-expert) thoughts, so you don’t feel ignored!

The question seems incomplete. Have you posted it in full?

Let’s assume (as you have done) that you are meant to encode each decimal digit of the ID as a 4 bit unsigned binary integer.

Because four extra zeroes must be appended to your 2nd block, the problem then is that you can’t distinguish between ID=173 and ID=1730. You would be better to treat your ID as 0173 (assuming leading zeroes are acceptable in the ID.)

The question tells you to "Convert each block to the polynomial". But you haven't done this - you might be required to explicitly write each block's polynomial (e.g. x⁴ + x² etc. for the the first block as you currently have it.)

If you were being asked to do a CRC, with generator = 11010 (5 bits), then you would have to add (5-1=) 4 zeroes to each block before dividing by the generator. That’s not in the instructions so it doesn’t look like a CRC.

You might want to ask whoever set the question for clarification.

I actually have posted in full. I have gotten in touch with who set the question, but no reply.
I do appreciate the response, though!

 

[Office_Shredder]

Hi @sumdood. (I typed SumDood but it renders as sumdood).

That's because you're looking for @SumDood_ with an underscore at the end!

 

[Steve4Physics]

That's because you're looking for @SumDood_ with an underscore at the end!

Aha! Should have gone to Specsavers!