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LDAP: calculating FCS

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LDAP: calculating FCS

Hi there!
I have a question on generating FCS field in LDAP packets. As you can see in recommendation Q.921 (text is available in the pdf-file from http://www.itu.int/rec/T-REC-Q.921/e) the algorithm is quite clear and necessary operations are described.
The main points there: FCS is based on two components
1) Checked sequence length
2) Checked sequence information (bits)

When checked on the receiving end after several operations we should calculate a remainder which is determined if there was no errors during the transmission. This remainder is 0001110100001111 in binary or 7439 in decimal.

The problem is next. I try to simulate this process: took an info sequence of 64 bits. But when tried to check it's correctness using just calculated FCS, I don't get the remainder, described above. My teacher said that the recommendation should be read between the rows :) But I can't read it in any other way. I'd be grateful if anybody explain me what's wrong.

P.S. I performed my calculations in Mathematica (file is attached). Let me know if you have any questions on it.

Edited by: admin on 05/16/2010 - 04:32