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    StatSN wraparound; 2 typos



    According to 2.2.2.2 (draft 15), the status sequence number space is 32-bit
    unsigned integers and the arithmetic operations are the regular mod(2**32)
    arithmetic.  Why is StatSN not specified to use serial number arithmetic
    (like CmdSN) to handle wrap-around?
    
    For example, I am working on a target implementation that keeps the
    information for response PDUs around until they are acknowledged by
    ExpStatSN from the initiator.  If the target sends two response PDUs with
    StatSNs equal to 2**32-1 and 0, and the initiator's next PDU has ExpStatSN
    equal to 1, then the target should consider both response PDUs acknowledged.
    Clearly, this will not happen with "regular" unsigned integer comparisons,
    since 2**32-1 > 1.  Perhaps it should be made explicit that comparisons on
    StatSN and ExpStatSN should use serial number arithmetic, which would handle
    the wrap-around.
    
    I have also found two typos in draft 15:
    
    Section 11.12 MaxRecvDataSegmentLength
    Last sentence "... if immediate data where sent" change "where" to "were".
    
    Section B.3 R2TSN DataSN use Examples
    Bidirectional DataSN Example "... in the alter case" change "alter" to
    "latter".
    
    Thanks,
    Anthony J. Battersby
    Cybernetics
    
    
    


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Last updated: Fri Aug 09 17:18:58 2002
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