[Ns-bugs] [Bug 988] New: MacRxMiddle::SequenceControlSmaller method

[code@nsnam.ece.gatech.edu]

http://www.nsnam.org/bugzilla/show_bug.cgi?id=988

           Summary: MacRxMiddle::SequenceControlSmaller method
           Product: ns-3
           Version: ns-3-dev
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P5
         Component: wifi
        AssignedTo: nbaldo at cttc.es
        ReportedBy: nbaldo at cttc.es
                CC: ns-bugs at isi.edu, mk.banchi at gmail.com
   Estimated Hours: 0.0


Mirko wrote:

i'd like take a look at the function MacRxMiddle::SequenceControlSmaller. The
first question is: what this function does? I suppose that it is used to figure
out if a packet is an "old" packet or not. Standard specifies that range of
sequence number are splitted in two parts: one corresponds to packets that can
be considered new and one to packets that can be considered old. For simplicity
we can consider a smaller range, for example, of 10 sequence numbers so with an
initial sequence number equals to 7 suppose to have next situation:

0  1  2  3  4  5  6  7  8  9
*  *  |  |  |  |  |  *  *  *

* = new packet
| = old packet

Now i used that function to discover if the packet number 2 is old or new in
comparison to packet number 7. So i used that logic (modified accordingly) but
the function returns the following results:

SequenceControlSmaller (7<<4, 2<<4) = true
SequenceControlSmaller (2<<4, 7<<4) = false

I think that the function should return always true because if 7 is an old
packet 2 in a new one and vice versa. What do you think about?

Second question: who uses this function?It seems that it never used...this
function would be very useful to me... what do you think about moving it to
qos-utils.h?

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