The use of statusDeterminationNumber in masterSlaveDeterminat ion

Frank Derks frank.derks at PHILIPS.COM
Thu May 3 10:23:15 EDT 2001


the figure only partly solves the problem. The text that I referred
to does not reflect what is in the figure, so this should be corrected.

Furthermore, since the values that statusDeterminationNumber can take
on are in the range 0..(2^24-1). The "modulo operation" with 2^24
has no effect whatsoever.

It would seem that the real intent is that the _absolute_ value of the
difference between the received statusDeterminationNumber and the
locally generated statusDeterminationNumber determines which party is
to become the master and which party is to becomes the slave. If the
difference is smaller than 2^23 then the party that received the
masterSlaveDetermination message becomes the master. Otherwise it
becomes the slave. In the case that the two numbers are equal, the
result is indeterminate.



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mike.nilsson at on 03-05-2001 16:04:45
To:     Frank Derks/HVS/BE/PHILIPS at EMEA2
Subject:        RE: The use if statusDeterminationNumber in masterSlaveDeterminat ion


The answer is in Figure C.4(v) of H.245.

Best regards

Mike Nilsson

Mike Nilsson
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> -----Original Message-----
> From: Frank Derks [SMTP:frank.derks at PHILIPS.COM]
> Sent: Thursday, May 03, 2001 1:51 PM
> Subject:      The use if statusDeterminationNumber in
> masterSlaveDetermination
> C.2.1.4/H.245 states the following:
> "If the terminal type numbers are the same, the statusDeterminationNumbers
> are compared using modulo arithmetic to determine which is master
> If both terminals have equal terminalType field values and the difference
> between statusDetermination field values modulo 2^24 is 0 or 2^23, an
> indeterminate result is obtained"
> The first sentence states that "modulo arithmetic" must be used to compare
> the numbers. I would say that that's a rather vague way of describing how
> the comparison must be done. Furthermore it does not tell me what the
> result
> must be for a terminal to be determined to be the master!
> According to the second sentence, I know how to obtain an indeterminate
> result. So any result that is not any of the two specified values is not
> indeterminate, but I still do not know what the meaning of the result is.
> "Modulo arithmetic" is, however, introduced, but it is not clear whether
> this is the modulo arithmetic referred to in the first sentence.
> Furthermore,
> what is the significance of a result of 2^23?
> I assume that the same rules that apply to the comparison of the
> terminalType
> field apply (i.e. the terminal with the higher value becomes the master),
> but this is not stated explicitly.
> Regards,
> Frank
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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