H.225v4 correction

Terry L Anderson tla at LUCENT.COM
Mon May 14 11:59:03 EDT 2001

There is a minor editing error in the prepub version of H.225.0v4.  In
section 7.6, concerning the definition of GloballyUniqueID, there is a
numbered list specifying the algorithm.  In item 5, the reference to
table 20 should be to table 19 (tables were renumbering from v3 and the
renumbering of the reference evidently didn't stay in synch).  Perhaps
this should be corrected in IG.

In addition, the specification of conditions underwhich the clock
sequence value should be changed (two paragraphs above the numbered
list) omits the case where the current UTC EQUALS the saved UTC.  It
specifies that the clock sequence value should be changed if the current
is LESS than the saved value (non-monotonic case) but a similar problem
occurs if the clock has not ticked (GID will not be unique).  It would
be better if the condition were reworded to say "if the current value
less or equal or the saved value was lost..." and the bullet item above
changed to "... the local value of UTC has gone backward or not
increased..." (or an additional bullet item added).  Admittedly, if the
recommended 100ns clock tick is used, the probability of the clock not
having advanced may be low, but not impossible as we move to faster
processors.  This problem is not new to v4 but since the correction
would not cause a compatibility problem, it would be good to correct.
If we do not choose to modify v4 through the IG we should at least make
this change in v5.

Terry L Anderson              mailto:tla at lucent.com
Tel:908.582.7013   Fax:908.582.6729
Lucent Technologies/INS/Voice Over IP Access Networks
Rm 2B-121, 600 Mountain Av, Murray Hill, NJ 07974
http://its.lucent.com/~tla (Lucent internal) http://www.gti.net/tla

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