H.323's "keepAlive" mechanism

Jean-Francois Mule jfmule at clarent.com
Mon Jan 29 17:42:43 EST 2001

I agree with Chris.
Some other sig protocols use the value of 0 in registration msgs to ask for
unregistration or indicate registration has expired.  This is consistent
with the definition of ttl and h323 implementors should agree on that.
Even though h225 does provide urq msg to properly unregister a terminal,
thus permitting to use the 0 value to indicate that the ras capability of
the endpoint for keepalives, allowing to use the value of ttl==0 to indicate
that keepalives are not supported is *not* recommended.

Jean-Francois Mule.

Chris Wayman Purvis wrote:
> > 2) If the EP does not specify a timeToLive, should this be
> treated as
> a value
> >    of "0" and does this make it impossible for a GK to impose any
> timeToLive
> >    value?
> I would suggest that this would imply that the endpoint does
> not support
> this
> feature.  I would, on the other hand, have thought (unless one of the
> standards
> says otherwise) that a value of "0" would mean that the registration
> expires
> immediately, which may not be terribly useful!  Not quite the same
> thing.

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