H.323 Annex E optional?

Paul E. Jones paul.jones at ties.itu.int
Sat Jul 31 12:12:53 EDT 1999


No, direct call routing is still possible.  Yes, one would have problems if
the GK allowed direct call routing to unknown endpoints and forced its
endpoints to always use Annex E-- that would not be a wise thing to do.

In some environments, it is possible that every endpoint will be Annex E
capable and the operators may want to force that mode of operation.  In some
cases, there may be a mixture of Annex E-capable and non-Annex E-capable
devices.  In that case, it would be unwise to force endpoints to use Annex
E, unless every call will be routed.  However, to maximize the usage of
Annex E where desired in a direct call model, the GK can learn from the LRQ
whether a remote endpoint supports Annex E and can tell the endpoint whether
to use or not to use Annex E in each ACF.


----- Original Message -----
From: Manoj Paul <mpaul at TRILLIUM.COM>
To: <ITU-SG16 at mailbag.cps.intel.com>
Sent: Friday, July 30, 1999 2:19 PM
Subject: Re: H.323 Annex E optional?

> > Paul,
> >
> > Okay, but what if the EP does not indicate that it has this capability?
> > 7.9.2/H.225.0v3 currently says that the EP _shall_ use an unreliable
> > if in receipt of an RCF with useAnnexECallSignalling set to TRUE.
> > Regardless of whether the endpoint indicated the capability in its RRQ.
> > following would eliminate the ambiguity and possible misunderstanding:
> >
> > 7.9.2/H.225.0v3: "useAnnexECallSignalling - If TRUE and
> > supportsAnnexECallSignalling was set to TRUE in the RRQ to which this
> > message is in response, the endpoint receiving this message shall use
> > signaling exclusively on an unreliable transport channel as described in
> > H.323 Annex E when placing calls."
>    Doesn't it mean that Gk can not adopt direct call routed model between
>    endpoints. Consider when the remote endpoint is not Annex E Compliant.
>    Now Ep1 sends call signalling messages *only* over
>    UDP (after receiving useAnnexECallSignalling = TRUE in RCF). This
>    routed call will not go through as Ep2 is not Annex E compliant.
>    Should Ep1 look into the callModel in ACF to figure out if it is
>    Gk/direct routed call. If Gk routed and useAnnexECallSig = TRUE,
>    do only UDP call signalling, and if direct routed, use Annex E
>    Mixed TCP and UDP procedures ?
>  -M.Paul.

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