TD-50/Osaka - Changes to the conferenceGoal field
Pete Cordell
pete at TECH-KNOW-WARE.COM
Thu Jun 22 06:12:00 EDT 2000
Rich,
I really don't want the second option. If you think the original is weak,
then I think the second option is far weaker. My feeling is that it buys us
nothing.
But as long as you can guarantee that we can remove it in Geneva if need be,
then I can go along with it. Otherwise I would prefer to remove it now and
attempt to re-insert it in Geneva. This seems more fail-safe. It's just
that I am aware that the process is getting tighter on what changes are
acceptable in Geneva. (For v3 no body was even allowed to turn up.) If we
can not make changes in Geneva I would prefer to remove it now and add it
into v5 if need be. This would be safer.
Pete.
=============================================
Pete Cordell
Tech-Know-Ware
pete at tech-know-ware.com
+44 1473 635863
=============================================
----- Original Message -----
From: Rich Bowen <rkbowen at CISCO.COM>
To: <ITU-SG16 at mailbag.cps.intel.com>
Sent: 22 June 2000 07:07
Subject: Re: TD-50/Osaka - Changes to the conferenceGoal field
> Pete, Bob,
>
> Support for packages would, of course, be optional in v4. The only
> mandatory requirement in v4 would be for an endpoint to recognize that a
> neededFeatures field is present, and if so, either process it or drop
> the call. The minimal requirement would be very simple to implement, so
> I don't know of any reason why vendors would ignore it.
>
> My suggestion would be to add the neededFeatures field for now and
> remove it in November if it's still controversial. It will be difficult
> to add fields after the White Paper is issued.
>
> - Rich
>
> Pete Cordell wrote:
> >
> > Rich,
> >
> > After some thought on the situation, my feeling is that if you think the
> > original method is unreliable, then I think the second suggestion works
even
> > less reliably. Basically the second solution stands zero chance of
working
> > with pre v4 entities, and based on Bob's comments will be an
implementation
> > issue for v4 and later.
> >
> > I therefore suggest that we remove neededFeature from the SETUP message
> > completely.
> >
> > I will say that I am VERY unhappy with this situation as it compromises
what
> > can be done with packages quite considerably. However, we have made
rush
> > decisions before which have come back to haunt us. By leaving this out
for
> > the time being we can hopefully get it right when we finally decide to
put
> > it in.
> >
> > Still, Bob should be pleased about this!!!
> >
> > Pete.
> >
> > =============================================
> > Pete Cordell
> > Tech-Know-Ware
> > pete at tech-know-ware.com
> > +44 1473 635863
> > =============================================
> >
> > ----- Original Message -----
> > From: Rich Bowen <rkbowen at CISCO.COM>
> > To: <ITU-SG16 at mailbag.cps.intel.com>
> > Sent: 21 June 2000 01:37
> > Subject: Re: TD-50/Osaka - Changes to the conferenceGoal field
> >
> > > Bob,
> > >
> > > It seems to me that the issue with the negotiation process you discuss
> > > below is that the call could be in an alerting state before the
> > > negotiation is done. On the other hand, if we make it mandatory in v4
> > > for the called endpoint to check the neededFeatures field then we
could
> > > avoid false starts, even if the endpoint doesn't support packages. Of
> > > course, that doesn't provide a solution for pre-v4 endpoints, but I
> > > don't think we have arrived at a reliable solution for that case, yet.
> > >
> > > Rich
> > >
> > > "Callaghan, Robert" wrote:
> > > >
> > > > Pete,
> > > >
> > > > As you well know, for H.323 mandatory is in the eyes of the
> > implementors.
> > > > If an implementor does not think that they are useful for him then
it
> > won't
> > > > be implemented. I think that Packages can be a useful service, but
not
> > > > mandatory. (I have yet to see a specific service to use Packages;
but
> > > > theoretically they are useful.)
> > > >
> > > > The problem is service that are mandatory, but have optional coding.
> > Annex
> > > > L has two coding formats in order to use v2 clients. I can seen
some
> > > > Packages services using the same technique - v4 uses Packages, v2
uses
> > > > nonStandardControl. I would prefer a negotiation process like that
for
> > RAS
> > > > negotiation - the originators asks for what is wanted, the response
is
> > what
> > > > is available. Then the originators chooses what to do. If this is
> > done,
> > > > there is no need to mess with conferenceGoals.
> > > >
> > > > Bob
> > > >
> > > > ------------------------------------------------------------------
> > > > Robert Callaghan
> > > > Siemens Enterprise Networks
> > > > Tel: +1.561.923.1756 Fax: +1.561.923.1403
> > > > Email: Robert.Callaghan at ICN.Siemens.com
> > > > ------------------------------------------------------------------
> > > >
> > > > -----Original Message-----
> > > > From: Pete Cordell [mailto:pete at TECH-KNOW-WARE.COM]
> > > > Sent: Tuesday, June 20, 2000 2:01 PM
> > > > To: ITU-SG16 at mailbag.cps.intel.com
> > > > Subject: Re: TD-50/Osaka - Changes to the conferenceGoal field
> > > >
> > > > Bob,
> > > >
> > > > You have made the perfect argument for leaving neededFeatures in the
> > > > conferenceGoal!
> > > >
> > > > Previously we could say that support for packages was optional
because
> > we
> > > > were relying on the conferenceGoal backwards compatibility method to
> > work
> > > > for V4 endpoints. This is because all the support packages need is
to
> > > > reject a call if neededFeatures is signalled.
> > > >
> > > > If we have to move neededFeatures to some other position, then
packages
> > MUST
> > > > become MANDATORY, at least in terms of recognising that
neededFeatures
> > are
> > > > present.
> > > >
> > > > I would imagine that you wouldn't like this.
> > > >
> > > > Pete.
> > > >
> > > > P.S. I believe you have expressed some concern that calls should be
able
> > to
> > > > continue even if certain features are not supported which may be
causing
> > you
> > > > to be worried about packages. This can be easily achieved with
> > packages.
> > > > Simply DON'T signal the features that you desire as neededFeatures,
> > signal
> > > > them as desiredFeatures. You then have the behaviour that you are
> > looking
> > > > for. The important thing here is that it gives the network
architect
> > the
> > > > choice of the behaviour that should happen. Or should Siemens
customers
> > > > take what they're given and lump it :)
> > > >
> > > > =============================================
> > > > Pete Cordell
> > > > Tech-Know-Ware
> > > > pete at tech-know-ware.com
> > > > +44 1473 635863
> > > > =============================================
> > > >
> > > > ----- Original Message -----
> > > > From: Callaghan, Robert <Robert.Callaghan at ICN.SIEMENS.COM>
> > > > To: <ITU-SG16 at mailbag.cps.intel.com>
> > > > Sent: 20 June 2000 14:53
> > > > Subject: Re: TD-50/Osaka - Changes to the conferenceGoal field
> > > >
> > > > > Rich,
> > > > >
> > > > > I agree that a v4 client that supports packages and further
supports a
> > > > > specific feature will respond. My comment is in regard to the
> > generation
> > > > of
> > > > > a negative message indicating that the feature is not support. If
a
> > v4
> > > > > client supports packages but not a feature, it will resond with a
> > negative
> > > > > message. However if the v4 client does not support packages, it
will
> > not
> > > > > respond at all. This is worse that the v2 or v3 clients if the
change
> > in
> > > > > conferceGoals is made. Therefor, my idea is that the change in
> > > > > conferenceGoal is not needed because than the v2, v3, and some v4
> > clients
> > > > > will work the same. This allows the addition of coding of package
> > > > > information to be anywhere other than conferenceGoal.
> > > > >
> > > > > Bob
> > > > >
> > > > > -----Original Message-----
> > > > > From: Rich Bowen [mailto:rkbowen at cisco.com]
> > > > > Sent: Tuesday, June 20, 2000 3:20 AM
> > > > > To: Callaghan, Robert
> > > > > Cc: 'Mailing list for parties associated with ITU-T Study Group
16'
> > > > > Subject: Re: TD-50/Osaka - Changes to the conferenceGoal field
> > > > >
> > > > >
> > > > >
> > > > > Bob,
> > > > >
> > > > > If the v4 client supports the features listed in the needFeatures
> > field,
> > > > > then it will respond with those same features listed in a
> > > > > supportedFeatures field, as an acknowledgement. Presumably if it
> > > > > acknowledges features in this way, then it will not ignore
packages
> > > > > related to those features.
> > > > >
> > > > > Rich
> > > > >
> > > > > "Callaghan, Robert" wrote:
> > > > > >
> > > > > > Rich,
> > > > > >
> > > > > > I question that the concept for forcing conferenceGoal to fail
will
> > even
> > > > > > work.
> > > > > >
> > > > > > The use of conferenceGoal will detect a v2 or v3 client through
a
> > > > failure.
> > > > > > But the version number will also detect the older versions. A
v4
> > client
> > > > > can
> > > > > > properly detect and decode the new structure. However, support
of
> > > > > packages
> > > > > > is optional, so the client can ignore the requirement to
evaluate
> > the
> > > > > > packages.
> > > > > >
> > > > > > Then what?
> > > > > >
> > > > > > Bob
> > > > > >
> > > > > > -----Original Message-----
> > > > > > From: Rich Bowen [mailto:rkbowen at CISCO.COM]
> > > > > > Sent: Sunday, June 18, 2000 5:14 PM
> > > > > > To: ITU-SG16 at mailbag.cps.intel.com
> > > > > > Subject: TD-50/Osaka - Changes to the conferenceGoal field
> > > > > >
> > > > > > All,
> > > > > >
> > > > > > In Osaka we agreed to add support for packages to H.225.0 along
the
> > > > > > lines of TD-50
> > (ftp://standard.pictel.com/avc-site/0005_Osa/TD-50.zip).
> > > > > > There was some concern raised about the proposed modifications
to
> > the
> > > > > > conferenceGoal field in the Setup message. The meeting report
> > states:
> > > > > >
> > > > > > "Some issues were raised about conflicts in the usage of the
> > conference
> > > > > > goal field between this new method and H.450.x. A possible
solution
> > is
> > > > > > to create a new field in the ASN.1 to avoid conflicts. The
editors
> > are
> > > > > > empowered to work with interested parties to resolve these
conflicts
> > in
> > > > > > the ASN.1 before the white paper is issued."
> > > > > >
> > > > > > The modification proposed in TD-50 was the addition of the
> > > > > > "neededFeatures" field to the confereceGoal field of the
Setup-UUIE:
> > > > > >
> > > > > > conferenceGoal CHOICE
> > > > > > {
> > > > > > create NULL,
> > > > > > join NULL,
> > > > > > invite NULL,
> > > > > > ...,
> > > > > > capability-negotiation NULL,
> > > > > > callIndependentSupplementaryService NULL,
> > > > > > --> neededFeatures NeededFeatureGoal
> > > > > > },
> > > > > >
> > > > > > where the NeededFeatureGoal structure is defined as:
> > > > > >
> > > > > > NeededFeatureGoal ::= SEQUENCE
> > > > > > {
> > > > > > basicGoal CHOICE
> > > > > > {
> > > > > > create NULL,
> > > > > > join NULL,
> > > > > > invite NULL,
> > > > > > capability-negotiation NULL,
> > > > > > callIndependentSupplementaryService NULL,
> > > > > > ...
> > > > > > } OPTIONAL,
> > > > > > features SEQUENCE OF SupportedFeatures,
> > > > > > ...
> > > > > > }
> > > > > >
> > > > > > An alternative approach would be to add a neededFeatures field
at
> > the
> > > > > > highest level of the Setup-UUIE ASN.1 instead of inside the
> > > > > > conferenceGoal structure, similar to the way the
desirededFeatures
> > and
> > > > > > supportedFeatures fields will be added (see TD-50), like this:
> > > > > >
> > > > > > Setup-UUIE ::= SEQUENCE
> > > > > > {
> > > > > > [snip]
> > > > > > --> neededFeatures SEQUENCE OF SupportedFeatures
> > OPTIONAL,
> > > > > > desiredFeatures SEQUENCE OF SupportedFeatures
> > OPTIONAL,
> > > > > > supportedFeatures SEQUENCE OF SupportedFeatures
> > OPTIONAL
> > > > > > }
> > > > > >
> > > > > > The motivation for adding neededFeatures to the conferenceGoal
field
> > was
> > > > > > to force a call failure when trying to setup a call to pre-v4
> > endpoint
> > > > > > and there is some v4 or later feature that is *required* for the
> > call.
> > > > > > The mechanism is intended to work like this:
> > > > > >
> > > > > > o The v4 EP sends Setup to the pre-v4 endpoint, and specifies
some
> > > > > > required feature in the neededFeatures field of the
conferenceGoal.
> > > > > > o The pre-v4 EP doesn't recognize the neededFeatures field as a
> > > > > > supported CHOICE for a conferenceGoal, so it sends Release
Complete.
> > > > > >
> > > > > > There would not be any conflicts with H.450, as suggested in the
> > meeting
> > > > > > report, because if the callIndependentSupplementaryService was
> > needed,
> > > > > > it would still be specified. The difference is that, if a
> > neededFeature
> > > > > > was also required, the H.450 goals would be specified inside the
> > > > > > NeededFeatureGoal structure, which v4 and later endpoints would
be
> > aware
> > > > > > of.
> > > > > >
> > > > > > These are the pros and cons of adding neededFeatures to the
> > > > > > conferenceGoal vs. adding it to Setup-UUIE, IMO:
> > > > > > o Advantages:
> > > > > > - *May* force an early call release if a required feature is
> > > > > > not supported by a pre-v4 endpoint.
> > > > > > o Disadvantages:
> > > > > > - ASN.1 and thus implementation would be more complex.
> > > > > > Potentially have to check the conferenceGoal in two
structures
> > > > > > instead of one.
> > > > > > - If pre-v4 EP sends Release Complete, there is no way to
> > > > > > know whether it was sent because of an unrecognized
> > > > > > conferenceGoal, because there is no ReleaseCompleteReason
> > > > > > defined for that purpose.
> > > > > > - H.323 does not require failing a call if the
conferenceGoal
> > > > > > is unrecognized, so the mechanism may not work at all.
> > > > > >
> > > > > > Although I think this mechanism is a good idea (and I supported
it
> > in
> > > > > > Osaka), at this point I don't think it would work reliably
enough to
> > > > > > justify the added complexity. So I would prefer the alternative
> > > > > > approach described above, adding the neededFeatures field
directly
> > to
> > > > > > the Setup-UUIE.
> > > > > >
> > > > > > Okay, fire away. :-)
> > > > > >
> > > > > > Regards,
> > > > > > Rich
> > > > >
> --------------------------------------------------------------------
> > > > > > Richard K. Bowen Cisco Systems, Inc.
> > > > > > VoIP Session Protocols Research Triangle Park, NC,
USA
> > > > >
> --------------------------------------------------------------------
> > > > > >
> > > > > >
> > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > > > > > For help on this mail list, send "HELP ITU-SG16" in a message to
> > > > > > listserv at mailbag.intel.com
> > > > >
> > > > > --
> > > >
> --------------------------------------------------------------------
> > > > > Richard K. Bowen Cisco Systems, Inc.
> > > > > VoIP Session Protocols Research Triangle Park, NC,
USA
> > > >
> --------------------------------------------------------------------
> > > > >
> > > > >
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > > > > For help on this mail list, send "HELP ITU-SG16" in a message to
> > > > > listserv at mailbag.intel.com
> > > >
> > > >
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > > > For help on this mail list, send "HELP ITU-SG16" in a message to
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> > > >
> > > >
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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> > >
> > > --
> > > --------------------------------------------------------------------
> > > Richard K. Bowen Cisco Systems, Inc.
> > > VoIP Session Protocols Research Triangle Park, NC, USA
> > > --------------------------------------------------------------------
> > >
> > > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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> --
> --------------------------------------------------------------------
> Richard K. Bowen Cisco Systems, Inc.
> VoIP Session Protocols Research Triangle Park, NC, USA
> --------------------------------------------------------------------
>
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