Re: Third party registration/group registration

7 Dec 2000


      Folks:
It may not be easy to standardize something in H.323 with respect to the
"Third Party." There are some situations where the role of the third party
is useful. However, the standardization criteria will depend what the
functions are and what the role to be played by the third party.
Let us consider two cases:
1. Third party registration
2. Third party call control
I have already mentioned some points with respect to "Third Party"
REGISTRATION. In this case, the third party, for example - my secretary will
register me for the meeting, will have no role as soon as the registration
is done. This may be a little difficult task in H.323 (although it is very
simple in SIP). (My guess is that we may be surprised to see that we may
have to decompose the H.323 functional entities to have this kind of
flexibility.)
Now, can we say the same for the third party call control?
The points that I am making are as follows:
1. Let us define the necessary functions (i.e., requirements) and the
criteria (e.g., roles, etc.) that need to be performed by the third party.
2. Then translate those functions and criteria in H.323 signaling messages
(if we can).
Best regards,
Radhika R. Roy
AT&T
-----Original Message-----
From: Agboh, Charles [mailto:Charles.Agboh@GTS.COM]
Sent: Thursday, December 07, 2000 11:00 AM
To: ITU-SG16@MAILBAG.INTEL.COM
Subject: Re: Third party registration/group registration
Chris
Some applicaitons of third-party registration
-secretary mode, where the secretary registers the current location
(e.g., tel:) for his boss;
- voicemail, where the voicemail system registers itself as a branch
location
regards,
charles
-----Original Message-----
From: Agboh, Charles
Sent: Thursday, December 07, 2000 3:57 PM
To: ITU-SG16@MAILBAG.INTEL.COM
Subject: Re: Third party registration/group registration
Chris,
Some ideas about why I think this could be a useful feature.....
It is the concept of third-party registration that I believe is not clearly
(if at all) specified in H.323.  "In third-party registration, the entity
issuing the request is different from the entity being registered."  This is
not equivalent to hunting down the list of alternateEnpoints for an Endpoint
I am trying to reach.    The key to this is who is requesting the binding
between an alias address and a transport address.
The entity making the request is using resources of the GK.  The GK may view
the entity that is  being registered as a client of the entiry that made the
request and may send CDRs  correlating the three parties entities.  The
3rd-party (as paul called it: the entity making the request) may be charged
for using the GKs resources.
Even though my friend bob has an H.323 complaint EP that is capable of
registering itself, I (3rd-party: as paul called it) can register bobs alias
at my GK and my GK will send CDRs to me at the end of *our* conference.
Bob may inheret some of my priveleges as a result of my action.
I don't have all the possible applications of this feature on my radar.
Best regards,
charles
-----Original Message-----
From: Chris Wayman Purvis [mailto:cwp@ISDN-COMMS.CO.UK]
Sent: Monday, December 04, 2000 2:26 PM
To: ITU-SG16@MAILBAG.INTEL.COM
Subject: Re: Third party registration/group registration
Charles,
...
I said that the "....H.323 EP must support RAS...".  We are down to the
case
...
where the H.323 EP user has disabled RAS.
I would argue that this means that the endpoint is not supporting RAS, and
has
become uncompliant...
...
Is it useful to have this feature (third-party registration) for this
specific case?  Its not defined in the standard and I think it should be
(i.e. From Pauls view, it could be useful for administrative reasons );
although there are ways to provide this feature in H.323v2 and H.323v4.
Please expand on why you think it's a useful feature, and what you think is
required for it.  I don't understand what you feel you need beyond what's
already there.  If you are acting as a gateway/IWF then you are handling all
call signalling, and the registration is not third-party.  If you are doing
Paul's "as if" case then it isn't "as if" if it requires any modifications
to
the standard.  If you wish to do anything else, you need to tell us WHAT as
I
for one don't understand what you're trying to achieve (and calling
"third-party registration") that doesn't come under the above headings.
Regards,
Chris
...
-----Original Message-----
From: Chris Wayman Purvis [mailto:cwp@isdn-comms.co.uk]
Sent: Monday, December 04, 2000 11:01 AM
To: Agboh, Charles
Cc: ITU-SG16@mailbag.cps.intel.com
Subject: Re: Third party registration/group registration
Charles,
...
By H.323 EP, I mean an H.323 EP that must support  RAS (by your
interpretation of the standard), but the RAS function can be disabled by
the
...
user (Pauls views ).  The GK is an optional H.323 entity.
I repeat that "The GK is an optional H.323 entity" does NOT imply "RAS is
optional in an endpoint".
...
...
Q4. Is Charles's actual application, where one entity is registering and
hence
presumably (although he's consistently failed to clarify) handling RAS
on
...
...
...
behalf of another compliant H.323 endpoint a possibility?
A4a (My position, with which I THINK you agree) No, on the grounds that
if
...
...
the
gateway/IWF can find a gatekeeper and use it, so can the endpoint.
A4b (Charles) Yes.
A4b Yes, the H.323 EP user may have disabled RAS or the H.323 EP is
turned
...
...
off (i.e.  SIP EP).
These are two complete separate cases.  We were discussing only the
(disputed)
case that the H.323 EP user has disabled RAS.  If the H.323 endpoint is
turned
off and a SIP endpoint is being used, the gateway is handling ALL H.323
call
...
signalling on behalf of the SIP endpoint.  In other words the gateway is
terminating H.323 call signalling and, as far as H.323 is concerned, IS
the
...
endpoint.  Or, to put it yet another way, the same device is handling RAS
as
...
is
handling all other call signalling.
Regards,
Chris
...
-----Original Message-----
From: Chris Wayman Purvis [mailto:cwp@ISDN-COMMS.CO.UK]
Sent: Friday, December 01, 2000 3:36 PM
To: ITU-SG16@MAILBAG.INTEL.COM
Subject: Re: Third party registration/group registration
Charles,
...
I am not a native English speaker (1/3), sorry for the mistake.   I
understand things better now.
I think we're getting closer now.  Don't worry about not being a native
English
speaker - please persevere.  I apologise if I've sometimes sounded harsh
in
...
my
responses - it's normally because I'm trying to make points quickly!  I
know
...
communicating in a foreign language is hard - which is precisely why
it's
...
...
important to make sure that nomenclature is clear and unambiguous!
...
Consider the following scenario;
A4:
An enpoint A (first-party) is switch off or does not "speak" H.323 (it
supports RAS).   I (third-party.  i.e.  IWF ) may want to be able to
register this endpoint which we will call EP A.    I register this
endpoint
...
with its "well-known" alias address which is binded to a transport
addresses
...
(not the one this EP usually uses when it is turned on. i.e.
transport
...
...
...
address of an H.323 complaint device like an answering machine called
AM).
...
...
The GK will now be able to route the call for EP A to the AM.  For the
EP
...
...
that does not "speak" H.323 the signaling will go to some entity that
will be able to "speak" H.323 and bind the RAS context created by the
IWF
...
...
(this may be the IWF itself).
Ah!  This is a COMPLETELY different scenario from that I was describing!
This
is simple.  All you are doing here is registering an alias somewhere
different
from what you may consider its "usual home".  The key to thinking about
this
...
is
that aliases are just that - they may only bind to particular devices
for
...
...
defined periods of time (the same user may use different endpoints on
different
days, but retain the same phone number).  The practicalities between IWF
and
...
the "transport address this endpoint uses when it is turned on" may get
somewhat hairy and certainly outside the remit of H.323, when it comes
to
...
...
ensuring that you don't have multiple devices trying to use the same
alias
...
...
in
the same zone simultaneously (sadly not permitted).
...
A5:  If I have a GK in my network, I may not allow "dubious" EPs to
have
...
...
...
direct access to my GK. <misprint corrected>
True, but not addressing the question.  The question is whether it is
permitted
to separate EP and GK with a proxy.  I don't know the answer to this
one!
...
...
Regards,
Chris
...
-----Original Message-----
From: Chris Wayman Purvis [mailto:cwp@isdn-comms.co.uk]
Sent: Friday, December 01, 2000 10:31 AM
To: Agboh, Charles
Cc: ITU-SG16@mailbag.cps.intel.com
Subject: Re: Third party registration/group registration
Charles,
I'll take these two mails together, as the point is the same.
H.225.0 section 7.7 states which RAS messages are mandatory, optional
etc.
...
...
for
different H.323 devices.  By mandating the support of these messages,
it
...
...
...
mandates the support of RAS, since  there is no proviso there for
"when
...
...
the
...
EP/entity is supporting RAS".
An aside, from a famous UK 80s sitcom on the subject of
"clarification":
...
...
...
"You don't issue clarifications to MAKE things clear: you issue them
to
...
...
put
...
you
IN the clear."
Regards,
Chris
-----Original Message-----
From: Chris Wayman Purvis [mailto:cwp@ISDN-COMMS.CO.UK]
Sent: Friday, December 01, 2000 10:46 AM
To: ITU-SG16@MAILBAG.INTEL.COM
Subject: Re: Third party registration/group registration
Paul,
I think we're starting to converge.  Let's separate this out now, into
separate
questions:
Q1. Are endpoint devices (in which term I include gateways etc
throughout
...
...
this
mail) required to implement RAS?
A1. Yes (agreed between you and me, disagreed by Charles).
Q2. How does an endpoint device know whether or not a gatekeeper is
present
...
in
the system, and hence whether or not to use RAS?
A2a (Your position as I understand it.)  Configuration, discovery on
startup,
give up if you don't find anything then.
A2b (My suggestion) Configuration, discovery on startup, retry at some
reasonable frequency (hourly?), take the three seconds to attempt
gatekeeper
...
discovery when someone makes a call to or from the endpoint in
question.
...
...
...
A2c (What we'll probably end up agreeing!)  Implementation decision.
Q3. What should an endpoint do if it attempts to register with all
discovered
gatekeepers, where there is at least one gatekeeper in the system, and
fails
...
(RRJ)?
A3a (My position) Shut itself down.
A3b (Anybody elses) ???
Q4. Is Charles's actual application, where one entity is registering
and
...
...
...
hence
presumably (although he's consistently failed to clarify) handling RAS
on
...
...
behalf of another compliant H.323 endpoint a possibility?
A4a (My position, with which I THINK you agree) No, on the grounds
that
...
if
...
...
the
gateway/IWF can find a gatekeeper and use it, so can the endpoint.
A4b (Charles) Yes.
This actually gives rise to a further question, which is (I believe)
open,
...
...
and
probably shouldn't be:
Q5. Can an endpoint be separated from its gatekeeper by a proxy?
Regards,
Chris
Paul Long wrote:
...
Chris,
(You and I inadvertently replied to each other privately. I thought
I'd
...
...
...
clean my email up a bit :-) and post it to the reflector.)
As you point out, gatekeepers are optional, but an endpoint may not
be
...
...
...
...
registered with a gatekeeper (hence, an "unregistered endpoint"). I
also
...
...
...
agree with you that an endpoint must implement and be able to use
RAS.
...
...
The
...
...
tricky part, though, is under what circumstances _shall_ an endpoint
use
...
...
...
RAS, i.e., at least attempt to register with a gatekeeper. It may
come
...
...
...
down
...
to a rather philosophical question. If an endpoint is required to
use
...
...
RAS
...
in
...
any way and ultimately discover and register with a gatekeeper only
if
...
...
...
there
...
is a gatekeeper in the "system," how does it know whether there is a
gatekeeper within the system without using RAS? Look like a
Catch-22,
...
...
but
...
my
...
take on it is that whether a gatekeeper is in the system must be
known
...
...
out
...
...
of band. That's the only way I know of to resolve these otherwise
contradictory issues.
Smith Micro builds endpoints that can be used in systems with and
without
...
...
gatekeepers. Because this vendor does not know whether the system
within
...
...
...
which the user will be deploying the endpoint contains a gatekeeper,
the
...
...
...
user presumably knows and has the discretion as whether to use RAS
via
...
a
...
...
...
Preferences dialog in the user interface. I think that's reasonable
and
...
...
...
compliant. Some vendors may build endpoints that are designed to
always
...
be
...
...
used within systems that contain gatekeepers, and that's fine, too,
and
...
...
...
compliant. However, IMO, besides probably being a bad marketing
decision
...
...
...
:-), an endpoint that does not support RAS at all is not compliant.
Paul Long
ipDialog, Inc.
-----Original Message-----
From: Chris Wayman Purvis [mailto:cwp@ISDN-COMMS.CO.UK]
Sent: Thursday, November 30, 2000 7:56 AM
To: ITU-SG16@MAILBAG.INTEL.COM
Subject: Re: Third party registration/group registration
Charles,
This comes up on this list every now and again, and the answer
doesn't
...
...
...
...
change.
The gatekeeper is an optional entity: TRUE.
RAS is optional: FALSE.
Endpoints (including gateways, IWFs, whatever you want to call them)
have
...
a
...
responsibility of trying to find one, registering with one if it can
and
...
...
...
SHUTTING ITSELF DOWN if it manages to find one or more gatekeepers
but
...
...
...
fails
...
to
register.  Only if all reasonable attempts to find a gatekeeper fail
should
...
an
H.323 endpoint operate without an active registration.
Let me give you the first couple of quotations from H.323 (I'm
looking
...
...
at
...
v4
...
determined, but I don't believe this has ever changed) I find on the
subject.
They're in section 7.2.2:
"As part of their configuration process, all endpoints shall
register..."
...
...
"Registration shall occur before any calls are attempted and may
occur
...
...
...
...
periodically as necessary (for example, at endpoint power-up)."
Oh, and I suggest reading H.225.0 section 7.7 "Required Support of
RAS
...
...
...
...
messages" as well.
How else could things work?  Consider the case where an endpoint (A)
is
...
...
...
trying
to make a call to another endpoint (B).  A issues an ARQ to its
gatekeeper,
...
asking permission to try a call; the gatekeeper rejects the call
(ARJ)
...
...
on
...
...
some
reasonable grounds (possibly a conceptual "do not disturb" notice B
has
...
...
set
...
up
with its gatekeeper).  A thinks "stuff this", unregisters from its
gatekeeper
("we don't want to worry about all that boring RAS stuff if it's
going
...
...
to
...
be
...
inconvenient to us") and sends the Setup message to B anyway -
resulting
...
...
(at
...
best) in an disgruntled B.
In other words, as soon as you allow endpoints to operate in the
presence
...
of
...
a
gatekeeper without registering with it and abiding by its decisions,
you
...
...
...
might
as well write all xRJ messages out of the protocol entirely!
If an endpoint is going to ignore RAS (and hence the standard) then
why
...
...
...
should
it bother having anyone else register on its behalf?  I refer you to
"Besides,..." in my last mail (which point you still haven't
addressed).
...
...
...
Regards,
Chris
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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...
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--
Dr Chris Purvis -- Development Manager
ISDN Communications Ltd, The Stable Block, Ronans, Chavey Down Road
Winkfield Row, Berkshire.  RG42 6LY  ENGLAND
Phone: +44 1344 899 007
Fax:   +44 1344 899 001
For help on this mail list, send "HELP ITU-SG16" in a message to
listserv@mailbag.intel.com


For help on this mail list, send "HELP ITU-SG16" in a message to
listserv@mailbag.intel.com
--
Dr Chris Purvis -- Development Manager
ISDN Communications Ltd, The Stable Block, Ronans, Chavey Down Road
Winkfield Row, Berkshire.  RG42 6LY  ENGLAND
Phone: +44 1344 899 007
Fax:   +44 1344 899 001
For help on this mail list, send "HELP ITU-SG16" in a message to
listserv@mailbag.intel.com


For help on this mail list, send "HELP ITU-SG16" in a message to
listserv@mailbag.intel.com
--
Dr Chris Purvis -- Development Manager
ISDN Communications Ltd, The Stable Block, Ronans, Chavey Down Road
Winkfield Row, Berkshire.  RG42 6LY  ENGLAND
Phone: +44 1344 899 007
Fax:   +44 1344 899 001
--
Dr Chris Purvis -- Development Manager
ISDN Communications Ltd, The Stable Block, Ronans, Chavey Down Road
Winkfield Row, Berkshire.  RG42 6LY  ENGLAND
Phone: +44 1344 899 007
Fax:   +44 1344 899 001
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
For help on this mail list, send "HELP ITU-SG16" in a message to
listserv@mailbag.intel.com
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
For help on this mail list, send "HELP ITU-SG16" in a message to
listserv@mailbag.intel.com
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
For help on this mail list, send "HELP ITU-SG16" in a message to
listserv@mailbag.intel.com
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Roy, Radhika R, ALCOO

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