Subject: [Megaco] Cancel ServiceChange Graceful

From: "Chuong N. Nguyen" <[email-masked]>
Date: Sun, 20 Jan 2002 16:12:55 -0600

Hi Tom

What are the possibilites of defining a mechanism of cancelling
ServiceChange Graceful?
That is MG send SC Graceful w/Delay=time.
Before time expired, MG wants to cancel this ServiceChange.

1) Can this be done in V1 by adding a new SC Reason like "916 SC
Graceful cancelled"?
2) Done in V2 - new SC Method or Reason?
3) Should be covered in draft-hss-megaco-control-association?

Thanks
Chuong

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From: Christian Groves <[email-masked]>
Date: Mon, 21 Jan 2002 14:14:58 +1100

I don't see that we need to add anything. Why can't the MG just issue a
SC with Restart, Service Restored? The specification already allows the
MG to do this.

Regards, Christian 

> 3) Should be covered in draft-hss-megaco-control-association?

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From: Christian Groves <[email-masked]>
Date: Mon, 21 Jan 2002 14:14:58 +1100

Regards, Christian

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From: Christer Holmberg <[email-masked]>
Date: Mon, 21 Jan 2002 07:59:14 +0200

Hi,

I agree with Christian. H.248 does not specify a way to "cancel"
commands - and if it does it shall be a generic way to do it, not only
for a specific case, and I think most agree that's not needed.

Regards,

Christer Holmberg
Ericsson Finland

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From: Christer Holmberg <[email-masked]>
Date: Mon, 21 Jan 2002 07:59:14 +0200

Hi,

Regards,

Christer Holmberg
Ericsson Finland

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From: "Chuong N. Nguyen" <[email-masked]>
Date: Mon, 21 Jan 2002 09:37:12 -0600

MG sends SC Graceful w/Delay and terminationID=ROOT.

If MG sends SC Restart w/Service Restorted and ROOT, does the MGC assume
that
1) SC Graceful w/Delay is being cancelled?
2) All terminations are back In Service?  Even the ones that were
originally OOS before the SC Graceful.

   1) Graceful - indicates that the specified Terminations will be taken
      out of service after the specified ServiceChangeDelay; established
      connections are not yet affected, but the Media Gateway Controller
      should refrain from establishing new connections and should
      attempt to gracefully tear down existing connections on the
      Termination(s) affected by the serviceChange command. The MG
      should set termination serviceState at the expiry of
      ServiceChangeDelay or the removal of the termination from an
      active context (whichever is first), to "out of service".

How should MGC implementation intepret the above highlighted statement?
Does this mean that MGC should not try to gracefully tear down existing
connections
before Delay timer expired?

But I think the above statement is telling MGC to try and gracefully tear
down
existing connections before Delay timer expired.

To be able to cancel Graceful w/Delay, it seems that MGC needs to wait
until
Delay timer expired before it tries to tear down existing connections.

But after Delay timer expired, MG will put all terminations out of service.

Therefore there is no such thing as MGC gracefully tearing down existing
connections.

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From: "Chuong N. Nguyen" <[email-masked]>
Date: Mon, 21 Jan 2002 09:37:12 -0600

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From: Christian Groves <[email-masked]>
Date: Tue, 22 Jan 2002 14:11:13 +1100

There is a timing dependency here. If the MG issues a SC Graceful then
the MGC will act on it. There will be a finite time that the MGC
operates under graceful mode. If a SC Restart w/Service Restored or
Service Change Cancel is issued during the graceful the MGC can't undo
what it had done in that finite time but the connections that stayed up
can remain up. If the SC Restart w/service restored or Service Change
Cancel is not received before the delay times out then it pretty too
late as the terminations will be torn down.

I don't understand why you say that the MGC must wait until the
servicechange delay timesouts before gracefully tearing down
connections?

Christian

"Chuong N. Nguyen" wrote:
> If MG sends SC Restart w/Service Restorted and ROOT, does the MGC
> assume that
> Does this mean that MGC should not try to gracefully tear down
> existing connections
> But I think the above statement is telling MGC to try and gracefully
> tear down
> Therefore there is no such thing as MGC gracefully tearing down
> existing connections.
> 
> 
> Christian Groves wrote:
>

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From: Christian Groves <[email-masked]>
Date: Tue, 22 Jan 2002 14:11:13 +1100

Christian

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From: "Chuong N. Nguyen" <[email-masked]>
Date: Tue, 22 Jan 2002 10:02:03 -0600

Maybe I need a clarification on what

     should attempt to gracefully tear down existing connections on
     the
     Termination(s) affected by the serviceChange command.

Does the MGC just do a CAMP_ON-OOS - that is wait until the subcribers hang
up normally and then
put the termination OOS after subscribers hang up (before delay timer
expired)?

Or MGC starts releasing the calls whether the subscribers hang up or not?

Thanks
Chuong

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From: "Chuong N. Nguyen" <[email-masked]>
Date: Tue, 22 Jan 2002 10:02:03 -0600

Thanks
Chuong

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From: Christian Groves <[email-masked]>
Date: Wed, 23 Jan 2002 13:51:22 +1100

G'Day Chuong,

The MGC could take several actions:
o not accept new calls to the MG. This has the effect of reducing
traffic.
o wait for subscribers to hand up normally.
o play a notification to subscribers that service will be interrupted
and then remove the termination.
o more?

So what the MGC does is largely application/service dependent.

Regards, Christian

"Chuong N. Nguyen" wrote:
>      should attempt to gracefully tear down existing connections
>      on the
> Does the MGC just do a CAMP_ON-OOS - that is wait until the subcribers
> hang up normally and then
> > >    1) Graceful - indicates that the specified Terminations will be
> >
> > > taken
> > > But after Delay timer expired, MG will put all terminations out of
> >
> > > service.
> > > > SC with Restart, Service Restored? The specification already
> > allows
> > > > the
> > > > MG to do this.
> > > >
> > > > Regards, Christian
> > > >
> > > > >   **** The opinions expressed are not those of Alcatel USA,
> > Inc
> > > > ****
> > > > >
> > > > >
> > >
> > > --

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From: Christian Groves <[email-masked]>
Date: Wed, 23 Jan 2002 13:51:22 +1100

G'Day Chuong,

Regards, Christian