Subject: RE: [Sigtran] M3UA IG v04

From: "J.Javier Pastor (EE/EEM)" <[email-masked]>
Date: Thu, 10 Jul 2003 12:54:14 +0200

Hi, 

Pls, see my answers inline..

Cheers // JAvier.

> -----Original Message-----
> From: Zannin, Francois [mailto:[email-masked]]
> Sent: jueves, 10 de julio de 2003 11:34
> To: J.Javier Pastor (EE/EEM); Ken Morneault; [email-masked]
> Subject: RE: [Sigtran] M3UA IG v04
> 
> 
> Javier,
> 
> See comment inline,
> 
> Regards,
> 
> Francois Z.
> 
> -----Original Message-----
> From: J.Javier Pastor (EE/EEM) [mailto:[email-masked]] 
> Sent: Thursday, July 10, 2003 10:49 AM
> To: Zannin, Francois; Ken Morneault; [email-masked]
> Subject: RE: [Sigtran] M3UA IG v04
> 
> 
> Hi Francois, 
> 
> Pls see below....
> 
> Cheers // Javier.
> 
> > -----Original Message-----
> > From: Zannin, Francois [mailto:[email-masked]]
> > Sent: miércoles, 09 de julio de 2003 16:21
> > To: Ken Morneault; J.Javier Pastor (EE/EEM); [email-masked]
> > Subject: RE: [Sigtran] M3UA IG v04
> > 
> > 
> > Ken,
> > 
> > My point of view on he question, see hereafter.
> > 
> > Regards,
> > 
> > Francois Z.
> > 
> > -----Original Message-----
> > From: Ken Morneault [mailto:[email-masked]]
> > Sent: Wednesday, July 09, 2003 3:56 PM
> > To: Zannin, Francois; J.Javier Pastor (EE/EEM); [email-masked]
> > Subject: RE: [Sigtran] M3UA IG v04
> > 
> > 
> > Francois,
> > 
> > Pls see comments below.
> > 
> > Regards,
> > 
> > Ken
> > 
> > At 10:15 AM 7/9/2003 +0200, Zannin, Francois wrote:
> > >Just some comment about the M3UA IG v04
> > >
> > >3.21 NOTIFY messages are missing in Examples section
> > >Figure (section 5.1.2)
> > >        a NOTIFY(AS-INACTIVE) must be sent from SGP to ASP2
> > after the
> > >ASP Up Ack
> > >
> > >Figure (section 5.1.3)
> > >        a NOTIFY(AS-INACTIVE) must be sent from SGP to ASP2
> > after the
> > >ASP Up Ack
> > >
> > >Figure (section 5.1.4)
> > >        Same remark, the Notify is sent to ASP1, ASP2 and
> > also need to
> > >be sent to
> > >      ASP3 after the ASP Up Ack
> > 
> 
> # It is sent at that point because n=2 for that particular 
> example. I.e. when 2 ASPs reach the ASP-INACTIVE state, # the 
> AS is considered in AS-INACTIVE state.
> 
> I can understand that SG(p) can hold the Notification while 
> there are not enough ASP UP to operate the minimum "n" ASP 
> potentially ready to "Activate" the AS. But if the AS is 
> still not Active when another ASP becomes "UP", a do not see 
> any reason not to send it the current state "inactive" for the AS.
> 
The reason was to follow the RFC and it says that NTFY is sent when the AS state changes. As n=2 for the general case AS becomes AS-INACTIVE after two ASP becomes INACTIVE. At that moment the AS changes state. According to the RFC the NTFY is sent to all the ASPs that are not ion DOWN state. This is what the example is showing. 

> If we look in the RFC, it is in charge of the ASP to 
> coordonate the activation of the AS. The SG cannot decide 
> which ASP have to send the ASP-Active for a particular AS (by 
> holding back the notify to other ASP).

Agreed. The SGP just sends the NTFY to those ASPs that are in INACTIVE or ACTIVE state. But it does not decide which ASP has to become ACTIVE or INACTIVE.

> 
> RFC 3332
>   4.3.4.3 ASP Active Procedures
>    ...
>    For the n+k redundancy case, ASPs which are in that AS should
>    coordinate among themselves the number of active ASPs in 
> the AS, and
>    should start sending traffic only after n ASPs are active.
>    ... 
> 

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---

From: "Brian F. G. Bidulock" <[email-masked]>
Date: Thu, 10 Jul 2003 05:13:41 -0600

J.Javier,

J.Javier Pastor (EE/EEM) wrote:                                                   (Thu, 10 Jul 2003 12:54:14)
> The reason was to follow the RFC and it says that NTFY is sent when the AS
> state changes. As n=2 for the general case AS becomes AS-INACTIVE after two
> ASP becomes INACTIVE.

Huh?  Section 4.3.4.1 ASP Up Procedures says:

   When an ASP Up message is received at an SGP and internally the
   remote ASP is in the ASP-DOWN state and not considered locked out for
   local management reasons, the SGP marks the remote ASP in the state
   ASP-INACTIVE and informs Layer Management with an M-ASP_Up indication
   primitive.

Also:

   AS-INACTIVE: The Application Server is available but no application
   traffic is active (i.e., one or more related ASPs are in the ASP-
   INACTIVE state, but none in the ASP-ACTIVE state).  The recovery
   timer T(r) is not running or has expired.
  
So the ASP-INACTIVE should be sent when the first ASP comes up.

Now I know that you propose to change this in 3.14 (which has not received
WG approval at all), but there is no reason to change this.  No traffic is
flowing.

Also, if you follow what Francois has pointed to, the example should
look like this (if you are choosing to withhold AS-ACTIVE):

        SGP                 ASP1                ASP2                ASP3
          |                   |                   |                   |
          |<------ASP Up------|                   |                   |
          |-----ASP Up Ack--->|                   |                   |
          |                   |                   |                   |
          |NTFY(AS-INACTIVE)->|                   |                   |
          |                   |                   |                   |
          |<-------------------------ASP Up-------|                   |
          |------------------------ASP Up Ack---->|                   |
          |                   |                   |                   |
          |------------------NOTIFY(AS-INACTIVE)->|                   |
          |                   |                   |                   |
          |<--------------------------------------------ASP Up--------|
          |--------------------------------------------ASP Up Ack---->|
          |                   |                   |                   |
          |--------------------------------------NOTIFY(AS-INACTIVE)->|
          |                   |                   |                   |
          |                   |                   |                   |
          |<--ASP Act (Ldshr)-|                   |                   |
          |----ASP Act Ack--->|                   |                   |
          |                   |                   |                   |
          |NTFY(Insuf. ASPs)->|                   |                   |
          |--------------------NTFY(Insuf. ASPs)->|                   |
          |----------------------------------------NTFY(Insuf. ASPs)->|
          |                   |                   |                   |
          |<-------------------ASP Act. (Ldshr)---|                   |
          |----------------------ASP Act Ack----->|                   |
          |                   |                   |                   |
          |--NTFY(AS-ACTIVE)->|                   |                   |
          |--------------------NOTIFY(AS-ACTIVE)->|                   |
          |----------------------------------------NOTIFY(AS-ACTIVE)->|
          |                   |                   |                   |
          |                   |                   |                   |

If you are not choosing to withhold AS-ACTIVE (the normal case that you
are trying to change with 3.14) it should look like this:

        SGP                 ASP1                ASP2                ASP3
          |                   |                   |                   |
          |<------ASP Up------|                   |                   |
          |-----ASP Up Ack--->|                   |                   |
          |                   |                   |                   |
          |NTFY(AS-INACTIVE)->|                   |                   |
          |                   |                   |                   |
          |<-------------------------ASP Up-------|                   |
          |------------------------ASP Up Ack---->|                   |
          |                   |                   |                   |
          |------------------NOTIFY(AS-INACTIVE)->|                   |
          |                   |                   |                   |
          |<--------------------------------------------ASP Up--------|
          |--------------------------------------------ASP Up Ack---->|
          |                   |                   |                   |
          |--------------------------------------NOTIFY(AS-INACTIVE)->|
          |                   |                   |                   |
          |                   |                   |                   |
          |<--ASP Act (Ldshr)-|                   |                   |
          |----ASP Act Ack--->|                   |                   |
          |                   |                   |                   |
          |--NTFY(AS-ACTIVE)->|                   |                   |
          |NTFY(Insuf. ASPs)->|                   |                   |
          |                   |                   |                   |
          |--------------------NOTIFY(AS-ACTIVE)->|                   |
          |--------------------NTFY(Insuf. ASPs)->|                   |
          |                   |                   |                   |
          |----------------------------------------NOTIFY(AS-ACTIVE)->|
          |----------------------------------------NTFY(Insuf. ASPs)->|
          |                   |                   |                   |
          |<-------------------ASP Act. (Ldshr)---|                   |
          |----------------------ASP Act Ack----->|                   |
          |                   |                   |                   |
          |                   |                   |                   |
          |                   |                   |                   |

This begs the question of a "Sufficient ASPs" notification that Francois
mentions, that does not exist but was mentioned a number of times.

Greg originally drew 5.1.4 as activating at about the same time to avoid
the question of withholding AS-ACTIVE.  It was discussing 5.1.4 that made
us come to the determination that the SGP MAY withhold AS-ACTIVE.

--brian

> At that moment the AS changes state. According to the
> RFC the NTFY is sent to all the ASPs that are not ion DOWN state. This is
> what the example is showing. 
> 
> Agreed. The SGP just sends the NTFY to those ASPs that are in INACTIVE or
> ACTIVE state. But it does not decide which ASP has to become ACTIVE or
> INACTIVE.
> 
> > 
> > RFC 3332

-- 
Brian F. G. Bidulock
[email-masked]
http://www.openss7.org/