Subject: RE: [Sigtran] M3UA IG v04 AS State Machine

From: "J.Javier Pastor (EE/EEM)" <[email-masked]>
Date: Tue, 22 Jul 2003 12:42:10 +0200

Hi Brian,

Pls, see below...

> -----Original Message-----
> From: Brian F. G. Bidulock [mailto:[email-masked]]
> Sent: viernes, 11 de julio de 2003 10:38
> To: J.Javier Pastor (EE/EEM)
> Cc: [email-masked]'
> Subject: Re: [Sigtran] M3UA IG v04 AS State Machine
> 
> 
> J.Javier,
> 
> That doesn't really answer my questions below.  Could you please
> clarify the proposal by answering the questions?
> 
> --brian
> 
> J.Javier Pastor (EE/EEM) wrote:                               
>                     (Fri, 11 Jul 2003 09:21:14)
> > Hi Brian, 
> > 
> > In the consensus text we have not add or remove anything 
> regarding the AS
> > state scope. Then it remains the same.
> > 
> > Cheers // Javier.
> > 
> > > -----Original Message-----
> > > From: Brian F. G. Bidulock [mailto:[email-masked]]
> > > Sent: jueves, 10 de julio de 2003 15:16
> > > To: [email-masked]'
> > > Subject: Re: [Sigtran] M3UA IG v04 AS State Machine
> > > 
> > > 
> > > Javier,
> > > 
> > > The AS State Machine illustrated in 3.14 is per-SGP.  Correct?

Yes
> > > 
> > > SGP can communicate with each other in an SG.  Correct?

It's an implementation option. I think there is nothing in the RFC that mandates or forbids this...
> > > 
> > > Why should an SGP pend when the last ASP goes ASP-INACTIVE for
> > > an AS with a given SGP?

Because hopefully another ASP may take over from it. And you don't need to stop all the traffic.
> > > 
> > > Cannot the SGP redirect traffic via another SGP that has ASPs
> > > active for the AS?

Implementation option. I think there is nothing in the RFC that mandates or forbids this option...
> > > 
> > > Example:
> > > 
> > >         _______                    _______
> > >        |       |______x    x______|       |
> > >        | SGP1  |         _________| ASP1  |
> > >        |_______|        /         |_______|
> > >         _______        /           _______
> > >        |       |______/           |       |
> > >        | SGP2  |__________________| ASP2  |
> > >        |_______|                  |_______|
> > > 
> > > 
> > > When ASP1 goes inactive (or down) w.r.t SGP1, cannot
> > > SGP1 direct traffic via SGP2?

M3UA draft defines SGP-ASP communication. Although you may use a proprietary communication between SGPs belonging to the same SG to distribute traffic. It basically depends on your implementation choice.
> > > 
> > > What is the state of the AS at SGP1?
> > > 
> > > In section 3.14 AC2PN says that:
> > > 
> > >   AC2PN: the last ASP in the ASP-ACTIVE state moves to
> > >   ASP-INACTIVE or ASP-DOWN states, causing the number of ASPs
> > >   in the ASP-ACTIVE [sic] drop below 1.
> > > 
> > > Is that the number of ASPs for SGP1?  for SGP2? for the SG?
> > > for all (both) SGs?

It depends on which SGP receives the ASPIA or ASPDN. Remember that the AS state is per SGP. Since nothing has been change on that regard.
> > > 
> > > In the RFC the AS state machine was per-SGP.  Is the 3.14 state
> > > machine per-SGP?

Yes.
> > > 
> > >    IA2AC: one ASP moves to [the] ASP-ACTIVE [state], causing
> > >    [the] number of ASPs in the ASP-ACTIVE state to be n.
> > > 
> > > When SGP1 receives an ASP Active and sends an ASP Active Ack
> > > to ASP1, how many ASPs are active for the AS?   1?  2?

This question is already answered saying that there is no change in the AS state scope: per SGP. If SGP1 didn't receive any other request from ASP2 then you only have one ASP active in SGP1 for that AS.

Cheers // Javier.

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