Re: M3UA: ASP Route Availability to SG/STP

Hi Brian, 

Thanks for your response but I'm still unclear whether when the AS
becomes active M3UA should immediately consider the route to the SG/STP
as available or whether it should wait for a DAVA. I'm also unclear
whether the SG should respond to DAUD concerning the SG/STPs Point Code
or not.

Best Regards

Howard


> -----Original Message-----
> From: Brian F. G. Bidulock [mailto:[email protected]]
> Sent: 02 September 2008 15:05
> To: Howard May
> Cc: [email protected]
> Subject: Re: [Sigtran] M3UA: ASP Route Availability to SG/STP
> 
> Howard,
> 
> I didn't say that an MTP-User at a signalling point receives an
> MTP-PAUSE for its own point code.  What I was saying is that an
> MTP-User at a signalling point can always generate an MTP-TRANSFER
> primitive for a given destination regardless of whether it has
> received an MTP-PAUSE for that destination.

My concern is not with the MTP3 User but rather whether M3UA at the ASP
should consider the route to the SG/STP as available. 

While an MTP user may generate MTP-TRANSFER primitives after receiving
an MTP-PAUSE I'm not sure that either ISUP or SCCP should. 

Section 7.22 of Q.711 explains that on receipt of an MTP-PAUSE The user
should wait for an MTP_RESUME and in the mean time is not allowed to
send messages to that signalling point.

Section 2.14 of Q.764 explains that on receipt of an MTP_PAUSE ISUP
cannot send messages to the affected exchange.

> 
> Also, SG do not issue DAUD, so what did you mean by "see whether
> the SG responds with DAUD"?

This was a typo, I meant to say DUNA.

> 
> DAVA and DUNA are equivalent to MTP-RESUME and MTP-PAUSE in this
> situation, and they represent the status of the signalling point
> in the SS7 network.  MTP does not send MTP-RESUME or MTP-PAUSE
> for its own signalling point code.
> 
> Precisely when M3UA sends a DAVA and DUNA however, is largely
> part of the NIF and out of scope of the RFC.  Achieving
> transparency with SS7 requires first a knowledge of how SS7
> behaves.
> 
> --brian
> 
> Howard May wrote:                            (Tue, 02 Sep 2008
04:47:26)
> > Hi,
> >
> > MTP normally generates PAUSE and RESUME indications for Routes it
> > maintains to remote signalling points. In this situation the
signalling
> > point in question is it's own signalling point for which it does not
> > normally have a route defined nor generate PAUSE and RESUME
indications.
> > Consequently I don't believe it is normal for MTP to generate a
PAUSE or
> > RESUME for this signalling point as you have described.
> >
> > Also I would expect the MTP User on the ASP to have some method
other
> > than generating User Messages to determine the route availability.
Is it
> > really the case that they have to send user messages to the SG and
wait
> > and see whether the SG responds with DAUD?
> >
> > I would expect either one or the other of the following to be
followed.
> >
> > 1) Presume available:
> > If the AS is active then M3UA on the ASP presumes the route to the
> > SG/STP is available and generates a RESUME to the AS.
> >
> > 2) Treat like any other Route:
> > The AS does not presume the route to the SG/STP is available but
must
> > treat the Signalling Point like any other by generating DAUD and
> > responding to DAVA and DUNA messages.
> >
> > Cheers
> >
> >
> > -----Original Message-----
> > From: Brian F. G. Bidulock [mailto:[email protected]]
> > Sent: 01 September 2008 18:03
> > To: Howard May
> > Cc: [email protected]
> > Subject: Re: [Sigtran] M3UA: ASP Route Availability to SG/STP
> >
> > Howard,
> >
> > In general, there is nothing stopping an MTP User from sending a
> > message for a destination, event if it has received an MTP-PAUSE.
> > Therefore, an ASP can send a message to 'Alpha' regardless of
> > whether it has received DUNA or DAVA.  MTP at the SG should treat
> > the ASP like any ohter MTP user or MTP peer and reissue a DUNA
> > (once for every 8 or 10 MTP-TRANSFER primitives for the unavailable
> > destination, or once every T8 for a peer arrangement).
> >
> > --brian
> >
> >
> > Howard May wrote:                            (Mon, 01 Sep 2008
10:56:53)
> > >
> > >    Hi, I would value some clarification on the following:
> > >
> > >
> > >    Does the M3UA protocol provision for any situation whereby an
ASP
> > can
> > >    route messages for point code `Alpha' to an SG without first
> > receiving
> > >    a DAVA for point code `Alpha' from the SG. Specifically if the
SG
> > >    terminates messages for PC `Alpha' does M3UA presume the route
to
> > >    `Alpha' from the ASP is available as soon as the ASP becomes
active
> > on
> > >    that SG (without the reception of DAVA)?
> > >
> > >
> > >    Or put slightly differently:
> > >
> > >    When connecting to an SG/STP such as shown in Figure 1 of RFC
4666
> > >    should the ASP presume to receive DAVA and DUNA indications for
the
> > >    Point Code of STP1 in the same manner as it would for any other
> > Route
> > >    or is the Point Code of STP1 different? Should the ASP presume
the
> > >    Point Code of STP1 is available as soon as the ASP is active on
> > SG1?
> > >
> > >
> > >    Best Regards
> > >
> > >
> > >    Howard
> >
> > > _______________________________________________
> > > Sigtran mailing list
> > > [email protected]
> > > https://www.ietf.org/mailman/listinfo/sigtran
> >
> >
> > --
> > Brian F. G. Bidulock
> > [email protected]
> > http://www.openss7.org/
> 
> --
> Brian F. G. Bidulock
> [email protected]
> http://www.openss7.org/