Re: M3UA: ASP Route Availability to SG/STP

one comment inline.

Thanks,
Tolga

> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On
Behalf
> Of Brian F. G. Bidulock
> Sent: Tuesday, September 02, 2008 12:03 PM
> To: Howard May
> Cc: [email protected]
> Subject: Re: [Sigtran] M3UA: ASP Route Availability to SG/STP
> 
> Howard,
> 
> There are three scenarios:  ASP/SG, multiple SG as STP and IPSP.
> I think that you are talking of the multiple SG as STP case.
> 
> For the multiple SG as STP scenario, the ASP can be viewed as
> a separate SEP with its own signalling point code distinct from
> that of the STP point codes.  The associations to the SG/STP can
> be viewed as a linkset.  The STP signalling point codes can be
> viewed as adjacent STP.  In the normal SS7 case where the SEP is
> connected by A-links, the STP signalling point codes are treated
> as available whenever a signalling link in the directly connecting
> link set is available at level 3, or whenever a routeset to the
> STP via the alternate STP is available.
[TOLGA]For this type of scenario I still consider SG as
hosting/terminating the MTP3 for the ASP PC. This preserves the M3UA
interface as mimicking MTP3/MTP3-User interface.
> 
> When the first association to an SG/STP pair becomes available to
> carry traffic (AS-ACTIVE), the ASP is acting in the role of a
> restarting MTP at an SEP.  Instead of traffic restart messages,
> the M3UA at the ASP can use the DAUD procedure to effect MTP
> restart.  When an association to an SG/STP becomes available and
> there is an existing association, or the ASP has sufficient recent
> knowledge of routing, the ASP is not a restarting MTP however the
> DAUD procedure may still be used to establish the availability
> of destinations via the SG/STP before starting or restarting
> traffic to the SG/STP.  Nevertheless, the ASP may simply restart
> traffic to the SG/STP and handle whatever DUNA messages it
> receives as a result of restarting traffic instead of using the
> DAUD procedures.
> 
> As regards the point code of the STP itself: the ASP is acting
> as a directly connected SEP (as though it was connecting using
> A-links) and therefore, as soon as a link in the linkset (in
> M3UA's case, an association) is available at level 3 directly
> connected to the STP, the STP's point code is available.  In
> SS7, no TFA or TFP is sent to the SEP on a directly connected
> A-linkset for the STP's own point code, only for point codes
> available via the STP.
> 
> So, yes, the ASP acting as an SEP in a multiple SG as STP case
> can assume that once it has an association to the SG/STP and is
> AS-ACTIVE for traffic via that SG/STP, it can assume that the
> SG/STP's point code is available.  However, the point I was
> trying to make is that the ASP can simply assume that any point
> code is available via an association and route traffic to it,
> dealing, of course, with any DUNA that it receives regarding
> the traffic it sends.
> 
> --brian
> 
> 
> Howard May wrote:                            (Tue, 02 Sep 2008
10:59:07)
> > 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
> 
> --
> Brian F. G. Bidulock
> [email protected]
> http://www.openss7.org/
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