Re: DUNA applies to SG as a whole

Brian

thank you very much indeed for your kind help and patience

Ilie
On 1/6/06, Brian F. G. Bidulock <[email protected]> wrote:
> Ilie,
>
> Ilie Glib wrote:                                                      (Fri, 06 Jan 2006 19:58:55)
> > Dan,
> >
> > Draft draft-ietf-sigtran-rfc3332bis-05.txt has the following statement
> >
> > 3.4.1 Destination Unavailable (DUNA)
> >
> >    The DUNA message is sent from an SGP in an SG to all concerned ASPs
> >    to indicate that the SG has determined that one or more SS7
> >    destinations are unreachable.  It is also sent by an SGP in response
> >    to a message from the ASP to an unreachable SS7 destination. As an
> >    implementation option the SG may suppress the sending of subsequent
> >    "response" DUNA messages regarding a certain unreachable SS7
> >    destination for a certain period to give the remote side time to
> >    react. If there is no alternate route via another SG, the MTP3-User
> >    at the ASP is expected to stop traffic to the affected destination
> >    via the SG as per the defined MTP3-User procedures.
> >
> > Thus I believe that in M3UA every SGP upon receiving a message towards
> > an unreachable destination sooner or later will answer with a DUNA to
> > the ASP. But of couse some traffic can be lost, which can be saved if
> > there is another SG with connectivity to the affected SPC.
> >
> > Apropo, SUA RFC does not have a statement like "DUNA is also sent by
> > an SGP in response to a message from the ASP to an unreachable SS7
> > destination"
> > So I could imagine an implementation that sends DUNAs from one SGP only.
> >
> >
>
> What is sent to the MTP-User and what the MTP-User expects of the
> MTP layer is specified in SS7 standards, not in M3UA.  The bis document
> makes statements that are out of scope here and should have moved the
> statement to the non-normative appendix.
>
> An SG would be best generate DUNA to each ASP in each affected AS
> under the following conditions:
>
> a) In the case where the AS point code is hosted by the SG, DUNA is
>   generated under the same conditions that MTP-PAUSE would be generated
>   to local MTP-Users are the SG.
>
> b) In the case of the multiple SG as STP configuration, DUNA is
>   generated under the same conditions that TFP would be generated and
>   sent to the AS point code, were the AS point code a normal SS7 SEP.
>
> Understand?
>
> --brian
>
>
> --
> Brian F. G. Bidulock
> [email protected]
> http://www.openss7.org/
>