Subject: Re: [Sigtran] M3UA(rfc 3332) DUPU from ASP

From: [email-masked]
Date: Sat, 26 Oct 2002 11:44:30 +0530

Hi
     Brian this is  true for SS7 node in SS7 domain too.but why does
                SS7 node generate UPU message when it is unable to notify MSU
                to intended user.
Regards
Kamesh

"Brian F. G. Bidulock" <[email-masked]> on 10/25/2002 04:44:46 PM

Please respond to [email-masked]

To:   Kamesh Kaul/HSS@HSS
cc:   [email-masked]

Subject:  Re: [Sigtran] M3UA(rfc 3332) DUPU from ASP

Kamesh,

Your example is of a situation where ISUP and SCCP are independent (one can
become unavailable while the other is not).  RK on DPC might be useful in the
situation where there is either only one user part, or when both ISUP and SCCP
live or die together (i.e., both are a nodal function and the node is either
active or inactive).

Nowadays it is very rare to have a TCAP stack which is not integrally tied
to call processing (ISUP).

--brian

[email-masked] wrote:                           (Fri, 25 Oct 2002 15:07:59)
>
>
> Hi
>      Brian then what is the advantage of having routing key type DPC.
>      Please clearify in which scenario it will be useful to have AS with
>      routing key type DPC only.
>
> Regards
> Kamesh
>

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

From: "Brian F. G. Bidulock" <[email-masked]>
Date: Sat, 26 Oct 2002 01:14:19 -0600

Kamesh,

Well, I suppose it was a quandry where to put it in SS7 too.  ISUP, for
example has its own UPT/UPA mechanism for restoring unavailable ISUP
peers.  At one time a general UPT/UPA mechanism was part of the MTP
(but didn't receive much/any support in the field).

While in the now distant past there may have been some degree of freedom
between MTP and MTP-Users (i.e, implemented on completely separate
processor subsystems), normally MTP and its users are distributed-
embedded or on monolithic redundant (fault tolerant) systems.  So it
is quite atypical for an MTP-User to fail independent of MTP.

For coordinated turndown/turnup of MTP-Users, there are other mechanisms.
SCCP has the mated pair configurations and the SCCP protocol supports
replicated subssytems directly within the protocol.  For ISUP, coordinated
turndown/turnup is accomplished through circuit blocking/unblocking and
reset procedures.  I think you will find that IUSP response to MTP-STATUS
indicating an unavailable ISUP at a peer will be of little use to ISUP.
What is more important is the state of circuits between the swithes and
the correct recovery procedures involve normal ISUP circuit reset and
blocking procedures.

I do not subscribe to "whole point code" routing keys (they are not
mandatory).  Perhaps a proponent of DPC only routing keys, such as John
Schantz can better answer your queries in that regard.

--brian

[email-masked] wrote:                                                           (Sat, 26 Oct 2002 11:44:30)