Re: ASP Capabilities value 0x2 of interworking field

Tolga,

Tolga Asveren wrote:                                                                 (Mon, 19 Dec 2005 10:29:48)

--X--snip--X--
> >
> > At least in writing the RFC, I assumed 'process' not to have
> > a normative value, but to try to capture the overall functionality
> > in a descriptive manner.
> [TOLGA]Yes, I agree with your that view. Now, if we revisit the main
> functionalities
> a)Relaying
> b)Hosting applications
> c)Interfacing with conventional SS7 networks (Actually this probably is
> irrelevant in terms of SUA, why should I care whether a peer interfaces with
> convetional SS7, what matters is only whether I should send messages for a
> specific destination to that peer or not)

Yes it matters.  Take some time to understand SUA before making such broad
statements.  SUA specifies interworking fields in the Called Party Address
that specifically control the mapping of the address into SS7 fields for
interworking with SS7 networks.

> 
> I believe it is clear that b) is supported by all process types, i.e. ASP,
> SGP and IPSP

No, not all SUA SGPs host applications.  Just as not all STPs support SCCP users.

> 
> For a), it is obvious that SGP supports it. ASP seem supporting it. In that
> case, what is the difference between SGP and ASP from provided functionality
> point of view? Why not call both of them SGP?

No, not all SUA SGPs support relaying.  Just as not all STPs act as an SCCP relay.

The SUA SGP, by definition, does c), interfacing with conventional SS7 newtorks.

> 
> If IPSP is supporting a), what is the difference between IPSP and SGP or
> ASP?Much more importantly than that, if one considers that IPSP is a direct
> relationship between 2 applications, how can one justify the concept of
> SUA-level relay for IPSP, this would mean that one does not have a direct
> connection between applications and why one shouldn't use ASP-SGP-ASP
> configuration(first figure below)? Shouldn't relay be performed on
> application layer, if such a need exists for IPSP case(second figure below)?

You are still thinking MTP.  Consider that you have an all-IP network with
not SS7 network interworking from the perspective of SCCP and SUA:  Where
are you going to place your GTT so that you can administrate your network?

Your first diagram would restrict GTT to be located at a node supporting SS7
network interworking, the SGP.  In an all-IP network there is no need for an
SGP, so that configuration is too restrictive.

In your second diagram, SCCP GTT is performed by SCCP or in the all-IP case
the SUA layer relay function.  No SCCP-User performs this function and it is
not possible to have the "application" or SUA-User perform the relay function.
(The interface lacks the primitives.)  Therefore, requiring an application to
do the relaying at IPSP2 is too restrictive.

What SUA does is permit the relaying capability to be added to any node in
the network (including ASP2 in your diagram below), allowing flexible placement
of the GTT function within the SUA network.

> 
> (I use ASP/IPSP to refer to the corresponding M3UA stack instances in the
> figures below)
> 
>   +-------+                 +-------+
>   | App1  |                 | App2  |
>   +-------+                 +-------+
>   | ASP1  |                 | ASP2  |
>   +---+---+                 +---+---+
>       |                         |
>       |                         |
>       |       +------+          |
>       +-------+ SGP1 +----------+
>               +------+
> 1- Relaying on SGP1
> 
> 
>  +-----+       +-----+        +-----+
>  |App1 |       |App2 |        |App3 |
>  +-----+       +-----+        +-----+
>  |IPSP1+-------+IPSP2+--------+IPSP3|
>  +-----+       +-----+        +-----+
> 2- Relaying on App2 (not in IPSP2 M3UA stack)
> 
> 
> AFAICS, asking IPSP2 M3UA stack to perform relaying is to push application
> layer functionality to M3UA stack (it will be M3UA stack which decides when
> to activate/deactivate RKs, the correlation/coupling between different As
> etc...)

Well, no, it is the same story for the "Transfer Function" as it is for
"SCCP Relay".  It would be a simple matter to add ASP Capabilities to M3UA
and permit transfer nodes to send SNMM.

--brian

> 
> >
> > Do you feel that we need to be more precise about this?  I don't
> > think that the 'process' has normative value in most RFCs.
> >
> > thanks,
> > John
> >
> 
> 
> 
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-- 
Brian F. G. Bidulock
[email protected]
http://www.openss7.org/