Subject: RE: SUA - SCMG

From: "Sidebottom, Greg [BCNR:7M01:EXCH]" <[email-masked]>
Date: Thu, 22 Mar 2001 02:39:05 -0500

Hi John, Gery

Comments below ...

 -----Original Message-----
From: 	[email-masked] [mailto:[email-masked]] 
Sent:	Friday, March 16, 2001 10:04 AM
To:	[email-masked]
Subject:	FW: SUA - SCMG

2nd try

> -----Original Message-----
> From: Loughney John (NRC/Helsinki) 
> Sent: March 16, 2001 16:58
> To: [email-masked];
> [email-masked]
> Subject: RE: SUA - SCMG
> 
> 
> Hi Gery,
> 
> > The whole question is whether we should support primary/backup
> > configurations with one node in the SS7 and the other in the 
> > IP network (SNR, SBR, SRT, but also SOR, SOG). Of course we 
> > want to keep all options open, but for a first version of the SUA, 
> > I'd like to keep things separated and only pass SSA, SSP and SST.
> 
> I concur.  I think that on an implementation basis, something
> could be done - but that would be out of scope of the current
> draft.
> 
> br,
> John
> 

[Greg]  I concur as well - but I wish to clarify that SSA, SSP and SST are
not really "passed on" from the SG.  (I talked to Gery yesterday and he
agreed that this is not really what he meant to say).  All SCMG messages
from the SS7 network are consumed by the SCCP layer at the SG where SCCP is
terminated - there is no SCCP layer in the ASP or IPSP.  

It may sound subtle but I am stressing that it is the SCCP SCMG in the SG
that must maintain the status of remote SCCP nodes in the SS7 network and
the status of "local" subsystems (even if now some of these subsystems may
actually be supported by one or a set of "remote" ASPs in the IP network).
In the case of SSTs from the SS7 network the SCCP layer responds based on
its local subsystem status knowledge - there is no SUA equivalent of an SST
from the SG to ASP.  

"Local" subsystem availability at an SG can be determined via knowledge of
the status of the ASPs and Application Servers that make up a "local"
subsystem.  The SUA draft doesn't cover this now but I think the SUA needs
to add the equivalent of the M3UA Signalling Point Management Cluster,
perhaps called a Subsystem Management Cluster, so the SG can sum the
availability of a local subsystem.  Then the SCMG at the SG is in a position
to report local subsystem availability changes to, and respond to any SCCP
Subsystem Test messages from, the SS7 network.

But, back to the original question from Bernard  2;^)  

With the above assumptions, the SG SCMG could still process a received SOR
from an SCCP peer and respond with SOG as appropriate, without involving the
SUA at all.   Or the SG could even generate an SOR when it wants to withdraw
a local subsystem.  But as Gery points out, all this really means is that
there is a primary/backup subsystem configuration where one subsystem is at
an SS7 node and the other is an ASP (or set of ASPs) in the IP network - I
'd agree to leave this scenario out.  

Regards,

   Greg

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