Subject: RE: [Sigtran] Sigtran Plugtest SUA/M3UA/M2UA/IUA - Day 2

From: Tolga Asveren <[email-masked]>
Date: Thu, 7 Nov 2002 15:04:53 -0500

Brian,
> Without a changeover/changeback or controlled rerouting 
> procedure it would be
> very foolish for an SG to change its loadsharing based on a 
> received SCON.
> Frankly, even *with* a rerouting procedure it would be very 
> foolish for an SG
> to change its loadsharing based on congestion whatsoever.  
> The possibilities
> for thrashing and scattering messages within an SLS is boundless.
[TOLGA]Why it is "foolish"? For example in the example I gave, which problem
cases would happen?
> 
> ANSI T1.111.4/Q.704 only allow use of the transfer restricted 
> procedure in
> response to congestion in very narrowly defined situations 
> (congestion on
> C-links and nodal congestion at an STP); and this is not one of them.
[TOLGA] Isn't the relationship between SG/ASP a MTP3/MTP3 user part
relationship? Even if one has multiple SGs, it is SGs which control SPMC.
IMO, in fact the strange thing is that messages loadshared to one SG are
generating TFC, whereas the ones loadshared to other ASPs don't. This
happens, if one follows current RFC.
> 
> The situation you describe is analogous to signalling links 
> in a link set.
[TOLGA] No, IMO it is similar to a case, where one distributes its user
parts.
> The "nodal" TFC procedures that SCON was intended to parallel 
> do not permit
> transfer-restricted or change in routing procedures as a 
> result of "nodal" TFC
> when routing to a SEP.
[TOLGA] IMO the procedures you are referring to define the relationship
between SPMCs and nodes in TDM domain and between SPMCs themselves, not the
relationship between SGs and ASPs. 
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---

From: "Brian F. G. Bidulock" <[email-masked]>
Date: Thu, 7 Nov 2002 13:22:38 -0700

Tolga,

Tolga Asveren wrote:                                                               (Thu, 07 Nov 2002 15:04:53)
> Brian,
> > Without a changeover/changeback or controlled rerouting procedure it would
> > be very foolish for an SG to change its loadsharing based on a received
> > SCON.  Frankly, even *with* a rerouting procedure it would be very foolish
> > for an SG to change its loadsharing based on congestion whatsoever.  The
> > possibilities for thrashing and scattering messages within an SLS is
> > boundless.

Because it is foolish.  Again, thrashing between ASPs and resulting message
missequencing and loss will likely result.

> > 
> > The situation you describe is analogous to signalling links in a link set.

MTP does not distribut to user entities based on SLS.  MTP distributes over
signalling links in a link set based on SLS.  SGs distribute to loadshared
ASPs based on SLS.  The situation is analogous to signalling links in a link
set.

> > The "nodal" TFC procedures that SCON was intended to parallel do not
> > permit transfer-restricted or change in routing procedures as a result of
> > "nodal" TFC when routing to a SEP.

But SCON is related to the SPMC, and not the AS.  Therefore, SCON only has
application in the scope of the SPMC and in terns of SS7 network management.
That is, it is not an "ASP congested" indication, it is a "signalling point"
congested indication.  Therefore, it has no applicability in the SG/ASP domain
and (even if it weren't foolish) one should not alter ASP loadsharing as a
result of receiving one.

--brian

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