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

From: [email-masked]
Date: Wed, 4 Dec 2002 10:13:11 +0530

Hi,

Please see some comments below.

> [Herve] I am not quite sure to understand the term "relay".
> [Herve] To clarify what I was meaning, let me take a very concrete exemple:
> SMS offlload. Let's consider the problem from an SMSC standpoint. The
> considered  SMSC is a new generation SMSC providing M3UA connectivity only.
> It will have to talk to several MSCs either directly through a full IP
> network or through STPs behind SGs, to HLRs  (SS7 or M3UA), SGSNs for
> GPRS,... etc. At some point in time, IPSP and ASP type of behavior will be
> required for this SMSC (at least for migration purpose of the
> infrastructure). The number of IPSP peers may be significant as well as the
> number of SGPs.

The RFC does not support ISPS connected to, or acting as STPs.  Only ASPs are
supported in connection to STPs (SGs).  Additional behavior was postponed for
extension draft.

Sandeep >> RFC does not allow M3UA to relay messages, but in case both SCCP and
M3UA layers at node acting as IPSP, SCCP layer can relay messages and this is
very much allowed in RFC. For example in case IPSP1, IPSP2 and IPSP3 are three
nodes and IPSP1 is connected to IPS2 and IPSP2 is connected to both IPSP1 and
IPSP3. In this case message from SCCP application at IPSP1 can be sent to SCCP
application at IPSP3 via IPSP2. SCCP at IPSP2 will relay message in this case.

> [Herve] The example given above is being developped now on the basis of what
> is described in the RFC text which fits the need.

As relay is not supported in IPSP, I suggest that you contribute to
work on an extension draft for SG-SG behavior.

Sandeep >> M3UA level relay is not really required as SCCP level relay is
present. In the scenario of SMS off-load, IPSP communication with SCCP level
relay can be used and there is no requirement for SG-SG communication. SG should
be required in the network in case Nodes in IP network needs to talk to SS7
network. For nodes within IP network to talk to each other SG should not be
required.

-Sandeep

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---

From: "Brian F. G. Bidulock" <[email-masked]>
Date: Tue, 3 Dec 2002 23:10:35 -0700

samahajan,

[email-masked] wrote:                                                     (Wed, 04 Dec 2002 10:13:11)
> application at IPSP3 via IPSP2. SCCP at IPSP2 will relay message in this case.

I'm suprised by your oversimplification of SCCP.  Although such an arrangement
could relay at SCCP performing GTT on forward SCCP messages, it takes MTP
relaying (STP function) to transfer messages in the backwards direction.  GTT
is not normally performed on responses (CL), nor is it normally performing on
DT1 or DT1 (CO).  Successful SCCP relay communications relies on STP function
at MTP for CL and typically also requires it for CO (non-coupling of
connection sections).  Such an IPSP would not be very useful for relay.

> network. For nodes within IP network to talk to each other SG should not be

Again, forward UDT can relay on GTT, however, the response requires STP
transfer at MTP.

--brian

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

---

From: Tolga Asveren <[email-masked]>
Date: Tue, 3 Dec 2002 22:20:14 -0800 (PST)

Sandeep,
> relay message in this case.
[TOLGA]The scenario you are describing is not relaying
on M3UA level. You introcude a new layer of
interworking functionality. IMO, it is odd that layer
n relies just on capabilities of layer n+1 for
relaying purposes.
> network. For nodes within IP network to talk to each
[TOLGA] My former comment also applies here. We are
using the term SG-SG just not introduce a new name. If
you think it as defining communication between IP
based signalling points, it is easy to see that it is
a very robust model, which solves most of the existing
problems. In the SG-SG draft several scenarios, where
such a communication is necessary is listed. 
> transmitted by this email including damage from

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