Subject: Re: What we have...?

From: [email-masked] (Lawrence Conroy)
Date: Tue, 6 Apr 1999 10:01:35 +0100

At 2:48 pm 5/4/99, Chip Sharp wrote:
..snip..
>...snip...
>>>
>>><beginning of explicitly biased personal comment>
>>>I myself am very skeptical that we will be able to do anything useful with
>>>IN triggers, beyond what SIGTRAN might eventually do.
>>
>>SIGTRAN is not dealing with ANY SS7 messages, so SIGTRAN will never do
>>anything with triggers.  (Nor is that what SIGTRAN needs to do.) What can we
>>do with the IN triggers?  Let us see, based on the example of Internet
>>Call Waiting:
>
>To clarify, sigtran will be transporting the SS7 messages to/from an IP
>host where the messages will be processed.  Igor is correct in that sigtran
>doesn't define any processing of SS7 application.  It is purely adaptation
>and transport.
>
>...snip...
To which I reply:
Um...I am really being brushed by a bus here.

Sigtran seems to have gained the idea of an IP node, in the middle of the
IP cloud, acting as the Signalling terminal point for a CSS7 message?

I had thought that it started out as an analysis of performance
requirements to ensure that we could tunnel a CSS7 message -> through <- an
IP cloud, with Signalling gateways (not Megaco ones, I think) at either
edge of the cloud.

If the intention is to TERMINATE the signalling exchange within the IP
cloud, then Christian's prezz in Minneapolis makes much more sense, but the
performance analysis is out the window - it was end to end, and Sigtran
goes from a small appetizer to the chaos of Megaco into a serious chunk of
work with all sorts of Signalling Interworking implications.

Hmm... this would be useful to know, so that we understand what's in and
out of scope for us, IMHO.

All the best, Lawrence
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From: Chip Sharp <[email-masked]>
Date: Wed, 14 Apr 1999 22:01:53 -0400

>IP cloud, acting as the Signalling terminal point for a CSS7 message?

This was one of the main reasons for sigtran. The SS7 and other signaling
protocols must be tunneled from the Signaling Gateway (SG) to the Media
Gateway Controller (MGC).  The MGC then controls the Media Gateways.

>IP cloud, with Signalling gateways (not Megaco ones, I think) at either

Tunneling SS7 messages through the IP network is in the charter of sigtran,
but the main focus of most people is the backhaul to the MGC mentioned above.

>work with all sorts of Signalling Interworking implications.

Well, in the megaco application, the signaling traffic terminates on the
MGC.  
The MGC will have to support ISUP/TUP for call control and will probably
support TCAP for things like IN, 800 number lookup, etc.  That is more or
less transparent to sigtran other than the obvious message transport and
performance requirements.

The sigtran protocol probably won't get into the interworking specifics of
the SG or the MGC although there are interesting discussions about this on
the list.  There are real questions such as where the pointcode is terminated.

Chip

>out of scope for us, IMHO.
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Chip Sharp                 voice: +1 (919) 851-2085 
Cisco Systems              Consulting Eng. - Telco   
Reality - Love it or Leave it.			
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