Subject: Re: [Sipping] RE: How to indicate trunk groups in URI?

From: [email-masked]
Date: Tue, 3 Sep 2002 15:56:26 EDT

In a message dated 8/30/02 7:40:49 PM Eastern Daylight Time, [email-masked] 
writes:

> I was quite enamored with this proposal at first but I think I have a major
> problem with it that I don't see how to solve.
> 
> Imagine ProxyA knows that it wants to send the call to a trunk group called
> tg55 and it has learned  (perhaps via TRIP) that ProxyB can handle calls to
> tg55. Now ProxyB might have several gateways gw2, gw3, and gw5 that handle
> calls to this trunk group but ProxyA does not know anything about this.
> 
> ProxyA wants to send an INVITE with something like tg55.*.proxyB.com to
> proxyB. This GW wildcard seems unreasonable.
> 
> Ideas to solve this?
> 
> Cullen
> 
> 

[MAP] I really need a diagram to visualize what you are describing. But it 
seems that this reflects a different idea of what a "trunk group" is for and 
why they need common ways to identify them. As defined in 
draft-peterson-iptel-gwreg-arch-00.txt, a trunk group is between "two 
switching systems". In this case, one of the "switching systems" is a gateway 
(or maybe a group of gateways) controlled by one device and the other 
switching system is a PSTN switch. The identifier is needed so that the two 
switching systems can communicate and other entities that need to communicate 
with the two systems (like admistration systems) have a common reference.

I do not understand the requirement in which "Proxy A knows" about tg55 which 
is at another device. In any routing, Proxy A should know about Proxy B and 
what it can handle (destination phone numbers, etc.). Proxy A should not have 
any concept or knowledge of trunk group identifiers at the gateways 
controlled by Proxy B. Yes, you're correct, Proxy A should not know anything 
about the fact that there are multiple gateways at Proxy B that terminate 
this trunk group.

(BTW, I continue to think it is a bad idea to allow a trunk group to span 
multiple gateways, but I guess it can be allowed.)

Mike Pierce
Artel

---

From: Michael Hammer <[email-masked]>
Date: Tue, 03 Sep 2002 16:23:08 -0400

Mike,

Could you clarify what you mean by gateway?  Does gateway correspond to the 
equivalent of a switching system, i.e. an MGC with multiple controlled 
media gateways, or do you refer to the media gateway itself?  It is not 
clear to me whether you have a composed or de-composed model in mind.

Mike H.

At 03:56 PM 9/3/2002 -0400, [email-masked] wrote:
>In a message dated 8/30/02 7:40:49 PM Eastern Daylight Time, 
>[email-masked] writes:
>
>
>seems that this reflects a different idea of what a "trunk group" is for 
>and why they need common ways to identify them. As defined in 
>switching systems". In this case, one of the "switching systems" is a 
>gateway (or maybe a group of gateways) controlled by one device and the 
>other switching system is a PSTN switch. The identifier is needed so that 
>the two switching systems can communicate and other entities that need to 
>communicate with the two systems (like admistration systems) have a common 
>reference.
>
>I do not understand the requirement in which "Proxy A knows" about tg55 
>which is at another device. In any routing, Proxy A should know about 
>Proxy B and what it can handle (destination phone numbers, etc.). Proxy A 
>should not have any concept or knowledge of trunk group identifiers at the 
>gateways controlled by Proxy B. Yes, you're correct, Proxy A should not 
>know anything about the fact that there are multiple gateways at Proxy B 
>that terminate this trunk group.
>

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