Subject: RE: [Sipping] Loose Routing Proposal

From: "Stephen Terrill (ERA)" <[email-masked]>
Date: Wed, 12 Sep 2001 18:28:04 +0200

Hi Juha,

As the S-CSCF may be different for different subscribers, this would require that the DNS infrastructure has, or can obtain, information related to "which user is on which SIP proxy" - and this may change for a number of reasons.  The question is whether the DNS is an approapriate mechanism to have such user based information.

..//Steve

-----Original Message-----
From: Juha Heinanen [mailto:[email-masked]]
Sent: Monday, September 10, 2001 3:55 PM
To: Drage, Keith (Keith)
Cc: Miguel A. Garcia; Rosen, Brian; 'Cullen Jennings'; [email-masked]
Subject: RE: [Sipping] Loose Routing Proposal

Drage, Keith (Keith) writes:

 > The issue is not DNS query time.

why can't they use the svr record of the user's domain to find out the
best s-cscf?  that way the information could be stored in dns.

-- juha

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Use [email-masked] for questions on current sip
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_______________________________________________
Sipping mailing list  http://www1.ietf.org/mailman/listinfo/sipping
This list is for NEW development of the application of SIP
Use [email-masked] for questions on current sip
Use [email-masked] for new developments of core SIP

---

From: Juha Heinanen <[email-masked]>
Date: Wed, 12 Sep 2001 20:06:31 +0300

> As the S-CSCF may be different for different subscribers, this would require that the DNS infrastructure has, or can obtain, information related to "which user is on which SIP proxy" - and this ma…

i didn't suggest the above.  what i tried to say is that the outbound
proxy can obtain from the dns (based on the caller's domain name) the
home "entry" proxy of the caller, which upon receiving an invite makes a
lookup to the subscriber database to find out the chain of "service"
proxies relevant to that subscriber.

by the way, the bombing indicent remainded me of another thing: it is
very bad if the mobile subscriber has no way to bypass the "home" proxy
and make a call directly via the visited network.  the reason is that
the "home" may have been blown to pieces.

-- juha

---

From: Michael Hammer <[email-masked]>
Date: Wed, 12 Sep 2001 13:33:43 -0400

Juhu,

Hopefully, the network has some physical dispersion and reconstitution plan.

Even without, fraud needs to be considered.  Why would a visited service 
provider provide service if he would later not be able to bill for 
it?  Although there may be some service agreements in place and some credit 
mechanism, in GSM the caller may need to replenish the "triplets" (or 
quintuplets if that is implemented) needed to authenticate the user 
terminal.  How does that come into play?

Note that in the US at least 911 calls should go through even without a 
subscription.

Mike

At 08:06 PM 9/12/2001 +0300, Juha Heinanen wrote:
>  > As the S-CSCF may be different for different subscribers, this would 
> require that the DNS infrastructure has, or can obtain, information 
> related to "which user is on which SIP proxy" - and this may change for a 
> number of reasons.  The question is whether the DNS is an approapriate 
> mechanism to have such user based information.
>

---

From: Juha Heinanen <[email-masked]>
Date: Wed, 12 Sep 2001 21:01:35 +0300

yes, the visited network needs to be able to authenticate the caller,
but once that has succeeded, the subsciber should have the choice to
make a call directly rather than being routed via the "home" network.

-- juha

---

From: "Henning G. Schulzrinne" <[email-masked]>
Date: Wed, 12 Sep 2001 14:14:05 -0400

> make a call directly rather than being routed via the "home" network.

Also, I would imagine that the visited network would not have to go back
to the home network for authentication for every call. If you know that
[email-masked] is indeed a Telia customer, you don't have to ask two
minutes later again.

In addition, while off-line or semi-off-line micropayment schemes aren't
all that popular today, one could imagine that they might catch on. So
we shouldn't be designing an architecture that imposes unnecessary
constraints just because today's billing system works a certain way.
-- 
Henning Schulzrinne   http://www.cs.columbia.edu/~hgs

---

From: "Eric Burger" <[email-masked]>
Date: Wed, 12 Sep 2001 15:08:59 -0400

Some carriers may chose not to do per-call authentication.  However, most
will do per-call authentication to stem fraud.  Many fraud detection systems
reside in the home network, as the home network can see a global view of
user activity.  Quite often accounts do get shut down in a X minute period.

Henning G. Schulzrinne wrote:
[snip]
Also, I would imagine that the visited network would not have to go back
to the home network for authentication for every call. If you know that
[email-masked] is indeed a Telia customer, you don't have to ask two
minutes later again.
[snip]

---

From: Michael Hammer <[email-masked]>
Date: Wed, 12 Sep 2001 15:08:01 -0400

The only problem with this architecture is that the 3GPP groups, I thought, 
were going to have the "virtual home environment" operating at the home 
serving node.  If the visited node is to control the features and services 
(e.g. personalized announcements) of the subscriber in the visited network, 
then it must be possible to transfer that logic to the visited system.  An 
assumption is that the user's phone will contain all the logic and data, 
but I'm not sure if the format of the mobile phones (e.g. a powerful enough 
but small battery) will support that.

The alternative is commodotized rather than personalized service.  Thoughts?

Mike

---

From: "Henning G. Schulzrinne" <[email-masked]>
Date: Wed, 12 Sep 2001 15:09:29 -0400

Announcements? This is signaling path, not media, so I don't see how
announcements come into play.

In general, I think it might help us if we identify at least examples of
home outbound services. The ones I've heard about so far (short-cut
dialing and outbound call filtering) seem interesting, but hardly
something I can't live without.

In general, I thought Juha made the point that this should be at the
discretion of the user. I may decide that sending my packets through NYC
when the servers are overloaded may not be worth the slight
customization afforded by the home proxy. Why shouldn't this be left to
the end system and user?

---

From: "Henning G. Schulzrinne" <[email-masked]>
Date: Wed, 12 Sep 2001 19:09:13 -0400

I wouldn't want to suggest that routing signaling through the home
network is not a good feature, for all the reasons you mention. It
should just be a feature by itself, i.e., the end user's (or programmed)
choice. In any event, we need to be able to obtain this information, but
the UE knows this already through the user name.

Michael Hammer wrote:
> 
> I was thinking in terms of personalized XML scripts that could signal
> connections to a media server or whatever.  My point without getting too
> specific was to explore whether in roaming to the visited network, does my
> experience change because the visited and home networks do things
> differently.
> 
> Earlier mobile networks had problems because things like *69 codes and such
> were not the same in all networks.  (Not a problem unless you moved in a
> wireline network.)  It wasn't until everyone agreed on a common meaning
> that the features became more widely accepted.
> 
> I have also seen new features stall in standards bodies because everyone
> could not agree on which keypresses had what effect on the call.  If I want
> to have voice-activated control of call setup where my voice commands
> essentially get translated into a series of signaling commands, and I
> happen to be in China, will I need to speak Chinese?
> 
> I agree that a lot of this human interface stuff should be in the user
> terminal.  Also, media doesn't need to be routed through the home
> network.  I was just trying to explore whether some valuable capability
> would be lost if the home network was dismissed from the signaling flows.
> 
> Mike

---

From: Michael Hammer <[email-masked]>
Date: Wed, 12 Sep 2001 19:06:31 -0400

Mike