Subject: [Speermint] re:LUF vs. LF

From: "Daryl Malas" <[email-masked]>
Date: Thu, 17 Jan 2008 14:38:28 -0700

I apologize for not responding to this discussion for awhile.  I would
like to propose the following updates:

>From this....

4.3.1. Look-Up Function
The Look-Up Function (LUF) provides a mechanism for querying an
internal and/or external database, which maintains a list of peered
host domains.

4.3.2. Location Function
The Location Function (LF) develops SED by discovering the Signaling
Function (SF), and SF's reachable host (IP Address and port).

In some cases, some entity (usually a 3rd party or federation)
provides peering assistance to either the originating SSP by providing
this function.  The assisting entity may provide information relating
to direct (Section 4.2.1) or indirect (Section 4.2.2) peering as
necessary.

To this....

4.3.1. Look-Up Function
The Look-Up Function (LUF) provides a mechanism for querying an
external centralized database of records accessible between two peers
or within the federation.  This database assists peers in the
discovery of target user agents by hosting a centralized set of
records between them.  (In some cases, a local replication of this
database may be used to potentially improve query performance;
however, functionally it is still the use of a centralized common
database among the peers.) These records are a set of addresses
associated with the user agents within the individual peer networks.
An example of this would be an external database hosted within a
federation utilized as a common registry among the peers of the
federation.  A peer queries (i.e. LUF) the database requesting an
address of record (AoR) by which it may deduce, though other means, a
URI necessary for routing correctly to the target destination user
agent.

4.3.2. Location Function
The Location Function (LF) takes the output of the LUF and further
develops the SED (See Section 3.3) by discovering the Signaling
Function (SF), and SF's reachable host (IP Address and port) of the
peer hosting the target destination user agent.

In some cases, some entity (usually a 3rd party or federation)
provides peering assistance to either the originating SSP by providing
this function.  The assisting entity may provide information relating
to direct (Section 4.2.1) or indirect (Section 4.2.2) peering as
necessary.

Comments?

--Daryl

_______________________________________________
Speermint mailing list
[email-masked]
https://www1.ietf.org/mailman/listinfo/speermint

---

From: "Elwell, John" <[email-masked]>
Date: Fri, 18 Jan 2008 09:20:32 +0000

Daryl,

I think it is wrong to talk about UAs here. The existence of UAs will be
known only within the target domain, i.e., by the that domain's
registrar and domain proxy. A peer domain trying to route to a target
domain just needs to know how to do that - to route to the target
domain. It does not need to know (and indeed should not be able to find
out) anything about UAs in the target domain. The proposed definition of
LuF completely confuses me.

It would also be helpful to say what is the input to the LuF. Is it just
a telephone number (in other words, the LuF is a kind of ENUM look-up,
resulting in a SIP URI for the target user)?

Also, my reading of the definition of LF is that it could simply
comprise the functionality specified in RFC 3263. I other words, it
takes a target SIP/SIPS URI and locates a server. If this is the case,
it might be better to express it in those terms. If there is some
distinguishing feature that makes a LF somehow different from RFC 3263
server location functionality, then the definition must be more precise.

By the way, is the term "location function" liable to be confused with
the well-established RFC 3261 term "location service"? We may need to
find a different term, but until I understand what the two terms are
intended to mean, I cannot propose an alternative.

John

> -----Original Message-----
> From: Daryl Malas [mailto:[email-masked]] 
> Sent: 17 January 2008 21:38
> To: [email-masked]
> Subject: [Speermint] re:LUF vs. LF
>

---

From: "Daryl Malas" <[email-masked]>
Date: Fri, 18 Jan 2008 08:15:59 -0700

John,

I can easily remove UA's and simplify it to domains.  Since, you are
still confused by the definition, can you please propose some new
wording for these two terms?

IMO, this draft is being held up by these two terms.

Thanks...

Daryl

---

From: "Elwell, John" <[email-masked]>
Date: Fri, 18 Jan 2008 15:39:44 +0000

Daryl,

Trying to keep it simple, how about the following?

LuF: A function that determines for a given request the domain to which
the request should be routed.
LF: A function that determines for a given domain the location of a SIP
server in that domain and optionally other information needed to route a
request to that domain.

I have tried to keep this to a minimum, but if it is heading in the
right direction we can add to it if necessary. However, I am in favour
of concise definitions.

John

> Sent: 18 January 2008 15:16
> To: Elwell, John
> Cc: [email-masked]
> Subject: Re: [Speermint] re:LUF vs. LF
> 
> John,
>

---

From: "Daryl Malas" <[email-masked]>
Date: Fri, 18 Jan 2008 08:55:46 -0700

John,

Thank you for suggesting some new language.  Please review these
updated definitions, and provide feedback.  I also suggested some
possible term changes to make sure there is no confusion with
'Location Service' in 3261.

LUF:

The Look-Up Function (LUF) provides a mechanism for determining for a
given request the target domain to which the request should be routed.

Suggested term change from Location Function to:
Location Determination Function
Location Routing Function (I prefer this one.)

LRF:
The Location Routing Function (LRF) determines for a given domain the
location of the SF in the target domain and optionally develops other
SED required to route the associated request to that domain.

Thanks...--Daryl

---

From: "Elwell, John" <[email-masked]>
Date: Fri, 18 Jan 2008 16:16:14 +0000

Daryl,

See below.

John 

> Sent: 18 January 2008 15:56
> To: Elwell, John
> Cc: [email-masked]
[JRE] OK

> Location Routing Function (I prefer this one.)
[JRE] OK

> SED required to route the associated request to that domain.
[JRE] Slight word change (e.g.,  don't like switching from "a given
domain" to "the target domain"):
"The Location Routing Function (LRF) determines for the target domain of
a given request the location of the SF in that domain and optionally
develops other SED required to route the request to that domain."

With these changes I think the definitions are simple, relate to each
other well, and clearly differentiate the two functions.

---

From: "Daryl Malas" <[email-masked]>
Date: Fri, 18 Jan 2008 09:28:22 -0700

Thanks, John.  (John, please make sure I captured your last updated
correctly.) Okay, here are the updated terms and definitions:

Look-up Function:

Location Routing Function:

The Location Routing Function (LRF) determines for the target domain
of a given request the location of the SF in that domain and
optionally develops other SED required to route the request to that
domain.

Please provide feedback if anyone has concerns.

Thanks...--Daryl

---

From: "Lee, Yiu" <[email-masked]>
Date: Fri, 18 Jan 2008 13:14:58 -0500

I like them except I am confused by the last sentence of LRF. What does
the "optically develops other SED required to route the request to that
domain" really mean? Can you enlighten with an example? 

-----Original Message-----
From: Daryl Malas [mailto:[email-masked]] 
Sent: Friday, January 18, 2008 11:28 AM
To: Elwell, John
Cc: [email-masked]
Subject: Re: [Speermint] re:LUF vs. LF

Look-up Function:

The Location Routing Function (LRF) determines for the target domain of
a given request the location of the SF in that domain and optionally
develops other SED required to route the request to that domain.

Thanks...--Daryl

On 1/18/08, Elwell, John <[email-masked]> wrote:
> > The Look-Up Function (LUF) provides a mechanism for determining for 
> > a given request the target domain to which the request should be
routed.
> > The Location Routing Function (LRF) determines for a given domain 
> > the location of the SF in the target domain and optionally develops 
> > other SED required to route the associated request to that domain.
> "The Location Routing Function (LRF) determines for the target domain 
domain."
> > > I have tried to keep this to a minimum, but if it is heading in 
> > > the right direction we can add to it if necessary. However, I
> > am in favour
> > > of concise definitions.
> > >
> > > John
> > >
> > > > still confused by the definition, can you please propose some 
> > > > new wording for these two terms?
> > > >