Subject: RE: [Ecrit] Emergency [mapping still needed?]

From: "James M. Polk" <[email-masked]>
Date: Sun, 11 Sep 2005 17:50:06 -0500

At 06:36 PM 9/8/2005 -0500, Winterbottom, James wrote:

>All this aside, I think that there are economies of scale, and
>functionality reasons why including a gateway such an ESRP are
>desirable, but these are more implementation details. Somewhere,
>something has to have sufficient knowledge to use location to route the
>signal to the next hop.

Not necessarily.

If the UA has the URI of the PSAP, no further mapping operation is 
necessary, and you're done, point-to-point.

How the UA got the URI *could* be from Layer 2/3 (DHCP) or a protocol at 
Layer 7, but prior to the emergency call. Either way, the mapping operation 
could already be done when the call is started.

>Cheers
>James

cheers,
James

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From: "Brian Rosen" <[email-masked]>
Date: Mon, 12 Sep 2005 10:37:15 -0400

I think that the idea that a phone gets its own location, recognizes
emergency calls itself, and does its own mapping is a Really Good Idea.  It
means fewer things have to work to get an emergency call through.

I think doing a mapping and caching it during "boot", and periodically
thereafter (that means both getting location, and mapping from time to time)
is the way to do that.

I'd prefer that the phone attempt mapping just before making an emergency
call.  If that works, using the result of that fresh mapping is best.  If
for some reason, that doesn't work, using the cached data is next best.

While I expect that the PSAP side will use the tools it has available to
turn a URI obtained from mapping to an IP address of an available
destination (i.e. PSAP) even if the original intended target was unavailable
(by, for example, having alternative records in the DNS, or even changing
the DNS), it's hard to make that always work when the world starts falling
apart.  I would really, really, not like to rely on "stale" data when an
emergency call occurs, so I would prefer that, if possible, the mapping be
fresh.

Brian

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf Of
James M. Polk
Sent: Sunday, September 11, 2005 6:50 PM
To: Winterbottom, James; Ted Hardie; ECRIT
Subject: RE: [Ecrit] Emergency [mapping still needed?]

Not necessarily.

cheers,
James

                                 *******************