RE: [Ieprep] Diffserv Code Point for Emergency calls

"James M. Polk" <jmpolk@cisco.com> Mon, 24 October 2005 03:42 UTC

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Date: Sun, 23 Oct 2005 22:42:34 -0500
To: "Reinaldo Penno" <rpenno@juniper.net>
From: "James M. Polk" <jmpolk@cisco.com>
Subject: RE: [Ieprep] Diffserv Code Point for Emergency calls
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Reinaldo

Actually, the PSTN does not give better priority to 911 calls (vs. normal 
calls), they just use separate cirucuits once the 911 call gets to the 
first Class-5 switch.  Typically, a Class-5 Switch will have a small number 
of dedicated circuits that connect directly to a 911 Selective Router 
(which is a special instance of a Class-5 switch). 911 calls are routed 
over these dedicated circuits towards the SR to then be routed to the 
appropriate PSAP. This isn't really anything special - since the circuit 
world is not bandwidth contending, they are circuit contending.

At 10:55 PM 10/23/2005 -0400, Reinaldo Penno wrote:


> > -----Original Message-----
> > From: James M. Polk [mailto:jmpolk@cisco.com]
> > Sent: Sunday, October 23, 2005 12:50 PM
> > To: Reinaldo Penno
> > Cc: ken carlberg; ieprep@ietf.org
> > Subject: RE: [Ieprep] Diffserv Code Point for Emergency calls
> >
> > Reinaldo
> >
> > Comments in-line
> >
> > At 02:29 AM 10/23/2005 -0400, Reinaldo Penno wrote:
> > >That is also possible and it might happen all the time.
> > >
> > >I think the threats you mention are quite valid but they will be no
> > >different if we have an emergency DSCP. The whole problem around
> > >contention of resources will continue to happen.
> > >
> > >My point is the same as before. How this hypothetical scenario is any
> > >different from what could happen today?
> >
> > Because, as I see it - and please correct me if I am seeing this
> > incorrectly - that doctor's call in the enterprise will not be starved
>off
> > by any other call.
> >
> > Yet, the way I have understood most, and I think the scenario you have
> > brought up, the emergency calls will starve off, or at least adversely
> > affect existing calls that can be the equivalent of EF marked in
> > treatment.
>
>[[Reinaldo]]
>
>But...the doctor call can will fight for resources in the same level as
>an emergency call. I guess we should introduce the concept of "personal
>emergency" and "collective emergency". If the building is burning up, I
>try to call the fire department, and the person in the next cubicle
>tries to call his priest, which call is more important? I guess this is
>a complex issue. We will not be able to resolve it here.
>
>If the PSTN today gives better priority to 911 calls, we should strive
>to do the same for VoIP calls.
>
>Regards,
>
>Reinaldo
>
> >
> > Plus there is the issue that most employees operate under a subtly
> > different set of laws and rules than the general public, usually
>starting
> > with when an employee candidate signs a contract of employment
>reducing
> > that person's rights in some ways.
> >
> >
> > >For example, today if something happens in an enterprise, will the
> > >emergency calls to 911 have better treatment than the doctor's call?
>You
> > >can also imagine a reversed scenario where I could argue that if the
> > >call made by the person in the next cubicle to his doctor blocks my
>call
> > >to 911 I will sue the company/telco.
> > >
> > >Any hospital in the US has the following recording "if this is an
> > >emergency, hang up and dial 911". If you really have an emergency,
>you
> > >should be calling 911, and not your doctor.
> >
> > While in general, I would agree with you, there are some cases in
>which a
> > doctor is who is to be called when you have an issue with something
>under
> > their care.  I have experienced this first hand to know it is true in
>the
> > US.
> >
> > >If you call your doctor, you
> > >are implicitly telling the "system" that this is not an emergency.
> >
> > That's the legacy system you are telling.  Whereas, with IP, we have
>many
> > more capabilities (or should) to be able to differentiate one call
>from
> > another. I believe that should one of the IETF's (and other SDO's)
>goals
> > for emergency calling.
> >
> > Please review ECRIT WG discussions as there are many references to
>this
> > capability being on the to-do list of many areas dealing with this
> > scenario.
> >
> >
> > >Somebody in a Telco told me that 911 calls are signaled different
>(which
> > >imply a priority over normal calls). Do you know if this a fact?
> >
> > Yes, there are special facilities that 911 calls traverse, after the
> > initial Class 5 switch towards the Selective Router, and on to the
>PSAP.
> >
> >
> > >Regards,
> > >
> > >Reinaldo
> > >
> > >
> > >
> > > > -----Original Message-----
> > > > From: James M. Polk [mailto:jmpolk@cisco.com]
> > > > Sent: Saturday, October 22, 2005 8:23 PM
> > > > To: Reinaldo Penno
> > > > Cc: ken carlberg; ieprep@ietf.org
> > > > Subject: RE: [Ieprep] Diffserv Code Point for Emergency calls
> > > >
> > > > At 08:45 AM 10/22/2005 -0400, Reinaldo Penno wrote:
> > > > >Your point is well taken James.
> > > > >
> > > > >Therefore, if we just continue with just EF for normal and
>emergency
> > > > >voice calls, the risk is the same, the drawback that I see is
>that we
> > > > >cannot prioritize emergency over normal calls.
> > > >
> > > > so here's the problem as has been presented to me by both
>regulators
> > >and
> > > > lawyers:
> > > >
> > > > In larger emergencies, many people will likely be calling for
> > >emergency
> > > > help, and some of them are not going to be calling (the equivalent
>of)
> > > > 911,
> > > > they will be calling their doctors directly - yet to "the system",
> > >these
> > > > will appear as normal packets, or normal voice (EF marked)
>packets. In
> > > > your
> > > > pondering, these packets will be subject to some form of lesser
> > >treatment
> > > > than perhaps the 10th or 100th call to 911, informing the PSAP of
>the
> > >same
> > > > event (perhaps a building burning).
> > > >
> > > > Here's the catch: who determined the 10th or 100th call to the
>PSAP is
> > > > more
> > > > important than the patient's call with their doctor - getting
> > >one-on-one
> > > > advice/help.
> > > >
> > > > I think the first lawsuit will stop that preferential treatment.
>I've
> > >had
> > > > this hinted to me by many
> > > >
> > > >
> > > > >So, in general an edge device that can perform SIP parsing and
>mark
> > > > >emergency calls with the emergency DSCP and others with EF DSCP.
> > > > >Alternatively, in a decomposed gateway scenario the SIP Proxy can
>let
> > > > >the router know that a certain call is an emergency and that it
> > >should
> > > > >be marked differently.
> > > >
> > > > or there could be a path coupled mechanism for such calls, but
>that
> > >has
> > > > its
> > > > challenges too
> > > >
> > > >
> > > > >Regards,
> > > > >
> > > > >Reinaldo
> > > > >
> > > > >
> > > > > > -----Original Message-----
> > > > > > From: James M. Polk [mailto:jmpolk@cisco.com]
> > > > > > Sent: Friday, October 21, 2005 11:02 PM
> > > > > > To: Reinaldo Penno
> > > > > > Cc: ken carlberg; ieprep@ietf.org
> > > > > > Subject: Re: [Ieprep] Diffserv Code Point for Emergency calls
> > > > > >
> > > > > > Reinaldo
> > > > > >
> > > > > > Adding fuel to a discussion that has churned on many lists
>over
> > >the
> > > > >last
> > > > > > several years, I'd really want to understand the threat
>anaylsis
> > > > >observed
> > > > > > by such a proposal (for a emergency DSCP) to ensure it could
>not
> > >be
> > > > >used
> > > > > > for a fairly trivial to generate DDOS on the network - even
>all
> > >the
> > > > >way to
> > > > > > the PSAP, or just used by neighbors wanting the very best
> > >throughput
> > > > >for
> > > > > > their game of Doom.
> > > > > >
> > > > > > At 10:57 AM 10/21/2005 -0400, ken carlberg wrote:
> > > > > > >Hello Reinaldo,
> > > > > > >
> > > > > > >>I read
> > > > > >
> > > > >
> > >
> >>http://www.ietf.org/internet-drafts/draft-ietf-ieprep-framework-10.txt
> > > > > > >>and was somewhat puzzled at section 4.1.2. I understand that
>the
> > > > >IETF
> > > > > > >>wants to be conservative in standardizing new DSCP, but it
>seems
> > >to
> > > > >an
> > > > > > >>emergency call DSCP would be accepted by the community (am I
> > > > >wrong?).
> > > > > > >
> > > > > > >well, from my own take, I would say that the "community" is
>not
> > > > > > >against an emergency call DSCP per se, but rather awaits
>specific
> > > > > > >proposals with a cautious mindset.  Recall from that section
> > >4.1.2
> > > > > > >that there is a need to define a behavior in addition to
> > >identifying
> > > > > > >a code point.  So if you want a code point of 1 or more bits
>for
> > > > > > >"emergency", what would be its defined forwarding behavior?
> > > > > > >
> > > > > > >one such proposal, primarily aimed at MLPP, is called
>Multi-Level
> > > > > > >Expedited Forwarding (MLEF) and can be found at:
> > > > > >
> > > >ftp://ftp.rfc-editor.org/in-notes/internet-drafts/draft-silverman-
> > > > > > >tsvwg-mlefphb-03.txt
> > > > > > >
> > > > > > >I would also suggest reading a counter proposal that avoids
> > >defining
> > > > > > >a new DSCP:
> > > > > >
> > > >ftp://ftp.rfc-editor.org/in-notes/internet-drafts/draft-ietf-tsvwg-
> > > > > > >mlpp-that-works-02.txt
> > > > > > >you can dig around the TSVWG archives over the past 2 months
>for
> > >some
> > > > > > >comments on the draft.
> > > > > > >
> > > > > > >-ken
> > > > > > >
> > > > > > >
> > > > > > >_______________________________________________
> > > > > > >Ieprep mailing list
> > > > > > >Ieprep@ietf.org
> > > > > > >https://www1.ietf.org/mailman/listinfo/ieprep
> > > > > >
> > > > > >
> > > > > > cheers,
> > > > > > James
> > > > > >
> > > > > >                                  *******************
> > > > > >                  Truth is not to be argued... it is to be
> > >presented.
> > > >
> > > >
> > > > cheers,
> > > > James
> > > >
> > > >                                  *******************
> > > >                  Truth is not to be argued... it is to be
>presented.
> >
> >
> > cheers,
> > James
> >
> >                                  *******************
> >                  Truth is not to be argued... it is to be presented.


cheers,
James

                                 *******************
                 Truth is not to be argued... it is to be presented.

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