[CAP] Presidential CAP questiion
David Aylward
daylward at comcare.org
Mon Oct 15 14:01:27 PDT 2007
Matt:
Your "single channel" concept is a much more limited view of
broadcasters than I think we should have. At least television, and
often radio, broadcasters have multiple channels of communication to the
public.
Certainly, priority is an issue if you want real time communication of
voice, video (and data), i.e. a presidential speech. But I thought we
were talking about CAP messages.
Any TV station worth its salt will be registered wherever it needs to be
(or polling relevant servers constantly) to get every
alert/warning/incident report affecting its area. It can use those
warnings in news broadcasts, crawls across the bottom of the screen,
list them all on its website, sent out all or some of them to those who
have registered for news alerts on its website. It can devote one of
its 4-5 digital channels to full time reporting on a disaster(s), while
mentioning other incidents on its other channels.
As to Presidential priority, I not sure we should always assume that the
top person in the hierarchy has the most important message. How can
the President or anyone other than people in Topeka know the relative
importance of a flood warning requiring evacuation of Topeka in the next
24 hours versus a chlorine spill on Main Street right now? And it's not
like we have to force TV stations to broadcast alerts and news about
emergencies!
I think we should focus on the standards (e.g. CAP) and architecture for
getting warning and alert messages to the systems that reach the public,
and then let the systems and their customers sort out what is important
to them.
David K. Aylward, Director
COMCARE - Emergency Response Alliance
1701 K Street NW Fourth Floor
Washington, DC 20006
Telephone: 202.429.0574 ext. 201 202.255.3215 (mobile)
202.296.2962 (fax)
daylward at comcare.org
This communication is intended for the use of the recipient to which it
is addressed, and may contain confidential, personal and/or privileged
information. Please contact us immediately if you are not the intended
recipient of this communication, and do not copy, distribute, or take
action relying on it. Any communication received in error, or subsequent
reply, should be deleted or destroyed.
-----Original Message-----
From: cap-list-bounces at lists.incident.com
[mailto:cap-list-bounces at lists.incident.com] On Behalf Of matt hoffman
Sent: Monday, October 15, 2007 4:39 PM
To: Rex Buddenberg
Cc: cap-list at lists.incident.com; Art Botterell
Subject: Re: [CAP] Presidential CAP questiion
Agreed, you point out very well why preemption doesn't really apply in a
packet-switched network, but the destination systems are still very
likely to have that need, correct? TV and radio broadcasts are just as
single-channeled as they ever were. So a Presidential message, while
not needing to preempt other messages at the router level, would have
enough priority to be handled differently at the broadcast level
(potentially pre-empting other broadcasts, if the current model is
followed) as well as being treated favorably at the server level, using
priority queuing techniques as you mention.
So, from the network perspective, we can say "high-priority" instead of
"pre-empting", but from the broadcasters' point of view, "pre-empting"
still applies.
The original poster, if I read him correctly, was asking whether there
was a source of messages that were of that highest priority that would
cause broadcasters to interrupt current broadcasts, as per the various
Executive Orders. The details of how the message gets from the source
to the destination needn't apply.
Rex Buddenberg wrote:
> I think the question really has to do with the nature of packet
> switching and the archaic circuit switched notion of pre-emption.
(With
> Presidential as just one instantiation)????
>
> In circuit-switched networks, a channel can carry only one application
> at a time. Which translates to user terms of 'gotta hang up on one
> conversation to pick up another'. Pre-emption is a means of forcing
the
> first conversation to close so one can barge in with the second. In
the
> interior of the network, pre-emption is represented by a parallel
'grab
> the circuit'. In abstract terms, circuit switched networks are
> connection-oriented.
>
> But in packet switched systems things change. Packets arrive at
routers
> from multiple applications in no particular order or organization.
> Layer 3 plumbing in the internet is expressly connectionless and
> stateless. Therefore, pre-empting' a connection makes no sense --
there
> aren't any. (*more below)
>
> This doesn't translate quite as intuitively to end system
applications.
> It may make sense to interrupt one human conversation to get a
> converser's attention. But this has nothing to do with the underlying
> plumbing any more.
>
> There was a working group in IETF a few years ago thrashing emergency
> services issues. Great amounts of flame and heat trying to get some
of
> the members to understand that 'pre-empt' belonged in places like SIP
> servers, not routers.
>
>
>
>
> *in most of the internet infrastructure, there's enough
overprovisioning
> that fiddling with packet priorities within a router makes no sense
> either -- there's nothing you can do to 'improve' service if there's
no
> congestion. The place where this does become important is at the
parts
> of the internet where we reach to mobile platforms -- the radio-WANs.
> But that's a different conversation, so I won't chase it here unless
> somebody rings back (it's my research area). Here the issue is not
> pre-emption in the customary sense, but a packet prioritization sense
> where 'the most important packets get handled first'. The definition
of
> 'most important' is always disputed along with the means of marking
> packets with appropriate labeling.
>
>
>
> On Mon, 2007-10-15 at 14:16 -0400, matt hoffman wrote:
>
>> Art is certainly the authority on this, but I'll second that
impresson.
>> I've worked on IPAWS-related prototypes implementing CAP interfaces,
but
>> I have never heard mention of any system that disseminated
Presidential
>> messages via anything other than the existing EAS framework.
>>
>> Matt
>>
>>
>> Art Botterell wrote:
>>
>>> Jim -
>>>
>>> I can't speak for FEMA, but I would expect that presidential
messages will go from WACA to FEMA for distribution through the IPAWS
framework to EAS, cellular and other dissemination media. Of course,
presidential alerts have been, to date, vanishingly rare.
>>>
>>> - Art
>>>
>>>
>>> Art Botterell, Manager
>>> Community Warning System
>>> Contra Costa County Office of the Sheriff
>>> 50 Glacier Drive
>>> Martinez, California 94553
>>> (925) 313-9603
>>> fax (925) 646-1120
>>>
>>>
>>>
>>>>>> "Jim Trawick" <JimTrawick at viaRadio.com> 10/15/2007 7:45 AM >>>
>>>>>>
>>>>>>
>>> Although there's been a lot of talk about the Presidential messaging
>>> possibilities in DEAS and at least three different versions of what
that
>>> might be (PBS, NOAA and DHS variations, that I'm aware of), is
anyone aware
>>> of a specific, currently available Presidential source (i.e.,
pre-empting
>>> all others, even those in progress, per various Executive Orders),
which is
>>> available in CAP format (or any other digital, text-oriented
format), and if
>>> so, what that current source might be, and through whom it might be
>>> currently available? Surely one must have been employed in the DMIS
EAN test
>>> back in June.
>>>
>>>
>>> Jim Trawick
>>> Senior Software Engineer
>>> viaRadio Logo Scaleable smaller no tag no background
>>> This list is not for announcements, advertising or advocacy of any
particular program or product other than the CAP itself.
>>> _______________________________________________
>>> This list is for public discussion of the Common Alerting Protocol.
This list is NOT part of the formal record of the OASIS Emergency
Management TC. Comments for the OASIS record should be posted using the
form at
http://www.oasis-open.org/committees/comments/form.php?wg_abbrev=emergen
cy
>>> CAP-list mailing list
>>> CAP-list at lists.incident.com
>>> http://eastpac.incident.com/mailman/listinfo/cap-list
>>>
>>> This list is not for announcements, advertising or advocacy of any
particular program or product other than the CAP itself.
>>>
>> _______________________________________________
>> This list is for public discussion of the Common Alerting Protocol.
This list is NOT part of the formal record of the OASIS Emergency
Management TC. Comments for the OASIS record should be posted using the
form at
http://www.oasis-open.org/committees/comments/form.php?wg_abbrev=emergen
cy
>> CAP-list mailing list
>> CAP-list at lists.incident.com
>> http://eastpac.incident.com/mailman/listinfo/cap-list
>>
>> This list is not for announcements, advertising or advocacy of any
particular program or product other than the CAP itself.
_______________________________________________
This list is for public discussion of the Common Alerting Protocol.
This list is NOT part of the formal record of the OASIS Emergency
Management TC. Comments for the OASIS record should be posted using the
form at
http://www.oasis-open.org/committees/comments/form.php?wg_abbrev=emergen
cy
CAP-list mailing list
CAP-list at lists.incident.com
http://eastpac.incident.com/mailman/listinfo/cap-list
This list is not for announcements, advertising or advocacy of any
particular program or product other than the CAP itself.
More information about the CAP-list
mailing list