Authority-to-Citizen Alert WG
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There are a variety of mechanisms that authorities have available to
notify citizens and visitors during emergency events. Traditionally,
they have done so with broadcast networks (radio and television). For
commercial mobile devices, broadcasting services such as the Public
Warning System (PWS), the Earthquake and Tsunami Warning System
(ETWS), and the Commercial Mobile Alert System (CMAS) are
standardized and are in various stages of deployment. The Internet
provides another way for authority-to-citizen alerts to be sent, but
it also presents new challenges. While there are some existing
layer 2 mechanisms for delivering alerts, the work in this group
focuses on delivering alerts to IP endpoints only.
The general message pattern that this group is intended to address is
the sending of alerts from a set of pre-authorized agents (e.g.,
governmental agencies) to a large population without undue impacts
on the networks serving that population. In particular, the message
pattern specified should avoid congestion and other denials of service.
The goal of this group is not to specify how originators of alerts
obtain authorization, but rather how an ATOCA system can verify
authorization and deliver messages to the intended recipients. A
critical element of the work are the mechanisms that assure that
only those pre-authorized agents can send alerts via ATOCA, through
an interface to authorized alert distribution networks
(e.g., iPAWS/DM-Open in the U.S.).
The ATOCA effort is differentiated from and is not intended to
replace other alerting mechanisms (e.g., PWS, CMAS, ETWS), as the
recipients of ATOCA alerts are the wide range of devices connected to
the Internet and various private IP networks, which humans may have
"at hand" to get such events, as well as automatons who may take
action based on the alerts. This implies that the content of the
alert contains some information, which is intended to be consumed
by humans, and some which is intended to be consumed by automatons.
Ideally, the alerts would contain, or refer to media other than text
media (e.g., audio and/or video). The initial work in the group is
focused on small messages, which may be mechanically rendered by the
device in other forms (text to speech for example). Future work in
the group may investigate rich media.
In situations of a major emergency there could be scenarios
where there are multiple alerts generated that may require that a
priority mechanism (defined by alert originator policy) has to be
used. The work on a resource priority mechanism is out of scope of
the initial charter, but may be revisited at a later date.
Which devices should get alerts is primarily driven by location.
The first set of recipients that must be catered for are those
within the area identified by the alert originator to be affected
by the emergency event. In many jurisdictions, there are regulations
that define whether recipients/devices within the affected area have
opt-in or opt-out capability, but the protocols ATOCA will define
will include both opt-in and opt-out mechanisms. The group will
explore how to support both opt-in and opt-out at the level of
communication protocols and/or device behavior.
Another class of recipients that are in scope of the work are
explicit opt-in subscriptions which ask for alerts for a specified
location, not necessarily the physical location of the device itself.
An example of such a subscription would be 'send me alerts for
location x' (previously determined as the location of interest).
This work may build on existing IETF GEOPRIV location work.
There are efforts in other fora on early warning, which will be
considered in this effort. For example, we expect to make use
of the OASIS Common Alerting Protocol (CAP) for the encoding of
alerts. OGC, ATIS, TIA, ITU-T, ETSI and 3GPP also have alert
efforts underway, and consultation with these efforts will be
undertaken to avoid unnecessary duplication of effort and also
to avoid unintentional negative impacts on the networks. Of course,
existing protocols for delivering messages (e.g., SIP, XMPP, or SMTP)
will be the basis for the message delivery system of this working group.
Any service discovery mechanisms defined by the group are expected
to reuse existing discovery frameworks.
The security implications of mechanisms that can send alerts to
billions of devices are profound, but the utility of the mechanism
encourages us to face the problems and solve them. In addition, the
potential performance and congestion impacts to networks resulting
from sending alert information to billions of devices must be
considered and solved if such a service is implementable. To avoid
manual configuration of servers distributing alerts a discovery
mechanism will be specified.