Trends in Technology: EAS Update


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So just how will it work? IPAWS will accept standards-based (CAP) alert and warning messages from emergency managers using existing state, local, territorial or tribal systems, or by way of an IPAWS Web interface. These messages will be forwarded to the IPAWS aggregator, which will in turn disseminate the messages via IPAWS OPEN (Open Platform for Emergency Networks). The entities (like 14,000 radio stations and 10,000 cable TV systems in the United States) providing that last mile reach to the public will retrieve pertinent emergency messages (formatted in CAP) from IPAWS OPEN by means of IP networks such as the public Internet. I should also note that the methods of receiving EAS tests that we've been using for years now will continue to exist; messages received from IPAWS OPEN will supplement them.

It wasn't clear when I composed my last article about CAP as to whether or not messages from IPAWS OPEN would be retrieved (pulled) or sent (pushed). According to one industry source I spoke with, it has been resolved that messages will be pulled. This makes a lot of sense from the aspect of network security; it is much more simple to configure a device to originate communication from the LAN side of a firewall or router than it is to configure that same router or firewall to allow unsolicited messages to come in from the public Internet to reach a host on the LAN. This of course also allows the owner of the CAP-enable device at the radio station to decide how frequently updates will be requested, and so forth. According to this same source, IPAWS OPEN will operate like any other large server, from a large (or many large) data centers and it will be the responsibility of FEMA to build a system large enough to handle the tens of thousands of CAP-enabled devices that will be querying it on a regular basis.

Take off your CAP

So now that you know something about IPAWS, let's take a closer look at CAP. Here are some of its most important aspects:

CAP is a simple, general format for exchanging all hazard emergency alerts and public warnings over all kinds of networks. It features the following:

  • Geographic targeting using latitude and longitude shapes and other geo-spatial representations in three dimensions
  • Multilingual and multi-audience messaging
  • Phased and delayed effective times and expirations
  • Updates and cancellations
  • Templates for the creation of warning messages
  • Digital signature capability
  • Facilities for audio and images

    In the course of researching this article I read the "Working Group 5A CAP Introduction Final Report" from CSRIC (Communications Security Reliability and Interoperability Council) and found there is more to the story regarding CAP and EAS.

    -- continued on page 3



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