InternetSystem
From APRSWiki
APRS Internet System
The APRS-IS is an Internet-based backbone network which interconnects APRS radio networks. The core network consists of three first-tier servers and numerous second-tier servers, providing a unified worldwide APRS stream to connected clients.
IGates connect the APRS-IS to radio networks, and typically consist of an Internet-connected PC, radio, and TNC.
(need discussion of ports and filtering)
APRS-IS also is used as a data source for databases like findu and APRSWorld.
APRS-IS is used to transport data that did not originate on RF and should not be gated to RF, some CWOP weather system reports for example.
