David and Others:
I am not a guru, but a know enough to get by. With Dstar, the backend connectivity is TCP/IP. Yes, the internet is used to get to the Trust server and to route traffic to the dstar network. Redundancy for each repeater stack could be built into each repeater site using RF. As an example, Draytek makes a triple wan router that does CLASS A LANS (needed for Dstar) http://www.draytek.com/user/PdInfoDetail.php?Id=21#PdInfo. One Port could be a direct connection to the internet, a second port could be a WIFI or 900MHZ link 30 miles a way to the internet and the third port could be a third connection using microwave to another mountain top with internet connectivity. If money was no object you could use long range Free Space optics (www.canoncanobeam.com) . Typical internet networking, BGP routing etc could all accomplish the redundancy needed for the internet at one location. Biggest issue is cost.... Not perfect, but there are multiple ways to skin the cat as the saying goes. Tom W8RED
