The algorithm used by the client when multiple
authentication/accounting servers are configured:
direct Use servers in order of precedence, each time beginning
with the highest precedence server and proceeding to
lower precedence servers if the the RADIUS request
fails, until the request succeeds or all servers have
been tried.
roundRobin Use servers in round-robin order, each time beginning
with the next round-robin-ordered server and proceeding
cyclically through servers if the RADIUS request fails,
until the request succeeds or all servers have been
tried.