The second point can have significant impact on the operational state of the system in a worst-case scenario: imagine one realm’s home server being inoperable. A user from that realm is trying to roam internationally and tries to authenticate. The RADIUS server on the hotspot location may assume its own national proxy is down because it does not reply. That national server, being perfectly alive, in turn will assume that the international aggregation proxy is down, which in turn will believe the home country proxy national server is down None of these assumptions are true. Worse yet: in case of failover to a back-up next-hop RADIUS server, also that server will be marked as being defunct, since through that server no reply will be received from the defunct home server either. Within a short time, all redundant aggregation proxies might be considered defunct by their preceding hop.