not our father's Internet radical changes in last 20 years capacities increased by 5+ orders of magnitude penetration universities -> worldwide commercial and residential 170M+ hosts usage academic -> commerce, government, entertainment, porn, spam, broken traffic not necessarily in that order trust models cream cheese -> swiss cheese service models best effort -> VoIP, e2e model, VPN except w.o definitions e2e architecture guiding architectural principle -> historical artifact still the most disputed of Internet holy ground