What is IPv6? (1) The answer to IPv4 address space problem IP address changed from 32bit to 128bit 32bit is smaller than worldwide human population IPv4 address shortage is a bondage to new application areas IPv4 addresses will run out around 2010-20? 4x10^9 -> 3.4x10^38 4 billion -> 340 undecillion A new starting point IPv4: used for 20 years, minimal implementation lacks almost everything IPv6: new standard features like multicast, PMTUD, IPsec, autoconfig Leverage the availability of advanced technologies An answer to routing table size issue IPv4: portable address (->CIDR), result in 50K entries IPv6: full CIDR + well-structured address assignment restricts DFZ routes to 8K