What has been learned from experience with IPv4? First and foremost, more than 32 bits are needed for addresses; the primary motive in developing IPv6 was the specter of running out of IPv4 addresses (something which, at the highest level, has already happened; see the discussion at the end of 1.10   IP - Internet Protocol). Another important issue is that IPv4 requires (or used to require) a modest amount of effort at configuration; IPv6 was supposed to improve this.