This document summarizes a training presentation on IPv6 theory. It includes sections on IPv4 address exhaustion, OSI layer review, Ethernet and TCP/IP segment formats, common protocols like HTTP and UDP, IPv4 and IPv6 header formats, IPv6 extension headers, IPv6 addressing including examples and shorthand, subnetting and netmasks, address types and scopes, multicast addressing, neighbor discovery, router advertisements, stateless address autoconfiguration, IPv6 support in Cisco IOS, and an example IPv6 network map and configuration.