Global Unicast
**
IPv6 global unicast addresses are similar to public IPv4 addresses. These addresses are allocated by the Internet Assigned Numbers Authority (IANA) to the Regional Internet Registries (RIRs). RIRs have the task of allocation to services providers and other local registries. IANA maintains an official list of the current state IPv6 address allocation at http://www.iana.org/assignments/ipv6-address-space/ipv6-address-space.xhtml
//
So, each company is assigned a unique IPv6 address block called a global routing prefix – a set of addresses that only one company can use. The company subnets its assigned IPv6 address block using addresses only from the block. As a result, IPv6 global unicast addresses are unique across the globe.