Unique local address

A unique local address (ULA) is an Internet Protocol version 6 (IPv6) address in the address range fc00::/7. These addresses are non-globally reachable (routable only within the scope of private networks, but not the global IPv6 Internet). Because they are not globally reachable, ULAs are somewhat analogous to IPv4 private network addressing. However, there are also significant differences, as each user of ULAs has a unique address range, whereas IPv4 private addressing is common to many users. Unique local addresses may be used freely, without centralized registration, inside a single site or organization or spanning a limited number of sites or organizations.