What does the presence of a global unicast address indicate in an IPv6 setup?

The presence of a global unicast address in an IPv6 setup indicates that the address is reachable globally on the internet. Global unicast addresses are unique across the entire IPv6 address space, which allows them to be routed on the global internet. This makes these addresses suitable for any device that needs to communicate over the internet without limitations based on local segments or unique address space.

Global unicast addresses are designed to be globally routable and assigned in a hierarchical manner to ensure they can be efficiently routed. In contrast, other types of addresses, such as link-local addresses, can only be used within a single network segment and are not routable beyond that local segment. Therefore, a global unicast address is essential for any device that requires direct access to external networks.