In IPv6, each network interface typically has at least one link-local address in addition to any other global addresses assigned to it. It is not strictly necessary to have both addresses (global and link-local) for an interface to work, but each type of address serves different purposes in the network.

We explain more about these addresses and their use:

Link-Local Address in IPv6

• Definition and Use: Link-local addresses in IPv6 are addresses that are only valid and unique at the link-local level (that is, on the same physical network or network segment). These addresses are used for communication between nodes on the same local network, network operations such as Neighbor Discovery, and for routing protocols.
• Automatic: Each IPv6 interface automatically generates a link-local address (starting with fe80::/10) when activated, even without manual configuration or presence of a DHCP server.

Global Address in IPv6

• Definition and Use: Global addresses are those that can be used to communicate on the broader Internet. Unlike link-local addresses, global addresses must be unique across the entire Internet and are typically provided by an Internet service provider or manually configured in a network environment.
• Configuration: They can be configured manually or assigned automatically through mechanisms such as DHCPv6 or stateless autoconfiguration (SLAAC).

Is It Necessary to Have Both Addresses?

• While the link-local address is automatically generated and is sufficient for some local network operations (such as initial configuration, diagnostics, or communications within the same local network), the global address is necessary to access resources outside the local network ( internet or extended networks).
• In most environments, interfaces will have both addresses configured: one link-local for local operations and at least one global for external communications.

Conclusion

In summary, for complete and effective operation on an IPv6 network, it is recommended to have both addresses configured on the interfaces: the link-local for local network functionality and the global for access to broader networks or the Internet.

However, for certain limited uses or test environments, a link-local address may be sufficient.