In IPv6, link-local addresses are unique within a single network segment or link, but can be repeated on different segments or network links that are not directly connected.

Link-local addresses in IPv6 are identified because they always begin with the prefix FE80::/10 and are designed to be used for local communication within the same physical subnet.

Repetition of Link-Local Addresses on Different Networks

Since link-local addresses are only valid within their own local network and are not routable, there is no problem for devices on different network segments to have the same link-local address.

This means that two devices on different and not directly connected network segments can have the same link-local address without causing communication conflicts.

MikroTik and Link-Local Addresses

On MikroTik devices, link-local addresses are automatically generated for all active interfaces that have IPv6 enabled.

These addresses are used for various purposes, including the Neighbor Discovery Protocol (NDP) and other automatic configuration and diagnostic processes within the local network.

Special Considerations

1. Uniqueness in the Same Network Segment: Although link-local addresses can be repeated on different network segments, each address must be unique within its own local network segment to avoid communication conflicts.
2. Address Generation: Link-local addresses on MikroTik devices and other equipment that supports IPv6 are generally generated automatically using the interface identifier based on the MAC address of the network interface, although they can also be configured manually if necessary.
3. Configuration and Diagnostics: It is important to ensure that link-local addresses are configured correctly and working as expected, especially in environments where multiple devices and complex network configurations are used.

Conclusion

In summary, link-local addresses can be repeated on different MikroTik devices as long as they are not on the same network segment.

This feature allows for simplified local network configuration and management without worrying about address shortages or conflicts across different network segments.

However, it is crucial to ensure that within the same network segment, all link-local addresses are unique to avoid communication problems.