Unnumbered just means you have no IP address exclusive to the link. IS-IS works without establishing IP connectivity at all, not just about tricks to handle lea

Unnumbered just means you have no IP address exclusive to the link. IS-IS works without establishing IP connectivity at all, not just about tricks to handle leaky internals. This also meant autoconfiguration or supporting non-ip protocols (like routed ethernet) is simpler, though I will admit that OSPFv3 adding default use of link local V6 for router interfaces made the gap smaller.