Yggdrasil builds a multi-hop IPv6 overlay network using peer-to-peer connections. You can string a whole bunch of nodes together using whatever means (cables, wireless or TCP peerings over the internet or any other network) and you get a full-mesh network where everyone can reach everyone else.
It's designed to be as minimal-configuration as possible and scalable in a way that many other mesh routing protocols aren't.
It's designed to be as minimal-configuration as possible and scalable in a way that many other mesh routing protocols aren't.