The novelty is that routing is based on cryptographic identity. Yggdrasil's IPv6 addresses are actually truncated representations of public keys. You configur

The novelty is that routing is based on cryptographic identity. Yggdrasil's IPv6 addresses are actually truncated representations of public keys. You configure the Yggdrasil software with a list of peers which it connects to over normal internet, but then when you route a Yggdrasil address your device talks to all its peers, who talk to their peers and so on until they find your destination. As I understand it, they optimize it by caching the routing information and using bloom filters to find the appropriate peer.