Teredo Protocol - [upd]

The Teredo protocol is a network transition mechanism defined in (updated by RFC 5991 and RFC 6346). Its primary purpose is to provide IPv6 connectivity to nodes located behind Network Address Translation (NAT) devices that do not support native IPv6 and cannot utilize other tunneling methods like 6to4 (which requires a public IPv4 address).

When Client A (Teredo) wants to communicate with Client B (Teredo): teredo protocol

To understand Teredo, one must understand the networking landscape of the early-to-mid 2000s. The Teredo protocol is a network transition mechanism