Teredo

This document specifies a set of extensions to the Teredo protocol. These extensions provide additional capabilities to Teredo, including support for more types of Network Address Translations (NATs) and support for more efficient communication. [STANDARDS-TRACK]

The Teredo protocol defines a set of flags that are embedded in every Teredo IPv6 address. This document specifies a set of security updates that modify the use of this flags field, but are backward compatible. [STANDARDS-TRACK]

We propose here a service that enables nodes located behind one or more IPv4 Network Address Translations (NATs) to obtain IPv6 connectivity by tunneling packets over UDP; we call this the Teredo service. Running the service requires the help of "Teredo servers" and "Teredo relays". The Teredo servers are stateless, and only have to manage a small fraction of the traffic between Teredo clients; the Teredo relays act as IPv6 routers between the Teredo service and the "native" IPv6 Internet. The relays can also provide interoperability with hosts using other transition mechanisms such as "6to4". [STANDARDS-TRACK]