As of IETF89, Microsoft plans to deactivate their Teredo servers for Windows clients in the first half of 2014 (exact date TBD), and encourage the deactivation of publicly operated Teredo relays. The temporary Teredo protocol includes provisions for a sunset procedure: Teredo implementation should provide a way to stop using Teredo connectivity when IPv6 matures and connectivity becomes available using a less brittle mechanism. In the long term, all IPv6 hosts should use native IPv6 connectivity. In effect, a host that implements Teredo can gain IPv6 connectivity with no cooperation from the local network environment. Thus, IPv6-aware hosts behind NATs can serve as Teredo tunnel endpoints even when they don't have a dedicated public IPv4 address. Teredo alleviates this problem by encapsulating IPv6 packets within UDP/IPv4 datagrams, which most NATs can forward properly. Many NAT devices currently deployed, however, cannot be upgraded to implement 6to4, for technical or economic reasons. In such a situation, the only available public IPv4 address is assigned to the NAT device, and the 6to4 tunnel endpoint must be implemented on the NAT device itself.
However, many hosts currently attach to the IPv4 Internet through one or several NAT devices, usually because of IPv4 address shortage. ( September 2021) ( Learn how and when to remove this template message)įor 6to4, the most common IPv6 over IPv4 tunneling protocol, requires that the tunnel endpoint have a public IPv4 address. Unsourced material may be challenged and removed. Please help improve this section by adding citations to reliable sources. The Teredo server listens on UDP port 3544. Christian Huitema developed Teredo at Microsoft, and the IETF standardized it as RFC 4380. Teredo should be disabled when native IPv6 connectivity becomes available. Teredo nodes elsewhere on the IPv6 network (called Teredo relays) receive the packets, un-encapsulate them, and pass them on. Teredo routes these datagrams on the IPv4 Internet and through NAT devices. Teredo operates using a platform independent tunneling protocol that provides IPv6 (Internet Protocol version 6) connectivity by encapsulating IPv6 datagram packets within IPv4 User Datagram Protocol (UDP) packets. Unlike similar protocols such as 6to4, it can perform its function even from behind network address translation (NAT) devices such as home routers.
In computer networking, Teredo is a transition technology that gives full IPv6 connectivity for IPv6-capable hosts that are on the IPv4 Internet but have no native connection to an IPv6 network.