Organizations are looking into the details of IPv6 and see if they are ready to shift from IPv4. For instance, IPv6 has a new header format, and hence, IPv4 routers that have not been designed to support IPv6 cannot parse the fields in the IPv6 header. On the other hand, Layer 2 protocols are not affected where internal switches and hubs don't need an upgrade or replacement. In these short posts I will be writing about some protocols that are often mentioned in the migration from IPv4 to IPv6 platforms.
Teredo is a tunneling protocol that allows clients located behind an IPv4 NAT device to use IPv6 over the Internet. It is used when no other IPv6 transition technology is available. Teredo's infrastructure includes client, servers, relays and host-specific relays:
Teredo Client: is a computer that is enabled with both IPv6 and Ipv4 and that is located behind a router performing IPv4 NAT. The client configures an IPv6 address with the help of a Teredo server and communications with other IPv6 clients through a Teredo relay.
Teredo Server: is a public server connected both to the IPv4 and to the IPv6 Internet and helps clients get their IPv6 address configuration, and facilitates initial communication either between two Teredo clients or between a Teredo client and an IPv6 host. Microsoft has deployed Teredo servers on the IPv4 Internet.
Teredo Relay: is a Teredo tunnel endpoint, which acts as IPv6/IPv4 router that can forward packets between Teredo clients on the IPv4 Internet and IPv6-only hosts.
Teredo host-specific relay: is a host that is enabled with both IPv4 and IPv6 and that acts as its own Teredo relay. Windows Vista and Windows Server 2008 include Teredo host-specific relay functionality. This host tunnels Teredo clients with global IPv6 addresses through the IPv4 Internet.