Unlike 6to4, where the two halves of a connection can use different relays, traffic between a native IPv6 host and a Teredo client uses the same Teredo relay, namely the one closest to the native IPv6 host network-wise. The Teredo client cannot localize a relay by itself (since it cannot send IPv6 packets by itself). If it needs to initiate a connection to a native IPv6 host, it sends the first packet through the Teredo server, which sends a packet to the native IPv6 host using the client's Teredo IPv6 address. The native IPv6 host then responds as usual to the client's Teredo IPv6 address, which eventually causes the packet to find a Teredo relay, which initiates a connection to the client (possibly using the Teredo server for NAT piercing). The Teredo Client and native IPv6 host then use the relay for communication as long as they need to. This design means that neither the Teredo server nor client needs to know the IPv4 address of any Teredo relays. They find a suitable one automatically via the global IPv6 routing table, since all Teredo relays advertise the network 2001::/32.