The 6bone is an independent outgrowth of the IETF IPng project that resulted in the creation of the IPv6 protocols intended eventually to replace the current Internet network layer protocols known as IPv4. The 6bone is currently an informal collaborative project covering North America, Europe, and Japan. One essential part in the IPv4 to IPv6 transition is the development of an Internet-wide IPv6 backbone infrastructure that can transport IPv6 packets. As with the existing IPv4 Internet backbone, the IPv6 backbone infrastructure will be composed of many Internet Service Providers (ISPs) and user networks linked together to provide the world-wide Internet. Until the IPv6 protocols are widely implemented and fully tested for interoperability, production ISP and user network routers will not readily place production Internet (IPv4) routers at risk. Thus a way is needed to provide Internet-wide IPv6 transport in an organized and orderly way for early testing and early use. The 6bone is a virtual network layered on top of portions of the physical IPv4-based Internet to support routing of IPv6 packets, as that function has not yet been integrated into many production routers. The network is composed of islands that can directly support IPv6 packets, linked by virtual point-to-point links called "tunnels". The tunnel endpoints are typically workstation-class machines having operating system support for Ipv6. Over time, as confidence builds to allow production routers to carry native IPv6 packets, it is expected that the 6bone would disappear by agreement of all parties. It would be replaced in a transparent way by production ISP and user network IPv6 Internet-wide transport. The 6bone is thus focused on providing the early policy and procedures necessary to provide IPv6 transport in a reasonable fashion so testing and experience can be carried out. It would not attempt to provide new network interconnect architectures, procedures and policies that are clearly the purview of ISP and user network operators. In fact, it is the desire to include as many ISP and user network operators in the 6bone process as possible to guarantee a seamless transition to IPv6.