End-to-end connectivity

End-to-end connectivity is a property of the Internet that allows all nodes of the network to send packets to all other nodes of the network, without requiring intermediate network elements to further interpret them. It was for the first time implemented in the CYCLADES-network.

The transmission control protocol/Internet protocol (TCP/IP) has this property.

However, many network elements and technologies do not have this property, such as network address translation. Without this property, each new protocol requires the specific support of network elements it travels through. This hinders deployment of new applications that use the Internet in ways other than opening TCP connections to other Internet hosts. Examples of hindered applications and protocols include IPsec, migration to IPv6 (tunneling IPv6 in IPv4), peer-to-peer applications, and networked games.

Sometimes end-to-end connectivity is deliberately broken for practical reasons:

• IPv4 address space is a limited resource and it is common to have fewer "real" IP address than one requires
• security, as using some kind of address translation also limits the routing scope, which means that computers behind NAT cannot be addressed directly from untrusted zones.

This trend divides Internet users into those who have "real" Internet connectivity and those who are restricted to use applications that only use outbound TCP connections.

See also

• End-to-end principle

External links

• End-to-End Ethernet Connectivity Fault Management in Metro and Access Networks Technology White Paper
• End to End E2E Links
• The Rise of the Middle and the Future of End-to-End Reflections on the Evolution of the Internet Architecture
• IPv6.com - Knowledge Center for Next Generation Internet IPv6