1. Evolving IP networks and uses

1.1 IP protocol and the Internet

The Internet Protocol (IP) was defined at the end of the 70s to unify communications within networks, and even more so between networks. It is the foundation of today's Internet. IP is located at Layer 3 ("network") of the OSI model, and relies on the notion of routers to route data to its destination (figure 1 ). It is an unreliable protocol (datagram mode), reliability being provided as required by a higher transport layer (using TCP (Transmission Control Protocol), for example).