The Internet is an interconnection of networks, or clouds. Individual networks are administratively distinct and opaque (or should be) to outsiders. The emphasis is on rich connectivity that allows data packets to find new routes, even if some part of the old route fails during a connection. This is possible because each packet is routed separately. In contrast, the telephony network routes calls, using the same path for the duration of the call. Failure of some portion of the pre-arranged path thus results in the loss of the call.

Hosts can be connected on the Internet through a number of network clouds and there are thus multiple possible paths. IP QoS must ultimately work in this environment.