3D Visual Communications

6.1 IP Networks

The backbone of today's widespread networking is the Internet technology that can be better characterized as a packet-switched, store-and-forward, communication network running the Internet family of protocols at the network and transport layers. This single-sentence description entails several key concepts that will be described in the following subsections. More detailed information on these topics can be found on the many very good current textbooks on networking, such as [1], [2] and [3].

6.1.1 Packet Networks

With the development of communication networks came the need to develop switching techniques so as to connect one network node to another network node through the communication process. In early networks, the adopted techniques followed a paradigm known as “circuit switching”. This paradigm is based on establishing at the beginning of a call, a connection between the communicating nodes that is maintained for the duration of the call. In this way, the resources needed for a communication session are exclusively reserved for that session for as long as it lasts. Probably the best example of a circuit switched system is the plain old telephone system (POTS), where the connection is established during dialing, and its resources are reserved until the call ends. An important property to note for circuit switching networks is that the reservation of resources for a connection effectively establishes a state within the network. Connection setup and tear-down ...