network. switching" rather than "circuit switching" Circuit-switched networks are based on Time Division Multiplexing (TDM), in which numerous Circuit switching signals are combined for transmission on a single communications line or channel. Once a connection is Circuit switching (see Figure 3.1-1): local exchanges made, a connection is established and remains through- connect to remote exchanges out the session. On the other hand, in packet-switched Each caller may make one call at a time networks relatively small units of data called packets are Line is unusable by others until call terminated routed through a network based on the destination Example: POTS (plain old telephone system) address contained within each packet. Breaking com- munication down into packets allows the same data path Packet switching to be shared among many users in the network. In converged networking, packet-switching technol- Technique used with digital connections to allow ogy is used to carry the information throughout the multiple calls to exist on same circuit network. Converged network supports all of the user's Data broken into small blocks ("packets") traffic types with packet-based protocols such as ATM, Packet includes extra information in Header (serial Frame Relay, or IP. Of these, the dominant protocol in number, destination address, etc.) the access, edge, and core of the network is the Internet Each packet routed to its destination individually Protocol (IP). A managed IP infrastructure for voice, Packets re-assembled into original message when video, and data transmission is a concept that has begun they reach destination to revolutionize the industry. It leverages the Internet SO that enhanced services can be offered at lower costs and Advantages of packet switching it motivates the development of a family of dynamic, Network supports many connections simultaneously next-generation, real-time applications. Voice, video, and data traffic have significantly different characteristics and Short messages not delayed by long