ion occursConnectionless network processes are often referred to as packet switched. In these processes, as the packets pass from source to destination, they can switch to different paths, as well as (possibly) arrive out of order. Devices make the path determination for each packet based on a variety of criteria. Some of the criteria (e.g. available bandwidth) may differ from packet to packet. Connection-oriented network processes are often referred to as circuit switched. These processes establish a connection with the recipient, first, and then begin the data transfer. All packets travel sequentially across the same physical circuit, or more commonly, across the same virtual circuit. The Internet is one huge connectionless network in which all packet deliveries are handled by IP. TCP (Layer 4) adds connection-oriented services on top of IP (Layer 3). TCP segments are encapsulated into IP packets for transport across the Internet. TCP provides connection-oriented session services to reliably deliver data. IP is a connectionless system; it treats each packet independently. For example, if you use an FTP program to download a file, IP does not send the file in one long stream of data. It treats each packet independently. Each packet can travel different paths. Some may even get lost. IP relies on the transport layer protocol to determine whether packets have been lost, and to request retransmission. The transport layer is also responsible for reordering the packets. You have learned that the port, or interface, where a router connects to a network, is considered part of that network; therefore, the router interface connected to the network has an IP address for that network. Routers, just like every other device on the network, send and receive data on the network, and build ARP tables that map IP addresses to MAC addresses. Routers can be connected to multiple networks, or subnetworks. Generally speaking, network devices map the IP...
