Circuit-switched networks use a direct, physical connection to transmit data back and forth. Message-switched networks send entire transmissions between intermediaries. Packet-switched networks route packets through virtual circuits.
After a network grows beyond the confines of the LAN, a carrier service is required.
Carriers provide a variety of services which are connected through remote access.
carrier services Data transfer services provided by telecommunications companies, such as AT&T, Sprint, or Verizon.
remote access A direct connection to a network using regular dial-up lines. After the connection is made, the user can work on the network as if in the office.
Remote access connections are established through either a dial-up network (DUN) or virtual private network (VPN).
The advantages of a VPN are that users benefit from faster network connections, privacy, and security.
dial-up networking (DUN) A client service using regular telephone lines to connect to a network.
Virtual Private Network (VPN) An alternative to using a dial-up network connection. Is a network connection between two computers. With a VPN, a remote user can securely access the internal network from a remote location. Data in the WAN is transported through various technologies:
Circuit switching
Message switching
circuit-switched network A network that creates a direct physical connection between the sender and receiver.
message switching A technology used to route an entire message from one system to another. That message is routed through intermediate (go-between) station and does not involve a direct physical connection between the sender and receiver.