A point to point link is also known as a leased line and which provides the communication between two remote locations through a carrier network such as Telecommunication Company. In circuit switching a carrier network is involved in establishing, maintaining and terminating communication session. In packet switching, the communication devices share point to point link to transfer packets from the source and destination. Dial-up services provide cost effective solutions for WAN connectivity.
The WAN technologies operate at the lowest level of the OSI layer model.
ATM or Asynchronous Transfer Mode is a high bandwidth and high speed wide area network technology that operates at the speed of 155Mbps. ATM is also called cell relay and it supports multiple data types such as data, voice, video etc. ATM uses fixed sized packets for data communication that are also known as packets.
Dial up WAN provide the cost effective communication solutions. Dial up demand and dial up backup is the two WAN dial up services. In a DDR, a router dynamically initiates a call on a switched circuit when it requires sending data.
In dial backup, switched circuit is used to provide the backup services for other types of networks such as PPP or packet switching.
X.25 is a data communication protocol in the packet switched networks. X.25 allows computers at the remote locations to communicate with each other through a centralized computer.
Frame relay is a very high speed and high performance WAN protocol. Frame relay operates at the physical and data link layers of the OSI model. Frame relay is a networking method that is designed for the data transmission between LAN and WAN.
Integrated Services Digital Network is a WAN communication method over the regular telephone lines.
In WAN, when a router has data for the remote site the switched circuit is initiated. When two remote networks communicate and authenticate then the communication starts. ISDN is the best example of the circuit switching network.
In packet switching the common carrier resources are shared between the remote networks. ATM, Frame Relay and X.25 are the examples of the packet switched networks. In this technology, the network has connections into the carrier networks and some portion of the carrier network is shared.
Channel Circuit Unit/Digital Circuit Unit is a device that is used to connect a router with the digital circuit like T1.
WAN routing is a technique of forwarding the packets towards the destination based on the IP address of the next hop.