How It Works
There are two parts to an establishing a connection with DDR: the physical connection and the digital connection. The physical connection consists of the actual cable that connects computers on the network and the network interface card that allows for communication over these cables. DDR uses existing Public Switched Telephone Network (PSTN) lines – or the network of all public circuit-switched telephone networks - to form a connection between the sender and receiver.
The second part of establishing a DDR connection consists establishing the digital signal. This requires one to determine the protocols to be used over the logical connection. DDR uses a Point-to-Point Protocol (PPP) link, which handles all networking functions such as sending, receiving and compressing the signals between two computers on the internet. In other words, the PPP link uses telephone lines to send signals between you and the computer containing your desired website when you wish make a connection to the internet.
DDR can be used both as a primary and as a backup connection. Today, DDR is mainly used for backup connections which go live when the primary connection fails. DDR connections are inherently slow and service fees are charged like phone calls depending on the uptime. DDR can be used with modems or Integrated Services Digital Network (ISDN) connections, which allow it to achieve a maximum connection speed of only 1.544 Mbit/s in the US and 2.048 Mbit/s in Europe and Australia.
Read more about this topic: Dial-on-demand Routing
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