Large companies that connect to the Internet to provide services to a large number of remote users might consider alternative transmission technologies, such as Asynchronous Transfer Mode (ATM), dedicated Frame Relay, or T3 Internet connections. In the near future, new technologies will provide additional options for connecting to the Internet. These technologies include ones such as Asymmetric Digital Subscriber Line (ADSL), which can operate over existing telephone wires, and cable modems that operate over coaxial cable television wiring.
The following table illustrates when ISDN technology can provide adequate bandwidth, based on minimum bandwidth requirements of different application types, and when alternatives to ISDN should be considered.
Table 4.1 Alternatives to ISDN
|
| Acceptable transmission technology | |
Audio | 28.8 kilobits per second (Kbps) | Analog | |
Audio | 144 Kbps | ISDN-BRI | |
Audio (CD quality) | 1.544 – 2.048 megabits per second (Mbps) for ISDN-PRI, T1 or E1;622 Mbps for ATM | ISDN-PRI, T1 or E1; ATM | |
Data communications | 9.6 Kbps – 28.8 Kbps for analog; 144 Kbps for ISDN-BRI | Analog; ISDN-BRI | |
Video (low end) | 144 Kbps | ISDN-BRI | |
Video conferencing | 1.544 – 2.048 Mbps for ISDN-PRI, T1 or E1; 622 Mbps for ATM | ISDN-PRI, T1 or E1; ATM | |
Video | 6 Mbps for ISDN-PRI; | Dedicated leased lines; ATM | |
Virtual reality programs | 6 Mbps for ISDN-PRI; | Dedicated leased lines; ATM | |
For more information about alternatives to ISDN, see Chapter 3, "Adding Bandwidth for Internet Connectivity."