8.8 Remote Connectivity
8.8.4 The modem configuration parameters which
must be set (serial port IRQ, I/O address, maximum port speed) for dial-up networking to function
In order for dial up modems to work properly with the dial-up network the parameters, such as serial ports, IRQs, and I/O addresses must be configured properly. Modems (Modulators/Demodulators) use a serial port for connection and attempt to use COM1 as its default. The EIA/TIA 232 serial standards determine how to connect a modem to a computer.

Serial ports, which are based on DB-9 (nine pins) or DB-25 (25 pins) connectors, are commonly known as COM1, COM2, COM3, and COM4 ports. Data terminal equipment (DTE) represents the computer side of the connection, while the data circuit-terminating equipment (DCE) represent the modem connection. Modems should be set properly; depending on the serial port, modem set up can be done through the start menu/control panel/modems.

Interrupt Request Levels (IRQs) provide a device a way to send interrupt signals to a computer. In many cases, for more than one (if not all) attempts to transfer data into a CPU, each device is issued an IRQ.  An input/output (I/O) address, a four digit hexadecimal number, enables the flow of data within the computer: Addresses are used to select the information to be accessed in memory or peripherals.

The maximum port speed is the speed a modem can support in kilobits per second.  An analog line, also known as a regular telephone line, can support speeds up to 56 kilobits per second using an analog modem.

The requirements for remote connection include:

  • The user must have a valid ID and password in order to access the network remotely. This includes accounts with PPP, SLIP, or RAS.
  • A remote server must be available to be accessed.
  • The appropriate hardware device, such as a modem or ISDN line must be enabled in order to communicate with the server.
  • Network protocols must be configured in order to access the remote server or network