Configuration Decisions

The standard method used by NetWare Link/PPP to establish switched-circuit connections relies on AT command exchanges with the attached modem.

Some modems and communications equipment, however, do not support AT commands. These devices might support V.25bis dialing or DTR-controlled dialing.

If your modem supports V.25bis dialing, it will have faster dialing time than an AT modem. No modem script or type needs to be configured. The modem, however, might need to have switch settings changed or might need front panel configuration changes. Refer to the manufacturer's documentation for detailed information. The V.25bis dial mode uses the WAN call destination telephone number.

DTR-controlled devices generally require that you configure the remote system telephone number at the DSU or modem. These devices usually provide a limited amount of nonvolatile memory for telephone number storage. Once the remote system telephone number is configured, whenever the device's DTR signal changes from off to on, the device attempts to initiate a call to the specified remote number. An on-to-off transmission of the DTR causes the device to terminate the connection.

Some modems support both AT commands and V.25bis or DTR-controlled dialing. If you have such a choice, consider the following:

• V.25bis might be preferable because it has a faster dialing time and no modem script is required. Programming a modem for V.25bis might be difficult or very easy, depending on the modem. It is worth investigating if V.25bis is an option. Using the V.25bis dial mode, NetWare Link/PPP can dial using the WAN call destination telephone number. On-demand connections can use a single interface and modem to connect to multiple remote systems sequentially.
• Using the AT command mode, NetWare Link/PPP can initialize the modem automatically, based on the specified modem type, and dial using the WAN call destination telephone number. On-demand connections can use a single interface and modem to connect to multiple remote systems sequentially.
• Preprogramming a DTR-controlled device can be both time-consuming and inconvenient. DTR-controlled devices are limited to calling a single remote system.