Motorola 326X V.34 SDC Sample Applications, Ensuring Optimum Network Performance in SDC Mode

Configuring the Modem

Refer to Appendix A for additional information on each of these methods.

Ensuring Optimum Network Performance in SDC Mode

The following parameters are critical for ensuring optimum network performance:

•Fast Call (AT*FC)

•DTE Rate (AT*DE)

•Flow (AT*FL)

•TpDlyMin (AT*TD)

Table 4-4shows 326X-SDC option set default settings.

Carefully note the following when configuring the modem for SDC operation:

•Fast Call. Both modems must be configured the same in order to connect. If one of the modems does not support Fast Call, change the default setting to Off.

•DTE Rate. For better link utilization and throughput, higher values than the default may be appropriate. (Refer to the DTE Rate description in Appendix A.) Refer to “Optimizing Network Performance” in the preceding section for more information.

•Flow/TpDlyMin. The default options assume the DTE can accept nondisrup- tive clock stoppage. For DTEs that cannot handle Rx/Tx clock stoppage without disrupting data, select a different option. In this situation, Motorola recommends that the default values not be used.

SDC Sample Applications

SDC Option Set 1—Async Calls to Central Site Using AT ACU

SDC Option Set 1 functions the same as described above for non-SDC modems. Refer to that section for application examples.

SDC Option Set 2—Sync Dial A/B Restoral

Single Channel Point-to-Point Digital Link Restoral (via A/B Switch)

When used as a dial backup device for a digital network, the SDC modem provides economical dial backup and/or disaster recovery, at synchronous speeds matching speeds available on the DDS circuit.

When used as a restoral device for Motorola 35XX DSU/CSUs (Figure 4-1), select SDC Option Set 2 in the local and remote SDC Modems. This places the modems in external timing, as digital services typically provide the network timing.

4-24 Configuring the Modem