Enterasys Networks X-PeditionTM manual Asynchronous and Synchronous Support

Asynchronous and Synchronous Support

Asynchronous and Synchronous Support

Synchronous and asynchronous interfaces can be configured for dialed connections to one or more destination networks. When requested, the

XSR uses dialing commands to send the phone number of the destination network to a modem. The modem then dials the destination modem and establishes a connection. Refer to Figure 10-1.

Calls can be placed using the following methods:

•AT commands on asynchronous ports

•V.25bis over synchronous interfaces

•DTR dialing for synchronous interfaces

Figure 10-1 Typical Dial Services Interconnection

Modem Modem

PSTN

XSRXSR

Ethernet Ethernet

AT Commands on Asynchronous Ports

On asynchronous ports, AT commands are used to establish and clear the call. Refer to your modem documentation for a list of supported commands and options. The modem should be configured to drive Data Carrier Detect and Clear To Send CCITT V.24 signals and accept input of the Data Terminal Ready signal set by the XSR.

V.25bis over Synchronous Interfaces

Dial services also support connections from the synchronous serial interface to any modem that supports V.25bis. V.25bis supports two modes of establishing or receiving calls: direct call and addressed call. Dial services support connections using the addressed call mode and synchronous, bit-oriented operation. The addressed call mode allows control signals and commands to be sent over the modem interface to set up and terminate calls.

Devices used for dialing out must support certain hardware signals in addition to V.25bis. When the XSR drops DTR, the device must disconnect any calls that are currently connected. When the device connects to the remote end, Data Carrier Detect (DCD) must be automatically asserted. For many V.25bis devices, raised DCD requires a special cable to crossover DCD and Data Set Ready (DSR) signals.

10-2 Configuring Dialer Services