Logging in through a pair of modems
You can use a pair of modems to remotely connect to the console port of the device over PSTN when the IP network connection is broken.
By default, modem dial-in is enabled, and you can dial in to the switch. The default user role is network-admin. To change modem dial-in parameters, see "Logging in through the console port locally."
To use a pair of modems to remotely log in to the device:
Connect one modem to the serial port of the PC and another modem to the console port of the device.
Connect each modem to the PSTN through a telephone cable.
Figure 6: Connecting the PC to the device through modems
Obtain the telephone number of the device-side modem.
Configure the following settings on the device-side modem:
AT&F—Restores the factory default.
ATS0=1—Configures auto-answer on first ring.
AT&D—Ignores DTR signals.
AT&K0—Disables local flow control.
AT&R1—Ignores RTS signals.
AT&S0—Forces DSR to remain on.
ATEQ1&W—Disables the modem from returning command responses and execution results, and saves configuration.
To verify your configuration, enter AT&V to display the configuration results.
NOTE:
The configuration commands and output vary by modem. For more information, see the modem user guide.
To ensure successful communication and to avoid data loss, verify that the modems are using a transmission rate higher than the console port's baud rate.
Launch the terminal emulation program on the PC and create a connection using the telephone number of the device-side modem.
Figure 7 through Figure 9 show the configuration procedure in Windows XP HyperTerminal. On Windows Server 2003, add the HyperTerminal program first, and then log in to and manage the device as described in this document. On Windows Server 2008, Windows 7, Windows Vista, or another operating system, obtain a third-party terminal control program first. Then, follow the user guide or online help of that program to log in to the device.
Figure 7: Creating a connection
Figure 8: Configuring the dialing parameters
Dial the telephone number to establish a connection to the device.
Figure 9: Dialing the number
After you hear the dial tone, press Enter as prompted.
If the authentication mode is none, the prompt <HPE> appears. If the authentication mode is password or scheme, you must enter the correct authentication information as prompted.
IMPORTANT:
Do not directly close the HyperTerminal. Doing so can cause some modems to stay in use, and your subsequent dial-in attempts will always fail.
To disconnect the PC from the device, execute the appropriate ATH command in the HyperTerminal. If the command cannot be entered, enter AT+ + +. When the word OK appears, execute the ATH command. The connection is terminated if OK is displayed. You can also terminate the connection by clicking in the HyperTerminal window.