Specifications

Managing IPX
21-16
Modem Considerations
Dial-In Modems
Keep the following in mind when using dial-in modems attached to the network
access server:
• Flow control for the dial-in modem and the access server port must match. CTS
is recommended for access server platforms that support CTS/RTS.
XON/XOFF is recommended for access server platforms that do not
support
CTS/RTS.
• Serial speed for the modem can be configured as high as 115,200 bits/s on some
access server platforms and as high as 57,600 bits/s on others. The access
server port will autobaud up to this speed when the port is configured for
autobaud.
• When autobaud is enabled, in most cases, typing a carriage return once per
second is sufficient to autobaud into the access server when the modem dial-in
connection is complete. In some cases (AppleTalk, for example), it may be
necessary to type a series of three carriage returns at a faster rate for a
successful autobaud.
• Modem DSR must be configured to cycle on modem hang-up. The access
server port is configured to log out the port when DSR cycles, making sure that
the Novell network connection goes away when the PC user is finished.
• Use the fastest modem available. Error-correcting modems that are currently
available provide up to 28,800 bits/s carrier speeds and serial port speeds to
115,200 bits/s. The access server serial ports will autobaud up to 115,200 bits/s.
Dial-Out PC Modems
Keep the following in mind when using dial-out modems attached to the PC:
• The PC should have a high-performance UART chip capable of high speeds
(16450 or 16550). The serial port baud rate of the modem is dependent on the
UART and the type of modem used.
• Normally, set the serial port baud rate of the modem to two to four times the
speed of your modem. The 8250 and 16450 UART chips can be more
susceptible to lower performance due to errors when run at higher speeds.