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Step 2—ASCII—Setting the Number of Virtual Devices
Virtual devices are used by the server system to direct output to devices on your
system. AS/400 Telnet server support automatically selects (and creates, if
necessary) these devices for you. You may also choose to create your own virtual
device under the QVIRCDnnnn virtual controller.
The option is available for you to allow the Telnet server support on the AS/400
system to automatically configure virtual controllers and devices. The QAUTOVRT
system value specifies the maximum number of devices that are automatically
configured by the system. Use the Change System Value (CHGSYSVAL) command
to change the value of the QAUTOVRT system value. For example, entering the
following command string changes the number of virtual devices that can be
allocated on a system to 50:
CHGSYSVAL SYSVAL(QAUTOVRT) VALUE(50)
Note: QAUTOVRT has been modified for Version 4 Release 2 to support numeric
values of 0 through 32500, and a special value of *NOMAX.
To determine and set the maximum number of users you want signed on to the
AS/400 system at any time, do the following:
1. Set the QAUTOVRT value to 32500, the maximum value allowed, or use the
*NOMAX value.
2. Let your users use pass-through, Telnet, and the virtual terminal application
program interface until you decide that the number of virtual devices created is
sufficient for normal system operation.
3. Change the QAUTOVRT value from 32500 to the number of virtual devices you
require for normal system operation.
If you have never allowed automatic configuration of virtual devices on your system,
the QAUTOVRT value is 0. A Telnet connection attempt with a dependence on
automatic creation of the virtual device then fails because the Telnet server does
not create more than the specified QAUTOVRT devices (zero). If you try to connect,
you receive a message (TCP2504) indicating that the Telnet client session has
ended and the connection is closed. In addition, the QTGTELNETS job in the
QSYSWRK subsystem on the AS/400 Telnet server sends a message (CPF8940)
indicating that a virtual device cannot be automatically selected.
If you change the QAUTOVRT value to 10, the next Telnet connection attempt
causes the Telnet server to create a virtual device. This virtual device is created
because the number of virtual devices on the controller (0) is less than the number
specified in the QAUTOVRT (10). Even if you change the specified number to 0
again, the next user attempting a Telnet connection succeeds. When a Telnet
connection attempt fails, the CPF87D7 message is sent to the system operator
message queue on the Telnet server system. The CPF87D7 message indicates that
the AS/400 server is not able to create a virtual device.
Security Considerations for ASCII Full-Screen Mode
The number of sign-on attempts allowed increases if virtual devices are
automatically configured. The number of sign-on attempts is equal to the number of
system sign-on attempts allowed multiplied by the number of virtual devices that
can be created. The number of system sign-on attempts allowed is defined by the
QMAXSIGN system value. The number of virtual devices that can be created is
defined by the QAUTOVRT system value.
212 OS/400 TCP/IP Configuration and Reference V4R4