X.25 Virtual Circuits as Serial Ports

Incoming Calls as login Ports

Remote terminal users can use an X.3/X.28/X.29 PAD to make an X.25 call to a UNIX system. When the incoming call arrives, the driver accepts the call, engages in a control packet conversation with the remote PAD, and passes the call on to getty for further processing.

If X.25 devices are not available for login because all devices already have users connected, the incoming call is cleared. The diagnostic code associated with this clear is "0xA3".

Adding More login Ports

All modem control devices in the system are available to be opened by the spawned getty. More devices can be created by following the instructions in

Interaction with a Remote PAD

When the virtual circuit is treated as a tty device, it is assumed that the remote device is connected to the packet network with a CCITT-compatible (X.3/X.28/X.29) Packet Assembler / Disassembler (PAD). X.29 command packets are used to determine PAD capabilities, then control the PAD parameters according to the tty-specific ioctl() calls that the application makes. An overview of X.29 and X.3 is provided in the Programmer's Guide.

As remote X.3 parameter manipulation is also an operations issue, this is also shown here. You may tell Netcom II not to manipulate an X.3 parameter with the padd -x option (par:val).

In the example below, ICANON is normally set for line-entry programs like csh, and not set for programs that do their own echoing like vi.

Parameter

Description

Control

1

Escape to Command Mode

The driver sets this parameter to 1 if ICANON is set; otherwise it is set to 0.

2

Echo

The driver sets to 1 if ECHO is set; otherwise, it sets to 0.

3

Forwarding

Set to 126 if ICANON is set (All characters less than SPACE (0x20) and DEL are forwarding characters); otherwise, set to 0.

4

Idle timer forwarding

Set to 0 if ICANON is set.

If ICANON is not set and VMIN is 1, then set to 1.

If ICANON is not set and VMIN is not 1, if VTIME is 1, then set to 1.

If ICANON is not set, VMIN is not 1, and VTIME is not 1, set this parameter to twice VTIME.

5

Ancillary Device Control

Set to 1 if IXOFF is set; otherwise, set to 0.

12

PAD flow control

Set to 1 if IXON is set; otherwise set to 0.

13

Line Feed Insertion

Set to 4 if ICRNL and ONLCR are set; otherwise, set to 0.

15

Line Editing

Set to 1 if ICANON is set; otherwise, set to 0.

16

Back Space Character

Set to ERASE character.

17

Line Kill Character

Set to KILL character.

19

Editing Service Signals

Set to 2 if ECHOE is set; otherwise, set to 8.

21

PAD parity

Set to 0 if IGNPAR is set; otherwise, if PARENB is set, then set to 1.

If neither IGNPAR, nor PARENB are set, then this parameter is controlled by PARODD.

If PARODD is set, this parameter is set to 3; otherwise set to 2.

Revision 6.1.0 (February 2003)

Parameter	Description	Control
`1`	Escape to Command Mode	The driver sets this parameter to 1 if ICANON is set; otherwise it is set to 0.
`2`	Echo	The driver sets to 1 if ECHO is set; otherwise, it sets to 0.
`3`	Forwarding	Set to 126 if ICANON is set (All characters less than SPACE (0x20) and DEL are forwarding characters); otherwise, set to 0.
`4`	Idle timer forwarding	Set to 0 if ICANON is set. If ICANON is not set and VMIN is 1, then set to 1. If ICANON is not set and VMIN is not 1, if VTIME is 1, then set to 1. If ICANON is not set, VMIN is not 1, and VTIME is not 1, set this parameter to twice VTIME.
`5`	Ancillary Device Control	Set to 1 if IXOFF is set; otherwise, set to 0.
`12`	PAD flow control	Set to 1 if IXON is set; otherwise set to 0.
`13`	Line Feed Insertion	Set to 4 if ICRNL and ONLCR are set; otherwise, set to 0.
`15`	Line Editing	Set to 1 if ICANON is set; otherwise, set to 0.
`16`	Back Space Character	Set to ERASE character.
`17`	Line Kill Character	Set to KILL character.
`19`	Editing Service Signals	Set to 2 if ECHOE is set; otherwise, set to 8.
`21`	PAD parity	Set to 0 if IGNPAR is set; otherwise, if PARENB is set, then set to 1. If neither IGNPAR, nor PARENB are set, then this parameter is controlled by PARODD. If PARODD is set, this parameter is set to 3; otherwise set to 2.