Document revision date: 19 July 1999

The Point-to-Point Protocol utility (PPPD) initiates and manages a Point-to-Point Protocol (PPP) network connection and its link parameters from an OpenVMS Alpha host system. This chapter describes the PPPD commands, with their parameters and qualifiers, that support PPP connections.

For information about the PPP driver and its programming interface, see the files PPP_INTERFACES.TXT and PPP_INTERFACES.PS in SYS$SYSROOT:[SYSHLP.EXAMPLES.PPPD.DOC].

6.1 PPPD Overview

The Point-to-Point Protocol utility (PPPD) allows you to initiate and control a Point-to-Point Protocol (PPP)-compliant network connection from an OpenVMS Alpha host and define its physical link parameters.

Specifically, you can use this utility to:

• Create an asynchronous (ASN) device. PPPD creates the device automatically if one is not currently associated with a serial port (such as TTA1).
• Set both PPP and ASN device characteristics such as flow control and baud rate.
• Inform the network stacks that there is a new physical transport that uses the PPP.
• Act as a simple terminal emulator when establishing a connection to a new system (asynchronous only).
• Display configuration information about the ASN and PPP device drivers as well as any ongoing PPPD sessions.

This section describes and provides examples of the PPPD commands. If you need to customize your PPP settings, command qualifiers are provided. However, most users will be satisfied with the default settings. Table 6-1 summarizes the PPPD command functions.

To invoke PPPD, enter the PPPD command at the DCL prompt as follows:

$ PPPD

The utility responds with the following prompt:

PPPD>

You can then perform PPPD operations by entering the appropriate commands. You can also enter a single PPPD command on the same line as the command that invokes the utility, for example:

$ PPPD CONNECT TTAO:

To exit from the Point-to-Point Protocol utility, enter the EXIT command at the PPPD> prompt or press Ctrl/Z. Either method returns control to the DCL command level.

For information about the PPPD utility, enter the HELP command at the PPPD> prompt.

Table 6-1 PPPD Command Summary

Command	Function
CONNECT	Establishes a network connection through the current physical port or a specified remote port.
DIAL_OUT	Allows direct access to a device to dial out over a modem or link to an external device.
DISCONNECT	Terminates the network connection and returns control to the terminal driver.
EXIT	Leaves the utility and returns you to the DCL command prompt ($).
HELP	Displays help text for PPPD commands.
SET	Determines the device and line characteristics for the specified terminal.
SHOW	Displays the device and line characteristics of the specified terminal.

6.2.1 CONNECT

This command establishes a network connection to a device located on the current physical port or specified remote port.

Format

CONNECT device-name[:]

Parameter

device-name[:]

Optional. Supplies the name of a device through which the network connection is made. The device name has the form ddcu where dd is the device code, c is the controller designation, and u is the unit number. LAN devices are specified as the name of the device that is unit 0. For example, the first terminal device on a LAN is specified as TTA0, the second as TTB0.

Qualifiers

None.

Description

The CONNECT command creates a link, or connection, to the device located on the current physical port or a specific remote port. When you enter this command, control passes to the PPP driver and an incoming transient network session is established. When the session is disconnected, the control of the host device returns to the terminal device driver.

Example

PPPD> CONNECT TTA1:
%PPPD-I-CONNECTTERM, converting connection on device _TTA1: to a 
Point-to-Point connection
      

The command in this example creates a temporary network connection to the serial port TTA1. The port is ready to receive the PPP setup negotiations initiated by the host at the other end of the serial connection.

This command provides access to a specific physical device to dial a modem or link to an external device.

Format

DIAL_OUT device-name[:]

Parameter

device-name[:]

Supplies the name of a device over which the network connection is made. The device name has the form ddcu where dd is the device code, c is the controller designation, and u is the unit number. LAN devices are specified as the name of the device that is unit 0. For example, the first terminal device on a LAN is specified as TTA0, the second as TTB0.

Qualifiers

/BREAK=break-character

Specifies a character sequence that you can use to interrupt the signal being currently transmitted. To interrupt the signal, type Ctrl/break-character. You can select any ASCII character from @ though Z, except C, M, Q, S, and Y. The default break character is ~.

/DISCONNECT=disconnect-character

Specifies a character sequence that you can use to terminate DIAL_OUT mode. To disconnect the call, type Ctrl/disconnect-character. You can select any ASCII character from @ though Z, except C, M, Q, S, and Y. The default disconnect character is \.

/SWITCH=switch-character

Specifies a character sequence that you can use to switch the line to PPP mode. To activate PPP mode, type Ctrl/switch-character. You can select any ASCII character from @ though Z, except C, M, Q, S, and Y. The default switch character is @.

Similar to the CONNECT command, this qualifier switches a line into PPP mode. If the packet negotiations fail, PPPD exits and the line is left in terminal mode. If line is set to /MODEM and /NOHANGUP, this can result in extraneous data, the ASCII representation of Internet Protocol (IP) packets, being transmitted across the open line.

Description

The DIAL_OUT command directs access to a specific physical device to dial a modem or access an external device.

Example

PPPD> DIAL_OUT TTA0:
Type control-~ to send a break, 
     control-\ to disconnect, 
 and control-@ to switch to a point-to-point connection. 
                                        
UNIVRS - Unauthorized access is prohibited 
Username:   SEBASTIAN
Password:   
 
   Welcome to OpenVMS (TM) Alpha Operating System, Version 7.1 on node UNIVRS 
    Last interactive login on Tuesday, AUGUST 13, 1996 02:39 PM 
    Last non-interactive login on Monday, AUGUST 12, 1996 02:16 PM 
 
$  PPPD CONNECT
%PPPD-I-CONNECTTERM, converting connection on device _TTB0: to a 
Point-to-Point connection
Ctrl-@ 
%PPPD-I-CONNECTTERM, converting connection on device _TTA1: to a 
Point-to-Point connection
      

This example illustrates using PPP with a direct serial link.

This command terminates the current network connection.

Format

DISCONNECT (device-name[:]

Parameter

device-name[:]

Optional. Indicates the name of a device over which the network connection occurred. The device name has the form ddcu where dd is the device code, c is the controller designation, and u is the unit number. LAN devices are specified as the name of the device that is unit 0. For example, the first terminal device on a LAN is specified as TTA0, the second as TTB0.

Qualifiers

None.

Description

The DISCONNECT command terminates the physical link to a network, independent of the state of the upper-level protocols. The physical device reverts to the appropriate terminal driver and the upper-level protocols receive a hang-up event. This command is often used to clear and reset port communication settings in the case of a system pause.

PPPD> DISCONNECT TTA1:

The command in this example terminates the current network connection established through the serial port TTA1.

Stops the execution of PPPD and returns control to the DCL command level. You can only enter Ctrl/Z if the line has not already been switched to PPP mode.

Format

EXIT ()

Parameters

None.

Qualifiers

None.

PPPD> EXIT

The command in this example leaves the PPPD utility and returns control to the DCL command level.

6.2.5 HELP

Provides online help information for using the PPPD commands.

Format

HELP [command-name...]

Parameter

command-name

The name of a PPPD command or PPPD command and command keyword. If you enter the HELP command with a command name only, such as HELP SET, PPPD displays a list of all of the command keywords used with the SET command.

Description

The HELP command is an online reference for PPPD commands. After you view an initial help display, press Return. The help display stops and the PPPD prompt is displayed. If you do not specify a command name, the HELP command displays general information on the commands for which help is available. Supplying a command name obtains syntax information for that command.

PPPD> HELP DISCONNECT

In this example, the HELP DISCONNECT command produces a description of the DISCONNECT command and shows the command format.

6.2.6 SET

Sets the communication line characteristics for a specific terminal device.

Format

SET device-name[:]

Parameter

device-name

Indicates the name of the device whose characteristics are to be set. The device name has the form ddcu where dd is the device code, c is the controller designation, and u is the unit number. LAN devices are specified as the name of the device that is unit 0. For example, the first terminal device on a LAN is specified as TTA0, the second as TTB0.

Qualifiers

/ADDRESS_COMPRESSION (default)

/NOADDRESS_COMPRESSION

Indicates whether the address and control fields are compressed.

/CLEAR_COUNTERS=(keyword,...)

Determines which counters to clear when trying to resolve performance problems. The default is to clear all counters. With this qualifier, you can specify one or more of the following keywords:

Keyword	Description
ALL	Resets all counters.
BAD_FCS_PACKETS	Resets the count of packets with a bad frame check sequence (FCS).
DATA_LOST	Resets the count of lost characters that were reported by hardware.
DROPPED_CHARACTERS	Resets the count of all characters thrown away.
FRAMING_ERRORS	Resets the count of characters with framing errors.
LONG_PACKETS	Resets the count of packets longer than the current maximum receive unit (MRU) setting.
RECEIVED_PACKETS	Resets the count of total packets received.
RUNT_PACKETS	Resets the count of packets with too few characters.
TOTAL_CHARACTERS	Resets the count of all characters received.
TRANSMITTED_PACKETS	Resets the count of total packets transmitted.

/CONNECT

Sets the line parameters and binds the ASN device to the physical terminal.

/ECHO=(FAILURE=value, INTERVAL=value)

Specifies the number of Link Control Protocol (LCP) echo requests and the interval between requests that must be sent without response before the line is considered down. The default number of echo requests is 0.

/FLOW_CONTROL=control-option

Indicates the type of flow control used over the physical link. You can specify one of the following keywords with this qualifier:

Keyword	Description
HARDWARE	Uses RTS/CTS flow control. If using this control, the transmit Asynch Control Character Map (ACCM) can be 0x0, 0x0, 0x0, 0x60000000. Only valid for lines set to /MODEM or /COMMSYNCH.
XON_XOFF (default)	Uses band flow control. If using this control, the optimal transmit ACCM is 0xA0000, 0x0, 0x0, 0x60000000. Only valid for asynchronous lines.

/HANGUP

/NOHANGUP

Determines the action that occurs when a session is terminated. This qualifier notifies the ASN driver when a modem hang-up is necessary due to an idle device. For example, when the last network connection is closed on a transient line that is set to /NOHANGUP, the line switches back to the terminal driver but the modem remains connected. This allows users to reaccess the line and log in without having to redial and reestablish the connection.

To use this qualifier, you must have PHY_IO privilege, or the line must have TT2$M_MODHANGUP already set.

/MAGIC_NUMBER_RETRIES=value

Specifies the number of attempts made to negotiate a magic number. Magic numbers are used to detect looped back connections. If you specify 0, no negotiations are made. If you specify 255, negotiation continues until a number is found. The default number of attempts is 5.

/MAXCONFIGURE=value

Indicates the number of configure-request packets sent without receiving a valid configure-ack, configure-nak, or configure-reject before assuming the peer is unable to respond. Specify a value in the range of 0 to 255. The default number of packets sent is 10.

/MAXFAILURE=value

Indicates the number of configure-nak packets sent without receiving a valid configure-ack before assuming that the configuration is not converging. Specify a value in the range of 0 to 255. The default number of packets sent is 5.

/MAXTERMINATE=value

Indicates the number of terminate-request packets sent without receiving a terminate-ack before assuming that the peer is unable to respond. Specify a value in the range of 0 to 255. The default number of packets is 2.

/MRU=size

Specifies the largest packet that can be received over the line. This value is used as part of the line negotiation, and the actual MRU setting can vary. Specify a value in the range of 6 to 1500. The default packet size is 1500.

/MTU=size

Specifies the largest packet that can be transmitted over the line. This value is used as part of the line negotiation, and the actual maximum transfer unit (MTU) setting can vary. Specify a value in the range of 6 to 1500. The default packet size is 1500.

/NETWORK_PROTOCOL=(protocol-name)

Specifies the the protocol allowed over the link. The default network protocol is TCP/IP.

/PASSIVE

/NOPASSIVE (default)

Notifies the PPP driver how to handle the PPP connection. It can either actively initiate the connection or wait for the remote host to start the connection.

/PERMANENT

/NOPERMANENT

Determines how the link is handled when a connection is closed or lost. If you specify /PERMANENT, the link remains in place with the PPP driver in control. If you specify /NOPERMANENT, the link is treated as a transient connection, and the terminal reverts to the terminal driver.

/PROTOCOL_COMPRESSION (default)

/NOPROTOCOL_COMPRESSION

Specifies whether the two octet protocol fields are compressed into a single octet.

/RECEIVE_ACCM=mask-value

Identifies the starting ACCM. This mask is used by the PPP driver to negotiate the final ACCM for asynchronous ports. Specify a mask in the range of 0x0 to 0xFFFFFFFF. The default mask value is 0xFFFFFFFF.

/RESTART_TIMER=msecs

Interval in milliseconds (msecs) used to time the transmission of configure-request and terminate-request packets. Expiration of the restart timer results in a timeout event and retransmission of the packet. Specify a value from 1 to 90. The default is 30 (3 seconds), which is intended for relatively slow speed links. For smaller, faster links, specify a smaller value.

/SPEED=(input-rate,output-rate)

Allows you to control the input and output speed of the line for asynchronous ports. To use this qualifier, you must have PHY_IO privilege, or the line must already have TT2$M_SETSPEED set.

Specify one of the following speeds: 50, 75, 100, 134, 150, 300, 600, 1200, 1800, 2400, 3600, 4800, 7200, 9600, 19200, 38400, 57600, 76800, or 115200. If your line allows split speed, you can specify different speeds for input and output. If you only specify one speed, it is used for both input and output.

/TRANSMIT_ACCM=mask-value,...

Identifies the starting ACCM. This mask is used by the PPP driver to negotiate the final transmit ACCM for asynchronous ports. Specify a mask in the range of 0x0 to 0xFFFFFFFF. The default mask value is 0xFFFFFFFF, 0x0, 0x0, 0x60000000, 0x0, 0x0, 0x0. The masks are ordered from low-order longword to high-order longword. Specify the longword mask until the last mask bits are set. The remaining longwords are set to 0. With eight longwords, there is one bit for every ASCII character position (from 0 to 255). The ASCII characters 0x20 through 0x3F and 0x5E cannot be quoted.

Description

Use the SET command to specify the communications characteristics of a terminal device. Communications characteristics such as address compression, flow control, and line speed determine how data is transmitted and received. These characteristics take effect as soon as you invoke the CONNECT or DIAL_OUT command.

PPPD> SET/PERMANENT TTA0: %PPPD-I-CONNECTTERM, converting connection on device _TTA0: to a Point-to-Point connection

In this example, the SET command is setting up a permanent network connection over the serial port TTA0.

6.2.7 SHOW

Allows you to display the communication characteristics for a specific terminal.

Format

SHOW device-name[:]

Parameter

device-name[:]

Supplies the name of the device whose characteristics are to be displayed. The device name has the form ddcu where dd is the device code, c is the controller designation, and u is the unit number. LAN devices are specified as the name of the device that is unit 0. For example, the first terminal device on a LAN is specified as TTA0, the second as TTB0.

Qualifiers

/ADDRESS_COMPRESSION

Indicates whether the address compression is on or off.

/ALL[=BRIEF] (default)

/ALL[=LONG]

Displays all the current device and communication settings. BRIEF formats the output for the screen. LONG displays each setting on a separate line.

/COUNTERS=(keyword,...)

Shows the current values for the specified counter(s). You can specify one or more of the following keywords with this qualifier:

Keyword	Description
ALL	Displays all counters.
BAD_FCS_PACKETS	Displays the count of packets with bad frame check sequence (FCS).
DATA_LOST	Displays the count of lost characters that were reported by hardware.
DROPPED_CHARACTERS	Displays the count of all characters thrown away.
FRAMING_ERRORS	Displays the count of characters with framing errors.
LONG_PACKETS	Displays the count of packets longer than the current maximum receive unit setting (MRU).
RECEIVED_PACKETS	Displays the count of total packets received.
RUNT_PACKETS	Displays the count of packets with too few characters.
TOTAL_CHARACTERS	Displays the count of all characters received.
TRANSMITTED_PACKETS	Displays the count of total packets transmitted.

/ECHO=(FAILURE=value, INTERVAL=value)

Specifies the number of Link Control Protocol (LCP) echo requests and the interval (in milliseconds) between requests that must be sent without response before the line is considered down.

/FCS_SIZE

Shows the current receive and transmit FCS size in bits.

/FLOW_CONTROL=(keyword,...)

Shows the current flow control setting used over the asynchronous physical link. You can specify one of the following keywords with this qualifier:

Keyword	Description
HARDWARE	Uses RTS/CTS flow control. If using this control, the transmit Asynch Control Character Map (ACCM) can be 0x0, 0x0, 0x0, 0x60000000. Only valid for lines set to /MODEM or /COMMSYNCH.
XON_XOFF (default)	Uses band flow control. If using this control, the optimal transmit ACCM is 0xA0000, 0x0, 0x0, 0x60000000. Only valid for asynchronous lines.

/HANGUP

Displays the action that occurs when a session is terminated.

/MAGIC_NUMBER_RETRIES

Shows the number of attempts that are made to negotiate a magic number.

/MAXCONFIGURE

Shows the number of configure-request packets sent without acknowledgment before assuming that the peer is not responding.

/MAXFAILURE

Displays the number of configure-nak packets sent before sending a configure-ack and before assuming that the configuration is not converging.

/MAXTERMINATE

Shows the number of terminate-request packets sent without acknowledgment before assuming the peer is unable to respond.

/MRU

Displays the largest packet that the line can receive.

/MTU

Displays the largest packet that the line can transmit.

/NETWORK_PROTOCOL

Displays the current network protocol(s) allowed over the physical link.

/PASSIVE

Indicates whether this is a passive or active line.

/PERMANENT

Indicates whether this is a permanent or transient (nonpermanent) line.

/PROTOCOL_COMPRESSION

Shows the status of protocol field compression.

/RECEIVE_ACCM

Displays the value of the current receive ACCM for asynchronous ports.

/RESTART_TIMER

Displays the interval used to time transmission of request packets.

/SPEED

Indicates the current input and output speeds of the line.

/TRANSMIT_ACCM

Displays the value of the current transmit ACCM for asynchronous ports.

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