DRPD(1M)

NAME

drpd - Realport Network Daemon

SYNOPSIS
drpd [ -dV ] [ -p port ] [ -s speed ] device node [ speed ]

AVAILABILITY
HP-UX

DESCRIPTION

Each instance of drpd supports a single connection between a UNIX system and a Realport client (such as a Digi Portserver). Each connection provides 8 to 64 Realport tty devices on the host.

Operation is as follows:

(1) The program decodes its command parameters, daemonizes, and opens the drp device for which it is responsible.

(2) The program allocates an unprivileged socket, and connects to the Realport server. If the connection is unsuccessful, the program continues to attempt a connection at regular intervals until the connection succeeds.

(3) Upon successful connection, the program begins normal operation. During normal operation the program copies all data received from the Realport server to the drp device, and all data received from the drp device to the Realport server.

(4) If the first byte of a packet received from the drp device is an FF (indicating an error status) the packet is sent to the network connection, but then the connection is shut down and operation resumes at step (2)

(5) If the network connection is lost, the program writes a zero-length packet to the drp device, indicating the error condition and then goes back to step (2).

(6) Operation continues until the program is interrupted by the drpadmin program or the system shutdown procedure. When interrupted the program closes the drp device. This action hangs up all associated tty devices.

Except for parameter errors, drpd syslogs all abnormal conditions with priority daemon.info.

Command parameters include:

device
    An integer in the range 0-999 indicating the logical connection number and the devices associated with this daemon. On HP-UX this is the same as the /dev/drpD minor device number.

node
    The node name or the TCP/IP dot address of the Realport server.

speed
    An optional parameter useful on slow speed WAN links. Speed is a formatted string containing 1 to 5 decimal numbers, separated by commas or periods. The numbers are:

    (a) Maximum link speed in bits/second
    (b) Highest delay for maximum speed in milliseconds
    (c) Minimum link speed in bits/second
    (d) Lowest delay for minimum speed in milliseconds
    (e) Estimated packet header size

    This parameter allows the user to configure a balance between latency (eg keystroke delay) and throughput. When the instantaneous delay between the UNIX system and the Realport client is below (b), the UNIX system transmits data at up to rate (a). However when the delay exceeds (d), data is send only at speed (c). When the delay is between (b) and (d), data is sent at a proportional value between (a) and (c).

    In each of these computations we assume a packet header size of (e) for each packet sent across the link. A value of 46 bytes is assumed by default; this value is appropriate for Encapsulated Ethernet over Frame Relay. A value of 8 should be used for PPP links with Van Jacobsen header compression.

    Most WAN users need specify only parameter (a) and let parameters (b) (c) (d) (e) take default values. For example most 56K Frame Relay links with a combination of terminals and printers can use a simple speed string of just 56000.

OPTIONS

-d  Enables verbose debugging information. May be specified twice for even more information.

-p port
    Realport server port number. Defaults to 771.

-s speed
    Inspects the given speed and then immediately exits. The program returns status 0 if the string is valid; otherwise it outputs an error message and returns status 2. This option is used by the drpadmin program.

-V  Prints the current version number.

EXIT STATUS
On normal completion with -V or -s returns exit status 0.

Upon receipt of an interrupt, or on a fatal execution error generates a syslog entry and exits with status 1.

On a parameter error generates a message to stderr, and exits with status 2.

SEE ALSO

ditty(1), drp(7), drpadmin(7)