PLIP(4)

NAME
plip - Option for the lpt driver to allow IP over Centronics parallel ports

SYNOPSIS
options PLIP
options COMPAT_PLIP10
options COMPAT_PLIP11

DESCRIPTION
The plip interface provides a way to transport IP over Centronics parallel ports. Protocols to communicate with Linux 1.0 and Linux 1.1 hosts are provided. By default the 1.1 protocol is used. To choose the 1.0 protocol use the link0 flag with ifconfig(8). In order to use the 1.0 protocol the kernel has to be compiled with COMPAT_PLIP10.

The COMPAT_PLIP11 option selects a default MTU of 1486 bytes. This is necessary to work around a bug that is present in the plip code for Linux 1.1.x and Linux 1.2.x.

NOTES
To connect two computers a "Laplink parallel cable" is used:

Signalname | Con A | Con B | Description
Data 0 | 2 | 15 | Data out 0
Data 1 | 3 | 13 | Data out 1
Data 2 | 4 | 12 | Data out 2
Data 3 | 5 | 10 | Data out 3/Wake out
Data 4 | 6 | 11 | Data clock out
/Ack | 10 | 5 | Data in 3/Wake in
Busy | 11 | 6 | Data clock in
No Paper | 12 | 4 | Data in 2
Select | 13 | 3 | Data in 1
/Error | 15 | 2 | Data in 0
Gnd | 18-25 | 18-25 | Ground

In both protocol versions Ethernet frames are used. The 1.0 protocol assigns an Ethernet address of the form FD:FD:ww:xx:yy:zz to the interface.

The 1.1 protocol uses FC instead of FD, with ww, xx, yy and zz are taken from the internet address ww.xx.yy.zz of the interface. Ethernet support has to be configured into the kernel in order to use the plip interface.

DIAGNOSTICS

plip?: tx hard error Packet transmission failed even after PLIPMXRETRY (20) retries.

plip?: rx hard error PLIPMXERRS (20) packets caused receive errors in sequence.

plip?: checksum error A packet with a bad checksum was received.

plip?: packet MTU A bogus packet longer than the Maximum Transmission Unit (MTU) length for the media was received.

SEE ALSO
lpt(4), ifconfig(8)

HISTORY
The plip interface appeared in NetBSD 1.0.