LANCE(3) LANCE(3)
NAME
lance - LANCE Ethernet device
SYNOPSIS
bind -a #l /net
/net/ether/clone
/net/ether/[0-7]
/net/ether/[0-7]/data
/net/ether/[0-7]/ctl
/net/ether/[0-7]/stats
/net/ether/[0-7]/type
DESCRIPTION
The LANCE Ethernet interface is a directory containing 9
stream directories: one for each of 8 Ethernet packet types
and a clone file.
Each stream directory contains files to control the stream,
receive and send data, and supply statistics. Incoming Eth-
ernet packets are demultiplexed by packet type and passed up
the corresponding open stream. Reading from the data file
reads packets at the head of the stream. A read will termi-
nate at packet boundaries. Each write to the data file
causes a packet to be sent. The Ethernet address of the
interface is inserted into the packet header as the source
address.
A stream is assigned a packet type by opening its ctl file
and writing connect n where n is a decimal integer constant
identifying the Ethernet packet type. A value of -1 stands
for all types. If multiple streams are assigned to a given
packet type a copy of the packet is passed up each stream.
Reading the type file returns the decimal value of the
assigned Ethernet packet type. Reading the stats file
returns status information and the Ethernet address of the
interface.
An interface normally receives only packets whose destina-
tion address is that of the interface or is the broadcast
address, ff:ff:ff:ff:ff:ff. The interface can be made to
receive all packets on the network by writing the string
promiscuous to the ctl file. The interface remains promiscu-
ous until the control file is closed. The extra packets are
passed up only streams of type -1.
SOURCE
/sys/src/9/port/devlance.c
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