.\"
.\" Copyright (c) 1996, 1997 Jonathan Stone.
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"      This product includes software developed by Jonathan Stone.
.\" 3. The name of the author may not be used to endorse or promote products
.\"    derived from this software without specific prior written permission
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
.\"
.\"	$NetBSD: le.4,v 1.2 1997/10/31 02:53:46 jonathan Exp $
.\"	$OpenBSD: le.4,v 1.3 1998/09/06 22:23:20 aaron Exp $
.\"
.Dd August 6, 1996
.Dt LE 4 pmax
.Os
.Sh NAME
.Nm le
.Nd
DECstation AMD 7990 LANCE ethernet interface
.Sh SYNOPSIS
.Cd "le? at mainbus	with le_pmax"		(3100 baseboard)
.Cd "le*? at tc	with le_tc"		(5000/200 baseboard)
.Cd "le? at ioasic  with le_ioasic"	(ioasic baseboard)
.Cd "le* at tc?	with le_tc"		(TC option cards)
.Sh DESCRIPTION
The
.Nm
driver provides access to a 10Mb/s Ethernet via the
.Tn AMD
7990
.Tn LANCE
Ethernet chip.  All
.Tn LANCE
interfaces on
.Tn DECstations  
are supported, as are interfaces on
.Tn "Alpha AXP"
machines with a
.Tn TurboChannel
bus.
.Pp
The
.Nm 
driver employs the Address Resolution Protocol described in
.Xr arp 4
to map between Internet and Ethernet addresses on the local
network.  Selective reception of multicast Ethernet frames is provided
by a 64-bit mask; multicast destination addresses are hashed to a
bit entry using the Ethernet CRC function.
.Pp
No support is provided for switching between media ports.  The
DECstation 3100 provides both AUI and BNC  (thinwire or 10base2) connectors.
Port selection is via a manual switch and is not software configurable.
The
.Tn DECstation
model 5000/200
.Tn PMAD-AA
baseboard device provides only a BNC connector.
The
.Nm ioasic
baseboard devices and  the 
.Tn PMAD-AA
.Tn TurboChannel
option card provide only an AUI port.
.Pp
.Sh SEE ALSO
.Xr intro 4 ,
.Xr inet 4 ,
.Xr tc 4 ,
.Xr ioasic 4 ,
.Xr arp 4 .
.Sh BUGS
On all front-ends, performance is impaired by hardware which forces
a software copy of packets to and from DMA buffers.  The
.Nm ioasic
machines  and the DECstation 3100 must 
copying packet to and from non-contiguous DMA buffers.
The 
DECstation 5000/200  and the
.Tn PMAD-AA 
must copy to and from an onboard SRAM DMA
buffer.  The CPU overhead is noticeable, but all machines can sustain
10Mbit media speed.
.Sh HISTORY
This
.Nm
driver is derived from a
.NM
driver that first appeared in
.Bx 4.4 .
Support for  multiple bus attachments first appeared in
.Nx 1.2 .