LE(4) OpenBSD Programmer's Manual (PMAX) LE(4)
NAME
le - DECstation AMD 7990 LANCE ethernet interface
SYNOPSIS
le? at mainbus with le_pmax (3100 baseboard)
le*? at tc with le_tc (5000/200 baseboard)
le? at ioasic with le_ioasic (ioasic baseboard)
le* at tc? with le_tc (TC option cards)
DESCRIPTION
The le driver provides access to a 10Mb/s Ethernet via the AMD 7990 LANCE
Ethernet chip. All LANCE interfaces on DECstations are supported, as are
interfaces on Alpha AXP machines with a TurboChannel bus.
The le driver employs the Address Resolution Protocol described in arp(4)
to map between Internet and Ethernet addresses on the local network. Se-
lective 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.
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
DECstation model 5000/200 PMAD-AA baseboard device provides only a BNC
connector. The ioasic baseboard devices and the PMAD-AA TurboChannel
option card provide only an AUI port.
SEE ALSO
arp(4), inet(4), intro(4), ioasic(4), tc(4)
BUGS
On all front-ends, performance is impaired by hardware which forces a
software copy of packets to and from DMA buffers. The ioasic machines
and the DECstation 3100 must copying packet to and from non-contiguous
DMA buffers. The DECstation 5000/200 and the 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.
HISTORY
This le driver is derived from a driver that first appeared in 4.4BSD.
Support for multiple bus attachments first appeared in NetBSD 1.2.
OpenBSD 2.8 August 6, 1996 1