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 provies 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 Prootocol described in arp(4) to map between Internet and Ethernet addresses on the local network. Selective recption 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
intro(4), inet(4), tc(4), ioasic(4), arp(4).

BUGS
On all front-ends, performance is impaired by hardware whic forces 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.