WL(4)                                                    BSD/i386 Kernel Interfaces Manual                                                   WL(4)

NAME

     wl -- T1 speed ISA/radio lan card

SYNOPSIS

     device wl0 at isa? port 0x300 irq 5

DESCRIPTION

     The wl driver controls a radio lan card system made originally by NCR, then ATT, now Lucent.  The system is spread-spectrum radio at around
     915 MHz (or 2.4 GHz).  With the supplied omni-directional antennae, about 400 feet (indoors, more outdoors) can be covered in circumference.
     This card can talk to the companion (wlp0) pccard.  Speeds vary from 1 megabit to theoretically 2 megabits (roughly T1 in speed).

     The card has three fundamental hardware units, a so-called PSA or programmable storage area, a radio modem, and a Ethernet lan controller.
     The latter component is the ancient (and not very honorable) Intel 82586 Ethernet chip.  Fundamentally it appears to the operating system as
     an Ethernet system, and speaks IEEE MAC addresses.  The radio modem simply translates Ethernet packets to/from radio packets, that are either
     at 2.4 GHz or 915 MHz depending on the radio modem.  It supports a collision avoidance scheme.  The lan controller supports promiscuous mode,
     broadcast, and multicasting (although there is a glitch in the latter).  "It thinks it is Ethernet".

     How it is used depends on the kind of antennae deployed with it.  Point to point applications are possible as are Ethernet-like lan use.  The
     vendor ships an omni-directional antennae that works in the vicinity of 400 feet (indoors).  Point to point antennae can be purchased that
     will go miles.

SETUP

     The card can either be initialized with the vendor supplied DOS setup software.  Typically minimally an IRQ, port, and Network ID must be
     supplied.  Michael Smith's wlconfig(8) utility can now be used to do this work from the UNIX side.  The card is "not" plug and play.  The
     network id controls whether one set of cards can hear another.  If different, cards will read physical packets, but they will be discarded by
     the radio modem.

CONTROL

     In addition to the config utility, there are several sysctl switches that can be used to modify runtime parameters.  The sysctl(8) variables
     are as follows:

     machdep.wl_xmit_delay <useconds>  This variable will cause the driver to insert a delay on transmit.  250 is the default.  The delay should
     probably be a bit longer on faster cpus and less on slower cpus.  It exists because the 82586 was not designed to work with Pentium-speed cpu
     systems and if overdriven will have copious xmit side errors.

     machdep.wl_ignore_nwid <0 | 1>  This switch defaults to 0; i.e., the nwid is not ignored.  It can be set to 1 to cause the nwid to not be
     used.  This may be useful when the device is in promiscuous mode as one can watch for all packets and ignore nwid differences.

     machdep.wl_xmit_watch <milliseconds>  This switch is not currently useful.

     machdep.wl_gather_snr <milliseconds>  This switch is not currently useful.

     There is also a signal strength cache in the driver.  It may be interrogated with wlconfig(8).  Incoming packets are checked for certain
     hardware radio-modem values including signal strength, silence, and quality, which range fro 0..63, 0..63, and 0..15 respectively.  Thus one
     can read out signal strenth values to see how close/far peer nodes are.  The signal strength cache is indexed by sender MAC address.  There
     are two sysctls that change how it filters packets.  Both are on by default.

     machdep.wl_wlcache_mcastonly <0 | 1>  By default this switch is on.  It forces the cache to filter out unicast packets.  Only broadcast or
     multicast packets are accepted.

     machdep.wl_wlcache_iponly <0 | 1>  By default this switch is on.  It forces the driver to discard non-IP packets and also stores the IP src
     address.  ARP packets are ignored, as are any other network protocol barring IPv4 packets.

CAVEATS

     The 82586 has numerous defects.  It may experience transmit-side errors when modern faster cpus send packets at it faster than it can handle.
     The driver (and probably the chip) does not support an all multicast mode.  As a result, it can be used with applications like mrouted(8)
     (ports/net/mrouted), but it must go into promiscuous mode for that to work.  The driver is slow to change modes from "normal" to promiscuous
     mode, presumably due to delays in the configuration code.

SEE ALSO

     sysctl(8), wlconfig(8)

     http://www.wavelan.com

HISTORY

     The wl driver was written by Anders Klemets (thousands of years ago?) and appears to be based on an even older Intel 82586 driver.  The 82586
     controller was one of the first (if not the first?) integrated lan controller on the block.  That does not mean it was the best either.
     Anders ported and or created a driver for the ISA wavelan and PCCARD wavelan system too (wlp).  Robert T. Morris, Jr. ported the Mach drivers
     to BSDI.  Jim Binkley ported them to FreeBSD 2.1.  Michael Smith ported the wl driver only to 2.2.2.  Jim and Michael have been maintaining
     them.  The current state of the driver is NOT ANYONE'S FAULT.  Thanks to Bernie Doehner and Robert Buaas for contributions.

AUTHORS

     Too numerous to mention.  See above.

BSD                                                             September 29, 2006                                                             BSD