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.
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.
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.