AN(4) BSD Kernel Interfaces Manual AN(4)
an -- Aironet Communications 4500/4800 IEEE 802.11FH/b wireless network
an* at pcmcia?
an* at pci?
an* at isapnp?
The an driver provides support for the Aironet Communications 4500, 4800
(aka Cisco 340), and Cisco 350 IEEE 802.11 wireless network adapters.
This includes the ISA, PCI, and PCMCIA varieties. The 4500 series
adapters operate at 1 and 2Mbps (FH) while the 4800 and 350 series can
operate at 1, 2, 5.5, and 11Mbps (DS). The ISA, PCI, and PCMCIA devices
are all based on the same core PCMCIA modules and all have the same pro-
gramming interface. However, unlike the Lucent WaveLAN/IEEE cards, the
ISA and PCI cards appear to the host as normal ISA and PCI devices and do
not require any PCMCIA support.
ISA cards can either be configured to use ISA Plug and Play or to use a
particular I/O address and IRQ by properly setting the DIP switches on
the board. (The default switch setting is for plug and play.) The an
driver has Plug and Play support and will work in either configuration,
however when using a hard-wired I/O address and IRQ, the driver configu-
ration and the NIC's switch settings must agree. PCI cards require no
switch settings of any kind and will be automatically probed and
All host/device interaction with the Aironet cards is via programmed I/O.
The an driver encapsulates all IP and ARP traffic as 802.11 frames,
though it can receive either 802.11 or 802.3 frames.
These are the modes the an driver can operate in:
BSS mode Also known as infrastructure mode, this is used when asso-
ciating with an access point, through which all traffic
passes. This mode is the default.
IBSS mode Also known as IEEE ad-hoc mode or peer-to-peer mode. This
is the standardized method of operating without an access
point. Stations associate with a service set. However,
actual connections between stations are peer-to-peer.
monitor mode In this mode the driver is able to receive packets without
associating with an access point. This disables the
internal receive filter and enables the card to capture
packets from networks which it wouldn't normally have
access to, or to scan for access points.
The an driver can be configured to use hardware Wired Equivalent Privacy
(WEP). It is strongly recommended that WEP not be used as the sole mech-
anism to secure wireless communication, due to serious weaknesses in it.
The an driver can be configured at runtime with ifconfig(8) or on boot
The following hostname.if(5) example configures an0 to join network
``mynwid'', using WEP key ``mywepkey'', obtaining an IP address using
an0: failed to allocate N bytes on NIC The driver was unable to allocate
memory for transmit frames in the NIC's on-board RAM.
an0: device timeout The Aironet card failed to generate an interrupt to
acknowledge a transmit command.
arp(4), ifmedia(4), intro(4), isapnp(4), netintro(4), pci(4), pcmcia(4),
The an device driver first appeared in FreeBSD 4.0. OpenBSD support was
added in OpenBSD 2.7. A version of the driver based on the one in NetBSD
was added in OpenBSD 3.9.
The an driver was written by Bill Paul <email@example.com> and ported
to OpenBSD by Michael Shalayeff <firstname.lastname@example.org>. Later the NetBSD
version of the driver by Atsushi Onoe was subsequently ported to OpenBSD
by Jonathan Gray <email@example.com>.
Scanning for access points is not currently supported.
BSD February 28, 2015 BSD