NAME
百度 ”通过30多年的摸索和实践，西安交大少年班的复试形式和内容日趋完备，形成了一套行之有效的模块。ral —
Ralink Technology/MediaTek IEEE
802.11a/b/g/n wireless network device
SYNOPSIS
ral* at cardbus?
ral* at pci?
DESCRIPTION
The ral driver supports PCI/PCIe/CardBus
wireless adapters based on the Ralink RT2500, RT2501, RT2600, RT2700,
RT2800, RT3090 and RT3900E chipsets.
The RT2500 chipset is the first generation of 802.11b/g adapters from Ralink. It consists of two integrated chips, an RT2560 MAC/BBP and an RT2525 radio transceiver.
The RT2501 chipset is the second generation of 802.11a/b/g adapters from Ralink. It consists of two integrated chips, an RT2561 MAC/BBP and an RT2527 radio transceiver. This chipset provides support for the IEEE 802.11e standard with multiple hardware transmission queues and allows scatter/gather for efficient DMA operations.
The RT2600 chipset consists of two integrated chips, an RT2661 MAC/BBP and an RT2529 radio transceiver. This chipset uses the MIMO (multiple-input multiple-output) technology with multiple radio transceivers to extend the operating range of the adapter and to achieve higher throughput. However, the RT2600 chipset does not support any of the 802.11n features.
The RT2700 chipset is a low-cost version of the RT2800 chipset. It supports a single transmit path and two receiver paths (1T2R). It consists of two integrated chips, an RT2760 or RT2790 (PCIe) MAC/BBP and an RT2720 (2.4GHz) or RT2750 (2.4GHz/5GHz) radio transceiver.
The RT2800 chipset is the first generation of 802.11n adapters from Ralink. It consists of two integrated chips, an RT2860 or RT2890 (PCIe) MAC/BBP and an RT2820 (2.4GHz) or RT2850 (2.4GHz/5GHz) radio transceiver. The RT2800 chipset supports two transmit paths and up to three receiver paths (2T2R/2T3R). It can achieve speeds up to 144Mbps (20MHz bandwidth) and 300Mbps (40MHz bandwidth.)
The RT3090 chipset is the first generation of single-chip 802.11n adapters from Ralink.
The RT3900E chipset is a single-chip 802.11n adapter from Ralink. The MAC/Baseband Processor can be an RT3290, RT5390 or RT5392. The RT3290 is a combo 802.11n and Bluetooth chip. It operates in the 2GHz spectrum and supports one transmit path and on one receiver path (1T1R). The RT5390 chip operates in the 2GHz spectrum and supports one transmit path and one receiver path (1T1R). The RT5392 chip operates in the 2GHz spectrum and supports up to two transmit paths and two receiver paths (2T2R).
These are the modes the ral driver can
operate in:
- BSS mode
- Also known as infrastructure mode, this is used when associating 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.
- Host AP
- In this mode the driver acts as an access point (base station) for other cards.
- 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 ral driver can be configured to use
Wired Equivalent Privacy (WEP) or Wi-Fi Protected Access (WPA1 and WPA2).
WPA2 is currently the most secure encryption standard for wireless networks
supported by OpenBSD. It is strongly recommended
that neither WEP nor WPA1 are used as the sole mechanism to secure wireless
communication, due to serious weaknesses. WPA1 is disabled by default and
may be enabled using the option "wpaprotos
wpa1,wpa2". For standard WPA networks which use
pre-shared keys (PSK), keys are configured using the
"wpakey" option. WPA-Enterprise networks
require use of the wpa_supplicant package.
The ral driver relies on the software
802.11 stack for both encryption and decryption of data frames on the
RT2500, RT2501 and RT2600 chipsets. On the RT2700 and RT2800 chipsets, the
ral driver offloads both encryption and decryption
of data frames to the hardware for the WEP40, WEP104, TKIP(+MIC) and CCMP
ciphers.
The transmit speed is user-selectable or can be adapted automatically by the driver depending on the number of hardware transmission retries.
In Host AP mode, devices with the RT2700, RT2800, RT3090, and RT3900E chipsets are compatible with clients using powersave.
The ral driver can be configured at
runtime with ifconfig(8) or on boot with
hostname.if(5).
FILES
The RT2501, RT2600, RT2700 and RT2800 chipsets require the following firmware files to be loaded when an interface is brought up:
- /etc/firmware/ral-rt2561
- /etc/firmware/ral-rt2561s
- /etc/firmware/ral-rt2661
- /etc/firmware/ral-rt2860
- /etc/firmware/ral-rt3290
The RT2500 chipset does not require a firmware file to operate.
HARDWARE
The following PCI adapters should work:
The following CardBus adapters should work:
The following Mini PCI adapters should work:
EXAMPLES
The following example scans for available networks:
# ifconfig ral0 scanThe following hostname.if(5) example configures ral0 to join network “mynwid”, using WPA key “mywpakey”, obtaining an IP address using DHCP:
nwid mynwid wpakey mywpakey inet autoconf
The following hostname.if(5) example creates a host-based access point on boot:
mediaopt hostap nwid mynwid wpakey mywpakey inet 192.168.1.1 255.255.255.0
SEE ALSO
arp(4), cardbus(4), ifmedia(4), intro(4), netintro(4), pci(4), hostname.if(5), hostapd(8), ifconfig(8)
HISTORY
The ral driver first appeared in
OpenBSD 3.7. Support for the RT2501 and RT2600
chipsets was added in OpenBSD 3.9. Support for the
RT2800 chipset was added in OpenBSD 4.3. Support for
the RT2700 chipset was added in OpenBSD 4.4. Support
for the RT3090 chipset was added in OpenBSD 4.9.
AUTHORS
The ral driver was written by
Damien Bergamini
<damien.bergamini@free.fr>.
CAVEATS
The ral driver does not make use of the
hardware cryptographic engine present on the RT2500, RT2501 and RT2600
chipsets.
The ral driver does not support any of the
802.11n capabilities offered by the RT2700, RT2800 and RT3090 chipsets.
Additional work is required in
ieee80211(9) before those features can be supported.
On the RT2500, RT2501 and RT2600 chipsets, host AP mode doesn't support power saving. Clients attempting to use power saving mode may experience significant packet loss.
Some PCI ral adapters seem to strictly
require a system supporting PCI 2.2 or greater and will likely not work in
systems based on older revisions of the PCI specification. Check the board's
PCI version before purchasing the card.