Supported Chipsets
One of the most important choices you face when building a
CUWiNware node is what wireless NIC to buy. Wireless NICs use a
variety of chipsets depending on the the manufacturer that makes
them. The chipset that your wireless NIC uses must have drivers in
NetBSD that support Ad-Hoc mode.
Theoretically different chipsets can be used in different nodes on
a CUWiNware network as long as they are supported by NetBSD but
because of various bugs/quirks in the firmwares of various chipsets,
it is often best to standardize on a single supported chipset for all
the nodes in your network.
Chipsets
-
Intersil Prism - The prism (version 2, 2.5, or 3)
chipset is used in some PCMCIA and PCI cards manufactured by D-Link,
Proxim, SMC, and others. This chipset is well supported in Ad-Hoc
mode with no real bells and whistles. This may be the best chipset
available if low cost PCI cards are needed for low-resource nodes.
-
Atheros - Atheros makes the most advanced 802.11x
NICs currently available. This is the chipset currently recommended
by the CUWiN team. Most tri-mode a/b/g cards on the market use the
Atheros chipset. The Atheros chipset features a Hardware Abstraction
Layer which puts most of what would traditionally be in the firmware
into software. This means that when/if the interface to the cards is
fully opened up to programmers, arbitrary control of power levels
and other low level features will be possible. Because future
versions of CUWiNware will take advantage of this fine grained
control we recommend investing in cards with this chipset
now. Atheros cards may be a bit more expensive than some of their
competitors and the drivers for the Atheros cards are not as mature
as those for the Prism cards so there may be bugs, but these drivers
are being actively developed and debugged by the CUWiN team.
-
Hermes - Most cards made by Orinoco, Lucent,
WaveLAN, and Proxim use the Hermes chipset. These cards have very
good sensitivity with low power radios and they are supported in
NetBSD but they suffer from serious firmware problems relating to
their IBSS ids. The IBSS id needs to be the same throughout the mesh
but cards with this chipset often "split" the IBSS in a way that can
only be fixed by rebooting all nodes on the network in a certain
order. This chipset should generally be avoided for any Ad-Hoc
network as just one Hermes chipset mixed in with other nodes can
cause a serious network split. Firmware upgrades do not appear to
completely solve this problem. Aironet/Cisco chipsets have the same
problem.
-
Other Chipsets - Development of drivers for new
chipsets is constantly in progress. Some manufacturers publish the
specs for their hardware which makes driver development fairly
straightforward. Other manufacturers keep their specifications
proprietary which means that NetBSD developers have to reverse
engineer the interfaces. Support for the ADMTek ADM8211A is
available now and support for other ADMTek chipsets such as ADMtek
ADM8211C/CR is expected soon. Support for the Realtek RTL8180 chipset has also been added.
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