Hi Phillipe -
well, Freifunk and others around the globe are successfully using mesh as network infrastructure for their daily communication needs. (I'm using multihop mesh as internet uplink since 4 years).
Here is how it works: Rather than using a zoo of different hardware use one that works, and that is the proprietary (I hate to support this!!!) Broadcom driver for the embedded Broadcom designs used in many 802.11b/g routers.
Get this and go ahead deploying your network. You'll love it. Particularly if you use Freifunk firmware. This is one key to success nowadays.
It is a pitty that Linksys USA is not selling WRT54GL's in the US (correct me if I'm wrong). So most people there are using Atheros SoC - Fonera, Meraki - which are all made by Accton/Taiwan. (Again, correct me if I'm wrong). While people in Europe, Africa and Asia are predominantly using WRT54GL.
As far as I understood Antonio Anselmi, recent RO.B.I.N. firmware works stable in ad-hoc with Atheros SoC.
I was working on a system for the Meraka institute in SA, for their 'Massive Mesh' grid, which was build to practically develop/test/verify mesh routing protocols and drivers. (I was running tests of OLSRD and all B.A.T.M.A.N. versions there.)
I have patched an older Madwifi which works rock-solid in the Meraka mesh. There is only one issue: Fragmentation does not work. To be precise: If you enable it, the cards won't send data packets greater than the fragmentation value anymore :-(
AFAIK this issue is still not solved.
Running different Madwifi VAPs in ad-hoc and master mode is something I didn't test. Last time that I have tested it (quite a while ago) it was a hack. And I was happy if my machine didn't lock up after a while. Since I performed those tests several months ago I can't say much about it.
I see it that way: Keep infrastructure clients separated from your mesh infrastructure - particularly keep clients away from your mesh channel. Otherwise you will degrade performance by using and re-using the same channel all the time. Even if Madwifi VAPs work stable-ish this doesn't perform well. A stupid but working access point is cheap, use the mesh as an uplink. Well, if all that you want is a very cheap mesh with a couple of nodes and want to accept performance issues, you may be fine with VAPs if the driver works.
The new ath5k driver in the most recent Linux kernel works in ad-hoc, but has range issues. As could be read recently in the news, Atheros is actively sponsoring development of their hardware for the kernel now (they are paying a guy to develop drivers).
cu elektra
Hi Elektra,
I haven't replied on the list about my problems with mesh networks but I think I narrowed my issues to exactly this: I have hardware at home that just doesn't like to see an access point with an ADHOC interface AND an AP interface.
The weird hardware: my macbook pro (atheros based?), and a dell truemobile 1400.
The same setup works flawlessly with a D-Link G-630 PCMCIA.
I don't know what to do to resolve these issues, but I will certainly not deploy a mesh network in these conditions where maybe 30%+ of the hardware doesn't work with adhoc mesh!
Tonight I'll try to switch my access points to 802.11b only and see if it's more compatible for adhoc+ap...
If you have any clue as to what to tweak in Madwifi to help with these compatibility issues, let me know :)
On 22-Apr-08, at 3:00 PM, elektra wrote:
In general the ad-hoc mode has been widely neglected by manufacturers and developers. From the first day I started to work on mesh networks I have been battling with firmware/driver issues. But as more and more people start using mesh networks the demand for working drivers is increasing. So we can expect that - finally, after many years - the situation will improve quickly.
It is a pity that Linksys USA is not selling WRT54GL's in the US (correct me if I'm wrong). So most people there are using Atheros SoC - Fonera, Meraki - which are all made by Accton/Taiwan. (Again, correct me if I'm wrong). While people in Europe, Africa and Asia are predominantly using WRT54GL.
Uh, hum... I think this was cleared up, but I have a lot of WRT54gls (in Texas) and I was also able to buy the T-Mobile version with 32MB RAM.
Cheers,
D Davis
thanks, elektra, would it be possible, that an usb stick with wifi chip and coded in software can be distributed? e.g. by foebud? we need a solution, where people use their laptop and not need to configure their routers. The Laptop or USB-Stick has the wifi chip... is there a wiki, where all wifi chips are listed and how the bug fixing for them is going on by whoom?
Maxx
Hi -
I can't recommend using a variety of different wireless hardware with different chipsets, drivers, firmware in a network - yet. And I don't know any USB stick that I would recommend. If someone reading this list has a working recommendation still available for purchase, please add a comment.
What we usually do is: Get a router supported by Freifunk/OpenWRT with Broadcom/Atheros SoC inside, reflash it with Freifunk Firmware and connect it to your notebook. Or: If you have Atheros in your notebook or PC with a self compiled recent Madwifi, fine. Otherwise replace the build-in card with something Atheros-based (you may have to modify your notebooks BIOS if you use IBM/Lenovo/HP, in order that the machine accepts the card), or insert a additional cardbus/express card with Atheros chipset, given that you still have a cardbus/express interface in your notebook. The Madwifi driver shipped with your favorite Linux distro may not work properly, so get it from madwifi.org and compile it against the Linux kernel that you are running.
With Atheros you can fix the IBSSID in order to overcome those notorious issues with cell-splitting, I also managed to perform this with IPW3945. Also OpenWRT/Freifunk does allow this with Broadcom hardware, too.
The command on a Linux-PC to fix the IBSSID is:
iwconfig <interface> ap <your preferred cell-id like 02:CA:FF:EE:BA:BE>
Note that this is non-standard behavior, and is unlikely to work with other cards. Actually upon request from Freifunk this was modified in the Madwifi driver.
Old Cisco Aironet 802.11b works for me (mostly) as long as the mesh is the only ad-hoc network around... I use it every day, it is running stable until I stop it. Also ancient Atmel 76c503 based USB sticks work - I used to build mesh routers with them in the old days ;-) Old Prism2, 2.5, 3 and Prism54 (Hard-Mac only) work, but are susceptible to cell-splitting (and may lock up if cell-splitting is already going on in your WiFi cell).
I have a Intel IPW3945 in a new notebook that works somehow with a little trick under Ubuntu (fix the Cell-ID in managed mode first, switch to ad-hoc, set essid, set channel, enable interface) - but from time to time I get hiccups that seem to be associated with firmware errors (reported in syslog) - then I need to reset the interface). The experience with IPW2200 was even worse with a notebook I used a year ago, but I didn't try that recently.
Broadcom would be an option, but the company doesn't provide drivers for Linux-PCs. There is an open-source driver but I don't know whether it actually works in ad-hoc mode now.
cu elektra
thanks, elektra, would it be possible, that an usb stick with wifi chip and coded in software can be distributed? e.g. by foebud? we need a solution, where people use their laptop and not need to configure their routers. The Laptop or USB-Stick has the wifi chip... is there a wiki, where all wifi chips are listed and how the bug fixing for them is going on by whoom?
Maxx
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