Mesh Quest

[Brian DeLacey]

Javier,

Your explanations were great and gave me a much better understanding of how
this works. With your help, I now have the mesh working.

The "mpath dump" command works and I can also now run "get mesh_param"
correctly. I'll expand the test mesh and see what we can do.

After I initially set up mesh machines, a ping attempt gave me the error
message "Destination Host Unreachable." I ran "iwlist mesh scan" (twice),
target devices appeared and ping was successful.

As an FYI, I was able to run "iw dev wlan0 interface add mesh0 ..." even
when wlan0 was still up. I now bring wlan0 down and things sure seem to work
better!

Regarding Ralink, I was successful using Edimax's 802.11g turbo mode PCI
card (EW-7128G) with a Ralink chipset. I used this with the latest drivers
from the compat-wireless-2.6 download.

Thanks for your very helpful respons!
    Brian


On Fri, Feb 13, 2009 at 1:53 PM, Javier Cardona <javier at cozybit.com> wrote:

> Hi Brian,
>
> Thanks for your e-mail.  Comments in line...
>
> > CONFIGURATION
> >
> > What level of functionality is expected to work in the present code base?
>
> http://o11s.org/trac/wiki/RELEASE_NOTES-0.2.1
> http://o11s.org/trac/wiki/RELEASE_NOTES-0.2.0
> + mesh portal functionality (bridging two networks over a mesh)
>
> > The mesh comes up with a default of Channel 1. Do I need to set my wlan0
> to
> > Channel 1 as well?
>
> The driver only supports mode of operation at a time (see
> http://www.linuxwireless.org/en/users/Documentation/modes) at a time.
> In other words, if you have mesh up, you should bring wlan0 down.
>
> > What mode should mesh0 be in? Ad-hoc?
>
> Mesh.
>
> > What mode is wlan0 set to? Do I set my wlan0 device to Ad-hoc mode in
> order
> > to find other mesh0 devices?
>
> No, bring wlan0 down.
>
> > Is mesh0 considered a device or an interface? a virtual device? What is
> the
> > difference?
>
> A virtual interface.
> Interface because it is the interface between the OS and the wireless
> device (aka wireless card).
> Virtual in the sense that there are more than one interfaces for a
> given wireless card.
>
> > Is wlan0 supposed to be up? or down? while the mesh is active?
>
> Down.  In fact, I believe that you get an error if you create a mesh
> interface while wlan0 is up.
>
> > Does wlan0 have an IP address? Is it the same or different from the mesh
> IP
> > address?
>
> You should assign an IP address to the mesh interface (let's call it
> mesh0, but it can have any name you choose).
>
> > Does the mesh0 interface have it's own IP address assigned? Is it the
> same
> > as wlan0 or is it different? Can it be the same? Must it be different?
>
> If you need to have mesh connectivity and connect to an access point
> at the same time, you need two wireless cards.
>
> > Do we need to assign a mode to the mesh interface? Or a particular mode
> to
> > the associated wlan0 device? ie. must it be ad-hoc?
>
> No.
>
> > PLATFORM CONSIDERATIONS
> >
> > Can I be a member of multiple meshes on one machine?
>
> Yes, but you need a separate wireless card for each mesh.
>
> > Can mesh0 interfaces be run across USB Wireless Adapters? Is the
> performance
> > as good / better / worse between USB and PCI?
>
> Probably about the same.  But we don't have hard data.
>
> > Is the performance of an onboard wireless modem (e.g. in a laptop) better
> > than a PCI card or USB adapter, or the same?
>
> The onboard wireless modem will probably be attached to the PCI bus so
> you'll get similar performance.
>
> > Can I run a wireless lan AND a mesh network at the same time, in parallel
> on
> > the same machine? (ie a normal, typical WiFi connection to an access
> point
> > to the internet at the same time as running a mesh0 network not exposed
> to
> > the internet?)
>
> Yes, but you need to wireless cards.
>
> > Why is mesh supported on some Atheros and Broadcom chipsets but not
> chipsets
> > of other vendors?
>
> Limited bandwidth and funding on our end.
>
> > Is a mesh driver support for Ralink close?
>
> Not that I know of.  You may want to ask that in linux-wireless
>
> > What can chipset vendors do to make mesh more widely accessible? (e.g.
> Ralink
> > publishes driver code as open source?)
>
> o11s requires that the wireless cards have a thin MAC (aka soft MAC)
> architecture.  That's the only requirement.
> Other than that, in order to modify the driver to support mesh you
> only need the card specs and time...
>
> > What is the easiest way to find out if your computer can support mesh?
>
> We keep a list of supported drivers here:  http://o11s.org/trac
>
> If you do lsmod on your laptop and one of those modules shows up
> (ath5k, b43, ...) shows up, mesh will work.
> Then follow the instructions here: http://o11s.org/trac/wiki/HOWTO to
> configure it.
>
> Cheers,
>
> Javier
>
>
> --
> Javier Cardona
> cozybit Inc.
>
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