ORBIT-USER: BSSID/CELL issues in ad-hoc mode

[Ivan Seskar]

This is a known problem even for small networks. In theory, it works if
you bring nodes sequentially up (i.e. bring the first node up set its ID
to something and then follow it up with other nodes - one by one).
Unfortunately it is "extremely" dependant on driver version :-( 

Ivan.

-----Original Message-----
From: owner-orbit-user at winlab.rutgers.edu
[mailto:owner-orbit-user at winlab.rutgers.edu] On Behalf Of Einar Vollset
Sent: Wednesday, August 23, 2006 5:40 PM
To: chris at orderonenetworks.com
Cc: orbit-user at winlab.rutgers.edu
Subject: Re: ORBIT-USER: BSSID/CELL issues in ad-hoc mode



How quickly are you bringing up each node? I had the same problems with
only 5 nodes on the grid when configuring them all at the same time,
like so:

for x in `echo $xcoords`
do
for y in `echo $ycoords`
do
   ssh root at node$x-$y modprobe ath_pci &
   ssh root at node$x-$y ifconfig ath0 down  &
   ssh root at node$x-$y wlanconfig ath0 destroy &
   ssh root at node$x-$y wlanconfig ath0 create wlandev wifi0 wlanmode
adhoc &
   ssh root at node$x-$y iwconfig ath0 essid einarnet &
   ssh root at node$x-$y iwconfig ath0 rate 5.5M &
   ssh root at node$x-$y ifconfig ath0 192.168.$x.$y up &
   echo "Configured node$x-$y"
done
done

..but bringing them up one by one worked (so far anyways):

for x in `echo $xcoords`
do
for y in `echo $ycoords`
do
   ssh root at node$x-$y modprobe ath_pci &&
   ssh root at node$x-$y ifconfig ath0 down  &&
   ssh root at node$x-$y wlanconfig ath0 destroy &&
   ssh root at node$x-$y wlanconfig ath0 create wlandev wifi0 wlanmode
adhoc &&
   ssh root at node$x-$y iwconfig ath0 essid einarnet &&
   ssh root at node$x-$y iwconfig ath0 rate 5.5M &&
   ssh root at node$x-$y ifconfig ath0 192.168.$x.$y up &&
   echo "Configured node$x-$y"
done
done

..This is with madwifi-0.9.2 (which may or may not be what's on by
default. Easy to install though)


The only way I found to set BSSIDs (this is for madwifi drivers), is
with the devices in AP mode:
iwconfig ath0 ap 00:00:00:00:00:00, etc. Perhaps you could do something
like setup one AP, bring up everyone else as a STA, Destroy the AP and
then switch to Ad-Hoc? Pretty hacky, and probably wouldn't work..

As an aside - it's interesting how little google knows about this -
suggests that large scale ad-hoc network experimentation is rather
uncommon.. :-)


p.s. I'd like to take a look at your tools if you wouldn't mind?

Cheers,

Einar




On Aug 23, 2006, at 5:22 PM, Sachin Ganu wrote:

> Hi Chris,
> I believe this functionality for Atheros is embedded in the HAL 
> somewhere. In other words, this now gets us into the wireless driver 
> domain (outside of ORBIT's control, unfortunately :-)
>
> If you are using ad-hoc mode, depending on how it is implemented, the 
> responsibility of cell formation and maintenance is distributed and 
> clearly there are some synchronization problems when the number of 
> nodes goes up.. Hence, some of them start to create their own BSSID's 
> for the same ESSID.
>
> .no solution yet...hence only commiserations. :-)
>
> -Sachin
>
> On 8/23/06, chris at orderonenetworks.com <chris at orderonenetworks.com>
> wrote:
>> I'm hoping someone can help.
>>
>> I've got most of the grid fired up and have huge problems with the 
>> radio's coming up with their own CELL/BSSID numbers and then changing

>> them about every 5 secs or so. This means that I am basically unable 
>> to build a network in the grid. Sandbox nodes have no such problems -

>> most likely this is a size related issue.
>>
>> Is there anyway to manually set the CELL/BSSID, or have the cards 
>> ignore this value so it doesn't matter?
>>
>> Thanks,
>> Chris
>>
>>