Hi Sivateja,
On Tue, Sep 18, 2012 at 2:39 PM, Sivateja Patibandla
<[email protected]> wrote:
> Hi Guys,
>
> I'm working on setting up a mesh network with multiple unmanned aerial
> vehicles. I'm working on Ubiquiti bullet 5 Ghz module. The hardware is
> AR2313 with ath5k driver. I'm currently doing testing with just two
> nodes (one is plane and one is ground station) being setup with . The
> problem I've noticed today is as follows: If A (ground station) and B
> (plane) are communicating and suddenly B goes out of range. Though, B
> comes back immediately in the range. Both nodes can't communicate to
> each other for at least a minute. The traffic is all UDP traffic. I
> had this problem in the lab environment too. I could only get the
> connection back by restarting the node B in lab environment. In the
> tests that involved using proprietary firmware of Ubiquiti in access
> point and station mode, there was no such delay in the link recovery
> after failure at all. Any comments on this problem will be
> appreciated.
I have no explanation for your observations. All I can say is that
the protocol should be able to handle the scenario you describe. If
you are willing to investigate this, you could start by simulating
link losses with hwsim and you should observe that flows are
reestablished as soon as the link is recovered.
What follows is an excerpt of one of our tests:
for i in `seq 1 5`
do
echo -n `date +%s` Breaking link:
echo 0 > /sys/kernel/debug/ieee80211/${PHY0}/hwsim/group
ping -q -I mesh0 192.168.77.11 -c 20 -i 0.1 -w 1 | grep loss |
cut -d, -f 3
sleep 1
echo -n `date +%s` Restoring link:
echo 3 > /sys/kernel/debug/ieee80211/${PHY0}/hwsim/group
ping -q -I mesh0 192.168.77.11 -c 20 -i 0.1 -w 1 | grep loss
| cut -d, -f 3
done
And this is the output we observe:
(...)
10 packets transmitted, 10 received, 0% packet loss, time 905ms
rtt min/avg/max/mdev = 0.123/0.274/1.235/0.324 ms
1348007532 Breaking link: 100% packet loss
1348007534 Restoring link: 0% packet loss
1348007535 Breaking link: 100% packet loss
1348007537 Restoring link: 0% packet loss
1348007538 Breaking link: 100% packet loss
1348007540 Restoring link: 0% packet loss
1348007541 Breaking link: 100% packet loss
1348007543 Restoring link: 0% packet loss
1348007544 Breaking link: 100% packet loss
1348007546 Restoring link: 0% packet loss
PASS
Hope that it helps.
Javier
--
Javier Cardona
cozybit Inc.
http://www.cozybit.com
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