[TRANSIENT] Peer XOs NOT shown in Neighborhood view when Power Management is enabled

Samuel Greenfeld greenfeld at laptop.org
Tue Dec 18 13:16:07 EST 2012

It sounds like you are having issues with multicast packet wakeups, which
have always been a bit of a sore spot.

I presume you are using ad-hoc networking, and have not left the XOs idling
to the point they shutdown their screen turns black and the wifi card is
turned off (~20 minutes?).  If this is with a schoolserver it still could
be a known issue but might be worth raising again.

Wake-on-LAN behavior with the 8686 wireless card is not as reliable at it
should be.  XOs need to wake up on multicast events to receive data
(multicast DNS) about the network neighborhood, but need to clearly hear
such announcements {i.e. no collisions with another data packet}, and
sometimes don't get them even if the XO is awake.  In crowded cities where
there are lots of access points and other computers nearby this becomes
more of a problem.

And since updates are only sent every few minutes, it could take quite a
while for everything to get synched up, with things lost along the way.

Schoolservers/Jabber servers use TCP connections, should be retrying at the
TCP level, and should not run into these issues unless a XO went fully into
suspend (black screen/etc.) with the wifi card off.  If a XO is connected
to a schoolserver/Jabber it will not show ad-hoc users even if they are on
the same network.

The ad-hoc networking model definitely could be improved but I do not know
if anyone has ever taken up that task.

There are several tickets on the subject; I do not recall filing any
against 13.1.0 yet though.

On Tue, Dec 18, 2012 at 12:40 PM, nitika.mail <nitika at activitycentral.com>wrote:

> Hi All,
>    Peer XOs are NOT shown in Neighborhood view  when Power Management is
> enabled.
> Tested on 31016o2 OLPC Image (Build 16) on two XO-1.75's... one Touch and
> the other Non-Touch. Following observations were made:
> 1. Having connected both the XO's to a network, when neighborhood view was
> seen on both the XO's, only one XO displayed the other in its neighborhood
> view. The second XO was all alone in the neighborhood view.
> 2. At some point, due to suspending an XO (or network re-connect), same
> thing can be observed on either of the XO's
> 3. When Power management was disabled and system rebooted, this issue was
> not observed.
> 4. This has yet been observed only on XO-1.75's.
> If anyone has observed this issue, please do advise.
> Also, does this call for raising a bug?
> Thanks and Regards,
> Nitika Mangal
> QA Manager
> Activity Central: http://activitycentral.com
> _______________________________________________
> Devel mailing list
> Devel at lists.laptop.org
> http://lists.laptop.org/listinfo/devel
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