Comments on: Fonera and its MTU (and the non-working wireless connection) http://zeta-puppis.com/2007/02/06/fonera-and-its-mtu-and-the-non-working-wireless-connection/ my very own personal corner Sun, 29 Aug 2010 17:26:31 +0000 http://wordpress.org/?v=2.9.2 hourly 1 By: Martin http://zeta-puppis.com/2007/02/06/fonera-and-its-mtu-and-the-non-working-wireless-connection/comment-page-1/#comment-83 Martin Sat, 24 Mar 2007 14:55:54 +0000 http://kratorius.simosnap.net/2007/02/06/fonera-and-its-mtu-and-the-non-working-wireless-connection/#comment-83 I've got the same problem, and I've noticed something interesting: My Fonera sits on a window board, very close to the radiator. Now when I turn the heat of the radiator on, this causes the "stuck beacon" messages to appear - when I move the Fonera away from the radiator (about 20 cm are enough), it stops altogether. This can be reproduced. As for the MTU: it's true that an MTU should not be higher than 1492 when using PPPoE, because 1492 + 8 (length of PPPoE header) = 1500, which is the maximum allowed TU. If your packet size exceeds 1500, your packets can (and will) get dropped by certain hosts in the internet. The interface ath1, however, is the private WLAN interface. No internet hosts involved (actually, no other hosts involved at all for the beacon stuff), so this should not be a problem. Beacons are really small packets anyway, so I wonder if or why they should be influenced by the MTU. Don't get me wrong here - I did some googling for "stuck beacons", and the causes seem to be quite complex and not well understood. I'm just pretty sure that in *my* case, heat was the problem. I’ve got the same problem, and I’ve noticed something interesting: My Fonera sits on a window board, very close to the radiator. Now when I turn the heat of the radiator on, this causes the “stuck beacon” messages to appear - when I move the Fonera away from the radiator (about 20 cm are enough), it stops altogether. This can be reproduced.

As for the MTU: it’s true that an MTU should not be higher than 1492 when using PPPoE, because 1492 + 8 (length of PPPoE header) = 1500, which is the maximum allowed TU. If your packet size exceeds 1500, your packets can (and will) get dropped by certain hosts in the internet.

The interface ath1, however, is the private WLAN interface. No internet hosts involved (actually, no other hosts involved at all for the beacon stuff), so this should not be a problem.

Beacons are really small packets anyway, so I wonder if or why they should be influenced by the MTU.

Don’t get me wrong here - I did some googling for “stuck beacons”, and the causes seem to be quite complex and not well understood. I’m just pretty sure that in *my* case, heat was the problem.

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