[conex] 2) False positives of the audit

Mirja K├╝hlewind <mirja.kuehlewind@ikr.uni-stuttgart.de> Mon, 03 June 2013 13:23 UTC

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From: Mirja =?iso-8859-1?q?K=FChlewind?= <mirja.kuehlewind@ikr.uni-stuttgart.de>
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Date: Mon, 3 Jun 2013 15:23:37 +0200
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Subject: [conex] 2) False positives of the audit
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Hi,

this question is directly related to the first one. If we have not done 
anything wrong at the sender but the audit still penalizes us because of 
wrong information at the audit, we need to detect this case at the sender and 
do something, e.g., as just proposed, send more credits.

My only guess right now, how to detect such a false positive of the audit at 
the sender is, that if we see congestion (loss or ECN) for more than one RTT 
eventhough we have reduces our sending rate it must be a false positive.

Thus in the worst case, we will see a large number of losses (upto all) 
induced by the audit. This will cause the sender to send further ConEx L 
marking and might lead to another throttling by the policer.
If the audit drops too less packets on the other hand, it is not a sufficient 
penalty and FEC might be able to compensate (at least for shorter 
transmissions).

Thus whenever there is a false positive by the audit, I currently would assume 
that this would strongly slow down or stop the transmission. But with the 
risk of loosing ConEx marked packets in the network and also not having 
sufficiently accurate ECN feedback, there will always be false positives.

Mirja