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[aqm] PIE vs. RED

"Bless, Roland (TM)" <roland.bless@kit.edu> Thu, 13 August 2015 12:28 UTC

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Date: Thu, 13 Aug 2015 14:28:27 +0200
From: "Bless, Roland (TM)" <roland.bless@kit.edu>
Organization: Institute of Telematics, Karlsruhe Institute of Technology
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Subject: [aqm] PIE vs. RED
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Hi,

while looking at the PIE presentation
http://www.ietf.org/proceedings/86/slides/slides-86-iccrg-5.pdf,
slide 6 shows that RED is far away from the PIE
queuing delay. However, I'm not sure that this comparison is
really fair if looking at the choice of the parameters.
The buffer limit is set to 2000 packets, which is IMHO too large
for a BDP of 10Gbit/s * 100µs = 125000 bytes. Assuming your average
packet size of 1000 bytes we get 125 packets as buffer size.
Then Min_th = 25 packets and Max_th = 63 packets in contrast
to Min_th=400 packets if you use a buffer for 2000 packets.
For 25 packets you would also get a queuing delay of only
20µs for RED which is then close to the PIE target...
Was there a particular reason for using a 16x larger buffer
than required? Am I missing something here?

Regards,
 Roland

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