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I have used version 1.10.1 to capture a 900 mbyte trace file. The trace file is a download of a resultant data set from a Netezza Data Warehouse query. I have run Wireshark Expert Infos against it and the Notes have recorded 128 Duplicate ACK's run a total of 25938 times. Does this indicate a heavily congested network between the laptop and the Server? I am using a 1 Gbit Netgear Switch with port mirroring off a 100 mbyte LAN. I am attaching the output. alt text

asked 02 Sep '13, 15:04

Zoberist's gravatar image

Zoberist
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"the Notes have recorded 128 Duplicate ACK's run a total of 25938 times."

The "Notes:128 (25938)" indicate that you have 25938 packets with 128 different types of a 'Note' - most of which are duplicate ACKS.

As a Duplicate ACK combined with the duplicate ACK # is treated as a unique event when in fact it is just an indication of an out-of-order arrival at the receiver, this number is kind of misleading. If you have a large windowsize offered by a receiver and a packet early in the window was dropped or delayed you'll see a dupack with increasing numbers, all reporting the same missing packet. The third dup ack (1095) seen at the sender will will trigger a fast retransmission (956).

Putting this in perspective: Receiving a 900MB file with only 412 'suspected Retransmissions' doesn't look like a high number to me.

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answered 02 Sep '13, 22:06

mrEEde's gravatar image

mrEEde
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edited 02 Sep '13, 22:19

Thank you very much !!!!

(03 Sep '13, 02:56) Zoberist
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question asked: 02 Sep '13, 15:04

question was seen: 1,500 times

last updated: 03 Sep '13, 02:56

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