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Wireshark-users: Re: [Wireshark-users] end-to-end delay calculation using tcp

From: Hansang Bae <hbae@xxxxxxxxxx>
Date: Wed, 16 Apr 2008 22:29:03 -0400
Fabiana moreno wrote:
So every retransmission is a packet lost?

Well, you can have duplicate retransmissions, but yes. But the manifestation will be different if you are the receiver or the sender. As the sender, you will *know* that you are resending a particular packet.

As a receiver, you will get a packet that is (seemingly) out of order, and you will send duplicate ack's to trigger a fast retransmission. In other words, packets 1, 2, 3 arrive, followed by 5, 6 7. You will then ack for #4.

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Thanks,
Hansang