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

["Fabiana moreno" <fvmoreno@xxxxxxxxx>]

So every retransmission is a packet lost?

On 10/04/2008, Hansang Bae <hbae@xxxxxxxxxx> wrote:

Fabiana moreno wrote:
> Hello guys,
>
> I am streaming a video using tcp and i was wondering how could i
> calculate certain parameters such as end-to-end delay or frame loss?? is
> it hard to acomplish?
>


You are streaming or downloading the video?  if you're streaming, I
guess you use a buffer of some sort?

end to end delay can be somewhat tricky but there are some rules of
thumb you can use to calculate it.

1)  Look at SYN and SYN+ACK.  The time it takes for syn_ack to come back
is your round trip delay
2)  Look at ACKs coming back after two successive full sized packets.
This too can be used to calculate the round trip time.  The reason is
that the receivers tcp stack will immediately ACK after receiving two
full size packets (w/o app intervention).

You can also look for packet loss by using the filter
"tcp.analysis.flags" display filter and looking for retransmissions.


--

Thanks,
Hansang
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