Re: [tcpm] TCP and applications [was Re: Aid passive estimate of tcp performance]

[Ángel Bartomeu Bonillo <abartomeu at swissms.ch>]

El 09/02/2012, a las 15:44, Wesley Eddy escribió:

> On 2/9/2012 3:15 AM, Ángel Bartomeu Bonillo wrote:
>> Well, the case that I had in mind was calculating the packet loss passively from the end user. The estimation for packet loss would be the number of retransmissions minus the number of spurious retransmission. In the Uplink traffic you know the real number of retransmission and you can estimate the spurious ones with the info in the DSAck. However in the downlink it is impossible since you know the spurious but not the real number of packets sent out by the other peer any approach would fail in cases like having the remote peer in slow start and being all the packets dropped. You never know if you do not get packets because either there are no packets to send or because they were lost.
>> 
> 
> Even from the sender-side where you know about all of the
> transmissions, you can still only compute an estimate due
> to sources of error like lost ACKs carrying DSACK information
> (as one easy example).
> 
> There is (in my opinion) a good description of some algorithms
> for different types of connections (DSACK-supported, SACK but
> no DSACK, and no SACK) and the associated sources of error in:
> 
> http://www.icir.org/mallman/papers/least-per-dec2003.ps
> Mark Allman, Wesley Eddy, Shawn Ostermann.
> Estimating Loss Rates With TCP.
> ACM Performance Evaluation Review, 31(3), December 2003.


Yeah Wesley I have already read that and a few others. That's why I am interested in the downlink. AFAIK the downlink is not covered in any other paper.
Thank you.

> 
> -- 
> Wes Eddy
> MTI Systems