thanks a bunch for your feedback. My reply is inline.
On 3/3/16 4:31 AM, Luca De Cicco wrote:
> Dear Ingemar and all,
>
> I hope not to hijack the topic,
No worries, but I changed the subject line to suit. I strongly support
those writing papers to submit them for discussion to the lists... I
read google scholar regularly but missed these.
Great. Thanks for taking time to browse the papers :)
>but I would like to add some bits to the
> interesting HAS/DASH
> discussion you bootstrapped.
> Regarding the performance of HAS/DASH adaptive streaming control
> algorithm, the reason for the
> poor performance of rate-based algorithms is due to the ON/OFF behaviour
> of the clients (i.e. video clients
> insert idle periods to control the buffer and concurrent TCP flows can
> take advantage of this).
> This phenomenon was first uncovered in the IMC 2012 paper that Te-Yuan
> et al. named "the downward
> spiral effect" and is also experimentally shown in the following paper
> in the case of several "rate based" algorithms
> (sorry for the advertisement ;)) where we proposed a buffer-based
> adaptive streaming control algorithm:
>
> http://c3lab.poliba.it/images/a/a1/Elastic-pv2013.pdf
> L. De Cicco, V. Caldaralo, V. Palmisano, and S. Mascolo
> ELASTIC: a Client-side Controller for Dynamic Adaptive Streaming over
> HTTP (DASH)
> Proc. of Packet Video Workshop 2013, San Jose, CA, USA, December 2013
This experiment can be easily repeated with various AQM,AQM/fq
technologies in the link.
The size of the drop tail queue is not documented...
IIRC the DT queue size was equal to the BDP. We have also run experiments with tc/netem but we didn't study the impact of AQMs on performance.
Is this the netshaper codebase? http://netshaper.sourceforge.net/ ?
"NetShaper that performs bandwidth shaping and allows
propagation delays to be set. This tool uses the nfqueue
library provided by Netfilter1
in order to capture and
redirect the packets arriving at the client host to a user space
drop-tail queue, where traffic shaping and measurement are
performed."
This is in a place where we would just plug the various algorithms into
the sqm-scripts and not do it in userspace.
The emulated base RTT is not documented. Arguably HAS traffic would
often have a lower base RTT than a random tcp link.
IIRC the baseRTT was set equal to 50ms.
The dynamic range of the selected rates seems low.
What do you mean by selected rates?
I am always harping on the need to test against an upload flow, and to
emulate asymmetric network links common in the home, in general.
> A more theoretical explanation of rate-based and buffer-based approaches
> can be found here
> where some properties of hysteresis buffer-based controllers are shown:
>
> http://c3lab.poliba.it/images/b/b1/Acc2015.pdf
Read this also. I guess a key thing I keep wanting to see is the effect
of a web traffic burst - and the reaction time changes with an upload
going on at the same time.
This can be easily set up. We have released a tool which is able to generate a relatively high number of HAS flows using a single machine (decoding/rendering of the video can be turned off but the dynamics of the control algorithm is not impacted). The tool is also useful to implement/compare different adaptive streaming control algos.
Please look at:
and the companion paper:
(And now I swear I'll stop with the advertisement!)
Cheers,
Luca