[e2e] A note on entropy Re: Are our models correct? Re: Just a very quick remark on system theory Re: Why don't we talk about segments/objects instaead of layers? Re: Lost Layer?

[Andrew Mcgregor]

You still need a model of the link's distribution of forwarding, to allow
any useful end-to-end conclusions.  That can be done, but of course those
distributions are often fairly pathological for wireless links.


On 22 February 2014 08:22, Detlef Bosau <detlef.bosau at web.de> wrote:

> Am 21.02.2014 18:10, schrieb Andrew Mcgregor:
> > You didn't read the paper I was pointing you at then.  It models the
> > window, and all the timers, and includes provision for cwnd clamping and
> > various other optional features of TCP.
> >
> > The limitations you point out are indeed things that happen in naiive
> > models.  Not all models are that naiive.
> Where I run into trouble with the paper you pointed to is the non
> decreasing level of entropy in closed systems.
>
> I think the model of Hui is a quite straight forward interpretation of
> VJCC.
>
> However, I encountered the most severe problems with wireless networks
> where you will fail to interpret the propagation of information as a
> "transport" of energy which is continuously conveyed between buffers /
> increasing the level of entropy.
>
> Perhaps the most important lesson I learned during the past 14 years is
> that there is no reasonable way to model mobile networks.
>
> Meanwhile, I think it is not even necessary to "model" links from a
> congestion control perspective to model links for a simple reason:
> Congestion does not occur on a link but on switching nodes.
> So the idea is to focus on the nodes - and not primarily on the links
> (which are reasonably dealt with by schedulers.)
>
>


-- 
Andrew McGregor | SRE | andrewmcgr at google.com | +61 4 1071 2221