[e2e] TCP Performance with Traffic Policing

Hagen Paul Pfeifer hagen at jauu.net
Thu Aug 18 13:36:48 PDT 2011

I started to comment a selected set of paragraph - because I feel that

* Detlef Bosau | 2011-08-18 21:57:39 [+0200]:

>It is a well proven attitude in science, to do research one step
>after another.
>Obviously, in Internetworking we have a certain problem with this
>one. Why couldn't we discuss those things in a number of papers
>and/or RFC proposals instead of playing around with these things,
>with absolutely no consideration of the rest of the world?
>If Quick ACKs are a good idea, there is no doubt that they will be
>accepted. However, I have a problem with working
>beside/without/against the community.
>My attitude is pursuing the discussion in the community (although I
>cannot do this to that degree I want to do for some reasons) instead
>of avoiding it.
>In some sense, Linux is the OS of the GNU generation: Gnu is Not Unix.
>And many of us use still BSD Unix as _the_ reference.
>When I look at Linux, we have Westwood and Reno Options and others as
>well. So, every user make mix up his own "salad of TCP flavours"
>wihout ging a simple thought to whether this make sense.
>This is an attitude of competitive playing - and I strongly expect
>our attitude to become more professional in the future.

There are several aspects here:

1) we choose on of the more conservative congestion control algorithm as the
default one. It was BIC for a longer time BUT as fast as several research
spotted out that there are some fairness issues in networks with a low RTT we
skipped to CUBIC. Linux WAS fast in adjusting the default CC algorithm! Faster
then any standardization body.

2) Remember: it was Sallys own CC algorithm - Highspeed TCP - standardized in
an RFC which IS unfair. Nothing prevents an algorithm from being unfair, only
by being standardized!

3) Linux implement an mechanism to PREVENT ordinary users from selecting an
unfair CC algorithm [1]. This is far more then any other operating system! If
you present some numbers where you spooted some unfairness - fine, this can be
discussed too!

4) And in the end: Linux do everything to be fair, knowing that it is used as
a Server/Networking OS. But you cannot stop users with root access to harm the
network. They can do everything beside selecting the CC algorithm (e.g.
starting traffic generator at line rate ...). [2]

Detlef, if you have solid and substantive concerns you can make a request! A
little bit off-topic now, you can start a separate thread here in e2e or in
tcpm (or email me off-list)

Cheers, Hagen

[1] http://www.amailbox.org/mailarchive/linux-netdev/2010/5/27/6278101
[2] http://blog.benstrong.com/2010/11/google-and-microsoft-cheat-on-slow.html

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