[e2e] Mixed ECN and Non-ECN traffic flows.

[Vadim Antonov]

Saad - this is a "tragedy of commons" situtation; if a small fraction of
people ignores rules they benefit.  If majority ignores rules, all lose.

What I am saying is that tweaked TCP stacks and "accelerators" ignoring
congestion control were tried and found no commercial success whatsoever -
and not because end-users were knowledgeable or civic minded.  They failed
simply because not a lot of people valued the (real) performance gains
high enough to purchase those devices or software packages.

BTW, ignoring congestion control does not mean just disabling cwnd code
in TCP -- you want to have FEC features to compensate for lost packets
and/or some form of large-window selective ACK.  Obviously, cumulative
ACKs w/o congestion control would perform very very poorly.

The "UDP" applications were all real-time, and so didn't have problems
with acknowledgements.

Also, historically speaking, the first widely deployed bulk traffic
application w/o congestion control was CU-See-Mee; this lead a coalition
of ISPs to filter CU-See-Mee traffic, thus forcing developers to fix it.
Been there, seen that :) Since then, the threat of boycott by network
operators (and general awareness of the congestion control issues) is what
is keeping streaming app developers in line.

--vadim

On Fri, 11 Oct 2002, Saad Biaz wrote:

> This is what many believed: "if I ignore congestion, I get better
> performance.... This is not true". When you ignore congestion control, you
> will hurt also yourself. Why do you think many applications initially
> based on UDP (without congestion control) finally added congestion
> control... Do the following experiment: deactivate congestion control from
> your TCP (comment out instructions that reduce cwnd ), and enjoy the
> "better" performance.