The phenomenon is called "lava flow", and is a classic anti-pattern illustrated at http://antipatterns.com/lavaflow.htm
Their approach to fixing is ancient, though: there are correctness-preserving refactorings for some of the problem space.

Alas, I don't know if middleboxes are correctable... maybe if they are ones which only care about the IP layer?

--dave

On 04/04/18 08:45 AM, Jesper Louis Andersen wrote:
On Tue, Apr 3, 2018 at 5:04 PM Jim Gettys <jg@freedesktop.org> wrote:
​To get to really good RTT's (with low jitter), you still need ​fq_codel (or similar).  You just can't get there by hacking TCP no matter how hard you try...


I agree with you on all points here. However, any change which patches an existing bad system is far more likely to win in the long run, also if it is bad in some way. Momentum is a killer of good solutions. I wish I had a ramification for this observation, but I currently don't.

My hunch is that every new generation of young programmers wants to put their mark on the system. As a result, they take what worked well on level N-1 and proceed to build N on top of it. But the beanstalk never withers, so each level is present in said stack, still, after all these years.

(Aside: The codel approach also has worked really well for me internally in Erlang systems as a way to maintain queue load. Far better than many other flow control schemes).


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David Collier-Brown,         | Always do right. This will gratify
System Programmer and Author | some people and astonish the rest
davecb@spamcop.net           |                      -- Mark Twain