[Bloat] The "Some Congestion Experienced" ECN codepoint - a new internet draft -

Mikael Abrahamsson swmike at swm.pp.se
Mon Mar 11 03:08:06 EDT 2019

On Sun, 10 Mar 2019, Jonathan Morton wrote:

> An interesting idea, but SCE marks will appear even when there's a lot 
> of congestion (at high rates, ie. probably every packet that doesn't 
> carry CE), as well as showing up at low frequency when the level of 
> congestion only warrants reducing the growth rate.  I think the word 
> "Some" is sufficiently descriptive, while "Slight" might cause people to 
> ignore it completely.

One way to handle this would be "buffering experienced" or something like 
that. Ie if this packet is being enqueued into a buffer with non-trivial 
number of packets in it, mark it.

The L4S proposal also has the property that their use of this last code 
point combination in the entire packet header (and this is a big thing, 
this is the last unicorn) also meant the packet was allowed to be 
re-ordered. I thought this was a big and nice thing, for other areas. This 
new proposal removes that property.

>From what I can see, L4S actually is quite novel and has the chance to 
seriously change the way queueing is done. This proposal seems more like 
"a little more of what we had before" which I do not think warrants 
claiming this last unicorn codepoint. I'd like its use to be truly novel 
and be more than a tweak.

Mikael Abrahamsson    email: swmike at swm.pp.se

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