[Codel] [RFC PATCH] codel: ecn mark at target

Kathleen Nichols nichols at pollere.com
Sat Aug 4 17:53:08 EDT 2012


Yes, why would a single delay of more than target be considered
as a reason to take action? I thought Van did a very nice job of
explaining this last Monday.

On 8/3/12 11:45 PM, Eric Dumazet wrote:
> On Fri, 2012-08-03 at 19:44 -0700, Dave Täht wrote:
>> From: Dave Taht <dave.taht at bufferbloat.net>
>>
>> The consensus at ietf was that ecn marking should start at
>> target, and then the results fed into the codel drop scheduler.
>>
>> While I agree with the latter, I feel that waiting an interval
>> before starting to mark will be more in-tune with the concept
>> of a sojourn time, and lead to better utilization.
>>
>> As I am outnumbered and outgunned, do it at target.
> 
> Well, thats a huge way to favor non ECN flows against ECN flows.
> 
> Marking _all_ ECN enabled packets just because last packet sent had a
> sojourn time above target is going to throttle ECN flows and let non ECN
> flows going full speed and take whole bandwidth.
> 
> Doing so is a nice way to keep users switching to ECN one day.
> 
> IETF could just say : ECN is doomed, forget about it, dont even try. 
> 
> 
> 
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