Re: [Cerowrt-devel] Ubiquiti QOS

[David Lang <david@lang.hm>]

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the problem is that paths change, they mix traffic from streams, and in other 
ways the utilization of the links can change radically in a short amount of 
time.

If you try to limit things to exactly the ballistic throughput, you are not 
going to be able to exactly maintain this state, you are either going to 
overshoot (too much traffic, requiring dropping packets to maintain your minimal 
buffer), or you are going to undershoot (too little traffic and your connection 
is idle)

Since you can't predict all the competing traffic throughout the Internet, if 
you want to maximize throughput, you want to buffer as much as you can tolerate 
for latency reasons. For most apps, this is more than enough to cause problems 
for other connections.

David Lang

  On Mon, 26 May 2014, David P. Reed wrote:

> Codel and PIE are excellent first steps... but I don't think they are the best 
> eventual approach.  I want to see them deployed ASAP in CMTS' s and server 
> load balancing networks... it would be a disaster to not deploy the far better 
> option we have today immediately at the point of most leverage. The best is 
> the enemy of the good.
>
> But, the community needs to learn once and for all that throughput and latency 
> do not trade off. We can in principle get far better latency while maintaining 
> high throughput.... and we need to start thinking about that.  That means that 
> the framing of the issue as AQM is counterproductive.
>
> On May 26, 2014, Mikael Abrahamsson <swmike@swm.pp.se> wrote:
>> On Mon, 26 May 2014, dpreed@reed.com wrote:
>>
>>> I would look to queue minimization rather than "queue management"
>> (which
>>> implied queues are often long) as a goal, and think harder about the
>>> end-to-end problem of minimizing total end-to-end queueing delay
>> while
>>> maximizing throughput.
>>
>> As far as I can tell, this is exactly what CODEL and PIE tries to do.
>> They
>> try to find a decent tradeoff between having queues to make sure the
>> pipe
>> is filled, and not making these queues big enough to seriously affect
>> interactive performance.
>>
>> The latter part looks like what LEDBAT does?
>> <http://tools.ietf.org/html/rfc6817>
>>
>> Or are you thinking about something else?
>
> -- Sent from my Android device with K-@ Mail. Please excuse my brevity.

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