IPv4 Address Exhaustion Effects on the Earth

Jim Gettys jg at freedesktop.org
Tue Apr 5 17:07:21 CDT 2011


On 04/05/2011 05:59 PM, Michael Proto wrote:
> On Tue, Apr 5, 2011 at 5:38 PM, Jared Mauch<jared at puck.nether.net>  wrote:
>> On Apr 4, 2011, at 4:30 PM, Jim Gettys wrote:
>>
>>> Note that the paper "Characterizing Residential Broadband Networks" by Dischinger, et. al. indicates that a large fraction (in their 2 year old sample, 30% or so) of broadband head ends are running without RED, and should be doing so if at all possible; alternatives are years out by the time they are tested and deployed, and operators running without it in congested systems are inflicting pain on their customers.
>> Something I've observed is if you are sending data 'upstream' on the cable modem setup i have (16 down/ 2 up) and you saturate the upstream, the buffering destroys any downstream capability at the same time.  I'm not even sure where to start diagnosing to explaining this to the carrier involved, as this isn't the desired behavior of a "business class" service.
>>
>> - Jared
>>
> Isn't this just a case or prioritizing outbound ACKs?
>
> http://www.benzedrine.cx/ackpri.html
>

Nope.  Your acks get delayed to what you are sending upstream, behind 
the downstream traffic.

Bufferbloat hurts both directions, once saturation occurs and your 
latencies start to go up.

Note that on many of these links, the RTT becomes (literally) as though 
you are half way (or further than) the moon.
                    - Jim






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