[BBLISA] slow wan link

[Daniel Feenberg]

On Fri, 8 Jun 2012, Bill Bogstad wrote:

> On Fri, Jun 8, 2012 at 8:35 AM, Edward Ned Harvey <bblisa4 at nedharvey.com> wrote:
>>> From: Bill Bogstad [mailto:bogstad at pobox.com]
>>> Sent: Thursday, June 07, 2012 11:35 AM
>>>
>>> I'm going to have to disagree with this.   A congested link SHOULD
>>> drop TCP packets so that congestion control knows to slow down.
>>> It's actually this thinking which results in deploying equipment and
>>> software that creates buffer bloat.
>>
>> What are you calling buffer bloat?
>
> I'm (attempting) to use the term as I understand Jim Getty does.   He
> coined the term in 2010 on his blog:
>
> http://gettys.wordpress.com/2010/12/03/introducing-the-criminal-mastermind-bufferbloat/
>
> If you aren't familiar with ongoing work on this issue, you shouldn't
> have trouble finding information about it.   This recent CACM article
> by Jim Gettys and Kathleen Nichols might be a good place to start:
>
> http://cacm.acm.org/magazines/2012/1/144810-bufferbloat/fulltext
>
> In addition, the Linux 3.3 kernel has new code in it to attempt to
> start dealing with the problem.  I'm not going to respond to the rest
> of your note until you let me know that I'm using the term incorrectly
> or that it isn't relevant to a discussion about whether networks
> should ever drop packets.

A simple explanation buffer bload comes from understanding that if a 10 
mbs link is presented with 12 mbs of traffic, 20% of the traffic must be 
dropped. If there is 10 seconds worth of buffer, then all the traffic not 
dropped is delayed 10 seconds. Because dropped packets will generally 
cause sources to slow down, the traffic presented will generally slow down 
to something very close to capacity and very few dropped packets, but with 
10 seconds of delay for every packet - not at all optimal.

dan feenberg

>
> Thanks,
> Bill Bogstad
>