Re: [Bloat] Failure to convince

[Jim Gettys <jg@freedesktop.org>]

On 02/11/2011 11:29 AM, richard wrote:
> I had an email exchange yesterday with the top routing person at a local
> ISP yesterday. Unlike my exchanges with non-tech people, this one ended
> with him saying Bufferbloat was not a problem because...
>
> "I for for one never want to see packet loss.  I spent several years
> working on a national US IP network, and it was nothing but complaints
> from customers about 1% packet loss between two points.  Network
> engineers hate packet loss, because it generates so many complaints.
> And packet loss punishes TCP more than deep buffers.
>
>    So I'm sure that you can find a bunch of network engineers who think
> big buffers are bad.  But the trend in network equipment in 2010 and
> 2011 has been even deeper buffers.  Vendors starting shipping data
> centre switches with over 700MB of buffer space.  Large buffers are
> needed to flatten out microbursts.  But these are also intelligent
> buffers."
>
> His point about network people hating packet loss points up the problem
> we'll have with educating them and the purchasing public that at least
> some is necessary for TCP to function.
>
> Not having been in charge of a major backbone recently, I have to admit
> that my understanding of today's switching hardware was to be able to
> deal with everything "at wire speed" with cut-through switching, unlike
> the store-and-forward typical switches and routers at the consumer
> level.

One response is that huge buffers actually induce higher packet loss 
rates on large transfers, when saturated.   A happy TCP has much less 
than 1% loss rates.

Also note that it isn't buffering per se' that is the problem here; it's 
unmanaged bloated buffers without signalling the hosts o fcongestion.

And yes, it's an education problem, and why I'm hopeful ECN can play a 
role in the equation.
				- Jim