[Cerowrt-devel] [Bloat] DC behaviors today

Mikael Abrahamsson swmike at swm.pp.se
Wed Dec 13 05:20:35 EST 2017

On Wed, 13 Dec 2017, Jonathan Morton wrote:

> Occasionally, of course, practically everyone in the country wants to 
> tune into coverage of some event at the same time.  More commonly, they 
> simply get home from work and school at the same time every day.  That 
> breaks the assumptions behind pure statistical multiplexing, and 
> requires a greater provisioning factor.

Reasonable operators have provisioning guidelines that look at actual 
usage, although they probably look at it in 5 minute averages and not 
millisecond as done here in this context.

So they might say "if busy hour average is over 50% 3 days in a week" this 
will trigger a provisioning alarm for that link, and the person (or 
system) will take a more detailed look and look at 5minute average graph 
and decide if this needs to be upgraded or not.

For me the interesting point is always "what's going on in busy hour of 
the day" and never "what's the monthly average transferred amount of 

Of course, this can hide subsecond bufferbloat extremely well (and has), 
but at least this is typically how statistical overprovisioning is done. 
You look at actual usage and make sure your network is never full for any 
sustained amount of time, in normal operation, and make sure you perform 
upgrades well before the growth has resulted in network being full.

Mikael Abrahamsson    email: swmike at swm.pp.se

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