[Cerowrt-devel] [Bloat] [Cake] active sensing queue management
david at lang.hm
Thu Jun 11 21:44:42 EDT 2015
On Thu, 11 Jun 2015, Sebastian Moeller wrote:
> On Jun 11, 2015, at 03:05 , Alan Jenkins <alan.christopher.jenkins at gmail.com> wrote:
>> On 10/06/15 21:54, Sebastian Moeller wrote:
>> One solution would be if ISPs made sure upload is 100% provisioned. Could be
>> cheaper than for (the higher rate) download.
> Not going to happen, in my opinion, as economically unfeasible for a
> publicly traded ISP. I would settle for that approach as long as the ISP is
> willing to fix its provisioning so that oversubscription episodes are
> reasonable rare, though.
not going to happen on any network, publicly traded or not.
The question is not "can the theoretical max of all downstream devices exceed
the upstream bandwidth" because that answer is going to be "yes" for every
network built, LAN or WAN, but rather "does the demand in practice of the
combined downstream devices exceed the upstream bandwidth for long enough to be
it's not even a matter of what percentage are they oversubscribed.
someone with 100 1.5Mb DSL lines downstream and a 50Mb upstream (30% of
theoretical requirements) is probably a lot worse than someone with 100 1G lines
downstream and a 10G upstream (10% of theoretical requirements) because it's far
less likely that the users of the 1G lines are actually going to saturate them
(let alone simultaniously for a noticable timeframe), while it's very likely
that the users of the 1.5M DSL lines are going to saturate their lines for
The problem shows up when either usage changes rapidly, or the network operator
is not keeping up with required upgrades as gradual usage changes happen
(including when they are prevented from upgrading because a peer won't
As for the "100% provisioning" ideal, think through the theoretical aggregate
and realize that before you get past very many layers, you get to a bandwidh
requirement that it's not technically possible to provide.
More information about the Cerowrt-devel