Re: Bottlenecks and link upgrades

[Baldur Norddahl <baldur.norddahl () gmail com>]

No plan survives contact with the enemy. Your careful made growth
projection was fine until the brass made a deal with some major customer,
which caused a traffic spike. Or any infinite other events that could and
eventually will happen to you.

One hard thing, that almost everyone will get wrong at some point, is
simulating load in the event multiple outages takes some links out, causing
excessive traffic to reroute unto links that previously seemed fine.

Regards,

Baldur


On Sat, Aug 15, 2020 at 10:48 AM Etienne-Victor Depasquale <edepa () ieee org>
wrote:

> I've seen the weekly profiles of traffic sourced from caches for the major
> global services (video, social media, search and general) for a specific
> metro area.
>
> For all services, the weekly profile is a repetition of the daily profile,
> within +/- 20%.
> That is: the weekly profile is obtained from the daily profile within +/-
> 20% of the average daily profile height.
>
> Given this regularity, as suggested by Louie Lee, then it seems that
> growth projections are meaningful.
> That is, the weely profile data, seem to provide a sound empirical basis
> for link upgrades.
>
> Since I'm not an operator, my comments need to be sprinkled with a pinch
> of salt :)
>
> Cheers,
>
> Etienne
>
> On Sat, Aug 15, 2020 at 2:43 AM Louie Lee via NANOG <nanog () nanog org>
> wrote:
>
> > Beyond a pure percentage, you might want to account for the time it takes
> > you stay below a certain threshold. If you want to target a certain link to
> > keep your 95th percentile peaks below 70%, then first get an understanding
> > of your traffic growth and try to project when you will reach that number.
> > You have to decide whether you care about the occasional peak, or the
> > consistent peak, or somewhere in between, like weekday vs weekends, etc.
> > Now you know how much lead time you will have.
> >
> > Then consider how long it will take you to upgrade that link. If it's a
> > matter of adding a couple of crossconnects, then you might just need a
> > week. If you have to ship and install optics, modules, a card, then add
> > another week. If you have to get a sales order signed by senior management,
> > add another week. If you have to put it through legal and finance, add a
> > month. (kidding) If you are doing your annual re-negotiation, well...good
> > luck.
> >
> > It's always good to ask your circuit vendors what the lead times are,
> > then double it and add 5.
> >
> > And sometimes, if you need a low latency connection, traffic utilization
> > levels might not even be something you look at.
> >
> > Louie
> > Peering Coordinator at a start-up ISP
> >
> >
> > On Fri, Aug 14, 2020 at 4:13 PM Radu-Adrian Feurdean <
> > nanog () radu-adrian feurdean net> wrote:
> >
> > > On Wed, Aug 12, 2020, at 09:31, Hank Nussbacher wrote:
> > > > At what point do commercial ISPs upgrade links in their backbone as
> > > > well as peering and transit links that are congested?  At 80%
> > > capacity?
> > > >  90%?  95%?
> > >
> > > Some reflections about link capacity:
> > > At 90% and over, you should panic.
> > > Between 80% and 90% you should be (very) scared.
> > > Between 70% and 80% you should be worried.
> > > Between 60% and 70% you should  seriously consider speeding up the
> > > upgrades that you effectively started at 50%, and started planning since
> > > 40%.
> > >
> > > Of course, that differs from one ISP to another. Some only upgrade after
> > > several months with at least 4 hours a day, every day (or almost) at over
> > > 95%. Others deploy 10x expected capacity, and upgrade well before 40%.
>
> --
> Ing. Etienne-Victor Depasquale
> Assistant Lecturer
> Department of Communications & Computer Engineering
> Faculty of Information & Communication Technology
> University of Malta
> Web. https://www.um.edu.mt/profile/etiennedepasquale