Re: Drops in Core

[Rafael Possamai <rafael () gav ufsc br>]

That was just an example, that list has to be completed on a specific
network or scenario, it changes dramatically. Imagine you were to create a
list for a DoD network instead of public peering based network, it would
change dramatically.



On Sat, Aug 15, 2015 at 12:28 PM, Glen Kent <glen.kent () gmail com> wrote:

> Why do you say that Layer 1 issues in the last mile would be very high?
> How is it any different from the first mile?
>
> On Sat, Aug 15, 2015 at 10:56 PM, Rafael Possamai <rafael () gav ufsc br>
> wrote:
>
> > Hi Glen,
> >
> > If you first list the causes of a dropped packet, then you can figure out
> > how likely they are at different points in time (first\last\peer\etc) by
> > making some assumptions.
> >
> > Here's an **example**:
> >
> > *Cause | Location | Likelihood*
> > Congestion | Last mile | Low
> > Congestion | First mile | Low
> > Congestion | Peering | Medium
> > Layer 1 | First mile | Low
> > Layer 1 | Core | Low
> > Layer 1 | Last mile | High
> >
> > You can even go as far as drawing a cause and effect diagram for each
> > location. Then you can collect real world data and fine tune your
> > assumptions.
> >
> >
> > Rafael
> >
> >
> > On Sat, Aug 15, 2015 at 11:47 AM, Glen Kent <glen.kent () gmail com> wrote:
> >
> > > Hi,
> > >
> > > Is it fair to say that most traffic drops happen in the access layers, or
> > > the first and the last miles, and the % of packet drops in the core are
> > > minimal? So, if the packet has made it past the first mile and has
> > > "entered" the core then chances are high that the packet will safely get
> > > across till the exit in the core. Sure once it gets off the core, then
> > > all
> > > bets are off on whether it will get dropped or not. However, the key
> > > point
> > > is that the core usually does not drop too many packets - the probability
> > > of drops are highest in the access side.
> > >
> > > Is this correct?
> > >
> > > Glen