Re: Drops in Core

[Justin Wilson - MTIN <lists () mtin net>]

I could see it going through several private peering, but not through multiple exchanges.  


Justin Wilson
j2sw () mtin net

---
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xISP Solutions- Consulting – Data Centers - Bandwidth

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Internet Exchange - Peering - Distributed Fabric




> On Aug 16, 2015, at 8:00 AM, Patrick W. Gilmore <patrick () ianai net> wrote:
>
> On Aug 15, 2015, at 1:41 PM, Job Snijders <job () instituut net> wrote:
> > On Sat, Aug 15, 2015 at 11:01:56PM +0530, Glen Kent wrote:
>
> > > Is there a paper or a presentation that discusses the drops in the core?
> > >
> > > If i were to break the total path into three legs -- the first, middle
> > > and the last, then are you saying that the probability of packet loss
> > > is perhaps 1/3 in each leg (because the packet passes through
> > > different IXes).
> >
> > It is unlikely packets pass through an IXP more then once.
>
> “Unlikely”? That’s putting it mildly.
>
> Unless someone is selling transit over an IX, I do not see how it can happen. And I would characterize transit over 
> IXes far more pessimistically than “unlikely”.
>
>
> [Combining responses]
> On Aug 15, 2015, at 1:21 PM, Owen DeLong <owen () delong com> wrote:
> > I would say that the probability of a packet drop at any particular peering
> > point is less than the probability at one of the two edges.
> >
> > However, given that most packets are likely to traverse multiple peering
> > points between the two edges, the probability of a packet drop along
> > the way at one of the several peering points overall is roughly equal
> > to the probability of a drop at one of the two edges.
>
> I’m a little confused why most packets are “likely to traverse multiple peering points”?
>
> Most packets these days are sourced from one of three companies. (Which Owen should know well. :) At least one of 
> those companies published stats saying the vast majority of packets are “zero or one” AS hop from the destination. I 
> cannot imagine Google or Netflix being 50% behind Akamai on that stat. Which clearly implies most packets traverse 
> “zero or one” AS hop - i.e. one or zero peering points.
>
> Finally, I would love to see data backing up the statement that packets are more likely to drop at one edge (assuming 
> the destination?) than at a peering point.
>
> -- 
> TTFN,
> patrick

Justin Wilson
j2sw () mtin net

---
http://www.mtin.net Owner/CEO
xISP Solutions- Consulting – Data Centers - Bandwidth

http://www.midwest-ix.com  COO/Chairman
Internet Exchange - Peering - Distributed Fabric