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