Drops in Core

[rafael at gav.ufsc.br (Rafael Possamai)]

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 at 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 at 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 at 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
>>>
>>
>>
>