Drops in Core

Matthew Petach mpetach at netflight.com
Sat Aug 15 18:14:14 UTC 2015


Quite the inverse, I'd say; most of the capacity
headaches center around the handoff between
networks, and most of the congestion points
I come across are with private peering links
where one party or the other is unwilling or
unable to augment capacity.  The first and
last mile are fine, but the handoff between
the networks is where congestion and drops
occur.
As others have noted, this will vary greatly
depending on the network in question--so
asking a broad community like this is going
to yield a broad range of answers.  You
aren't going to find one single answer, you'll
find a probability curve that represents the
answers from many people running different
networks.
You'll find the location of packet drops tends
to shift depending on where companies are
willing to spend money; some companies
will spend money on the access layer to
ensure no drops happen there, but are
less willing to pay for capacity upgrades
at peering handoffs.  Other networks will
short-change their access, but maintain a
well-connected peering edge.

So--short answer is there is no one answer
to your question.  Collect the different answers,
plot the curve, and decide where along the
curve you want *your* network to land,
and build accordingly.  Nobody has infinite
money, so nobody builds to a level to ensure
zero loss probability to every destination around
the planet.

Matt



On Sat, Aug 15, 2015 at 9:47 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
>



More information about the NANOG mailing list