[App_rpt-users] Reliability / Network Stability

[Tom Hayward]

On Tue, Jun 27, 2017 at 9:50 AM, Loren Tedford <lorentedford at gmail.com> wrote:
> That's great David however most people don't want to spend the time and
> energy into getting a pfsense box and fighting with their provider unless
> they can get reasonable idea of what is going on the network side of
> things.. I agree ping's packet loss isn't everything but I have found that
> mtr is still good basic for individuals looking to trouble shooting network
> issues..
>
> I can't help what providers block out on their end of the network.. However
> ping times and percentage of packet loss is a good start just to get an
> idea..
>
> I am sorry i didn't add nothing is perfect..
>
> So in curiosity side in the linux world what tool would you use to diagnose
> your connections?? This is assuming you already use ping commands and
> netstat commands etc..

Loren,

I think you missed David's point. He's saying that ICMP loss to core
routers is not an accurate assessment of their packet forwarding
ability. These routers have dedicated hardware to forward packets and
can do so at line rate. However, when a ping comes in addressed to
them, this does not get handled by the dedicated packet forwarding
chip. It must be sent to the CPU for processing. If the CPU has some
free time, it will parse the ICMP packet, find the echo request, and
send an echo reply. If the CPU is busy, it'll just ignore the packet.
Pings are the lowest priority in a router like this.

To test for packet loss, use an end-to-end tool on the same protocol
as your application. In this case, test for UDP loss and jitter. You
can do that with a tool like iperf:
https://iperf.fr/

Tom KD7LXL