[e-nsp] Packet loss/drop investigation

[Youssef Ghorbal]

More on the subject.
I've done mirroring on the port directly connected to the phone, the
traffic dump shows clearly egress packet loss for 10s.
Now, I've done mirroring on the uplink port of the stack and the
traffic dump does not show any ingress packet loss.

=> packets do arrive correctly from upstream switch and get dropped
somehow on the way between the ingress port (the uplink) and the
egress port (connected to the phone)

The traffic dump shows also that during the 10s packet loss a huge
rate of arp requests hit the switch (~2000/s)

This leads to some DOS protect features that get triggred on the
stack, the problem is that I have no DOS/flood protection enabled in
the configuration. Also, all DOS/Flood related counters I'm aware of,
are null (show dos-protect, show ip-security, show ports rate-limit,
show ports congestion)

I'll try to generate fake arp at high speed rates and see if the
problem triggers. If the problem is reproductible at will, it will be
more easy to push diag further.

Youssef
--------------------
On Thu, Aug 9, 2012 at 6:15 PM, Youssef Ghorbal
<youssef.ghorbal at gmail.com> wrote:
>> Well, the only what I can propose is to mirror port where phone is and
>> dump the traffic. Than - analzye.
>
> I'm pretty sure that there is packet loss. The traffic dump will
> confirm that but I'm not sure I'll be able to see where it's
> happening.
>
> I'll do it anyway to confirm the packet loss and see if there any
> 802.1p pause packets flying around. After that I'll give Erik's
> suggestion a shot.
>
> I'll let you know whenever I found out the root cause of this.
>
> Youssef