Nexus 7000 F1 input discard counter increases during high load?

[tuure.vartiainen]

Hi,

any ideas what would cause Nexus 7000 input discard counter to increase on F1 card's port when traffic through the port is high?

I have a setup where Cisco UCS C200 M2 server (Ubuntu Linux OS) is connected with 10GBase-SR optic to Cisco Nexus 5548 (NX-OS

version 5.0(3)N2(2a)) which has 10GBase-LR uplink connected to Cisco Nexus 7000 (NX-OS version 6.0(1)) F1 card. All optics are Cisco labeled.

Normally there is 30-100 Mbps traffic on that N5k <-> N7k uplink and none of error/drop counters are increasing, but when testing throughput/generating traffic with iperf (http://iperf.sourceforge.net/) on UCS server, input discard counter of N7k F1 port connected to N5k starts to increase and increasing stops when iperf is shutdown.

F1 line card console shows that when input discard counter is increasing, "show hardware internal errors" shows that errors:

298  PL0 Ingress RDROP Qth non DE VL0

330  PL0 Ingress RDROP Qth non DE octets VL0

are increasing on that same uplink port. Any ideas what those errors above could be or mean?-)

[tuure.vartiainen]

I forgot to mention in a first post that the input discard counter and line card error counters seem to increase only when a throughput goes above ~2 Gbps and maximum throughput cap seems to be around 4.5-5 Gbps.

I have also tested the setup with different optics (SR and LR), but the line card port is still dropping packets under higher load.