Ingress exception counters

[m0tash]

Hey, all!

Does anyone know something about FPGA Exception global counters? Especially these counters:

flow_fpga_rcv_igr_INTFNF
flow_fpga_rcv_igr_IPFRAGMENT
flow_fpga_rcv_igr_PROTO

I see packet drops on FPGA showed by counter flow_fpga_ingress_exception_err. Also the counter has the same rate as flow_fpga_rcv_igr_INTFNF. I'd like to understand what kind of traffic hits such behavior.

Thanks

[JayGolf · Accepted solution]

Hi @m0tash ,

The FPGA handles processes like VLAN tagging, routing lookups, and certain Layer 2/3 operations.

flow_fpga_rcv_igr_INTFNF = Interface not found. Increments when the fpga receives a packet and cannot find a corresponding interface. 
flow_fpga_rcv_igr_IPFRAGMENT = IP fragmentation. Increments when MTU is exceeded and packets are fragmented.
flow_fpga_rcv_igr_PROTO = Protocol. Increments when unsupported protocols are passed through. 

Your "flow_fpga_ingress_exception_err" is an aggregation of the various counters of the fpga. So if the value of "flow_fpga_rcv_igr_INTFNF" is almost exactly the same then its likely the "flow_fpga_rcv_igr_INTFNF" is the reason for your "flow_fpga_ingress_exception_err errors".

There could be issues with VLAN tagging like if you are sending traffic with a 802.1q tag for which there is no corresponding sub-interface on firewall, you will see this counter. 

Do you notice any specific issues or were you just poking around the counter logs?