there are a few reports of curious HighDiscardRate events on the forum and a customer is seeing this event on most of his WS-C2950G-24-EI. The event is appearing in different time ranges on the 2 uplink ports of the device.
Currently my assumption is that it is caused by a wrap around of one of the counters that is used to calculate the discard rate.
I found some interesting facts:
- the InputPacketDiscardRate and the InputPacketRate do have bogus values of 1.7xxxE7
- I found 197 entries of this kind in the FH database for 'InputPacketDiscardRate' but only 4 different numeric values (from which 169 entries do have the same value)
- I do not find any curious OutputPacketDiscardRate but do also see a wrap around of the counters in the MIB (which could be a random issue)
I assume DFM still uses the 32-bit counter instead of the 64-bit counters for the gig Interfaces and does not have any mechanism to detect the wrap around of the counter.
I added the active and cleard DFM events as well as an snmpwalk of the ifTable (forgot to walk the ifMib for the high capacity counters...)