Where is the definition for event 0x1133a?

Document ID : KB000015904
Last Modified Date : 14/02/2018
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Introduction:

This Doc references the threshold calculations made for event 0x1133a = PERCENT DISCARDS THRESHOLD EXCEEDED

Question:

We are seeing an Alarm come in listed as 0x1133a = PERCENT DISCARDS THRESHOLD EXCEEDED 

 

Can you provide more information on this Event? 

Environment:
Platform Independant
Answer:

 

The MIB used is RFC1213-MIB: http://www.alvestrand.no/objectid/1.3.6.1.2.1.2.2.1.15.html 

For determining what packets are being dropped - try running a sniffer trace on the port and investigating the packet detail.

 

 

- ifInDiscards and ifOutDiscards represent the packets that are discarded 

even though nothing prevented them from being passed (good packets that 

were discarded to free up buffer space is an example) 

 

- ifInUnknownProtos on the other hand represents the total number of 

packets discarded because of an unknown or unsupported protocol 

 

Calculations are as follows: 

 

Spectrum uses the following OIDs or objects to show Interface Errors & 

Discards for an interface. 

 

ifInErrors (1.3.6.1.2.1.2.2.1.14) 

ifOutErrors (1.3.6.1.2.1.2.2.1.20) 

 

Typically % Error will be the sum of above two OIDs, divided by Delta total 

packets . 

 

ifInDiscards (1.3.6.1.2.1.2.2.1.13) 

ifOutDiscards (1.3.6.1.2.1.2.2.1.19) 

ifInUnknownProtos (1.3.6.1.2.1.2.2.1.15) 

 

Similarly for % Discards , it will be sum of above three OIDs, divided by 

Delta total packets . 

 

Other than above OIDs Delta total packets is calculated based on following 

OIDs. 

ifInUcastPkts (1.3.6.1.2.1.2.2.1.11) 

ifInMulticastPkts (1.3.6.1.2.1.31.1.1.1.2) 

ifInBroadcastPkts (1.3.6.1.2.1.31.1.1.1.3) 

ifOutUcastPkts (1.3.6.1.2.1.2.2.1.17) 

ifOutBroadcastPkts (1.3.6.1.2.1.31.1.1.1.5) 

ifOutMulticastPkts (1.3.6.1.2.1.31.1.1.1.4) 

 

Spectrum gets the value of above OIDs from device every ten seconds. 

For example, at 0th second spectrum got values of above OIDs. These values 

will be called as initial values. At 10th second, Spectrum will get again 

more values of above OIDs. These values will be called as final values. 

Now Spectrum will calculate the difference between the initial and final 

value divided by delta time for each OIDs. To calculate % Error a formula 

will look like as follows:- 

% Error = ( ( delta_in_error_pkts + delta_out_error_pkts ) ) 

/ delta_total_pkts; 

Where 

delta_in_error_pkts = final_value_ifInErrors initial_value_ifInErrors/ 

delta time 

delta_out_error_pkts = final_value_ifOutErrors- 

initial_value_ifOutErrors/delta time 

Similar way delta_total_pkts and % Discards will be calculated. 

% Error and % Discards both are calculated in unit of 1/1,000,000th of a 

percent. 

 

So to calculate the "% Discard", typically formula will look like:- 

% Discard = ( ( delta_ifInDiscards + delta_ifOutDiscards + 

delta_ifInUnknownProtos ) ) 

/ delta_total_pkts;