11-07-2013 05:34 AM - edited 03-07-2019 04:28 PM
I have a monitor session process set up to forward data from 4 ports to a single output port. I am surprised to see that on the output port, the rate of output drops is steadily increasing:
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 153449
Queueing strategy: fifo
Output queue: 0/40 (size/max)
30 second input rate 0 bits/sec, 0 packets/sec
30 second output rate 59,733,000 bits/sec, 7698 packets/sec <I added the commas, nice view I think.
The output drops are being blamed for another applications failure to adequately monitor the combined output of the four ports. I do not see how at 60Mbps, this interface should be dropping so much traffic. THanks in advance for any suggestions!
11-07-2013 06:01 AM
11-07-2013 08:10 AM
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A common issue with the 3560/3750 series, is "shallow" buffers. I.e. if there are bursts of traffic that exceed the ports transmission rate, the port will drop packets even though the "average" transmission rate isn't high.
Mapping 4 ports to 1 port could create such a situation. Although you have your load average set to 30 seconds, a lot can happen within 30 seconds.
11-07-2013 01:40 PM
"Total output drops" is not a "network issue", per se.
This counter increments when the downstream clients starts dropping packets. This happens when the downstream packet can't process the volume of incoming traffic.
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