Packets are discarded because the transmitting machine may have run out of outbound packet buffers. (Packets can’t be transmitted because they are deferred into buffers, filled, and then discarded) This can occur if there is not enough outbound bandwidth available to transmit all requested data. It is suggested that you increase the bandwidth of the link, or increase the number of transmit buffers on this device.
To fix this problem:
Cause 1: Insufficient memory is allocated for outbound packet buffers. This may be modified in the device’s configuration.
Cause 2: The network interface may not be fast enough to process all of the outbound packets. Employing a faster speed interface may remedy this problem.
If the interface shows low utilization on the graphs and numbers, but has high bursts (like 100% utilization for 10-15 seconds), it may still make sense to increase the bandwidth on the link so these burst conditions don’t create outbound discards.