RX Packet drops investigation on Authentication Manager 8.x
Originally Published: 2021-08-05
Last Modified: 2023-10-06
Article Number
000044246
Applies To
Authentication Manager 8.x
Issue
 ifconfig or netstat -i commands show dropped RX packets

User-added image
 
Cause
Beginning with kernel 2.6.37, it has been changed the meaning of dropped packet count. Before, dropped packets was most likely due to an error. Now, the rx_dropped counter shows statistics for dropped frames because of:
  • Softnet backlog full  -- (Measured from /proc/net/softnet_stat)
  • Bad / Unintended VLAN tags
  • Unknown / Unregistered protocols
  • IPv6 frames when the server is not configured for IPv6

If any frames meet those conditions, they are dropped before the protocol stack and the rx_dropped counter is incremented.
Resolution
Working as designed
Notes
In order to check the packet drops run tcpdump -i eth0 to check if there is unintended VLAN tags or unknown protocols.

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