This article explains some of the possible reasons for TX/RX drop packet counters increasing on APMsAn increasing counter of TX/RX dropped packets can be observed on VAPs. Counters are accessible with "
netstat -i", "
ifconfig" or with the XOS command "
swatch" (option "
vsx_1 (CBS): [vs1] ~# netstat -i
Kernel Interface table
Iface MTU Met RX-OK RX-ERR RX-DRP RX-OVR TX-OK TX-ERR TX-DRP TX-OVR Flg
Goal: To explain the reasons that may cause TX/RX drop counters to increase.
TX drop counters explained:
The "TX-DRP" counter is normally increasing when the VND driver recognizes that the APM is operating as a non-master VAP in a VAP group (the master/non-master status can be verified by running "
show ap-vap-mapping") and the APM is trying to respond to a broadcast (typically a response to an ARP request). Even though broadcasts are received and processed by all VAP group members (NPM takes care of the packet replication) only the master VAP is allowed to answer the broadcast. These packets are therefore dropped for a valid reason by the VND driver on non-master VAPs.
RX drop counters explained:
Possible legitimate reasons for a packet to be dropped by the VND driver on the receiving (RX) side:
1) When running Check Point VSX, non-management circuits have IP addresses defined under VRRP only and auto-configured with
backup-stay-up option. All packets arriving to such circuit will be dropped and counted as "downRx" (in "
cat /proc/cbs_vnd/stats"). There is one exception: in a case where the interface is part of MLT group-inteface, LACP frames are allowed to pass the circuit.
2) RX drop count can be especially high on a circuit configured for Check Point synchronization - see the section References for more information about this topic.
Virtual Network Device. A Linux kernel object representing a logical network interface. A virtual network device is directly mapped to an NPM circuit.
RX drop count high on a Check Point sync circuit: KB Article #5235 - "RX errors may be observed on the CheckPoint synchronization interfaces on the APM"
Imported Document ID: 000019412
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