Install Guide

Discard Counters
The Dell Networking OS discard counters counts the packets or frames which are legitimate but dropped due to lack of
operation of the higher layer protocol. The discard counters do not count the errors such as runts, giants, throttles, CRC,
overrun, underrun, symbol error, etc.
For example, when an OSPF packet is received on a switch which has OSPF disabled, the packet gets dropped due to filter
processor (FP) entry and the discard counter gets incremented. However, the packets that are forwarded to the CPU are
dropped at the interface level and a copy of the packet is forwarded to the CPU. Therefore, the discard counter is increased
when a packet matches an FP entry, irrespective of the action defined in the FP entry to avoid pipeline processing in the
hardware.
Display discard counters
● View the discard counters.
EXEC Privilege Mode
show interfaces
Points to remember:
1. Following are some of the major protocols that can be dropped based on the FP rule entry, if those protocols are not
configured or blocked. All these drops are accounted as discard counters.
● LLDP BPDU redirects
● ARP
● STP/RSTP BPDU redirects
● BGP
● OSPF
● ECMP and LAG show cases
● VLT LLDP PDUs
● VLT DOT1x PDUs
● VLT PE ECP PDUs
● VLT IPM1 sync frames
● VLT ARP sync frames
● VLT TTL1 packets tunneled
● VLT ARP replies tunneled
● VLT STP BPDUs tunneled
● FEFD
● VRRP frames redirects
● ARP reply packets
● GVRP traffic redirects
● LACP traffic redirects
● Common VLT control frames
2. Packets are dropped due to user defined ACLs.
3. Multicast traffic with the TTL value 1.
4. Multicast traffic is not part of any group or special group that has to be processed by the CPU.
5. In addition to the above protocols, the filter processor rule also drops Yellow and Red packets if QoS is configured on the
system.
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Interfaces