How to understand and interpret sp-* interface statistics

This article describes how to interpret sp-* interface statistics.

For a physical interface or logical unit, input statistics refer to statistics of the packets entering the interface, while output statistics refer to statistics of the packets leaving the interface. This behavior is reversed for sp-* interfaces.

In sp-* interfaces, statistics are reported from the PFEs (ingress/egress) perspective.

The configuration below is used to explain how to understand and interpret sp-* interface statistics.

Configuration

Explanation & Example

For sp-* logical interfaces, the interface statistics are reported from the ingress and egress PFEs perspective.

Packets leaving the PFE towards the service-pics inside sp-* logical interface are represented as output packets, and the packets leaving the service-pics outside sp- logical interface towards the egress PFE are represented as input packets.

Inside interface

  • Packets leave the ingress PFE and enter the service PIC for processing.
  • Counters are reported from the PFEs perspective.
Inside interface

  • Processed packets leave the service PIC towards the egress PFE.
  • Counters are reported from the PFEs perspective.
 

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Prasanna

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