Correlation Key

Napatech Link-Capture™ Software Features

Intel® PAC
Napatech SmartNIC
Content Type
Feature Description
Capture Software Version
Link™ Capture Software 12.11

This chapter describes the correlation key functionality.

Applies to

Note: This chapter does not apply to the following SmartNICs.
  • NT200A02 running on the 2 × 100 Gbit/s FM1 image
  • NT200A02 running on the 2 × 40 Gbit/s FM1 image nor on the 8 × 10 Gbit/s FM1 image
  • NT100A01 running on the 4 × 25/10 Gbit/s FM1 image
  • NT100A01 running on the 4 × 10/1 Gbit/s FM1 image
  • NT40A01 running on the 4 × 10/1 Gbit/s SLB image.


The correlation key is a unique key calculated as a hash of a configurable subset of the frame content:

  • A 64-bit correlation key is generated in hardware for all wire speeds.

  • Dynamic header information (for example TTL) can be masked out.

  • The correlation key calculation is configured per frame category (for example IP protocol or TCP port number), using the filter functionality.

  • 16 different correlation key recipes can be defined.

  • The correlation key is delivered in dynamic packet descriptor 4 or part of it in extended descriptor 9.


Typical applications for the correlation key feature include:
  • Quality of service monitoring and assurance in a mobile telecom network. The correlation key feature makes it possible to identify packets as they traverse the network, independently of protocol encapsulation. This enables for example measurement of latency between different nodes in the network.

  • Packet deduplication in application software. Correlation key generation in hardware offloads the CPU intensive CRC calculations from the host application.

  • Packet deduplication in hardware (see Deduplication).