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Open Traffic Generator (OTG) APIs and data models are northbound API specifications for modern Traffic Generators and Protocol Emulators designed to test Layer 2-7 network devices. They include support for testing forwarding as well as control planes. OTG APIs are:

  • Open
  • Vendor-neutral
  • Intent-based
  • Declarative

The formal model specification can be found on GitHub under Open Traffic Generator organization. To explore the model, a viewer friendly ReDoc rendering is available as well. The OTG APIs support both REST and gRPC interfaces.


OTG is an actively developed specification, with contributions from real use cases. The model defines the following components of a traffic generator configuration:

  • Test Ports with Layer 1&2 capabilities, including:
  • Emulated Devices with Layer 2&3 features:
    • IPv4, IPv6 interfaces
    • ARP, IPv6 ND
    • BGP, IS-IS routing protocols
  • Traffic Flows
    • associated with either Test Ports, or Emulated Devices
    • expressing L2-4 properties like Ethernet, IPv4/IPv6, TCP/UDP
    • stateless or stateful capabilities for transport protocols
    • with implementation-specific application payload
  • Run-time Metrics and traffic Capture capabilities

Example OTG Diagram

Fig. 1. OTG diagram with Traffic Flows between Emulated Devices, running via a Device Under Test (DUT)


To apply OTG in practice, an OTG-compatible tool, typically a Traffic Generator, is needed. There are several implementations available, and the list is growing:


There are multiple ways to communicate with a Traffic Generator via the OTG API:

  • otgen command-line tool is an easy way to start with
  • snappi library to accelerate development of Test Programs written in Python or Go
  • direct REST or gRPC calls as an alternative to using snappi
  • custom OTG client applications

snappi and gosnappi provide client side API libraries for the OTG specifications for Python and Golang respectively. For other languages, SDKs can be built using OpenAPI Generator (for REST API) or protobuf tools (for gRPC).

Use Cases

Real use cases are the basis of OTG evolution. Notable open-source projects leveraging OTG:


Use our community resources to get help with Open Traffic Generator applications, develop your own implementation, or contribute to OTG: