A new class of test gear for NFV-based services

July 1st, 2016 by · 1 Comment

This Industry Viewpoint was contributed by Charanya, Product Marketing Manager at Veryx Technologies

Next-generation Ethernet/IP services that depend on Software Defined Network (SDN), Network Function Virtualization (NFV) and Cloud technologies, utilize virtual network functions (VNFs) that are chained together to realize a network service (NS). While these NFV-based services derive the benefit of high agility and low costs, assuring service performance is a challenge. This is because the traditional hardware-based testing and visibility solutions are not always up to the task. The reasons for this are given below.

Firstly, it is challenging to use traditional hardware-based service assurance solutions to determine the performance of these network services because of the dynamically changing VNF locations. In the NFV architecture, network services are created by chaining VNFs that are distributed across virtualized servers in a data server. These VNFs can be orchestrated across the servers within a datacenter or across datacenters.

Secondly, traditional hardware-based service assurance solutions cannot necessarily keep up with the real-time changes occurring in NFV based services. NFV-based network services are activated and de-activated based on user requests and are made available for user requested duration. NFV allows changes to the network services in real time, which in turn requires simultaneous changes in test functions. Since real-time flexibility is of great value to customer, the service provider needs to be able to also provide test and monitoring capabilities that are dynamic in nature and available on-demand.

Finally, traditional hardware based service assurance solutions are incapable of getting full visibility into the network in NFV environments. Network services in NFV environments are more often than not created by chaining VNFs within the same virtual server. This however, limits the visibility to the data flowing across these VNFs in a server, and results in a blind spot.

As a result of the foregoing reasons, there is a need for a new class of solutions to facilitate complete testing and visibility in NFV networks. In this regard, ETSI* has been standardizing test functions as virtual test agents (VTAs) in the ETSI MANO* architecture.

Enter the Virtual Test Agent (VTA)

Virtual Test Agent is a test VNF that can that can co-exist with other VNFs and can be stitched together to the VNF service chain. By associating itself with the service chain, VTA accurately measures service performance and ensures service assurance, while overcoming the limitations faced by traditional hardware-based service assurance solutions.

Virtual Test Agent Characteristics

Some of the key characteristics of a VTA as put forth by ETSI are as defined below:


As a test VNF, VTA should be dynamic enough to align itself with dynamic, on-demand service offered. This means that the VTA should be instantiable whenever required and removed whenever it is not required based on the need –either for performance measurement or troubleshooting purposes.


The Virtual Test Agent measurement should continue even when any of the VNFs in the Forwarding Graph migrates to provide optimal performance. The Virtual Test Agent should be flexible enough to be orchestrated based on VNF migration in order to guarantee service assurance.


Test agent should have minimal CPU and memory requirement. It should not impact the performance of VNFs that reside on the same server as the Virtual Test Agent. Thus, with these characteristics in place, service providers would be able to leverage Virtual
Test Agent based solutions to test service availability, performance bottlenecks and SLAs for network services implemented using NFV.

*ETSI – European Telecommunications Standards Institute
*ETSI MANO – ETSI Management and Orchestration


About the Author
Charanya (charanya.balasubramanian@veryxtech.com) is currently working as a Product Marketing Manager at Veryx Technologies (www.veryxtech.com). She handles product marketing efforts for Veryx solutions in emerging technologies such as SDN, Cloud and NFV.


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Categories: Industry Viewpoint · NFV

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