Addressing the Data Growth Challenge

As network traffic increases, there is a need for high-speed networks to ensure service level and capacity. In telecom networks and data centers, serving hundreds of thousands of users, 100G network links are deployed to keep up with the growing demand. Consequently, there is a need for testing and troubleshooting on the networks at 100G link speed.

Benefits of network traffic replay

Today, as there are so many services and subscribers depending on stable data networks, quality and maturity are critical when deploying new solutions. Testing new network solutions or new versions of networking products or applications is a challenge because synthetic test cases do not disclose all potential issues. Replaying real production network traffic provides more realistic test scenarios. Moreover, the test coverage can be extended by replaying traffic from many different networks.

In case of network issues, efficient troubleshooting reduces the disruptions and potential down-time of services. Network traffic replay provides a powerful tool for reproducing and analyzing issues in a lab environment, not affecting the production network. Identification of network issues requires precise replay, throughput-wise and timing-wise. For example, traffic micro-burst can only be recreated in a lab environment if the solution supports full throughput and precise timing of packets replayed.

What are the options?

There are complete solutions for capture and replay of 100G network traffic in the market today. In some cases, these products match the actual need, but in other cases the solutions are way too expensive, have too many features or cannot be customized to special use cases.

An alternative approach is to build your own replay solution, using a COTS server, a standard Linux OS and a 100G smartNIC. The COTS server has all the horsepower and I/O performance needed to run 100G replay. Linux OS enables use of open source software or easy application development and feature customization. The smart NIC ensures full throughput transmit for any packet size, with precise transmit timing, with some smart NICs having one-nanosecond time resolution.

Build your own 100G replay solution

A high-performing 100G replay solution requires certain qualities from the building blocks.

To obtain maximum replay performance, it is recommended to have maximum memory bandwidth available in the server. The server should be populated with the maximum number of DDR4 memory blocks to allow full use of all the memory channels. Another recommendation is to use dual rank DDR4 or memory blocks running at least 2133 MHz or higher. To replay large files, the packet store output performance limits the maximum average replay speed. Fast Solid State Disks should be considered for high- speed replay.

The Smart NIC must support a 100G network interface with line-rate capture and transmit for any packet size, high-precision time stamping of received traffic, high-precision transmit timing, an efficient buffer system and an optimized DMA scheme over the PCIe interface.

Open source capture and replay applications are available, and some Smart NIC vendors include tools for capture and replay in their software suite. The application should use server memory for buffering traffic from packet store before transmission. This is to compensate for the difference between 100G peak network packet rate and maximum read rate from the packet store.

Directing Traffic

High-speed networks are becoming a necessity as network traffic grows exponentially. 100G links need testing and troubleshooting to ensure quality service, and network traffic replay enables testing outside the production network. You can buy complete capture and replay solutions or build your own. With the right building blocks, you can create a customized solution that saves money and still delivers the high performance you and your customers need.

About the author: Sven Olav Lund is a Senior Product Manager at Napatech and has over 30 years of experience in the IT and Telecom industry. Prior to joining Napatech in 2006, Sven Olav was a Software Architect for home media gateway products at Triple Play Technologies. From 2002 to 2004 he worked a Software Architect for mobile phone platforms at Microcell / Flextronics ODM and later at Danish Wireless Design / Infineon AG. As a Software Engineer, Sven Olav started his career architecting and developing software for various gateway and router products at Intel and Case Technologies. He has an MSc degree in Electrical Engineering from the Danish Technical University.

Edited by Mandi Nowitz