Technologies | Stateful TCP

A new test paradigm: Re-defining traffic blasting and measurement at Layer 4

Eight-five percent of traffic on the Internet today is (stateful) TCP traffic deriving from e-mail, web-surfing and bandwidth-intensive peer-to-peer applications. Consequently, industry is moving away from basic stateless traffic blasting at layers 2 and 3, and towards a model that validates stateful forwarding performance at layer 4.

“Equipment vendors and service providers have a need to characterize forwarding performance at higher layers for more meaningful evaluation, especially in the context of increasingly intelligent switches and routers.”
                                                      - Dr. Bijan Jabbari, president of Isocore

N2X re-defines packet-blasting to a new world of connection-blasting, stateful traffic blasting, and ultimately, transaction-blasting. N2X’s stateful TCP traffic model provides unprecedented scalability and flexibility to quickly find the non-drop rate of forwarding devices in the presence of stateful traffic. 

Hardware-based TCP emulation makes a difference.

N2X implements TCP emulation in hardware, allowing wire-rate generation of stateful TCP traffic using a fully featured TCP stack that includes re-transmissions and dynamic windowing. N2X overcomes the limitations of traditional CPU/software-based solutions, which must simplify or omit TCP emulation characteristics to reach higher levels of bandwidth.

CPU-based TCP solutions cannot scale while reflecting the dynamic TCP behaviors that can wreak havoc on network resources and impact the timely delivery of higher-priority service traffic. The performance measurements that result from these types of TCP implementations provide little insight into how the device or system will behave in a real-world network deployment.

In comparison, the Agilent N2X provides a hardware-based TCP implementation that can scale to line-rate gigabit Ethernet while maintaining a fully featured TCP stack, even under the stress of realistically short packet lengths, which can frequently be less than 100 bytes. N2X is the only solution that offers a dynamic traffic load ‘slider bar’ that allows users to immediately adjust traffic load on the fly. Users can set up TCP connections and simulate applications at rates of hundreds of thousands per second. This enables network equipment manufacturers and service providers to test network equipment in a realistic and reliable fashion. An additional advantage is that the hardware implementation produces consistent results between test runs, which is critical for identifying the variables impacting performance and for completing regression tests.

Complimentary Products

The new N2X N5575A Stateful TCP Traffic and Measurement License is complimented by the N2X N5576A Data Application Software License and existing N2X multi-service test functionality to provide an Integrated L2-7 test solution that combines both stateful and stateless traffic generation and analysis, from Layers 2 through 7 in a unified software and hardware platform.

Key Features

• Characterize L4 forwarding performance with “Connection Blasting”
• Load a GbE pipe with stateful TCP traffic at line rate
• Emulate a fully-featured TCP stack: fast retransmit, slow start, congestion avoidance
• Measure the interaction between TCP flows and queuing mechanisms
• Measure real-time goodput on TCP traffic