Abstract

Agilent Technologies commissioned The Tolly Group to evaluate its RouterTester, a network simulation system specifically designed for testing the performance of gigabit and terabit routers. 

This Tolly Group evaluation examines Agilent Technologies’ RouterTester, a carrier-class network simulation system built to validate the performance, scalability, and traffic-management behavior of gigabit and terabit routers. Tested in August and September 2000, the system was configured with OC-12c (622Mbit/s) and OC-48c (2.488Gbit/s) Packet over SONET/SDH interfaces and designed to emulate complex Internet conditions that stress modern high-end routers. The report highlights RouterTester’s ability to advertise an effectively unlimited number of routes, generate multiple IP traffic streams, simulate route flapping, measure route convergence, and analyze QoS behavior under congestion.   

Tolly verified that RouterTester could advertise hundreds of thousands of routes and transmit variable-length packets over those routes while measuring forwarding performance across mixed OC-12c and OC-48c Packet over SONET interfaces. In the forwarding and stability tests, the system simulated neighboring routers on each interface using BGP-4 and generated full-mesh traffic across 10,000, 120,000, and 327,680 routes. It also simulated route updates by advertising and withdrawing routes at rates up to 500 updates per second while traffic was flowing, allowing engineers to measure the impact of routing churn on throughput. 

The report also validated RouterTester’s convergence analysis capabilities. As described on pages 2 and 3, the system could withdraw a preferred route, shift traffic to an alternate path, and measure when the new route first received traffic, when the old route stopped receiving traffic, and when the new path reached full offered line rate. This provided a detailed “snapshot” of router behavior during convergence events. 

For QoS testing, RouterTester encoded IP Precedence and Differentiated Services Code Point markings and measured packet loss, latency, and throughput for multiple priority streams under oversubscribed conditions. The test bed used one Agilent E7901A OC-48c module, two E7902A OC-12c modules, synchronized event and timing lines, and a Juniper Networks M20 router as the device under test. Overall, the report presents RouterTester as a comprehensive high-speed router test platform capable of simulating both current and emerging Internet-scale routing conditions.