Spirent Communications Unveils Avalanche AfterBurner Technology for Gigabit Wire-Speed Layers 4-7 Performance Testing.

Business Editors/High-Tech Writers

NetWorld+Interop 2003 Las Vegas

LAS VEGAS--(BUSINESS WIRE)--April 29, 2003

Innovative Technology to be Demonstrated at N+I in Spirent's Booth

#7375 Raises the Bar for High-Performance Testing by Enabling More

Than 400,000 Connections Per Second Per Port

Spirent Communications(TM) (NYSE:SPM), a worldwide provider of integrated performance analysis and service assurance systems for next-generation network technologies, today announced Avalanche AfterBurner(TM) technology for the Avalanche SmartBits product line. The new technology, to be demonstrated on April 29 at NetWorld+Interop in Las Vegas in booth #7375, breaks all previously set performance benchmarks by effectively saturating a Gigabit link with TCP/IP connections.

"We recognize this innovation from Spirent as a significant breakthrough for testing high-performance products such as ours," said Chandra Kopparapu, vice president and general manager of Service Provider Business Unit at Foundry Networks. "Testing a high performance Layer 4-7 system such as our ServerIron requires a powerful testing product. The Avalanche AfterBurner helps us in not only testing the current ServerIron systems, but also in developing new next generation systems."

Avalanche AfterBurner technology highlights Spirent's continuing series of innovations in the Layers 4-7 space and offers the industry an effective method for performance testing extremely high-end firewalls, server load balancers (SLBs) and large scale infrastructures built from clusters of high-end equipment. Spirent's Avalanche AfterBurner enables in excess of 400,000 TCP connections per second on a single Gigabit link. The high-performance technology runs on the award-winning TeraMetrics(TM) platform and will be integrated with Avalanche SmartBits software.

"This is a demonstration of a technology that proves Spirent's continuing leadership in the Layers 4-7 security and web infrastructure space," said Andrew Foss, president of Spirent Communications' Northern California Performance Analysis -- Broadband operations. "Avalanche AfterBurner enables current TeraMetrics customers to test the highest performance L4-7 devices in the industry, providing them with tremendous on-going return on their investment in Spirent's products."

The Avalanche AfterBurner will be available to Avalanche SmartBits customers in August 2003.

About Avalanche

Avalanche is designed for network equipment manufacturers, service providers and Web site managers that demand absolute realism and control under all conditions. Avalanche challenges any computing infrastructure's ability to stand up to the load and complexity of the real world. Avalanche can generate in excess of 30,000 HTTP requests per second, and supports HTTP/1.0, HTTP/1.1, HTTPS, RTSP/RTP (Apple QuickTime(R)), RealSystem(R) streaming, Microsoft(R)Windows Media(R) 8 and 9 Series, SMTP, POP3, DNS, Telnet and FTP. In addition, Avalanche can generate Distributed Denial of Service attack traffic inline with any mix of multi-protocol traffic. Through clustering, Avalanche can scale to the needs of even the world's largest infrastructures. Many leading corporations use Avalanche to ensure that their products and services excel in real-world conditions. Real-world conditions are accurately replicated by simulating error conditions, realistic user behavior, and maintaining over one million open connections from distinct IP addresses. Current customers include AT&T, BEA, Cable & Wireless, Cisco Systems, CNET, Deutsche Bank, eBay, Extreme Networks, F5 Networks, Forbes.com, Foundry Networks, Intuit, MSNBC, Network Appliance, NetScreen, Nortel Networks, NTT DATA, SBC Communications, and WatchGuard. http://www.spirentcom.com/avalanche.

About Spirent Communications

Spirent Communications is a worldwide provider of integrated performance analysis and service assurance systems for next-generation network technologies. Spirent's solutions accelerate the profitable development and deployment of network equipment and services by emulating real-world conditions in the lab and assuring end-to-end performance of large-scale networks. www.spirentcom.com

Spirent Communications is a wholly owned group of Spirent plc, an international network technology company. Spirent plc is listed on the London Stock Exchange (LSE:SPT). The company is also listed on the New York Stock Exchange (ticker: SPM; CUSIP number: 84856M209). www.spirent.com

Spirent, Spirent Communications and the Spirent logo are trademarks of Spirent plc. All other trademarks or registered trademarks are held by their respective companies. All rights reserved.

This press release may contain forward-looking statements that are based on current expectations or beliefs, as well as assumptions about future events. By their nature, forward-looking statements are inherently predictive, speculative and involve risk and uncertainty because they relate to events and depend on circumstances that will occur in the future. You should not place undue reliance on these forward-looking statements, which are not a guarantee of future performance and are subject to factors that could cause Spirent's actual results to differ materially from those expressed or implied by these statements. These risks include the risks described from time to time in Spirent's SEC periodic reports and filings. We undertake no obligation to update our forward-looking statements, whether as a result of new information, future events or otherwise.