Spirent Communications Highlights Product and Service Innovations at Networld + Interop Las Vegas 2004.

Business Editors/High-Tech Writers

NetWorld+Interop 2004 Las Vegas

Booth #1435

LAS VEGAS--(BUSINESS WIRE)--May 11, 2004

At this year's Networld + Interop tradeshow, Spirent Communications(TM) (NYSE:SPM)(LSE:SPT) will showcase its "All Points Tested" exhibit and theme, demonstrating -- both on and off the show floor -- one of the industry's most far-reaching and complete portfolios of testing products for enterprises, network equipment manufacturers and carriers.

Behind the scenes at N+I, the eNet network will rely on Spirent's performance analysis and service assurance systems to prevent network outages and proactively monitor the state of this show's network. Spirent Communications' equipment was used during hot-staging to verify the reliability and usability of the world's largest portable network that provides the high-speed network services to N+I exhibitors, conferences, meeting rooms and attendee messaging centers.

On the floor, Spirent Communications will:

-- Showcase its new industry-first performance analysis and

service assurance solutions;

-- Demonstrate a full range of communications test and management

capabilities with several major customers through Spirent's

"Tested with Spirent" program;

-- Participate in N+I's speaking program; and

-- Be recognized again this year as a "Best of Interop" finalist

Demonstrations of Spirent's Capabilities

Spirent's Avalanche and Reflector products are being used to simulate high volume web traffic in a Cisco DDOS mitigation demonstration. For this demonstration, Cisco chose the Avalanche to simulate multiple HTTP clients and the Reflector to simulate HTTP servers. The Layer 7 traffic flows being generated by the Spirent devices provide the best simulation of high volume web traffic from the Internet to a web data center. The Cisco DDOS mitigation demo shows how Cisco's Anomaly DetectorXT 5600 and GuardXT 5650 defend the data center against DDOS attacks while ensuring business continuity for the various network based services hosted at the typical data center.

ClearSight Networks will demonstrate its new 10-gigabit analyzer using Spirent's TeraMetrics 10-Gigabit performance test module and TeraRouting Software. ClearSight will show their devices' full-line capture and decode capability as well as the capability of their software to do network analysis and troubleshooting at the application layer for IPv4 and IPv6 networks. ClearSight's software and Spirent's TeraMetrics hardware and TeraRouting software are past Networld + Interop Best of Show winners.

Foundry will demonstrate wire-speed, 480 million packets-per-second IPv6 switching and routing using its flagship Terabit-class 10 Gigabit Ethernet switch, the BigIron MG8. The BigIron MG8 will be equipped with 32 ports of 10-Gigabit Ethernet, employing the Spirent SmartBits 6000C performance analysis system to generate IPv6 traffic.

Foundry also will demonstrate the industry's highest connection performance and Denial of Service (DoS) attack protection with its most innovative ServerIron Layer 4-7 switches. The demonstration uses one of the largest Layer 4-7 test beds consisting of Spirent's Web Avalanche and Reflector products.

Spirent Speaking at Networld + Interop

Mark Fishburn, Spirent's vice president of Technical Strategy and chairman of the board of the Metro Ethernet Forum, will participate in the Performance and Data Center Conference Track. Mark will address performance analysis, planning and testing. He also will give the keynote address to the Metro-Ethernet track. Andy Huckridge, senior product marketing manager of Spirent's IP Telephony group, will address VoIP architectures and deployment as part of the Internetworking Conference track.

In Spirent's Booth

At booth number 1435, Spirent will showcase a broad range of enterprise network testing products including its Architecture for Converged Testing (ACT) on its Abacus 5000 IP Telephony Migration System, a finalist for the 2004 Best of Interop awards in the Network Test & Measurement category. Other products showcased in the booth include:

 -  Wireless
    --  Spirent Mobility 2500 Wireless Data Test System

 -  Data Center
    --  Spirent Avalanche Application and System Testing

 -  Security
    --  Spirent Avalanche and Reflector Security and Network
        Infrastructure Testing
    --  Spirent TeraVPN IP-VPN Scalability and Performance Tester

 -  Infrastructure
    --  Spirent SmartBits 10 Gigabit Ethernet Performance Analysis
        Test System
    --  ClearSight Application-Layer Network Analysis

 -  Routing/IPv6
    --  Spirent Router Testing

 -  Training & Test Services
    --  Spirent ServiceEdge Care Support and Maintenance Programs
    --  Spirent ServiceEdge Express Customer Engineering and Test
        Services
    --  Spirent ServiceEdge Tutor Comprehensive Instruction and
        Certification
        --  Spirent Campus Online Training

About Spirent Communications

Spirent Communications (www.spirentcom.com) is a global provider of integrated performance analysis and service assurance systems that enable the development and deployment of next-generation networking technology such as Internet telephony, broadband services, 3G wireless, global navigation satellite systems, and network security equipment. Spirent's solutions are used by more than 1,500 customers in 30 countries, including the world's largest equipment manufacturers, service providers, enterprises and governments. Based in Rockville, Maryland, Spirent Communications reported 2003 revenue of $394 million and has 1,800 employees worldwide. The company is the largest business group of Spirent plc, traded on the London and New York Stock Exchanges (LSE:SPT)(NYSE:SPM)(CUSIP number: 84856M209). www.spirent.com. Spirent Communications' sales to the United States government are made through Spirent Federal Systems. www.spirentfederal.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.