This document was revised on 25 September 2009. For more information, see the Corrections page on gartner.com.

The key criterion in the Magic Quadrant for Application Delivery Controllers (ADCs) focuses on a vendor's ability to provide critical capabilities for important application deployment challenges in the enterprise. Vendors at the forefront of these challenges will emerge as more viable and stronger.

The market for data center-based solutions to optimize the delivery of applications across the network continues to develop, and our expectations increase with each revision of the Magic Quadrant. As a result, the Magic Quadrant axis depicts a shift up and to the right with each revision. Consequently, vendors must progress to maintain their positions in the new Magic Quadrant.

New use cases of the ADC technology continue to emerge, reflecting the significant innovation in the market. These technologies apply across a growing base of enterprise applications that may or may not use the Internet, or have little or no roots in Internet and browser-based technologies. Although the market emerged from load-balancing solutions to improve the availability and reliability of websites, the time has long passed since load balancing and Secure Sockets Layer (SSL) termination for basic HTML traffic were viable by themselves. Browser-based applications often are a major impetus for investing in these technologies; however, many enterprise applications that appear to be browser-based actually employ thick clients that run in the browser, that don't run over HTTP(s) or have the capability to bypass standard browser capabilities, such as compression. ADCs are often key components of diverse environments such as portals, ERP systems, Microsoft Outlook and Office Communications Server (OCS), control points for virtualization, adjuncts to enterprise service buses (ESBs) or a service within service-oriented architecture (SOA) and, increasingly, as an element of application development environments.

The emergence of Ajax and other rich-client interfaces further complicates the environment. As a result, there's a need for solutions with broader payload parsing, as well as inspection and optimization techniques, including client-resident software.

ADCs reside in the data center, typically ahead of front-line Web servers. They're deployed asymmetrically (only at the data center end) and are designed to improve the availability, efficiency, performance and security of Web-based or Internet Protocol (IP)-based applications. ADCs enhance the performance of Web-based and related applications for end users by providing a suite of services at the network and application layers. These services may include:

• Layer 4 through Layer 7 redirection, and load balancing and failover
• TCP connection multiplexing
• Server off-load (for example, SSL termination and TCP connection management)
• Data compression
• Network-address translation
• Network-level security functions, distributed denial-of-service protection and server cloaking
• Compression
• Caching

A more-advanced class of ADCs, advanced platform ADCs (AP ADCs), operate on a per-transaction basis and achieve application fluency. These devices become actively involved in delivering the application and providing sophisticated capabilities, including:

• Application layer proxy, which is often bidirectional and stateful
• Content transformation
• Adaptive compression
• Selective caching of dynamic content
• Dynamic use of browser cache
• HTML or other application protocol optimizations
• Web application firewall
• XML validation and transformation
• Rules and programmatic interfaces to access ADC capabilities from within applications or influence the services based on application state

AP ADCs provide simplified deployment and extensibility, and are being deployed between the Web server tier and the application or services tier (for SOA servers).

Most AP ADCs incorporate rule-based extensibility that enables the customer to customize the behavior of the AP ADC. For example, a rule might enable the AP ADC to examine the response portion of an e-commerce transaction, and strip off all but the last four digits of credit card numbers. In some cases, organizations are using these capabilities as an alternative to modifying Web applications.

Many AP ADCs incorporate a programmatic control interface (open application programming interfaces [APIs]) that enables them to be controlled by external systems, including application servers, data center management and provisioning applications, and network and system management applications. This capability may be used for regular, periodic reconfigurations (such as end-of-month closing) or may be driven by external events (such as taking an instance of an application offline for maintenance). In some cases, the APIs link the AP ADC to server virtualization systems and data center provisioning frameworks to deliver the promise of real-time infrastructure.

A new use of ADCs is the emergence of the ADC as a key element of application development environments. Rather than coding common functions into all applications, the ADC can perform these functions for all applications as a service. These functions include authentication, logging, usage measurements, security enforcement (for example, hiding credit card information). Putting these functions in the ADC ensures that they are applied consistently across all applications.

ADCs provide a set of functions to optimize enterprise application environments. The market evolved from the load-balancing systems that were specifically developed to ensure the availability and scalability of websites. Enterprises use ADCs to optimize reliability, end-user performance, data center resource use and security for a variety of enterprise applications.

Criteria for inclusion in the Magic Quadrant for ADCs include:

• The vendor has released products for general availability, and has demonstrated its commitment to this market.
• The vendor is focused on delivering solutions to the enterprise market, and demonstrates relevance to Gartner clients.
• The vendor must have achieved at least 1% market revenue share in the overall ADC market in 2008.

Due to increasing client demand for more (and often lower-cost) alternatives, we have lowered our revenue threshold to 1% of the total ADC market. This has resulted in A10 Networks, Array Networks, Barracuda Networks and Crescendo Networks being added to the Magic Quadrant.

Nortel Networks has been dropped due to the sale of its Alteon application switch business unit to Radware in March 2009.

While it offers an enterprise-focused SoftADC with a broad feature set, ActivNetworks was not included because it did not meet the market share requirements.

We analyze the vendor's capabilities across broad business functions. Vendors that have expanded their products across a wider range of protocols and applications, have improved their service and support capabilities, and have focused on improving enterprise applications will be more highly rated in the Magic Quadrant analysis.

Product/Service evaluates the capabilities of the products or solutions offered to the market. Key items to be considered for the application delivery market are how well the products address enterprise application needs, the breadth of the products (in terms of different functions), and scale — from entry-level products to high-end products. We also look at the level of integration, flexibility and innovation that the vendor demonstrates in its products. We include products that provide load balancing, SSL termination, connection management, compression, protocol manipulation, global redirection, some aspects of security enforcement and other related technologies, including Ajax and other rich-client technologies. A key aspect that demonstrates continued execution in this area is how the vendor expands the types of applications that are optimized. Although we don't expect vendors to have every technology option in their products, we expect them to offer a comprehensive and flexible solution for enterprises that clearly demonstrates a focus on enhancing enterprise applications.

Overall Viability (Business Unit, Financial, Strategy, Organization) includes an assessment of the organization's financial health, the financial and practical success of the business unit, and the likelihood that the individual business unit will continue to invest in the product, offer the product and advance the state of the art in the organization's product portfolio.

Sales Execution/Pricing looks at the vendor's capability to get the product into the market efficiently. In this market, we look for specialist capabilities — that is, a vendor and associated channels that can understand and deliver solutions for optimizing a range of data center applications. Having strong field sales and application engineering to supplement specialist channels will help vendors in this area. As product complexity grows, a comprehensive professional service offering has emerged as an important factor. Another factor involves partnerships with leading application providers or system integrators (SIs) that provide bundled solutions to the enterprise. In this emerging market, to date, pricing is a secondary decision criterion. As the market matures and expands to include small or midsize businesses, customer pricing will become more important. Additionally, we expect global distribution and support to serve large enterprise accounts.

Market Responsiveness and Track Record focuses on the vendor's capability to respond, change direction, be flexible and achieve competitive success as opportunities develop, competitors act, customer needs evolve and market dynamics change. This criterion also considers the provider's history of responsiveness.

Marketing Execution measures the clarity, quality, creativity and efficacy of programs that are designed to deliver the organization's message to influence the market, promote the brand and business, increase awareness of the products, and establish a positive identification of the product/brand and organization in the minds of buyers. This "mind share" can be driven by a combination of publicity, promotions, thought leadership, word-of-mouth and sales activities.

Customer Experience looks at a vendor's capability to deal with post-sales issues. Because of the specialized nature of the application delivery market, and the impact of product bugs on an enterprise's capability to conduct critical business functions, vendors are expected to escalate and respond to issues in a timely fashion with dedicated and specialized resources, and to have detailed expertise in many specific application environments. Another consideration is a vendor's capability to deal with increasing global demands. Additional support tools and programs are indications of a maturing approach to the market.

Operations looks at the organization's capability to meet its goals and commitments. Factors include the quality of the organizational structure, including skills, experiences, programs, systems and other vehicles that enable the organization to operate effectively and efficiently on an ongoing basis.

Ability to Execute reflects the market conditions and, to a large degree, it is our analysis and interpretation of what we hear from the market. Our focus is assessing how a vendor participates in the day-to-day activities of the market (see Table 1).

These criteria have been fine-tuned to reflect the expanding use of these technologies in the enterprise.

Market Understanding looks at the technology provider's capability to understand buyers' needs and to translate those needs into products and services. Vendors that show the highest degree of vision listen to and understand buyers' wants and needs, and can shape or enhance those wants and needs with their added vision. As an example of the expectations in this category, we look at how vendors have enhanced their portfolios to address new application environments.

Marketing Strategy examines the messages and methods that the vendor uses to disseminate these messages. Are the messages clear and differentiated? Are they consistently communicated throughout the organization, and externally through the website, advertising, customer programs and positioning statements?

Offering (Product) Strategy looks at a vendor's product road map and architecture, which we map against our view of enterprise requirements. We expect product direction to focus on optimizing enterprise application performance and security. Specific technologies may include connection management, security enforcement, application enhancements, and emerging solutions for enterprise WAN deployment and related technologies. The timely incorporation of new application architectures (such as SOA, Web services, Ajax and Session Initiation Protocol [SIP]) also contributes to this score.

Business Model assesses a vendor's approach to the market. Does the vendor have an approach that enables it to scale the elements of its business (for example, development, sales/distribution and manufacturing) cost-effectively, from startup to maturity? Does the vendor understand how to leverage key assets to grow profitably? Can it gain additional revenue by charging separately for optional, high-value features? Other key attributes in this market would be reflected in how the vendor uses partnerships to increase sales. The capability to build strong partnerships with a broad range of application vendors and associated SIs demonstrate leadership.

Innovation measures a vendor's capability to move the market into new solution areas, and to define and deliver new technologies. In the application delivery market, innovation is key to meet rapidly expanding requirements, and to keep ahead of new (and often more-agile) competition.

Completeness of Vision distills a vendor's view of the future, the direction of the market and the vendor's role in shaping that market. We expect the vendor's vision to be compatible with our view of the market's evolution. A vendor's vision of the evolution of the data center and the expanding role of ADCs in an SOA are important criteria. In contrast to how we measure Ability to Execute criteria, more of the rating for vision is based on direct vendor interactions, and on our analysis of the vendor's view of the future (see Table 2).

A leader has exhibited the ability to shape the market by introducing additional capabilities in its product offerings, and by raising awareness of the importance of these features. Key capabilities for a leader revolve around the AP ADC capabilities that focus on enterprise application capabilities. We expect a leader to have strong or growing market share, especially in the AP ADCs, and to have solutions that resonate with an increasing number of enterprises. Expertise in complex data center application deployment also is a necessity to be a leader in the Magic Quadrant for ADCs.

A challenger in this market is a follower from a product or innovation perspective, but it has also demonstrated the capability to take its products into the market and show their relevance to a wide audience.

Visionaries are vendors that have provided key elements of innovation, and can be illustrative of the future of the market. However, they lack the capability to influence a large portion of the market; they haven't expanded their sales and support capabilities on a global basis; or they don't have the funding to execute with the same capabilities as a vendor in the Leaders quadrant. Examples of innovation are the capability to deal with XML traffic, or an early developer of client capabilities.

Niche players provide a more-limited set of capabilities, and haven't demonstrated enough vision or focused execution to warrant a stronger position in our analysis.

• A10 Networks presents a straightforward approach to ADCs (its "Faster, Better, Greener" marketing is an illustration of that direction). A10 has shown some limited success in enterprise and service provider (SP) markets, primarily in Asia, although it is expanding more into North America.
• A strong set of advanced ADC features — including compression and caching, as well as scripting and APIs — allows A10 to solve many application deployment issues. These features are available across the range of hardware platforms and come as part of the base platform.
• A10 delivers very cost-effective solutions.

• A10 has shown little innovation beyond price/performance. As a late entrant, it has attempted to follow the best of the ADC market vendors without adding to the state of the art.
• A10 has not demonstrated significant capabilities to work in complex enterprise application and data center environments.
• As one of the smallest companies in the ADC market, A10 does not have the level of customer-facing resources compared with many of the other vendors.

• Array Networks has demonstrated very strong execution in the markets it is targeting. With 70% of its sales coming out of China and Japan, Array represents a strong alternative in these markets. The vendor is planning on taking this focus to India as a next step.
• Array's product offering continues to broaden with increasingly high-performance, application-focused platforms with hardware options for compression and SSL to boost performance.
• Array has a clustering solution to allow the product to scale into larger environments. It also has introduced some basic application and network security functions that add to the product scope.
• Array delivers a strong price/performance alternative to more-mainstream vendors, especially in its focused markets.

• Array's geographic focus requires that enterprises check local coverage capabilities in the other regions into which Array is selling.
• Array delivers mainstream features, but little in the way of application integration or deep skills, to assist in complex application environments.
• Array is one of the smaller players in the ADC market; and support, especially outside its target markets, may tax large deployments.

• Barracuda Networks has developed a broad reach and is a well-known brand in the midmarket.
• The Barracuda Web Application Firewall product contains a solid feature set for ADC and security.
• Barracuda delivers very cost-effective solutions.

• The level of investment in the products is somewhat limited, due to the lower price points offered by Barracuda. Don't look for Barracuda to innovate (outside of price).
• Barracuda's professional services are not as strong as the leading vendors when it comes to more-complex implementations.
• The product offering still shows some immaturity and inconsistency between its basic Load Balancer product and the more advanced Web Application Firewall/ADC platform, although work is under way to integrate the underlying foundation and features of the two platforms.
• Barracuda's brand is not well-known in the large enterprise market for ADCs, thus limiting its opportunities.

• Brocade delivers performance-oriented, standard ADC solutions that scale to the highest performance levels in the market.
• Brocade has a large installed base in SP and hosting facilities, which shows the proven reliability of Brocade's solutions.
• Brocade recently renewed its product offering with the new ServerIron ADX portfolio, with some of the features expected for more-sophisticated application deployment.

• Despite a noticeable improvement in features, Brocade has shown limited expertise in solving application performance challenges within the data center, and generally focuses on solutions that do not require customization.
• Brocade has a somewhat confusing array of varying hardware platforms, including the ServerIron, ServerIron Plus and new ServerIron ADX families.
• Brocade has been slower than the leading vendors to embrace scripting (now available in what Brocade calls Content Switching framework (CSW) and open APIs for external integration to provide more-extensible capabilities to the ADC.
• Brocade has not provided a vision for SoftADCs or for integrating application security functionality into its platform.

• Cisco has a large and loyal customer base combined with a substantial installed base of legacy Content Service Switch/Content Switching Module (CSS/CSM) load-balancing solutions. These customers represent an opportunity for Cisco to sell its higher-performance load balancers.
• On the Application Control Engine (ACE) module, Cisco pioneered virtualized load-balancing features that are attractive for basic, but large-scale, infrastructure load-balancing requirements.
• Cisco has developed a pay-as-you-grow licensing model to reduce the number of platforms to a minimum and to provide flexibility to its customer base.
• Cisco represents a cost-effective solution if you only require off-the-shelf features.

• Based on client feedback, Cisco has demonstrated very limited application knowledge compared with its competitors, making it difficult for the vendor to help enterprises solve complex application deployment problems.
• The inconsistent asymmetric acceleration feature set between the ACE 65xx module and ACE 4710 appliance can represent operational challenges for enterprises that require these features in different form factors and platforms.
• The future of the ACE module is somewhat uncertain, as Cisco has not yet announced plans for a next-generation service architecture.
• We have observed a decline in the number of client interactions asking about Cisco ACE solutions, which mirrors a decline in revenue in recent quarters. Cisco ADC shipments fell by 33% quarter-over-quarter during 1Q09, and a further 15% in 2Q09, which suggests Cisco is struggling to sell its ADC products independently of its broader product line.

• Citrix has a reputation for delivering high-performance ADCs with an increasingly rich set of advanced features.
• Citrix has well-developed global channel coverage with a broad set of Citrix products, from server and application virtualization to AP ADCs and WAN optimization.
• Citrix's recent introduction of the NetScaler VPX SoftADC opens up new opportunities for broader deployment of ADCs, bundling ADCs into development environments and especially integrating into Citrix Xen-based virtualization solutions.
• With its traditional software business, Citrix has a good understanding of the applications environment.
• Citrix is in a solid financial position, with an increasing share in the ADC market.

• Citrix NetScaler lacks the comprehensive application delivery vision of F5's product, although Citrix is still among the industry leaders in this category.
• Citrix has yet to establish a strong user community that helps promote and support its products.
• While easy to use, the NetScaler ADC products have somewhat limited rule-processing capabilities when compared with programmatic approaches.
• Not all the Citrix channels are capable of selling and supporting the full spectrum of NetScaler features; therefore, enterprises need to select their Citrix channels more carefully if they expect to take advantage of the full range of Citrix solutions.

• Crescendo Networks has a broad set of AP ADC features, with a strong focus on Web 2.0 applications.
• Crescendo developed an inference engine (termed "Elastic Resource Control") that dynamically adapts ADC behavior to application load and mix, therefore simplifying configuration challenges.
• Crescendo demonstrates good performance within the throughput limitations of its platform.

• Crescendo is a relatively small vendor in a market dominated by a number of much larger vendors. Its size has forced Crescendo to focus geographically in Europe, the Middle East and Africa (EMEA) and the Asia/Pacific region, at the expense of other regions.
• Crescendo's delivery of new, higher-performance platforms with 10G interfaces (such as the CN-7790) has been slower than the competition, restricting its capabilities at the top end of the market.
• Crescendo has achieved limited market/brand visibility.

• F5 Networks has a broad and comprehensive vision with industry-leading understanding of the needs of application development, deployment and management.
• The vendor has a comprehensive feature set with a full range of extensibility delivered through iRules and iControl, and integration with popular integrated development environments (IDEs), such as Eclipse and .NET/Visual Basic.
• F5 has developed a very large community of committed users (using F5's DevCentral portal) that helps fuel the use of iRules to solve unique data center application challenges, creating a loyal and engaged user base.
• F5 has a solid financial position and continued market-leading position.

• F5 has been slow to introduce a SoftADC and to explain the role of SoftADCs in its product offering.
• Although we expect this to be remedied by 1H10, lower-end platforms today cannot run the full gamut of software options that are the true value-add for F5. This has forced some customers to buy more-expansive platforms just to get features, not because they need the performance.
• F5 has a solid reputation for engineering execution and first to market the delivery of advanced features. As the TMOS feature set has grown richer, the cycle time between releases has become less predictable and has caused F5 to fall behind in some areas, such as the delivery of SoftADCs.
• Enterprises need to engage with knowledgeable engineering and online resources to ensure they get maximum value from the product offering.

• Radware's OnDemand Switch allows customers to scale environments through license keys, thus reducing the number of platforms that cover a wide range of performance requirements.
• Radware's five-year platform availability guarantee (plus three additional years of support) removes concerns that customers will be forced to upgrade platforms to gain access to new software features and extends the useful life of current platforms.
• Radware has delivered an innovative advanced proxy-based SIP solution for collaboration services, such as Microsoft OCS, as well as for key deployments in service provider networks.
• Behavioral-based security capabilities are well-suited to emerging threats and illustrate Radware's commitment to integrated security capabilities.
• Radware recently acquired the former Alteon business from Nortel Networks and has demonstrated a clear approach to delivering value to this large installed base. This contributed to a 30% quarter-over-quarter boost in revenue during 2Q09.

• Radware has shown spotty geographic sales and channel coverage, particularly in North America.
• Radware has not provided a compelling vision for SoftADCs or for how its products integrate with popular IDEs.

• Zeus Technology has demonstrated excellent performance and price/performance on off-the-shelf hardware, particularly on Sun Microsystems/Solaris environments.
• Zeus has had a clear and compelling vision for the AP ADC market with solid products to back it up. Zeus understands the links between ADCs, application development and deployment in a virtualized world.
• Zeus was the first vendor to deliver SoftADC with flexible licensing suitable for cloud hosting centers, application developers and a range of enterprise solutions.

• Zeus continues to struggle to find the right model for distribution of its unique offering.
• Other larger, more-established vendors with broad product offerings and strong brands are introducing SoftADCs with similar licensing programs, which could impact Zeus' ability to increase its growing, but currently niche, opportunities.
• Zeus is a small vendor with limited resources and market visibility.