Load Balancers Are Dead: Time to Focus on
2 February 2009
Gartner RAS Core Research Note G00164098
When looking at feature requirements in front of and between server tiers, too many organizations think only about load balancing. However, the era of load balancing is long past, and organizations will be better served to focus their attention on improving the delivery of applications.
This research shifts the attention from basic load-balancing features to application delivery features to aid in the deployment and delivery of applications. Networking organizations are missing significant opportunities to increase application performance and user experience by ignoring this fundamental market shift.
- Enterprises are still focused on load balancing.
- There is little cooperation between networking and application teams on a holistic approach for application deployment.
- Properly deployed application delivery controllers can improve application performance and security, increase the efficiency of data center infrastructure, and assist the deployment of the virtualized data center.
- Network architects must shift attention and resources away from Layer 3 packet delivery networks and basic load balancing to application delivery networks.
- Enterprises must start building specialized expertise around application delivery
What you need to Know
IT organizations that shift to application delivery will improve internal application performance that will noticeably improve business processes and productivity for key applications. For external-facing applications, end-user experience and satisfaction will improve, positively affecting the ease of doing business with supply chain partners and customers. Despite application delivery technologies being well proved, they have not yet reached a level of deployment that reflects their value to the enterprise, and too many clients do not have the right business and technology requirements on their radar.
What's the Issue?
Many organizations are missing out on big opportunities to improve the performance of internal processes and external service interactions by not understanding application delivery technologies. This is very obvious when considering the types of client inquiries we receive on a regular basis.
In the majority of cases, clients phrase their questions to ask specifically about load balancing. In some cases, they are replacing aged server load balancers (SLBs), purchased before the advent of the advanced features now available in leading application delivery controllers (ADCs).
In other cases, we get calls about application performance challenges, and, after exploring the current infrastructure, we find that these clients have modern, advanced ADCs already installed, but they haven't turned on any of the advanced features and are using new equipment, such as circa 1998 SLBs. In both cases, there is a striking lack of understanding of what ADCs can and should bring to the enterprise infrastructure.
Organizations that still think of this critically important position in the data center as one that only requires load balancing are missing out on years of valuable innovation and are not taking advantage of the growing list of services that are available to increase application performance and security and to play an active role in the increasing vitalization and automation of server resources. Modern ADCs are the only devices in the data center capable of providing a real-time, pan-application view of application data flows and resource requirements. This insight will continue to drive innovation of new capabilities for distributed and vitalized applications.
Why Did This Happen?
The "blame" for this misunderstanding can be distributed in many ways, though it is largely history that is at fault. SLBs were created to better solve the networking problem of how to distribute requests across a group of servers responsible for delivering a specific Web application. Initially, this was done with simple round-robin DNS, but because of the limitations of this approach, function-specific load-balancing appliances appeared on the market to examine inbound application requests and to map these requests dynamically to available servers.
Because this was a networking function, the responsibility landed solely in network operations and, while there were always smaller innovative players, the bulk of the early market ended up in the hands of networking vendors (largely Cisco, Nortel and Foundry [now part of Brocade]). So, a decade ago, the situation basically consisted of networking vendors selling network solutions to network staff. However, innovation continued, and the ADC market became one of the most innovative areas of enterprise networking over the past decade.
Initially, this innovation focused on the inbound problem — such as the dynamic recognition of server load or failure and session persistence to ensure that online "shopping carts" weren't lost. Soon, the market started to evolve to look at other problems, such as application and server efficiency. The best example would be the adoption of SSL termination and offload.
Finally, the attention turned to outbound traffic, and a series of techniques and features started appearing in the market to improve the performance of the applications being delivered across the network. Innovations migrated from a pure networking focus to infrastructure efficiencies to application performance optimization and security — from a networking product to one that touched networking, server, applications and security staff. The networking vendors that were big players when SLB was the focus, quickly became laggards in this newly emerging ADC market.
As the market shifts toward modern ADCs, some of the blame must rest on the shoulders of the new leaders (vendors such as F5 and Citrix NetScaler). While their products have many advanced capabilities, these vendors often undersell their products and don't do enough to clearly demonstrate their leadership and vision to sway more of the market to adopting the new features.
The other challenge for vendors (and users) is that modern ADCs impact many parts of the IT organization. Finally, some blame rests with the IT organization. By maintaining siloed operational functions, it has been difficult to recognize and define requirements that fall between functional areas.
Why We Need More and Why Should Enterprises Care?
Not all new technologies deserve consideration for mainstream deployment. However, in this case, advanced ADCs provide capabilities to help mitigate the challenges of deploying and delivering the complex application environments of today. The past decade saw a mass migration to browser-based enterprise applications targeting business processes and user productivity as well as increasing adoption of service-oriented architectures (SOAs), Web 2.0 and now cloud computing models.
These approaches tend to place increased demand on the infrastructure, because of "chatty" and complex protocols. Without providing features to mitigate latency, to reduce round trips and bandwidth, and to strengthen security, these approaches almost always lead to disappointing performance for enterprise and external users. The modern ADC provides a range of features (see Note 1) to deal with these complex environments. Beyond application performance and security, application delivery controllers can reduce the number of required servers, provide real-time control mechanisms to assist in data center virtualization, and reduce data center power and cooling requirements.
ADCs also provide simplified deployment and extensibility and are now being deployed between the Web server tier and the application or services tier (for SOA) servers. Most ADCs incorporate rule-based extensibility that enables customization of the behavior of the ADC. For example, a rule might enable the ADC to examine the response portion of an e-commerce transaction to strip off all but the last four digits of credit card numbers. Organizations can use these capabilities as a simple, quick alternative to modifying Web applications.
Most ADCs incorporate a programmatic interface (open APIs) that allows them to be controlled by external systems, including application servers, data center management, and provisioning applications and network/system management applications. This capability may be used for regular periodic reconfigurations (end-of-month closing) or may even be driven by external events (taking an instance of an application offline for maintenance). In some cases, the application programming interfaces link the ADC to server virtualization systems and data center provisioning frameworks in order to deliver the promise of real-time infrastructure.
What Vendors Provide ADC Solutions Today?
During the past five years, the innovations have largely segmented the market into vendors that understand complex application environments and the subtleties in implementations (examples would be F5, Citrix NetScaler and Radware) and those with more of a focus on static feature sets and networking. "Magic Quadrant for Application Delivery Controllers" provides a more complete analysis and view of the vendors in the market.
Vendors that have more-attractive offerings will have most or all of these attributes:
- A strong set of advanced platform capabilities
- Customizable, extensible platforms and solutions
- A vision focused on application delivery networking
- Affinity to applications:
- Needs to be application-fluent (that is, they need to "speak the language")
- Support organizations need to "talk applications"*What Should Enterprises Do About This?
Enterprises must start to move beyond refreshing their load-balancing footprint. The features of advanced ADCs are so compelling for those that make an effort to shift their thinking and organizational boundaries that continuing efforts on SLBs is wasting time and resources. In most cases, the incremental investment in advanced ADC platforms is easily compensated by reduced requirements for servers and bandwidth and the clear improvements in end-user experience and productivity.
In addition, enterprises should:
- Use the approach documented in "Five Dimensions of Network Design to Improve Performance and Save Money" to understand user demographics and productivity tools and applications. Also, part of this requirements phase should entail gaining an understanding of any shifts in application architectures and strategies. This approach provides the networking team with much greater insight into broader IT requirements.
- Understand what they already have in their installed base. We find, in at least 25% of our interactions, enterprises have already purchased and installed an advanced ADC platform, but are not using it to its potential. In some cases, they already have the software installed, so two to three days of training and some internal discussions can lead to massive improvements.
- Start building application delivery expertise. This skill set will be one that bridges the gaps between networking, applications, security and possibly the server. Organizations can use this function to help extend the career path and interest for high-performance individuals from groups like application performance monitoring or networking operations. Networking staff aspiring to this role must have strong application and personal communication skills to achieve the correct balance. Some organizations will find they have the genesis of these skills scattered across multiple groups. Building a cohesive home will provide immediate benefits, because the organization's barriers will be quickly eliminated.
- Start thinking about ADCs as strategic platforms, and move beyond tactical deployments of SLBs. Once organizations think about application delivery as a basic infrastructure asset, the use of these tools and services (and associated benefits) will be more readily achieved.
Note: We have defined a category of advanced ADCs to distinguish their capabilities from basic, more-static function load balancers. These advanced ADCs operate on a per-transaction basis and achieve application fluency. These devices become actively involved in the delivery of the application and provide sophisticated capabilities, including:
- Application layer proxy, which is often bidirectional
- Content transformation
- Selective compression
- Selective caching of dynamic content
- HTML or other application protocol optimizations
- Web application firewall
- XML validation and transformation
- Rules and programmatic interfaces