Enterprises employ a wide range of applications and services: email, VoIP, IM, file transfer, video conferencing, business IPTV services, storage backup and recovery, etc. Each application has unique requirements for bandwidth as well as timing or delay sensitivity. VoIP can suffer from poor quality and dropped calls. Streaming video may break up or take a long time to start playing.
There is a popular perception that a high QoS equates to a high QoE (Quality of Experience) and that any quality problems can be accommodated by adding more bandwidth. That perception is wrong but it persists.
In order to optimize the QoE, which is the quality parameter that matters the most, a set of QoA (Quality of Application) metrics is needed. Therefore the optimum QoE can only come from a combination of QoS and QoA. This is the issue that application assurance solutions address.
Why It's Needed
Enterprises rely on their business applications for day-to-day operations, so it’s important to know how they are performing. Not knowing is a serious issue and its impact is growing for a number of interrelated reasons:
* Most apps were designed for the LAN, not the WAN;
* More and more apps are being centralized at data centers
* Real-time voice, multimedia and business-critical data applications are converging;
* Availability and performance must be optimized across multiple locations;
* And the issue is compounded by the fact that many if not most IT departments have limited resources.
WAN Optimization Controllers
Application optimization/acceleration solutions based on standalone CPE appliances have been available for some time. The industry term for these devices is WAN optimization controller (WOC).
WOCs do assure performance of individual applications using application identification and optimization as well as manipulation of the application flow through caching and compression.
They have been primarily deployed between large sites served by TDM connections, but due to their lack of scalability and high cost have not proven effective for deployment in multi-site, distributed networks.
There is a significant capital cost; the appliances must be installed at each location, so truck rolls are required; and managing hundreds or thousands of devices that form an overlay network is complex and costly, so there is an additional burden on under-resourced IT staff.
That’s why IT has minimal or even zero visibility on the real-time performance of the enterprise’s various and varied applications over the WAN. In a survey conducted by HP, 83% of IT Directors did not know what applications were running on their networks! And 87% indicated that the top issue was achieving consistent end-to-end application performance.
Network-Based Assurance
Network-based application assurance solutions are embedded within the operator’s IP/MPLS network and they are designed to support hundreds or thousands of enterprise VPNs. There is no need to install anything on site and it is easy for the service provider to activate new sites.
An application-assured VPN represents a significant evolutionary step from today’s service-aware model, which supports the convergence of IP voice, data and video and that has the performance and resiliency necessary to run latency-sensitive applications. This model has enjoyed considerable success. But--and it is a very big but--it's a QoS centric approach. A high QoS assures the performance of the network, but it does not recognize the applications. The new model builds on the success of service-aware VPNs and goes on to assure the performance of the applications, i.e. it's a model that is QoA centric. Add this parameter and you can realize the requisite QoE for all application types.
Why It's Welcomed
Application assurance goes to the heart of what matters most to an enterprise: the predictable performance of its voice and data applications.
An Ovum study conducted in Europe and the US indicated that 30% of the enterprises would pay extra for an improved QoS that guaranteed the performance of mission-critical applications. And 20% said they would be prepared to pay for consultancy services that helped them with application performance monitoring and reporting. A similar study conducted by IDC showed that 51% of 368 enterprises would use a managed WAN optimization service from an operator.
How It Works
An application-assured VPN ensures per-application performance objectives are met through application recognition and optimization. This is enabled through a network-based approach that provides per-application classification and end-to-end assurance from both trusted and untrusted CPE devices. So, how is it done?
In one example, Alcatel-Lucent has designed a solution that enables service providers to deliver application assurance as well as performance monitoring and reporting for both IT management and the provider.
The operator simply hot-inserts an Application Assurance Integrated Service Adapter (AA-ISA) into the chassis of an existing Ethernet Service Switch or Router. The baseline function is to identify the various applications in order to enable dynamic per-service, per-site and per-application QoS policy control. The term per-application QoS equates to QoA, which was introduced at the beginning of this article.
The Primary Deliverables
Application assurance enables per-application refinements that can either optimize the performance over the WAN or prioritize one application over another. In addition, it can generate data that enables visibility of applications and their performance behavior over the VPN.
These reports are critically important for enterprises as they are faced with operational challenges due to limited resources as well as increasing cost constraints. Without an application reporting capability, they are effectively running blind.
Conclusions
Scalable application assurance has the look of a compelling business proposition, one that meets the market need for enhanced application performance over the VPN. The concept is also a logical evolutionary step for service providers.
Bob Emmerson is a freelance writer who lives in The Netherlands. Email: [email protected] Web: www.electric-words.org
