Last time, we pointed out that network organizations have the opportunity to both show business value and do good things for the careers of network professionals by demonstrating how they ensure that the company’s key business applications exhibit acceptable performance. We also pointed out that ensuring acceptable application performance is difficult as it requires the tight integration of planning, optimization, management and control. Regrettably, most application delivery solutions do not provide a rich set of well integrated planning, optimization and management functionality. In fact, some WAN optimizations products can cause existing planning and management functionality to break. Today, we’ll discuss some of the problems with the current application delivery solutions and detail how NetQoS and Cisco have worked together to solve at least some of the problems.

This newsletter will follow the common convention of referring to a WAN optimization product as a WAN Optimization Controller (WOC). Before an IT organization deploys a WAN optimization solution, there is a single TCP session between the user’s PC and the application server in the data center. As part of deploying the solution, the IT organization installs a WOC in selected branch offices and a WOC in the data center. After the installation is complete, there are three TCP sessions: one session is between the user’s PC and the WOC in the branch office, another is between the branch office WOC and the WOC in the data center, and the third is between the data center WOC and the application server.

Going from one TCP session to three can break your current approach to managing your network. In particular, assume that before the WAN optimization solution was deployed there was a device in the data center that was monitoring the end-to-end performance of applications. This monitoring device relied on information in the TCP header and this worked well when there was a single TCP session between the PC and the application server. However, once the WOCs have been deployed that device in the data center is now only monitoring the TCP session between the data center WOC and the application server. As a result, the IT organization has lost the ability that it had to monitor the end-to-end performance of its applications.

Steve Taylor is president of Distributed Networking Associates and publisher/editor-in-chief of Webtorials. Jim Metzler is vice president of Ashton, Metzler & Associates.