Fast-forward to a time when service-oriented architecture (SOA) deployments are more widespread and applications consist of multiple services supplied by many providers. "In some cases a small increase in network delay has a very big increase in application delay," Metzler says. "With SOA, when you have the WAN coming into play three or five or seven times [in a single transaction], you've got potential for significant delay," he says.

Greater use of virtualization technologies also will complicate things: Imagine a branch-office user on a virtualized desktop accessing a branch-office router over a virtual LAN to get to applications running on virtual servers in the data center, consultant Metzler posits. With so many systems and configuration scenarios, how does IT troubleshoot a performance problem?

It comes down to stellar management capabilities and fine-grained visibility into network applications and traffic, industry watchers say. These are works in progress for most network-optimization vendors.

To improve monitoring and visibility, some vendors have been working on integrating their technologies tightly. Cisco and NetQoS, for example, last summer announced plans to embed the performance-management vendor's monitoring and reporting technology in Cisco's Wide Area Application Services (WAAS) gear.

Another development trend that's upping the complexity quotient is the addition of third-party products to WAN-acceleration devices. Riverbed customers, for example, can run DNS, DHCP, IP address management and other network services from Infoblox on their Steelhead appliances thanks to a technology partnership the two vendors struck in April. Cisco, too, plans to let customers run a stripped-down version of Microsoft Windows for DNS, DHCP and print services on its WAAS gear, Gartner's Skorupa says.

These pairings can help enterprises reduce the number of physical appliances running in branch offices, but they raise more management issues - particularly concerning IT personnel. For example, adding a Web-application firewall to an acceleration device makes it something an IT security team wants to control. Adding dynamic Web caching to an appliance brings application developers into the mix.

Vendors then have to win over not only network buyers but also, perhaps, storage staff, server teams, security specialists or application developers. "One of the challenges for application-delivery controller vendors, in particular, is that as they develop these more advanced features, they may wind up having to sell the same box to three different people in the company," Skorupa says.

In addition, roles-based access becomes critical. "When you aggregate functions, you need to make sure that you still can disaggregate the management functions so that you can have the appropriate separation of management," Skorupa says.

That's not unprecedented; Cisco's Application Control Engine devices can be deployed by a network team and the applications fine-tuned by specialists, Network World blogger Morris points out. "The underlying blade itself and the basic construct of the load-balancer are controlled by the network team, but then each application's load-balancing can be virtualized all the way into configuration and given to an application team."

Morris sees WAN-acceleration boxes also heading in that direction, whereby application and infrastructure teams share configuration responsibilities, with application specialists making the more detailed, protocol-specific optimization decisions. (See story, "Dear IT: Forget the technology")

For IT departments, the trend provides one more pressing reason to break open the lines of communication among application, data-center and network teams. The sooner the better; plenty is at stake.

Data center consolidation projects won't be successful if application performance over the WAN is insufferable. No one will applaud network teams if an SOA deployment intended to conserve development resources falls flat because the Web services run too slow. It's time to start thinking strategically.