12.8 Conclusion

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Business-critical applications often struggle to compete with less important traffic for the finite amount of bandwidth available on corporate networks, especially across WANs. The result is that end-user response times can fall below acceptable levels, which decreases productivity. If this condition persists, business processes and revenues may be impacted. This has led to the availability of policy-based network management tools from a variety of vendors. QoS policies can be defined once and deployed with a single command to routers, switches, traffic shapers, network interface cards, and even application servers.

Policy-based QoS management tools make it easier to configure and control network resources to accommodate network changes and new applications. For example, a business may want to ensure that its month-end financial statements are produced on time. To improve the response time of the financial applications around these business deadlines, a policy can be configured and deployed to assign the highest priority to this application’s traffic during the last few days of the month. When the deadline is met, the policy can return network resources to other applications as they were originally set up. The result is that all applications are served in an appropriate manner without the company having to spend for more bandwidth in a futile effort to stay ahead of the performance curve.

SLAs on packet services can ensure adequate levels of performance. SLAs offer service guarantees and credits to customers if various performance metrics are not sustained. In some cases, the customer need not even report the problem and provide documentation to support its claim. The carrier or ISP will report the problem to the customer and automatically apply appropriate credits to the invoice, as stipulated in the SLA. As noted, however, not all carriers and ISPs follow this practice, preferring instead to put the burden on customers to report incidents that violate the SLA. This means that the customer must have appropriate tools to monitor performance metrics with the idea of enforcing compliance and documenting the results. These tasks are also performed by bandwidth management systems or add-on modules to these systems.

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