Quality of service

Whose responsibility is it anyway?

Packet networks have become popular in recent years as the means of extending mission-critical applications across the enterprise, including remote branch offices, telecommuters and mobile professionals. The choice for transport will usually boil down to Internet protocol (IP), frame relay or asynchronous transfer mode (ATM), depending on the mix of applications and their performance requirements in terms of such metrics as cost, reliability, availability and latency.

With the plummeting price of bandwidth, the temptation is to simply add more of it to improve application response time over these networks. Under this approach, certain applications would have more bandwidth to hog, leaving mission-critical and real-time applications gasping. Without careful bandwidth management, routine HTTP traffic, for example, can make implementation of voice over IP with any degree of efficacy impossible.

Getting ahead of the performance curve requires a more practical solution—the use of bandwidth management tools that can enable the network to effectively support many more users and applications.

With such tools, all applications are given a set amount of bandwidth in accordance with their priority, which is determined by each application’s performance requirements. This method saves on the cost of bandwidth, however cheap, and also eliminates the need to buy more equipment, manage more boxes, invest in more diagnostic tools and add more skilled personnel.

Large enterprises usually want to take responsibility for the quality of service (QoS) function and require only basic connectivity from a carrier. With so many devices to manage, however, administrators can easily get bogged down performing manual QoS configurations to fully optimize the enterprise network. The use of policy-based bandwidth-management solutions makes this task less tedious and error prone.

Some policy-based tools are available as software solutions installed on existing routers located on the network’s edges. Others are implemented in hardware, requiring the purchase of dedicated devices, also deployed at the network edges. Either way, a rules-based interface allows network administrators to set up dedicated classes of service for the various applications, which instructs the edge devices on how to handle the different traffic types. Depending on the specific solution, the rules can be configured separately for each device or downloaded to a group of devices in one operation.

Smaller, resource-constrained firms might be better off subscribing to the managed services of an integrated communications provider (ICP) that can support IP, frame relay and ATM to handle the growing number of diverse business applications that are being extended to distributed locations. The ICP configures, installs and manages the customer premises equipment, and the access and transport links, as well, ensuring the optimal performance of all applications. Performance should be backed with a service-level agreement, management reports and complete life-cycle services.

With an ICP, small and midsize companies can get managed IP, frame relay and ATM services with levels of performance to suit each application’s performance requirements, even for voice calls. All of these protocols can even be supported out of the same integrated access device connected to T-1, NxT-1, T-3 or OC-3 access facilities. The consolidation of multiple traffic types and the assignment of QoS to each application results in the optimal blend of bandwidth efficiency, response-time performance and cost savings—with one carrier, one point of contact and one monthly invoice.

An ICP can also split the traffic by protocol to separate networks—advantageous when a company wants 10-Mbps connectivity to the Internet, for example. In this case, the ICP would take the company’s IP traffic and pass it through its multiservice network as an ATM permanent virtual circuit, configured for a constant bit rate class of service for smooth, consistent traffic flow to the nearest network access point on the Internet backbone.

Finally, ICPs give smaller companies the opportunity to take advantage of the most appropriate technology, or easily migrate between them as their needs change, without having to deal with multiple service providers, equipment vendors and integrators.

Muller is senior technical consultant at e.spire Communications in Herndon, VA, www.espire.com. Send comments to guest@comnews.com.