Businesses connecting their local networks to the Internet today are placing a great deal of attention on the Service Level Agreement (SLA) that they receive with their Internet connection. The SLA will detail the Quality of Service (QoS) that the provider offers with their service – in other words, their guarantee that the connection and the service will deliver as promised. In the past, suppliers have avoided making these kinds of guarantees. The large number of suppliers and a lack of coordination between them made it difficult to measure and track performance. As the Internet has matured, aggressive suppliers are concentrating more on customer service. Some Internet Service Providers (ISP's) now offer SLA's that differentiates them from competitors, and they can demand the same high-quality service from their suppliers. SLA's should cover such topics as connection availability, performance, and response time when outages or problems occur.

Connection availability is the amount of time that the connection is "up" and usable. Uptime figures usually exclude planned maintenance periods. Promised connection availability of 99.9% can be obtained. Standard SLA's usually offer something a few tenth of a percent less than that. SLA's designed for business users will have higher guarantees. Gray areas can exist when using separate Internet Service Providers and telephone carriers. An ISP may have a problem receiving traffic from the dealership. The dealer would consider the circuit unusable. The carrier may consider the line up if that the circuit is alive at both ends. Confusion over configuring and provisioning circuits is often blamed on the other supplier. It is best to combine elements of SLA’s so suppliers reselling services cannot hide behind another supplier’s lack of quality service.

Performance is measured both by the consistency of the connection and by the amount of data that can be sent using the connection (the bandwidth). Consistency guarantees are usually measured by the amount of latency on a connection. This is determined by sending traffic (called pinging) from one end of the network to the other. Performance SLA’s are restricted to the portion of the network that the carrier controls. Since the carrier is not providing a telephone or leased line directly from the dealership to the OEM’s data center, they must hand traffic off to other carriers. Once it has been handed off, the carrier will no longer guarantee its speed or even its safe arrival. Carrier SLA’s cover performance from the dealership router (the beginning of their network) to the point where they exchange traffic with other carriers (the end of their network). As a guideline, round-trip latency within the United States should be less than 85 milliseconds for wired connections. Watch the wording of performance SLA’s carefully. Find out how many exchange points traffic will have to go through. With the involvement of additional carriers and exchange points, the additional complexity can effect performance.

The bandwidth of the connection is measured by the amount of data that can be sent over the connection each second. SLA’s should clearly state the promised bandwidth. For connections that do not provide consistent bandwidth, the guarantee should be based on minimum performance. If the connection does not provide equal bandwidth going to and from the dealership, both minimums should be listed. Bandwidth can be checked by sending a large file over the network using a utility program that employs the File Transfer Protocol (FTP). These products are publicly available. You can also use performance tools that are available on some websites. The “Useful Websites” listing at the end of this chapter contains a link to such a site.

Problems never seem to be resolved fast enough. In order to make sure that the dealership has an acceptable level of service, the SLA should detail when service is available as well as how quickly response is expected. This is especially critical with telephone circuits, because a physical repair may be required to solve the problem. Consideration should be given to the need for support on the weekends or late at night. A Standard SLA offers daytime/workweek coverage. Business-level offerings can add later hours and weekend coverage. If charges are incurred for problems after hours, the charges should be noted. If necessary, full 24/7 coverage can be obtained.

All guarantees made must be measurable and monitoring the service will verify that guaranteed service levels are being obtained. Carriers should be asked to provide statistical reports on a regular basis to quantify their performance. The SLA should also detail the penalties that can be imposed on the provider if the service is not delivered as expected. Generally, these penalties are limited to credits applied to the account with the carrier or service provider.