Managing Service Level Agreements:
The Swarthmore College Case

A liberal arts college outside of Philadelphia used network management devices to allocate bandwidth fairly between students, faculty, and others, diffusing a potentially explosive issue with a simple, clear SLA.

by Azi Ronen [December 14, 2001]

Azi Ronen is the Executive Vice President of Technology and Marketing of Allot Communications, overseeing product strategy, development, and marketing. Before joining Allot Communications in 1999, Mr. Ronen was the vice president of marketing for VoIP pioneer VocalTec Communications. At RADLINX (which was acquired by VocalTec in 1998) he was the vice president of research and development for five years, managing product development of Fax over IP and remote access servers.

Internet service providers (ISPs) are facing many problems when trying to satisfy their customers' needs while reaching financial stability. All types of service providers face stiff competition, and all are constantly seeking new ways to improve services in order to have an edge over the competition.

Service Level Agreements (SLAs) play a major role in an ISP's effort to survive and succeed in the current environment. On the one hand, SLAs provide users with the basic guarantee that their costs will equal the service they receive. On the other hand, SLAs allow service providers to generate higher revenues by offering premium service plans.

Universities and colleges face unique challenges when providing Internet access to students in dormitories. A major problem is "bandwidth hungry" students who expect their room and board fees to include endless bandwidth. As bandwidth is actually provided at a flat fee, the students consume every piece of it, especially by downloading music through services such as Napster. While universities responded to the strain on network resources by limiting music sharing applications or outright banning them, Swarthmore College took a different approach.

Instead of managing service levels for the entire university network as is typical, Swarthmore tailored its service level agreements to apply to individuals within the network, extending a great level of service to each subscriber in the network as a whole—essentially acting as an ISP.

Located in suburban Philadelphia and ranked one of the top liberal arts colleges by US News and World Report, Swarthmore College has 800 faculty members and staff and 1,500 residential undergraduates. Ninety-five percent of students own a computer and have a fast Ethernet LAN port in their room. From the fall of 1998 to the end of 2000, the consumption of bandwidth increased five fold, making it obvious to the manager of networking and systems, Mark Dumic, that he needed to do something to control the service.

The first action was to monitor network use. "We found that several students accounted for 5 Mbps—50 percent of our total bandwidth at the time. We contacted these students and requested they limit their use," says Dumic, "but that resulted in a bad reaction from the students who did not like this Big Brother approach."

Dumic decided to use bandwidth management technology to free up network resources. He bought a bandwidth management device—the NetEnforcer AC-301 from Allot Communications—and placed it in front of his Internet Access router (shown left). He then examined the various policies he could set to govern various network bandwidth behavior. There were several options, like handling each bandwidth hungry application individually (such as limiting Napster to a total of 1 Mbps, an approach taken by many universities who use bandwidth shapers) or trying to build a priority mechanism. He found that in his case, those options were either too complex to plan or too limiting for users.

Instead, he decided to act like an ISP. "Each student gets a guaranteed amount of bandwidth but can't monopolize the Internet connection. There is no need to monitor and make judgments about content. Nor is there any Big Brother role or academic freedom issues," says Dumic.

Student usage was defined by a policy that limited and guaranteed total use of the Internet to a certain level of traffic, creating an SLA. This allowed students to access the bandwidth for any use, but more importantly, assured available bandwidth for mission critical data. "It is an easy approach to explain, like having a residential ISP connection of a certain speed," says Dumic.

The college's average consumption went down from 20 Mbps (total incoming and outgoing traffic) to 11 Mbps and eliminated any one person's ability to monopolize the network. Although some students were unhappy and complained that connection speeds to the Internet were now slower, the main reasons were not the traffic policies but other technical problems in the computers and applications used.

However, some students still wanted access to more bandwidth. One solution Swarthmore considered was to take the ISP similarily a step further and offer a premium bandwidth for a fee. To supplement the 256 Kbps given to every student as part of the standard SLA, Swarthmore planned to offer "a DSL-like" SLA which provided 640 kbps to each student paying an extra $40 a month. By using the NetEnforcer from Allot, the university could have easily instituted such an approach, thus creating an additional revenue stream.

But when the Student Council debated the idea, the students voted it down. Instead, Swarthmore went from capping student bandwidth to using the prioritization features of the NetEnforcer to allow students to use excess bandwidth when it was available. The new policy provides students with a guaranteed minimum of 256 Kbps in both incoming and outgoing directions but allows students to use more bandwidth if it is available. Most of the time, students have access to significantly more than the minimum bandwidth, especially during off-peak hours. The 256 Kbps minimum guaranteed bandwidth ensures that students get enough bandwidth to do academically oriented activities.

Under this system, non-residence hall users—faculty, staff, and people in public areas—have higher priority for the excess bandwidth after the student minimums have been satisfied. Once these needs are met, however, students in the residence halls share equal access to the remaining bandwidth up to the college maximum of 10 Mbps. The new policy ensures two things, that the College gets maximum benefit from the Internet bandwidth for which it is paying, and that all members of the College community have reliable Internet access with minimal constraints on individuals.

The SLA makes additional bandwidth available when students are most active on the Internet, such as nights and weekends, eliminating complaints from students and yet still protecting the university's network from being monopolized by one user.

Given today's world in which bandwidth remains a limited resource (in spite of all the hype stating otherwise) there is a need to be fair to all customers by not allowing a few to use up all of the bandwidth. Colleges and universities can offer better plans for higher prices to interested customers or institute the approach taken by Swarthmore College. Many service providers can do the same—especially those providing fixed wireless Internet access services.

Service providers today can deploy a complete SLA provisioning, enforcement, and verification system that will allow them to improve the Quality of Service offered to their customers and generate more revenues from the service provided.

Essential to the provisioning process is the ability to retrieve customer information from the customer care and billing system or a user directory. This automatic process allows one to define each customer or user only once in the usersirectory and to automatically retrieve the SLA tier level (often called "Gold," "Sliver," and "Bronze"). Each service level defines a guaranteed minimum bandwidth commitment to the customer as well as an upper limit to available bandwidth.

A device commonly known as the Policy Server (such as NetPolicy from Allot Communications) collects this information from the customer care and billing system and distributes these policies to the enforcement devices.

The enforcement process, handled by bandwidth management devices, ensures that each customer will get the service they are paying for based on their SLA. In addition, the device sends accounting information to the billing system.

The verification (or billing) process is managed by billing and reporting systems. Because the billing systems are able to obtain extensive information from the enforcement device regarding traffic—address, applications used, service applied, and traffic sent—they can create a very advanced invoicing scheme based on the real use of the network services. Reports (accessible through the Web) should be made available to the customers, showing them what they were doing, what service levels (actual bandwidth) they used, and where they spent their money.

To summarize: what Swarthmore College did with its student community is an example of how service providers must be proactive to retain customers. Using bandwidth management techniques, they must offer SLAs to their customers, both to assure a consistent level of service to all users sharing the same limited media (air) and to offer tiered services—such as a premium ("gold") service plans—to achieve higher per-customer revenue.

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