Watching the WAN

Every enterprise relies on a service provider for at least some of its IT needs. Even if a firm doesn’t use a provider for Web hosting or e-commerce applications, it’s bound to rely on one for WAN connections to outlying offices.

While an enterprise might know the availability, traffic patterns and weaknesses of its own network, there’s no way to know exactly how reliable its carrier’s network is. So how can an enterprise ensure its mission-critical applications are being treated as mission critical by its carrier?

Increasingly, the answer is through service-level agreements (SLAs). Negotiated between an enterprise and its carrier, an SLA sets certain goals for the carrier and in some cases calls for penalties if those goals aren’t met.

For WAN services, most enterprises already have SLAs in place, according to Jay Pultz, an analyst with consultancy Gartner Group Inc. in Stamford, Conn. And if they don’t have one in place they should.

“It gets the enterprise out of having to do due diligence on what kind of technology a carrier is using,” Pultz said. “We feel strongly that there should be a tight SLA any time a major contract is signed with a communications carrier.”

Details written into each SLA will vary depending on what kind of WAN service an enterprise wants, Pultz said.

For example, the minimum measures on a frame relay SLA should include latency, guaranteed throughput (committed information rate), a network availability figure and a mean time for repairs if a major outage occurs.

At their lowest level, SLAs outline goals carriers are expected to meet. At their most effective, SLAs penalize carriers for failing to meet those goals.

Whether or not an enterprise is able to get penalty guarantees included in an SLA will often depend on both the size of the contract and the size of the carrier.

“If it’s a small contract or a second- or third-tier carrier, it may be harder to get an SLA with guarantees,” Pultz said.

Kevin Vachon, president and CEO of Ottawa-based Nuvo Network Management, said many of the organizations he has encountered are not familiar with the use of SLAs. Nuvo is a network management outsourcing company that offers varying degrees of WAN and LAN management services.

Many of Nuvo’s clients will ask the company what its standard SLA is and go with that, Vachon said. Only a couple have been more demanding and asked for guarantees to be included in the SLA, so that if Nuvo’s services are not what was promised, the client gets compensation.

Negotiating an SLA is one thing. Making sure its objectives are met is another.

There are basically two ways to track SLA compliance, Pultz said. One way is to trust the carrier and the monthly service-level reports it provides.

The other way is to use a tool that measures WAN performance. Vendors providing such tools include Paradyne, Visual Networks and NetReality.

More and more enterprises are opting for the latter option, Pultz noted, largely because, as WAN traffic grows, enterprises are becoming more interested in knowing why it is growing.

“Enterprises want to know what’s going on in the network in a higher level of detail,” he said. “Applications such as SAP and Oracle have fairly stringent network requirements and as those apps are rolled out, network managers want to know what’s going on.”

NetReality’s various WAN tools, for example, allow managers to view such things as latency, response time, mean time between failures and mean time until repair, according to NetReality president Yoram Valent.

He said the tools are being deployed for two principal reasons — enterprises want to know what’s happening on their WAN links and carriers want to provide differentiated services.