Any time data travels on the public network, even for a comparatively small portion of a trip, no service provider can offer a 100 percent guarantee of the delivery performance. Nonetheless, ISPs are beginning to offer SLAs designed to approach the reliability and availability of private networking.
While ISPs may not be ready for the most mission-critical traffic, they increasingly are becoming an option for mission-essential data.
NASDAQ.com, which contracts with three ISPs, uses Internap Network Services Corp., of Seattle, for 80 percent of its traffic, said John Delta, vice president and general manager of the NASDAQ Web site, in Rockville, Md. Although there remains a distinction between the mission-critical data of the stock market network and the mission-essential data of the Web site, the distinction is fading, Delta said.
"Anything that reflects badly on the Web site reflects badly on the trading system. The lines are blurring," Delta said. "We try to quantify everything on the site."
Typically, ISPs can deliver 99 percent availability but with as much as 200-millisecond latency and more than 1 percent dropped packets, according to Andrew Schroepfer, president of Tier 1 Research Inc., in Minneapolis. Increasingly, ISPs are finding creative ways to raise the ante, either by expanding their infrastructure over which they have subscriber control or by amalgamating others networks. The resulting network configurations have emboldened ISPs to begin championing SLAs (service-level agreements).
Internap, the 10th-largest business ISP, touts a "proactive" SLA, guaranteeing 100 percent network availability over the major Internet backbones, 55-ms-or-less latency and no more than 1 percent packet loss. Last week, Internap unveiled independent validation of the metrics behind its SLA by an Internet performance measurement company, Gomez Networks Inc.
Until now, network performance monitoring technology has not been sufficiently advanced to effectively measure the health of routers and other network devices, Schroepfer said. "Youve been able to do ping tests forever, but now, SLAs become a meaningful item to the customer."
Internap can provide the guarantee because of an "overlay" network, which connects its private network access points to the major backbone providers. "They dont own a network, but they do," Schroepfer said. While Internap does not actually own the network, it effectively controls the infrastructure by contracting with big providers. "When you contract with Internap, youre contracting with multiple networks," he said.
ISPs with their own network infrastructure, such as Cogent Communications Inc., in Washington, can raise the ante by minimizing the distance a customers traffic travels over the Internet. Cogent, which recently received bankruptcy court approval to acquire the customers and network equipment of defunct PSINet Inc., offers 99.99 percent availability with no dropped packets and 75-ms latency.
Cogent keeps a customers data on its 17,400-mile fiber-optic network, which links 21 cities in North America, until the last possible handoff point to the public network before its destination.