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Going With The Flow

As businesses use their data networks to deliver more applications and services, monitoring and managing the network for problems and ensuring high performance can become a challenge. A shift to flow-based network monitoring is proving fruitful for some.

In the past, network monitoring usually involved checking to see that network devices were working properly and that data packets were moving from one location to another in a timely fashion. But metrics such as packet round-trip time, packet loss, and packet delay weren't all that relevant to users who were more interested in how well applications and services were delivered to their desktops.

Network managers now are spending more time looking at application performance and bandwidth utilization using a variety of tools from networking vendors such as Apparent Networks, Cisco Systems, Compuware, Coradiant, NetQoS, NetScout, Network General, Network Physics, and Visual Networks. Those tools monitor "flows" of like data, usually tied to a specific application, and make use of information from Cisco switches and routers, called NetFlow information, to provide what's generically known as flow-based network monitoring.

Real-Time Analysis
Jeff Duke, senior network engineer at the Indiana Department of Technology, uses 30 Sniffer systems from Network General to oversee a Gigabit Ethernet network used by tens of thousands of state officials and employees. Earlier network-monitoring systems sent activity reports for later analysis. "I couldn't see data, packets, or flows in real time," he says. "It wasn't even near real time. I was looking at a week ago."

With the Sniffer systems installed throughout the network at key locations such as firewalls and other access points, Duke says he gets "all the stats on a flow or set of flows, and I can troubleshoot any problem that comes up." The state will migrate to a 10-Gigabit Ethernet network, and good network-monitoring tools are crucial, Duke says. "As the network gets bigger, application troubleshooting gets bigger," he says.

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