Network Instruments last week unveiled a product designed to help network managers collect more data for analysis of network performance on gigabit networks.

The company's network Test Access Ports (nTAP) can monitor links and copy the full-duplex data stream to an analysis system. Network Instruments says that unlike a span or mirror port, nTAP doesn’t drop packets or affect switch performance while it monitors.

"Most of the monitoring on networks with switches has been done through a span or mirror port, which works perfectly for half-duplex conversations, but it doesn't always work for full-duplex," says Douglas Smith, president and co-founder of Network Instruments. "If the total aggregate utilization exceeds 100 megabits, packets start getting dropped, and the full conversations cannot be analyzed."

The nTAP appliance sits between a switch and another device on the network, and allows link traffic to flow unaffected. The appliance collects data, copies conversation streams and sends the data to an analysis engine or management console. It’s about the size of a CD-ROM drive, Smith says, and plugs into a switch. The device not only monitors traffic and collects data, but also reports on errors in the physical network layer from both sides of a full-duplex link. Plus, nTAP doesn't require administrators to bring down the link to set it up, so there is no interruption in traffic, the company says.

"A lot of people are moving to gigabit and want to be able to monitor those links completely, without shutting links down or losing packets," Smith says.

Network Instruments' products typically compete with those of Network General. This product line competes with that of Net Optics, a Sunnyvale, Calif., company that offers custom fiber and copper-based products, including analyzer switches, splitter taps, redundant port selectors, test and simulation products, and converters.

NTAPs come in a variety of flavors: 10/100 Copper nTAP; 10/100/1000 Copper nTAP; 10/100/1000 Conversion nTAP (SX/LX); Single-Channel Optical nTAP; Four-Channel Optical nTAP; and Six-Channel Optical nTAP. All are available now, with prices ranging from $395 per device to $2,395 per device.

Ann Bednarz is associate news editor at Network World.