NetScout tracks speed blocks

Like many network experts, Ken Wong often hears users complain that the network is

"It becomes a black hole," said Wong, an electrical engineer at the National
Institutes of Health. "Where is the network slow?"

NIH runs a WAN backbone of four Fiber Distributed Data Interface rings with about 100
routers from Cisco Systems Inc. of San Jose, Calif.

Wong has remote monitoring tools from NetScout Systems Inc. of Chelmsford, Mass., to
track network performance, but RMON can't always tell him why a user is having trouble
with a specific application.

Troubleshooting "has a Zen-like quality to it now," Wong said. "It
relies heavily on our expertise."

NIH has been working with NetScout to make the art of analyzing network application
performance into more of a science. Wong called this the next logical step in RMON and
RMON2 tools.

NetScout has come up with an application response time management information base, or
ART MIB, that will extend current network probe capabilities.

The first release is expected late this year, and seven network equipment manufacturers
plan to incorporate it into their products.

RMON monitors networks proactively, letting administrators specify conditions for which
they want alerts. RMON2 monitors specific application types. ART MIB will take this a step
further by letting an administrator monitor response times for a specific application at
different points on the network and pinpoint the slowdowns.

On the NIH campus, research groups generate applications that eventually migrate to the

"Our users develop programs and applications based on their needs," Wong
said. "Sometimes we are part of the development, sometimes not. And when we're not
part of the development, it can cause problems."

An application that works great on a LAN may not work well at all when it's rolled out
to the entire campus and must hop from router to router over the WAN.

The current method of locating problems is time-consuming. "We bring a sniffer
out, sit down for a half-day or so and look at some packet catches to try to figure out
where it's slow," Wong said.

With ART MIB on a probe to measure response time at two points--one near the server and
another near the client--the administrator can see how quickly the server fills the
request as well as how quickly the data moves over the network.

Quantifying this shows the user where the problem is, if the network isn't at fault,
and suggests steps that might correct it.

ART MIB uses the protocol directory, applications layer matrix and network layer matrix
tables of the RMON2 standard. It matches request packets against response packets and
measures the elapsed time.

NetScout also is developing an application flow monitor console, which will let the
administrator measure traffic characteristics of specific networked applications. That
product is due for release in the last quarter of this year.

The initial ART MIB will troubleshoot only on IP and IPX networks; more protocols will
be added in later versions. NetScout will build ART MIB into its entire line of LAN,
switch and WAN probes. Customers who buy the company's Resource Monitor, which remotely
monitors any Simple Network Management Protocol-compliant device, will get an ART MIB

ART MIB also will be available in products from Cisco; BGS Systems Inc. of Waltham,
Mass.; CACI Products Co. of La Jolla, Calif.; Concord Communications Inc. of Marlborough,
Mass.; DeskTalk Systems Inc. of Torrance, Calif.; Kaspia Systems of Beaverton, Ore.; and
Network General Corp. of Menlo Park, Calif.

About the Author

William Jackson is a Maryland-based freelance writer.

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