Netscaler: 320,000 TCP connects/sec

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From: Rohit Khare (
Date: Tue May 02 2000 - 10:03:35 PDT

NetScaler's Secret: Suppressing The Surge

By Todd Spangler, Inter@ctive Week
May 1, 2000 6:56 AM ET

Networking start-up NetScaler has spent the past two years quietly
developing a new technique for dramatically improving Web site
performance - and it almost sounds too good to be true.

NetScaler, which plans to officially unveil its technology this week,
said its system can instantly boost a Web site's performance by a
factor of two and hasten server response by up to 100 times during
heavy loads. And, according to the company, it can do that without
any other changes to a site's infrastructure.

Michel Susai, NetScaler's president and chief executive, called the
company's technology an "Internet surge protector." He said the
NetScaler devices are designed to absorb sudden spikes in Web traffic
- so-called flash crowds - in the same way an electrical surge
suppressor handles surges in power.

"Our technology lets the Web servers do more of what they're supposed
to be doing, which is serving requests," he said. The system's secret
sauce is based on a straightforward, but somewhat arcane, concept:
Basically, NetScaler's WebScaler device preprocesses certain Internet
Protocol (IP) requests associated with retrieving Web pages, a
technique the company calls Web Transaction Management.

Here's where it gets a bit technical. WebScaler takes care of the
normally processor-intensive tasks involved in setting up and
processing users' Transport Control Protocol requests, off-loading
those duties from the site's Web servers. So instead of requiring
servers to initiate a new TCP session for each and every Web page
object someone is downloading - which is a lot of overhead, given the
relatively small files on Web pages - the device keeps its own
persistent TCP connections open to the origin servers. The server can
fire back the content to users much faster since the connection is
already open.

Susai said a single WebScaler, configured with 192 megabytes of
memory, is able to handle 320,000 TCP requests per second, well above
what today's busiest Web sites receive. Analysts said the NetScaler
technology represents an entirely new category of Internet
infrastructure products - call it "IP connection management," said
Peter Firstbrook, a research analyst at Meta Group.

"I think it's really significant," he said. "This is a great tool
that's really going to help Web sites."

NetScaler's technology is different from server load-balancing
switches, such as those from Alteon WebSystems and ArrowPoint
Communications. Instead of distributing user requests among an array
of servers, NetScaler's system simply passes through each user
request to a server connection that's already in place. With a
load-balancing switch, each TCP connection must still be established,
Susai said.

Another way to think about the NetScaler technology is that it
multiplexes client-side requests to back-end Web servers
transparently to the other pieces of the infrastructure, said Mike
Schafir, NetScaler's vice president of marketing. The technology can
also deflect large-scale denial-of-service attacks, like those that
recently brought down Yahoo! and other sites, he said. When the
WebScaler receives a bogus TCP request, it simply drops the
connection instead of passing it through to a server.

Founded in December 1997, NetScaler has received $50 million in
funding from Credit Suisse First Boston, Gabriel Venture Partners,
AboveNet Communications, executives at Exodus Communications and
other individual investors, Susai said. NetScaler's initial customers
include, and Excite@Home; the company also has
reseller agreements with AboveNet, Exodus and Global Crossing.

NetScaler plans to introduce its first WebScaler products next week
at the Networld+Interop show in Las Vegas. Susai said the baseline
system will cost about $40,000 for two units in a redundant

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