> News > 2001
> NetScalar 3100: Ad Fast
By Karen J. Bannan & Rob
April 18, 2001
Web sites want their content to load quickly.
Not surprisingly, companies that serve ads to
Web pages want their content to load even fast
er. At least, that's the view of Alfredo Botelho,
founder and CTO of Zedo, a San Francisco-based
Internet advertising firm.
Zedo provides targeted advertising to half a
dozen medium-size gaming and chat Web sites and
a women's interest portal, each with more than
100 million page views per month. To get visitors
to click through while they wait for a page to
load, ads need to load first. Botelho did two
things to accomplish this. He added the NetScaler
3100 to his company's infrastructure and at the
same time signed up f or Akamai's content distribution
network to get the ads closer to end users.
The combination seems to be working.
Ads are loading up to four times as fast as before,
which results in an increased number of click-throughs.
"The fact that the ad comes up now way before
the page's content is what we call prime-time
advertising," says Botelho.
The process of adding the 3100 was simple, since
NetScaler handled all the integration. The entire
installation was completed in less than a day,
and without any additional infrastructure upgrade
to the Zedo network or servers.
The NetScaler 3100 ($20,000 list) is an appliance
that sits in front of a Web site's server farm,
providing strong scalability as well as protection
against big surges in traffic.
The 3100 works by enabling persistent HTTP 1.1
connections between the back-end server infrastructure
and itself. As external Web site requests are
made, the 3100 multiplexes these requests (combines
multip le signals for transmission over a single
line) from the numerous client connections into
a smaller number of well-regulated, persis tent
TCP connections and HTTP requests. This effectively
reduces the load on the Web server, freeing up
valuable system resources. The 3100 optimizes
the management of HTTP connections, handling the
chores that servers aren 't very efficient at,
such as setting up and tearing down connections.
The 1U rack-mountable 3100 includes three 10/100
Ethernet ports (in, out, and fail-over, if you
have multiple NetScalers, which cost $30,000 for
a pair). The NetScaler 3200 model (not tested)
offers Gigabit Ethernet support.
Performance test results were impressive. The
3100 was able to manage over 340,000 concurrent
TCP sessions with a Windows 2000 Web ser ver while
averaging between 143 to 202 HTTP gets per second,
depending on the back-end server infrastructure.
The 3100 has a 966-MHz Pentium III processor
with 512MB RAM, and it runs on a modified FreeBSD
2.4 kernel. Keyboard and monitor ports are located
on the back of the unit.
NetScaler includes installation services in the
purchase price, though we had little trouble installing
the system. Initial installation is completed
via a console cable provided in the box. We used
HyperTerminal to configure basic settings, such
as the IP address. We needed to configure a "mapped"
IP address, similar to a virtual IP address, which
creates the persistent connections to the servers
on the back end.
You can then manage the 3100 in several ways:
through the command line, a console, or an adm
inistrative Java applet. To use the Java interface,
we had to edit a file to include the 3100's IP
address and the ma pped IP address. We also had
to invoke and run several registration files before
launching the applet's GUI. This part of the product
needs more development, and NetScaler should compile
the applet int o a unified whole.
The 3100's centralized logging feature can be
a boon for administrators. It can log activity
for multiple servers, significantly easing administration.
It also supports SNMP traps, enabling administrators
to manage through framework application s such
as HP OpenView, Tivoli, or Unicenter.
The 3100 includes a feature known as SureConnect.
SureConnect lets sites offer alternative content
when Web servers are suddenly overloaded by unexpected
traffic, such as that generated by a new product
announcement or a news story. Rather than turning
potential customers away from the Web site, SureConnect
puts visitors in to a queue and estimates the
wait time for service. While visitors are waiting,
it presents them with discounts or other interesting
information , and it automatically returns each
visitor to the site once the requested page becomes
available. The technology can also tell the difference
between Web server delays and those due to appli
We tested the 3100's surge protection by launching
a barrage of Syn attacks against it. During Syn
attacks, Web pages are still served to clients,
but at a slower rate. We were finally able to
max out the CPU when we launched a barrage of
over 100,000 simultane ous Syn, Ping of Death,
Land Attack, and Smurf attacks at the unit. Without
the 3100, the server's CPU would have maxed out
at well below 10,000 attacks.