Cache buys better Web dynamics
- By Dan Carney
- May 08, 2000
The well-known shortcoming of the World Wide Web is the fact that it takes
time — "forever" as many people like to put it — to move information from
a server to a user's desktop, no matter if that server is on the other side
of the globe or down the street.
There are many reasons why Web pages can take a long time to download,
but two of the most common causes are slow Internet connections and overburdened
Web servers pushed to their limits.
Federal users from the U.S. Army to the Food and Drug Administration are
discovering that Web caches can solve both problems and provide an additional
layer of defense against hackers to boot. Plus, deploying cache can help
agencies postpone expensive network upgrades that were meant to improve
Internet access time.
The concept behind Web caches is not new. Web browsers have long used
cache to retain recently downloaded Web pages so that if the user returns
to those sites, the browser only needs to reload those components on the
page that have changed. The user sees the page almost instantly, and traffic
over the often-limited Internet connection is reduced.
Web caching servers expand on this model, putting a depot for frequently
visited sites between an agency's server and the Internet. Such caches can
work two ways:
* They can hold all of the most recently accessed Web pages for everyone
on the server. For example, after a user visits the National Weather Service
site to check on the progress of a hurricane, and calls to a colleague to
take a look for himself, this second user will get to see the satellite
picture almost instantly. That is because the computer retrieves the image
from the local Web cache, rather than from the NWS server.
* Alternatively, if a Web site operator, such as the National Weather
Service, needs to accelerate response time because a lot of users are hitting
its site, a cache containing the most-downloaded information can speed pictures
to users without bogging down the server with constant requests for the
In fact, 54 percent of information on Web sites is suitable for caching,
according to a survey by The HTRC Group LLC, San Andreas, Calif. "That means
they can use Web caching to increase performance for a significant amount
of their Web site," said Greg Howard, an analyst for HTRC.
In a survey of Web sites last year, the time to load pages was quite
slow, said Peter Christy, research director for Jupiter Communications Inc.
"Page fetch times were about eight seconds," he said. "People realized that
you want something much faster. Under one second is the right goal."
Average time to load pages has fallen as Web caches have gained popularity,
said Christy. "Much of the improvement is due to the deployment of caching."
"Sooner or later, Web caches will be a standard part of the network architecture,
like a router or a firewall," said Dan Brigati, director of federal sales
for CacheFlow Inc. "When you go from a T-1 connection to a T-3, you certainly
are not getting 35 times the performance. The Internet isn't strategic,
but the intranet certainly is."
That may have been true in the recent past, but not anymore, said Walter
Henderson, federal sales manager for Network Appliance Inc. "A lot of employees
need to get to the Internet as part of their job," he said. "It is not just
"You use a cache when you are looking to lower Internet access costs or
to at least delay your network's increase in bandwidth," said Alex Benik,
an analyst for The Yankee Group, Boston. "It is a pretty compelling cost
"We think the use of caching is very cost effective, by a factor of
ten, over network improvements," Christy said.
Such effectiveness is driving rapid growth in Web caching server sales.
"We see the market growing 100 percent in 2000, over 1999 [figures]," Benik
Web caching server prices start at about $2,500 and go as high as $80,000,
depending on the configuration and brand. The investment can produce many
benefits for agencies:
* A cache may let agencies forego network upgrades. "I would put it
on the gateway to the Internet to reduce the need for bandwidth," said Peter
Firstbrook, a research analyst for Meta Group Inc., Stamford, Conn. "It
may mean the difference between needing a T-1 and needing a [much more expensive]
* Small Web caching servers can help small field offices get better
performance from their dial-up connections, said Roy Wells, director of
product marketing for Ramp Networks Inc. That is because the server not
only accelerates access speed, it also can double bandwidth available from
dial-up connections by coordinating two modems. "It allows modem pooling,
which looks like a single connection to users," he said.
* A cache can increase security by acting as a buffer between a Web
server and the rest of the Internet as the server handles all incoming requests
for information. This way intrusive requests from hackers trying to break
into a server never actually reach the server. They only talk to the Web
cache, which runs a specialized operating system that has fewer potential
entrances for hackers than a more general-purpose operating system.
"It reduces vulnerability because our product has fewer points of entry
than most network devices," said Greg Govatos, director of marketing for
"Putting a cache in front of a Web server tends to improve security
because it doesn't have as many means of entry," Christy said.
And even if a cached Web site got hacked, it would soon be updated with
the correct information when it refreshed its content, Firstbrook said.
"It is like graffiti on a wall. If you paint over it every morning, it becomes
uninteresting to paint it in the night."
* Web caching servers are also a good location for tools such as filters
used to screen undesirable sites. "Web caches give you the opportunity to
put Playboy.com out there and block it," said Jay Mulkerin, local-area
network campus architect for Nortel Networks.
Another security tool that can be deployed on the cache is a filter
to protect against denial-of-service attacks that flood sites with false
requests for information. "It is an easy place to put the tools to defend
against that," Christy said.
An alternative to a dedicated Web caching server is to run software on the
Web server that provides caching functions. Microsoft Corp., Netscape Communications
Corp. and Novell Inc. all offer caching tools for their software, but the
dedicated appliances are easier to install and manage. "We definitely like
the appliances better," said Firstbrook. "They are plug and play, they are
secure and they don't use a well-known operating system [so they are less
vulnerable to attack]," he said. "They are optimized for what they do."
"You just plug it in and you don't have to do anything," said Mulkerin.
"It will intercept the addresses automatically. You plug it in and away
— Carney is a freelance writer based in Herndon, Va.