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To: Miguel Octavio who wrote (122)6/30/1998 3:09:00 PM
From: Francis Gaskins  Read Replies (1) | Respond to of 1945
 
Cache Confusion Shuts Down Site, by Chris Oakes
wired.com
4:00am 30.Jun.98.PDT

When a major Internet backbone provider installed
a new technology designed to speed up its
network, some unintended side effects caused an
e-commerce snafu that has called the technique
into question among some experts.

The incident exposed unforeseen perils of caching,
a technology that promises faster delivery of Web
content and reduced network traffic load on
Internet Service Providers (ISPs) and corporate
networks.

"It resulted in a number of our customers getting
double-charged and others not getting charged to
their credit cards properly," said Dr. Irvin Gleim,
owner of Gleim Publications, which uses the
CyberCash system to sell training publications
from its Web site.

"[Our site] was affected to such a degree that for a
short period of time we had to shut down our
secure server and not take any more
transactions," Gleim said.

The problem essentially came down to a case of
mistaken identity. It began when Digex, a national
backbone network service provider that fed traffic
to Florida Digital Turnpike, Gleim's ISP, introduced
a caching system from Inktomi (INKT).

Caches copy popular Web content onto servers or
other machines residing on networks closer to the
end user. The technique is used to check a Web
page's "freshness," so that if sites in the cache
are getting old, a new page is requested from the
originating Web site.

The cache allows an ISP to deliver clones of Web
pages from the cache rather than fetching the
faraway original page, a process that can save
delivery time and cut down on network load.

But when Digex installed Traffic Server, an Inktomi
caching software product, a critical connection
began to fail between Gleim's Web site and the
CyberCash payment system that he uses to
process transactions.

Each transaction made at Gleim's site involves an
interaction between the site's Web server and a
CyberCash server. Normally, the CyberCash
server would recognize Gleim's server by its IP
address, and therefore "trust" that the connection
-- and thus the transaction -- was legitimate.

When the CyberCash server saw requests coming
from a cache, which has a different Internet
address than the Gleim Publications server, it
didn't recognize the originating server and rejected
the payment requests.

Gleim Publications, understanding that the
problem took place as a result of Digex's
networks, says it is considering legal action
against the service provider for damages.

"Because of transparent caching, it was coming
from the wrong IP address," said Florida Digital
Turnpike network administrator Jon Lewis.

When asked for the details of the problem
experienced by Florida Digital Turnpike and its
customers, Pritchard said Digex would not be
likely to comment on a relationship with a specific
customer.

Digex spokesperson Ben Pritchard said
customers were notified by email that the Traffic
Server service would be installed.

"Most of them, once they've seen the benefit from
[the Traffic Server], don't want to exclude
themselves from it," said Franklyn Howell, the
company's senior manager of technical support.

Howell did acknowledge that some of its
customers using its cached router had particular
issues "where IP-based authentication was going
on."

She added that in those specific cases, Digex
"would take a look" at circumventing the cache for
some customer traffic.

Lewis said he wasn't pleased with Digex's initial
response when he called the company's attention
to the problem.

"The original response I got from them last week
was, 'This is the way it was, and that's life,' and I
didn't react too well to that." After indicating his
ISP would be looking elsewhere for network
access, however, he said Digex showed a
willingness to try to address the problem.

Florida Digital Turnpike's Lewis said the only email
he received from Digex prior to that company
installing the cache did not address the cache
specifically. It only notified customer networks of
anticipated downtime as Digex performed a router
upgrade that would speed the delivery of Web
pages, he said.

Digex's Howell said an email further clarifying the
caching issue is due to go out on Tuesday.

"We probably would have asked them to do this
for just our dialup IP address ranges if anything at
all," Lewis said, if he'd received more specific
information. Generally, Lewis said he would like
more control over what is and isn't cached.

Lewis said Digex's proposal currently involves his
ISP keeping track of which destination IP
addresses should not be "proxied" through the
cache. But he was not enamored of the idea that
this would require registering each IP address with
the service.

Paul Gauthier, Chief Technology Officer for
Inktomi, developer of the caching technology in
use at Digex, posted a note to the network
administrator's mailing list in response to
concerns.

"The problems being highlighted are not new or
unknown and there are standard remedies in use
by Inktomi's Traffic Server customers and other
users of transparent caching," he wrote.

Gauthier said the disruption of existing services,
correctness of cached content, and
confidentiality/legal issues with transparent
caching are all addressed by Inktomi's
development and technical support group.

Disruption of service problems are possible but
rare, Gauthier said. He added that the workaround
-- passing CyberCash traffic onward without any
attempt to proxy or cache the content -- was
easily implemented.

Issues of confidentiality and disclosure should be
resolved between ISPs and network administrators
deploying the technology, Gauthier said.