Enterprise content delivery networks (eCDNs) are moving content such as rich media and bandwidth-intensive files closer to end users within company networks. eCDNs consist of servers, caches, routing software, and management tools. They help improve application performance and relieve network strain. Vendors are developing techniques to cache dynamic content at network edges. Future eCDNs may cache and deliver application code, databases, and multimedia to remote offices for richer client experiences over bandwidth-constrained connections.

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Living on the edge
By David L. Margulius
March 15, 2002 1:01 pm PT
What began with Victoria's Secret may soon be coming to a WAN near you. Since the late 1990s, high-traffic Web sites h
CDNs (content delivery networks) from companies such as Akamai and Digital Island to help them handle peak loads and
events such as the Victoria's Secret Webcasts. Service providers, too, have long supported the technology, investing hea
caching hardware and software that allow them to manage bandwidth utilization within their networks.
But with the decline of ISPs, the dot-
com bust, the reluctance of large
media companies to put their content
online, and most importantly a wave
of bandwidth-intensive business
applications, attention is now shifting
to content delivery in the enterprise.
Many companies are now using CDNs
to push traditional static content,
frequently-accessed data, and large
files (for example, PDF documents,
streaming video, e-learning
applications, and corporate
presentations) closer to the edges of
their networks where they can be
more easily accessed by end-users.
Other companies have begun
deploying CDN technology to deliver
dynamic, database-driven content for
business software such as ERP and
CRM.
Why? Because to many enterprises, a CDN's promise of faster application performance a
network availability is just too good to pass up. Couple that with the growing telecommu
and the rise in Net-enabled business services, and it's no wonder companies are mulling
possibilities of edge networking.
Building a better network
A typical CDN consists of a group of servers, caches, and routing software capable of m
frequently used content closer to end-users, thus maximizing bandwidth efficiency and
network scalability and availability.
"It's essentially a store-and-forward mechanism that relies on repeat access to generate
performance," The Yankee Group analyst Neal Goldman explains.
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2. To understand how an enterprise CDN works, imagine the architecture of a public CDN l
which relies on 13,000 servers (caches) located in datacenters and ISPs around the wor
network uses a "pull-based" mechanism to keep local caches primed with the most freq
requested content.
For example, when a Web surfer connected to an ISP in Boston clicks on a photo of New
Patriots quarterback Tom Brady on CNN.com's Web site, the photo is "pulled" to the Aka
closest to that user's ISP. Anyone else in the network who subsequently requests Brady's photo gets it from the same ca
than CNN's origin server, thus cutting down on bandwidth and eliminating router hops. Meanwhile, infrequently accessed
content that has passed its "time-to-live" freshness date are regularly flushed out of the network.
And that's not all: CDNs can also monitor network conditions to calculate optimal routing, minimize packet loss, balance
loads, and provide route-around and fail-over capabilities.
Of course, in the enterprise the challenge is a bit different. Although the environment behind the firewall may be more p
and the universe of potential users better known, eCDNs (enterprise CDNs) must also provide more controlled distributio
because the consequences of network disruption within a company are greater than on the public Internet.
As with a public CDN, an eCDN consists of load balancers, caches, and proxies, all coordinated by a single software syste
an enterprise will also deploy management tools to control the content flowing across the network. Publishing tools can i
content management systems to inject the appropriate content into the network, such as material in the correct languag
particular geographical region. Bandwidth management tools allocate scarce WAN bandwidth among various users and a
Routing tools set cache hierarchies so that, for example, if a file is not found in Kuala Lumpur, the system can check for
Security and access tools restrict access to certain users or until certain times. And monitoring and reporting tools overs
using what and bill bandwidth costs to the right departments.
Things gets tricky when you try to distribute live video, which typically consumes a huge amount of network capacity. Gi
most Web video is delivered using real-time streaming protocols like RealVideo or Windows Media, the process of pushin
content efficiently to the edge of the network requires special software proxy caches that can "multicast," or receive one
the origin server and pass it along to multiple simultaneous viewers.
This approach enables wider distribution than unicasting, which broadcasts all streams directly from the origin server. Fo
Steve Jobs' latest Macworld keynote Webcast topped out at 16.5Gbps and was served simultaneously to a total of 80,00
Without multicasting, that would not be possible.
Alternatively, enterprises can address the challenge of live video by offering it on-demand, thus flattening the demand c
making the content easier to cache. How effective is that strategy? Jim Ni, director of product management at CDN vend
Networks, thinks that, eventually, on-demand distribution will be an effective substitute for live distribution.
"After the second CEO Webcast, the guys in Singapore aren't going to wake up [in the middle of the night] to watch it liv
[anymore]," Ni predicts.
The City of San Diego is a case in point. San Diego now distributes all its city council meetings via Webcast, using an eC
Network Appliance to also deliver the videos on-demand. Fire and police training videos, as well as videos of the city's se
for maintenance personnel, are also available.
To Allen Myers of the city's data processing group, San Diego's eCDN makes sense because it relieves the city's network
gargantuan video files from what would otherwise be a drag on response times. And as more business-related video and
technologies come online, the need for eCDNs is only going to increase. "You're going to suck up the bandwidth with the
generation of apps real quick," Myers says.
New frontiers for edge delivery
With each passing day, public and corporate Web content becomes more and more dynamic or database driven. At the s
the distributed computing revolution rolls on. In response to both of those trends, CDN and eCDN vendors have begun d
techniques to enable the caching of dynamic page elements and, in some cases, even applications.
For example, a group of vendors including Akamai, Oracle, and BEA Systems has introduced a markup language called E
Side Includes) that enables edge servers to recognize, cache, and render specially tagged dynamic content or perform d
transformations at the edge of the network, based on various environmental variables.
"I could look at a user's cookie at the edge of the network, note that they're a Libra, and deliver that horoscope," explain
Taylor, director of product marketing at Akamai. "Without ESI, a single piece of dynamic content on the page renders th
uncachable."
Other vendors, such as F5 Networks and Network Appliance, have developed their own ESI-like algorithms. And some in
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3. leaders, such as Cisco and Microsoft, have been conspicuously absent from the ESI parade, leaving open the question of
standard will benefit from the heavyweights' support.
Furthermore, to improve the performance of browser-based applications (such as ERP and CRM systems) from remote o
vendors are working on software that can identify and serve as much of the presentation layer and underlying data as po
the edge.
"The end-user thinks the application is slow, and it's really the network," observes F5's Ni. "The first baby step is to take
bitmaps, and [cache] them out there [on the edge]."
Other eCDN vendors are claiming to already support the caching of XML constructs while holding the session with a remo
and even on-the-fly transformation for wireless formats.
It's all part of a return to rich-client computing, according to industry watchers such as The Yankee Group's Goldman, w
rise in locally empowered applications and clients with data and application logic, as well as a built-in presentation policy
CDNs] have to be able to deliver code at the edge," Goldman says.
In a year or two, CDNs may even be able to deliver JavaServer Pages (JSPs), VBScript, Active Server Pages (ASPs), and
Enterprise JavaBeans (EJBs). "And the more the network is distributed across multiple peers, the more complex manage
monitoring becomes," Goldman adds.
These developments also put eCDN vendors on a convergence course with the storage world.
"One of these large branch office caches can have two gigabytes of storage," notes Amit Pandey, senior marketing direct
Network Appliance, which also sells storage. "That looks to me more like a file server."
Finally, a raft of startups is emerging to build the next generation of edge-delivery technology -- always an encouraging
emerging technology. From low-cost, peer-to-peer architectures (such as those marketed by Kontiki and CenterSpan), d
content caching solutions (Xcache Technologies, Chutney Technologies, and SpiderSoftware), and packet-level caching s
(Expand Networks), to "pre-fetching" tools (Fireclick), "difference send" accelerators (FineGround Networks and Speedw
management solutions (NetReality, Response Networks, and NetScout), there's no shortage of innovative thinking these
long as you don't mind living on the edge.
See our related illustration, "Caching on the edge".
Return to our Network management package.
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4. Content delivery networks for the enterprise
Content delivery technology, born on the public Internet to help Web sites handle peak
loads and improve performance, is now moving into the enterprise. Enterprise CDNs help
firms distribute bandwidth-intensive content, such as rich media, throughout a WAN,
especially to remote offices with low-bandwidth connections. The new networks consist of
servers, caches, routing software, and a host of management capabilities (including
bandwidth allocation, content publishing, security, tracking, and reporting). The next
phase in eCDN development, already under way, will have the ability to deliver dynamic,
database-driven content and improve application performance at the edge.
Opting for outsourcing
For various reasons, enterprises large and small are feeling a tug toward network
management outsourcing. But for now, most are just experimenting in a market many
label as still "immature."
Dominating the space right now are MSPs (managed service providers), dinged lately by
sagging revenues and customer confusion. Meanwhile, mighty telcoms and systems
integrators are charging into the MSP market -- a move likely to change market
dynamics.
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Yet the network outsourcing market is seeing "a fair amount of activity," notes Martha
Young, research director at Boulder, Colo.-based Enterprise Management Associates. That
activity is scattered among companies of all sizes, as businesses get comfortable with the
idea of handing over some network management duties.
"I don't think outsourced services are just a middle-market play. Enterprise customers
will chose to outsource certain elements of their business, too," offers Mike Twomey, vice
president of channels and business development at Tivoli, an Austin, Texas-based
software supplier to MSPs.
There is a commonality among the tasks users settle on in taking the plunge. At first,
"they're likely to start with tasks that are small, simple, and well-boxed," says Corey
Ferengul, senior program director at Meta Group in Stamford, Conn.
Those functions might include managed firewalls, managed VPNs (virtual private
networks), or managed WANs. Users polled also cite monitoring services and LAN
management as natural first candidates for outsourcing.
"I realized I had a rapidly growing network infrastructure and I was about to take on
newer technologies such as video conferencing and online medical records," recalls Tom
Riemer, IT director at South Shore Mental Health in Quincy, Mass.
"I had a sinking feeling that I had legacy issues around our closed, private network," he
adds. "I also needed talent."
After a somewhat exhausting and often confusing look at options, Riemer tapped MSP
InteQ to take on basic network management and monitoring tasks.
"Not everybody out there that calls themselves an MSP really is one. We had to do our
homework to figure out who the MSPs really were," Riemer says.
At issue is the fact that MSP can describe a host of vendors; the label is applied to those
that remotely manage infrastructures kept physically within an enterprise, as well as
vendors hosting networking tasks in an outside datacenter. IT managers must often sort
out the nuances to determine which best meets their needs.
"We did ponder doing this in-house," says Dave Cooper, director of field systems and
technology at Wickes, a lumber and building supply company in Vernon Hills, Ill. Cooper
eventually hired MSP NetSolve to monitor the company's Frame Relay network and to
remain an "eight-to-five shop" -- plus, augmenting personnel and skills of existing staff
seemed inefficient, he says.
Most MSP users indicate that outsourced security and storage services are likely
candidates for further network outsourcing, although those plans hinge on company
strategy and the economy. As Cooper says, "A lot will depend on our business, what
types of initiatives we do."
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