Caching in

As service providers continue their quest for differentiation, caching can provide a way to offer enhanced services.

Amid this era of unprecedented revenue opportunities, service providers also sense a danger. A host of new competitors - cable operators, competitive local exchange carriers, interexchange carriers, ISPs, Internet telephony service providers, next generation telcos, satellite/wireless companies, telecom resellers and Web hosting providers - have crept into service providers' markets, each tightly focused on a particular type of service offerings or a narrower target market.

In the new reality, traditional carriers fear that their perceived role is being diminished to that of an important-but-unglamorous background player - part of the underlying infrastructure, a provider of little more than dumb pipes.

But they don't want to let that happen. Traditional carriers are racing to pull themselves up the value chain, positioning themselves to realize the promise of content-oriented services. Newspaper business sections are teeming with reports of mergers and acquisitions in which traditional network carriers pair with Internet companies that bring the know-how and focus to deliver on customers' expectations for high-quality transmission of live and on-demand multimedia content.

Carriers also are honing their networks to meet the new challenge. One trend is the increased reliance on Internet caching. Many carriers already have deployed caching appliances at regional or metropolitan area points of presence (POPs) to ensure optimal Internet performance for subscribers and to curb WAN bandwidth costs.

Now carriers are deploying these devices, which act as content accelerators, to aid Web sites in moving content closer to their target users. These deployments are occurring at the edges of large-scale data centers and at DSL termination sites, for example. By amplifying the power of Web sites, caching appliances can help carriers differentiate their content-oriented services with performance and intelligence (Figure 1).

Caching options, carrier needs

Internet caches reside between a user's browser and a content Web server. Caches intercept Web requests on behalf of end users, pull content from source servers and, when relevant, store the content locally so that subsequent requests from a particular group of users for the same content are satisfied more rapidly. Content is then moved closer to end users.

Internet caching systems fall into three categories: traditional proxy servers, general-purpose caching servers and purpose-built caching appliances.

Traditional proxy servers are intermediary devices that perform many functions, including accepting and either answering or forwarding client requests on to another proxy server or the origin server. A general-purpose caching server consists of standard server hardware, an operating system (OS), such as Sun Microsystems' Solaris or Windows NT, and caching application software.

However, neither of these types of products lives up to carriers' requirements. The performance and scalability delivered by proxy server software is insufficient, management is resource-intensive and configuration options are limited. General-purpose caching servers generally deliver better performance than proxy server software, but the maintenance burden is substantial, entailing ongoing troubleshooting and upgrading.

And because these servers consist of non-specialized hardware running a general-purpose OS with an additional software layer, caching performance is not optimized. Scalability, device security, price/performance ratio and reliability are sub-par. Finally, because general-purpose caching servers are cobbled together from different vendors' products, obtaining single-source ownership of a problem can be difficult.

The purpose-built Internet caching appliance - as opposed to a multipurpose device re-engineered to include caching functionality - is the successor to these two technologies. The following points illustrate why:

- Performance. Speed is the most important benefit that an Internet caching solution can deliver, and some purpose-built appliances deliver response time gains for requested content by as much as tenfold.

At the same time, content accuracy isn't sacrificed for speed. Without negatively affecting overall system performance, some vendors' appliances intelligently monitor the source of the Internet content they are locally serving. Thus, content accuracy is ensured.

- Scalability. An Internet caching solution offers plug-and-play installation. Remote management and configuration allow carriers to expand their content delivery infrastructure with the implementation of additional Internet caching appliances as traffic volumes soar.

- Security. With an appliance that processes HTTP traffic and nothing else, security is enhanced because there are no hacker entry points. By deploying such an appliance outside the firewall, expensive firewall resources are freed of the HTTP burden that can comprise more than 95% of the typical load.

- Reliability. Carrier-class reliability is a hallmark of today's leading purpose-built caching appliances. These are self-contained, interoperable hardware; Internet caching appliances look, feel and behave like traditional voice networking gear.

Caching appliances already reside in many carriers' regional or metro area POPs. These are "client-side" implementations designed to help subscribers enjoy optimal Internet performance and help carriers keep WAN bandwidth costs in check.

For example, C1 Communications, a North American carrier, deployed Internet caching appliances in network hubs as a customer satisfaction tool to ensure that enterprise subscribers enjoy the full benefit of their DSL connections.

In another example, New Zealand carrier Clear Communications deployed Internet caching appliances to make more efficient use of WAN links and to take advantage of those cost savings by pricing services more aggressively. With caching appliances serving much of the content requested by its users, less traffic reached the WAN. Because international bandwidth is very expensive and because a majority of user requests are for content from the United States, the appliances helped the New Zealand carrier cut costs.

Emerging opportunities

Content-oriented services are the next great revenue wave awaiting carriers. Enterprises want to combine rich media with the Web's broad reach to communicate more effectively with employees, partners and customers. Web-based multimedia online training, corporate broadcasts, product and service demonstrations, interactive advertising, business-to-business exchanges, pay-per-view audio and video entertainment - these are the types of leading-edge applications that have created the market demand for high-quality content-oriented services.

Such services include Web-site acceleration, distributed content networks and remote intranet acceleration. In each service, the carrier's primary goals are to enable content providers to deliver a better end-user experience globally and to scale capacity to accommodate greater traffic loads without performance degradation.

In a Web site acceleration service, caching appliances are deployed in front of content servers to increase the number of users that a site can serve simultaneously and to deliver optimal Web response times for users, regardless of demand spikes (Figure 2).

As a result, use of the content provider's Web server central processing unit decreases. In addition, the offload boosts the capacity of the Web server to process other traffic such as secure e-commerce transactions. Faster response times encourage users to browse longer - and make more online purchases.

Therefore, the value of the content provider's advertising space inflates, and the content provider's firewall resources are conserved.

Distributed content networks expedite delivery of up-to-date content to users globally by replicating content from origin servers on private or shared, geographically dispersed servers (Figure 3). Content providers are made less vulnerable to Internet latency because, again, content is moved closer to users - this time via domain name server and server load balancing technologies.

Distributed content networks must be secure, highly available, scalable and cost-effective for carriers to attract and retain customers for these services. Internet caching - deployed in front of the server farm - delivers all four. Requests for distributed content are routed to an appropriate cache. This ensures that requests do not have to travel across the entire network to be fulfilled.

Content personalization is one of the more compelling possibilities created by private distributed content network services. Content owners now can begin basic URL substitutions, where a standard Web page might include directives for each remote, server-side cache to insert an image specific to its location. In this way, advertising can be customized per region. Finer content personalization is enabled as caches are deployed closer to smaller segments of users.

A remote intranet acceleration service speeds corporate content to remote users securely and, in turn, boosts employee productivity (Figure 4). Because most content requests are satisfied by caching appliances deployed at remote sites, fewer requests for content must traverse the WAN to content servers in the corporate headquarters. Consequently, bandwidth costs are checked.

Optimized for new opps

Vendors of caching appliances are layering their products with additional intelligence for the proliferation of these content-oriented services.

Internet caching appliances are being optimized for the intricacies of server-side deployments - for example, where the cache resides in front of a content site's server farm. In this type of configuration, the appliance manages a well-known, finite set of content that millions of Web users around the world can access.

As such, server-side caching has requirements distinct to that of client-side caching, in which a known group of users access potentially millions of Web sites. The market's most sophisticated caching appliances optimized for server-side deployments are tuned to deliver fast responses during peaks in demand and to maintain operation even during denial of service attacks perpetrated by hackers.

Streaming media support is natively integrated in the OSs of some of today's Internet caching appliances. No longer viewed as a layered service, streaming has emerged as a fundamental technology component by some vendors. When streaming capabilities are tightly integrated, Internet caching appliances can eliminate the image or audio inconsistencies and alleviate network congestion.

The OSs of Internet caching appliances are being integrated with usage-based billing systems to help carriers overcome the limitations of flat-rate pricing for content services. Enacting usage-based pricing models based on content type enables carriers to differentiate their content-oriented services on price competitiveness and personalization. Internet caching appliances enhanced with subscription filtering capabilities enable carriers to differentiate their offerings by allowing their customers to set and enforce Web use policies. The ability to screen content enables enterprises to ensure that productivity is not threatened. It also enables schools to ensure that their students are not accessing inappropriate content.

Going higher

Carriers are fine-tuning their businesses and their networks for new opportunities.

Greater reliance on Internet caching appliances is an important part of this strategy as content delivery and acceleration technologies gain prominence in carrier networks rivaling that of routing.

These content accelerators hold the performance and intelligence necessary to enable carriers to roll out content-oriented services that produce recurring revenue streams and high-bandwidth billings. With a low upfront investment, carriers can scale the capacity of Web sites to accommodate spikes in usage, offload content providers' CPUs to handle more simultaneous, secure transactions and eliminate the threats posed to corporate productivity by Internet latencies.

And the unique suitability of the appliance model for carrier networks - with its emphasis on ease of implementation and use, scalability, reliability and security - will help providers of these advanced services keep profit margins high.