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230 Chapter 4 • Performance Enhancement Technologies ■ Weighted percentage This option allows you to assign performance weights to each server in a community.These weighted percentages can then be used to calculate which servers are capable of processing con- nections faster, so as to receive the largest number of connections. ServerIron increases network resiliency for your mission-critical applications, and includes essential, dependable features that will ensure applications’ avail- ability. If there is a server or application outage, the ServerIron can provides mil- lisecond detection and failover to the next server that is located within the same logical community that supports that application.This will guarantee that your data will continue to flow and your applications are always available to the client. An added feature that will help you meet your customer needs for uptime is a hot standby redundant switch capability that can protect your users against loss of session.The ServerIron creates primary and secondary switches that have identical configuration parameters.The secondary switch (or failover switch) will continu- ously monitor the traffic that passes through the primary switch. If the primary switch fails, the secondary switch will take over without losing user sessions or connectivity. Content Delivery Networks The Internet has grown to the point where its value transcends IP connectivity for the support of Web pages and email. ASPs, content providers,Web-based pub- lishers, and e-businesses look to the Web for high-performance, reliable transport for bandwidth-intensive, multimedia content such as IP (XoIP), e-commerce transactions, special events, news, and entertainment services. With this need, there comes the requirement to develop dynamic multimedia content.The networking industry’s focus from Layer 3 connectivity issues is shifting to the creation of intelligent, Layer 4–7 networks that can support the rigorous response-time requirements of these new types of content.The emphasis is now turning to content delivery networks (CDN). Some of the reasons for the movement to CDN include: ■ The speed of development and deployment can be much faster at the higher network layers. ■ There is a need to grow to improve quality of service and quality of experience for more-demanding clients. ■ Content providers must scale to service larger audiences who often consume the same content. www.syngress.com 130_ASP_04 6/19/01 2:45 PM Page 230 Performance Enhancement Technologies • Chapter 4 231 CDNs can also leverage the abilities of strategically placed distributed caching, load balancing, and Web request redirection systems.They ensure that, based on closeness and server resource utilization, content is delivered in the most efficient manner to the user requesting it.This benefits the end user (and there- fore, the content provider), as well as connectivity providers, who receive the benefits of a streamlined bandwidth consumption implementation. Content is normally served from a cache server, which in this model can also be called a surrogate, which is located on the edge of a network, close to the user. The surrogate mirrors the content provider’s primary servers, which are located in a CDN service provider’s data center.This enables CDN service providers to deliver the highest-quality experience to the end users, who are intolerant of response-time interruptions. Some of the reasons that are driving the CDN’s growth are the network design and application requirements of content providers, which are causing increasing numbers of content publishers to consider the economic savings that are offered by CDN service providers. Sites that deal with streaming-media events (such as live conference events and training companies), high-volume e-commerce transactions during holiday seasons, and interactive videoconferencing sessions are just a few of the businesses that are capable of receiving these benefits. The task of keeping these complex content sites advantageously dispersed and available to a wide base of users can be a costly and time-consuming undertaking for content providers.Web content providers need the following to productively build and maintain their multimedia content: ■ Near-100 percent (99.999) server uptime and availability, while still delivering fast response times to users. ■ The ability to reach a wide base of customers in a cost-effective, scalable manner. ■ Content management and monitoring tools that allow providers to keep their content fresh ready, and track user activity. Today’s Content Delivery Landscape Most of the larger content service providers have hosted their own content while monitoring and managing their own Internet connections. However, as Web usage for a business foundation proliferates the market and content distribution demands increase, there has been a mass conversion to CDN-type service providers.The www.syngress.com 130_ASP_04 6/19/01 2:45 PM Page 231 232 Chapter 4 • Performance Enhancement Technologies reasons for this migration include increases to the performance and reliability of their content services, while lowering their total cost of ownership. Content providers are driving the industry, and their vendors, to develop stan- dardized new technologies.The trends also motivated the industry to construct and implement peering and settlement capabilities among CDN service providers to ensure dependable, high-quality service levels.Two industry groups, the Content Alliance and the Content Bridge Alliance, are establishing these technical and business standards along with the Internet Engineering Task Force (IETF). Functional Components of a CDN The components that are necessary for a CDN to function properly include the following: ■ There should be a redirection service that makes sure that a client’s Web request is directed to the “closest” cache server. ■ Distribution services that are comprised of a distributed set of surrogate servers, so that cache content can be accessed on behalf of a Web owner’s point-of-origin server. This enables traffic to bypass heavily congested areas of the Internet. An example of this is when IP multicast might be implemented as a component of the distribution services such as a medium for updating mirrored caches. ■ An accounting and billing system that enables the CDN provider to monitor, log, and bill the content provider based on use (the amount of bandwidth consumed by users who access the content provider’s site). These systems have also evolved to enable CDN providers to crossbill multiple providers for CDN internetworking services. How Do CDNs Work? CDNs are able to provide QoS to the Internet’s IP-based backbone, which helps to eliminate or minimize delay (sometimes referred to as “World Wide Wait”). These latency issues are usually unnoticeable when the application that in use is providing email or static Web page downloads. However, as we move to a world that uses multimedia-rich applications for entertainment services, online gaming, live videoconferences, and streaming broadcasts, all of which are susceptible to response-time delays, extra preparation must be taken to ensure the delivery of a quality experience for the client. www.syngress.com 130_ASP_04 6/19/01 2:45 PM Page 232 Performance Enhancement Technologies • Chapter 4 233 CDNs are capable of addressing these response-time delays by minimizing the number of Internet backbones that an application request and return path that streaming or downloadable content must pass through. Surrogates are one pos- sible way to do this by hosting replicated content in cache servers located on the network edge.This setup enables CDN service providers to deliver content that is stored on these cache servers to be just one hop away from the end user. User requests to a content provider’s Web site are redirected to dispersed data centers that the CDN providers own or lease. Setting up rules, and using the encoding methods that are dictated by the CDN service provider accomplishes redirection.The CDN maintains a service that is able to do lookups, which help steer user requests to the content surrogate that is closest to the client. CDN service providers also use load-balancing technology to determine if the content server is available and considered the closest. As noted earlier in this chapter, this load balancing can take the form of software or hardware (such as a network appliance) from a third-party vendor. CDNs are also using content switching or application-layer (Layer 4–7) switching to further enhance QoS abilities.This enables the CDN routers and switches to examine IP address information, and account for the specific response-time requirements of the application or content being requested.These Layer 4–7 switching capabilities can also be delivered in the form of software that overlays the router or switch, or as server software that runs in concurrence with the router or switch. The surrogates contain software that is able to create logs that track usage and billing information, which is then collected by a central database in the CDN ser- vice provider’s data center.This information can then be used to determine what to charge for the CDN services provided.These pricing models are generally based on usage, with a fixed rate billed per megabit per second of usage.This col- lected information by surrogates can also be used to deliver content management capabilities, based on usage trends and performance information, to the customer as a part of the CDN service package. Who Needs CDNs? So, who really benefits from CDNs? The list includes content publishers, CDN service provider specialists, ISPs, CDN infrastructure component makers, local access telecommunications providers, and the content consumers in the public market and in the private sector. Usually, the CDN service providers “own” the content provider clientele, while the ISP or local access provider “own” the end customers (the consumer of the content). www.syngress.com 130_ASP_04 6/19/01 2:45 PM Page 233 234 Chapter 4 • Performance Enhancement Technologies The following are brief looks at each type of provider, why they need CDNs, and what their requirements are. Content Providers Content provider organizations build content for the Web, and are faced with delivering content that has dynamic characteristics to customers who require high levels of service. One of the major issues facing the content provider market is the need for QoS levels in content delivery, as this is what attracts and main- tains clientele.The following are examples of companies that are in the content provider category: ■ Owners of e-commerce sites, who are concerned about response times for Internet browsers and transaction times for customers ■ Retailers who want to broadcast promotional events ■ E-learning developers, virtual universities, and traditional sales training companies that are adding Web-based versions of their classes ■ News organizations that want to present Web-based video news coverage ■ TV stations, radio stations, and entertainment companies that want to use the Web to deliver entertainment services ■ Businesses that have mission-critical Internet-based content Many content providers host and manage their own Internet content sites, and also support mirrored content servers in multiple locations.The reason for this is that CDNs are relatively new and little is known, and there is a perception that there are high costs associated with CDN services. Currently, some companies are becoming well known in the CDN market- place. Akamai Technologies Inc., Inktomi, and Digital Island Inc., for example, are priced at a per-megabit per-second of usage.These prices often seem high to content providers when compared with the per-megabit per-second of usage that is charged by most plain Internet hosting and connectivity services such as AboveNet Communications and Exodus Communications Inc.This cost is some- what dispersed as content providers find themselves needing to run multiple data centers to efficiently serve content based on geographical location, and start totaling up the necessary hardware resources, network connectivity costs, and the human resources that are required to support their sites on a 24 by 7 timeframe. Calculations by HTRC Group, a networking research firm in San Andreas, California, indicate that as content distribution is outsourced from content www.syngress.com 130_ASP_04 6/19/01 2:45 PM Page 234 Performance Enhancement Technologies • Chapter 4 235 providers, their performance increases and their support costs decrease.The rea- sons are the same as those found in a typical network outsourcing model; by being able to use the economics of scale, breadth of skill set, and networking expertise, companies that focus on the distribution of network content for many companies are able to priced better, faster service to each customer by sharing their resources. What Do Content Publishers Require from CDNs? Content providers require a combination of hosting and distribution capabilities, so they are pushing the industry to develop newer products and to work together more effectively, not only on technical levels, but also conform to business stan- dards as well. As discussed earlier in the chapter, this resulted in the formation of two industry groups, the Content Alliance and the Content Bridge Alliance. These companies try to foster IETF standards for the interoperability of CDNs on technical and business levels. ■ Multiple provider capabilities Many of today’s largest publishers are taking advantage of CDN services to help them leverage their services. In the past, the coverage offered by a single service was adequate to sus- tain the relatively limited amount of multimedia content that was com- monly used by the Internet. Now, content providers are requiring a broader network reach, but don’t want to deal with creating many rela- tionships with multiple CDN service providers.Therefore, these content providers are looking for interoperability among CDNs, where the owners of the CDN could reimburse each other for shared distribution services.This helps to give content providers a more ubiquitous model and more flexibility to choose or change providers. ■ The ability to edit/redirect Web links Content providers who use CDN services need to be able to edit their content and the links in their Web pages to point to the network of their CDN service provider. In the past, this required that changes be made to their internal naming conventions to that of the CDN operator. One of the drawbacks associ- ated with this change is the fact that it tends to lock the provider into the redirection of content that is confined to a single CDN, which has often discouraged some Web site owners from using CDN services. There are generally two accepted methods that are used by content providers to redirect their links to a CDN service provider’s network. www.syngress.com 130_ASP_04 6/19/01 2:45 PM Page 235 236 Chapter 4 • Performance Enhancement Technologies The first works when CDN service providers tell the content provider to refer its internal Web links in its own DNS server to the DNS name of the CDN.This method makes it easier for content providers to change CDN service providers.The second method requires that the content provider program the name of the CDN service provider into its own DNS, (this is also referred to as canonical names, or C-names).The tradeoff with this method is that the content provider will gain a broader set of content management and network visibility capabilities, since its server is integrated into the CDN network infrastructure, but it is not as easy to change providers. There are also efforts to assist content providers through products from companies such as CacheFlow Inc. and Novell Inc.They have cre- ated an application that works as front end for a content publisher’s Web site and helps to perform URL rewriting on the fly.This protects the publisher from having to rewrite the Web pages and redirect user requests. It also prohibits the publishers from having to obligate them- selves to a CDN. Currently, these rewriting solutions will work with multiple service providers’ CDNs, but are only able to redirect content to just one provider. ■ Content management/usage visibility There are now complex, yet user-friendly content management tools that are a critical success factor for CDN services. Content providers must be able to redirect their con- tent to (multiple) CDN sites with minimal configuration and support; and have access tools that assist to refresh their content. Many CDN ser- vice systems are designed around a pull model for HTTP objects, which allows the ability to update distributed surrogates throughout the CDN. The surrogates use an algorithm that allows them to detect a mismatch between the surrogate and the point-of-origin server.When a mismatch is detected, the surrogates will perform an update to themselves. CDN service providers also supply their content provider customers with a Web-based front end.This allows the content provider to see what con- tent is being served, and purge and update content as necessary. Content providers use these tools to track usage histories and trends. This information is required for reporting and promoting their sites to potential advertisers. It is often used to see usage trends to determine how to tweak their content to make it more attractive to customers and provide a better quality of experience.This allows the ability for some content providers to personalize their services and applications at the www.syngress.com 130_ASP_04 6/19/01 2:45 PM Page 236 Performance Enhancement Technologies • Chapter 4 237 edge of a CDN provider’s network, and helps to better target users in a given location, similar to a local newspaper or Yellow Pages directory. The preceding capabilities make CDN migrations more flexible and less inva- sive on the part of the content provider, and contribute heavily to the acceptance and use of CDN services. CDN Service Providers CDN service providers today include companies such as Akamai, Digital Island, epicRealm Inc., Inktomi, InterNAP Network Services Corp., Mirror-Image Internet Inc., and Speedera Networks Inc.The business model of these companies is to bring management and QoS to what have been mostly best-effort services to date. They are looking to serve the growing market needs of their content provider customers and help to deliver content that require higher levels of service to end users.This trend gives CDN service providers an opportunity to add levels of con- trol to the Internet, and to build themselves significant revenue streams. Several of the early adopters of the CDN model have developed proprietary technologies for caching, content management, and load balancing. Some of these companies include: ■ Akamai Akamai makes exclusive use of its own technology to optimize its ability to deliver better service to its clients. ■ InterNAP InterNAP has created a software application called the ASsimilator, which works with the Border Gateway Protocol (BGP) moving data traffic from the ISP network that is closest to the user requesting the data, directly to the ISP backbone to which the content provider customer is connected. In order to make this work, InterNAP has created business partnerships with some of the world’s largest ISP backbone providers. When a customer makes a request to a Web site, the InterNAP partner ISP identifies it and transports the message to an InterNAP-owned data center.The traffic is then forwarded to the content provider’s Web site.This setup bypasses ISP-to-ISP NAPs for public peering, and avoids much of the congestion on the Internet. Many CDNs are currently owned and managed by a single body. However, there is a shift in thinking that is driving multivendor CDNs and allowing con- tent providers and clients to benefit from the use of multiple providers.This is a www.syngress.com 130_ASP_04 6/19/01 2:45 PM Page 237 238 Chapter 4 • Performance Enhancement Technologies very scaleable way to add and maintain QoS and connectivity without having to design and implement their own infrastructures. What CDN Service Providers Require. A CDN service provider will need to migrate from proprietary network intelli- gence to allow for the greater implementation and utilization for a multivendor design to fully realize its capabilities. Software functions that will be required from CDN manufacturers include: ■ The ability to handle accounting and billing This assists the CDN in the ability to charge customers based on the tracking of usage between multiple CDN service providers that host and deliver content for common customers. ■ Content signaling technologies These signaling technologies indi- cate when content should become invalid or when it should be refreshed, and can be extended across multiple CDNs providers. ■ E-commerce capabilities (such as credit card verification, security, transaction processing) This capability can be used for the delivery of entertainment type services such as pay-per-view and gaming. ■ The ability to provide third-party clearinghouse services These services are created to assist in the resolution of shared services among CDN service providers. www.syngress.com The Content Bridge Alliance and the Content Alliance The Content Bridge Alliance is testing a concept for third-party clearing- house services, using Adero Inc. in the multivendor delivery of content from America Online (AOL). The Content Bridge Alliance was created to proof a multivendor CDN model concept, before defining the technolo- gies to be used in the design of these networks. In this testing model, vendors are participating in real-world multivendor CDN trials. The Content Alliance alternatively has been working to define tech- nology that supports multiple business models, not just the clearing- house model, but also joint private peering. Designing & Planning… 130_ASP_04 6/19/01 2:45 PM Page 238 Performance Enhancement Technologies • Chapter 4 239 CDN Deployment Basics and Considerations Three main architectures are used for deploying CDN services: ■ Facilities-based CDN The provider owns data centers and provides network services across a wide geographic area, and distributes these ser- vices to end users. Usually, these are large ISPs that have built a CDN that works in conjunction with their Internet access and connectivity services. ■ Distributed or multinetwork CDN In this type of deployment, CDN servers are placed in the PoPs of multiple facilities-based providers (the more the better), which creates an internetwork of CDN servers that spans multiple ISP backbones.This model is also referred to as a meta-CDN and is currently used by Akamai and Speedera. ■ Hybrid CDN Companies that are deployed with this model maintain and monitor some of their own facilities, but also use the infrastructures of other ISPs or CDN service providers. Digital Island is an example of this model. Network Service Providers ISPs and colocation companies that sell IP connectivity services are looking for ways to differentiate themselves and add new streams of revenue. ISPs that currently comprise the Internet backbone are moving quickly to implement CDN technolo- gies such as load balancing and caching for the benefits they offer. By imple- menting these solutions, ISPs are more capable of monitoring and managing bandwidth, which is simply good business for network service providers who are looking to keep bandwidth costs low and traffic flow for their customers high. Due to the nature of deploying these technologies, companies are deciding to become CDN providers on their own by offering content peering and internet- working agreements with other existing CDNs.They could also adopt other business models so that they may “plug in” their networks to multiple CDN infrastructures.They might for example, buy “edge” services from CDN providers to deliver broadband content to their own clients. This means that local access providers are capable of delivering content for the “last mile,” and using caching and load-balancing capabilities for internal ben- efits. A company might do this because it may not have the network coverage to catch the attention of large content providers, but could get paid as the source for the ultimate delivery of the content from those providers. www.syngress.com 130_ASP_04 6/19/01 2:45 PM Page 239 [...]... from becoming an ISP www.syngress.com 251 130 _ASP_ 04 252 6/19/01 2: 45 PM Page 252 Chapter 4 • Performance Enhancement Technologies Solutions Fast Track Web Caching and How It Works The intent of caching is to move Web content as close to the end users or the edge of the network as possible for quick access to improve the customers’ satisfaction levels, and gives your ASP the competitive advantage Hardware... to be considered include a version control feature, site recovery and rollback capabilities, scheduled publishing, logging features, and built-in security features www.syngress.com 255 130 _ASP_ 04 256 6/19/01 2: 45 PM Page 256 Chapter 4 • Performance Enhancement Technologies Q: What types of applications are ideally suited for development as traffic server extensions? A: Content filtering, content transformation,... Scalability and How It Affects Your Business s Fault Tolerance Features and Issues s SAN Solutions Offered by Various Vendors Summary Solutions Fast Track Frequently Asked Questions 257 130 _ASP_ 05 258 6/19/01 2:46 PM Page 258 Chapter 5 • Storage Solutions Introduction Within the last decade, we have seen a complete transformation in computing technology.The Internet has helped shape our current view of business,... devices The LocalDirector is considered a stateful device, as it is able to monitors and can track all TCP connections that are occurring between clients and servers www.syngress.com 253 130 _ASP_ 04 254 6/19/01 2: 45 PM Page 254 Chapter 4 • Performance Enhancement Technologies Foundry Networks’ ServerIron Foundry’s ServerIron Web switches provide high-performance content and application-aware traffic and... www.syngress.com 130 _ASP_ 05 6/19/01 2:46 PM Page 2 65 Storage Solutions • Chapter 5 of miles away by using the existing network infrastructure of the Internet, or a customer computer might mount a drive on a remote server over a private wide area network (WAN) connection such as a T1 In both of these cases, the server being accessed is, for all intents and purposes, acting as NAS Figure 5. 2 Network Attached... Content Delivery Network (CDN) system was developed to help service providers to deploy content delivery services so that they could realize new profit opportunities www.syngress.com 130 _ASP_ 04 6/19/01 2: 45 PM Page 255 Performance Enhancement Technologies • Chapter 4 Frequently Asked Questions The following Frequently Asked Questions, answered by the authors of this book, are designed to both measure... incorporate existing content-aware applications that are required to build scalable and highly available infrastructures www.syngress.com 130 _ASP_ 04 6/19/01 2: 45 PM Page 249 Performance Enhancement Technologies • Chapter 4 Akamai and F5 Networks’ Combined Offerings Akamai and F5 Networks have developed a complementary set of offerings that can provide you with both high speed and reliability for your sites (Figure... service provider business models, and enable service providers to build value with CDN offerings or use CDN technology to augment their hosting service offerings www.syngress.com 130 _ASP_ 05 6/19/01 2:46 PM Page 257 Chapter 5 Storage Solutions Solutions in this chapter: s Upfront Concerns and Selection Criteria s Directly Attached Storage in Your Infrastructure s Network Attached Storage Solutions s Storage... determines which server should receive new requests www.syngress.com 130 _ASP_ 04 6/19/01 2: 45 PM Page 253 Performance Enhancement Technologies • Chapter 4 Distributed load balancing sends packets across dispersed networks, which can be located in geographically separate areas from the local server Load Balancing Solutions from F5 As more servers are added to the DNS round-robin rotation, traffic will... tolerance are also major concerns that an ASP must address, I have provided separate sections that discuss some of the potential issues in some detail www.syngress.com 130 _ASP_ 05 6/19/01 2:46 PM Page 259 Storage Solutions • Chapter 5 Upfront Concerns and Selection Criteria Currently, there are many differing manufacturers of storage-based equipment, and several methods of delivering storage solutions . infrastructures. www.syngress.com 130 _ASP_ 04 6/19/01 2: 45 PM Page 248 Performance Enhancement Technologies • Chapter 4 249 Akamai and F5 Networks’ Combined Offerings Akamai and F5 Networks have developed. to redirect their links to a CDN service provider’s network. www.syngress.com 130 _ASP_ 04 6/19/01 2: 45 PM Page 2 35 236 Chapter 4 • Performance Enhancement Technologies The first works when CDN service. video, and Enterprise applications. www.syngress.com 130 _ASP_ 04 6/19/01 2: 45 PM Page 244 Performance Enhancement Technologies • Chapter 4 2 45 ■ Monitor and report on usage and performance This will