Cisco Cache Engine

• More Information on Cisco Cache Engine

Overview

WAN Traffic Congestion and the Caching Solution

In operation, when a user first requests particular Web content, the Cache Engine intercepts the request, fetches the Web page from the remote server, and sends the content to the user while simultaneously storing the content locally. The system satisfies subsequent requests for the same content from local storage. The Cache Engine has the built-in intelligence to determine what can and should be cached. (For  example, stock price data is not cached, but the banners and buttons on the stock quotation Web page are cached for  a configurable period). The Cache Engine can also dynamically refresh content stored locally. The result is  much higher-performance Web access for the end user, with a significant reduction in WAN traffic volume.

Features at a Glance

• Transparent to Web browsers---A Cisco IOS router sends all Web traffic---and only Web traffic (TCP port 80)---to the  Cache Engine, without requiring any changes to client browsers. In this manner, caching is entirely transparent to the browser (clients do not have to point at any particular cache device to benefit from Web caching). The end user notices only that Web page access times improve.
• Scalable on a system wide basis---Multiple Cache Engines can be installed to form cache farms. Customers can incrementally add up to 32 Cache Engines to a cache farm, with each additional engine taking on an even portion of  the network load. Because caching happens in parallel with other traffic handled by the router, and because each engine takes on an equal share of the stored Web content, the Cache Engine provides linear scaling of storage and connections as engines are added. (Two Cache Engines provide twice the storage and connection capacity of a  single Cache Engine.)
• High performance---The Cisco Cache Engine is a specially designed, dedicated Internet appliance. It uses special- purpose, thread-oriented software to achieve extremely high performance. The engine's real-time operating system avoids the relatively high overhead per process that plagues general-purpose operating systems.
• Extensive reporting and logging capabilities---Each Cache Engine provides detailed reporting and logging capabilities to monitor operation, performance, usage, and savings. Built-in graphing capabilities are available for hourly, daily, and monthly historical trending. Local and external logging capabilities are also available for more comprehensive tracking functions.
• Fault-tolerant and fail-safe---If any single Cache Engine fails, the Web Cache Control Protocol reassigns the traffic load among the remaining Cache Engines. When the  failed Cache Engine comes back on line, the system "heals" itself by intelligently reassigning traffic to the newly functioning Cache Engine. If all Cache Engines fail, the router sends Web traffic to the intended remote server just  as it did before the Cache Engine was installed---for true fail-safe operation with no loss of network functionality.
• Simple to deploy and manage---Installation involves connecting the Cache Engine to a 10/100-Mbps Ethernet port on the  router and executing a small set of router and  Cache Engine configurations commands. All other Cache Engine configuration options are set using a standard Web-browser interface. The  management for all engines within a farm is accessible through a single Web interface. In addition, the Web Cache Control Protocol only needs to run on the router that redirects Web traffic to the Cisco Cache Engines. Thus, a  network-wide Cisco IOS upgrade is not required.
• Hierarchical deployment---Because the Cache Engine is transparent, customers can place Cache Engines at several levels in a network hierarchy. Web requests can be fulfilled from any layer in the hierarchy. Additional Cache hierarchies can be constructed using the Internet Cache Protocol (ICP).

Benefits

• Cost savings due to WAN bandwidth reduction---Service providers can place Cache Engines at strategic points on their networks to  improve response times and lower the bandwidth usage on their backbones. Service providers can  station Cache Engines at strategic WAN access points to serve Web requests from a local disk rather than by accessing the (distant or overrun) Web servers. In enterprise networks, the dramatic reduction in bandwidth usage due  to Web caching would allow a lower-bandwidth (lower-cost) WAN link to serve the same user base.
• Improved productivity for end users---The response time of  a  local Web cache is much faster than the download time for the same content over the host site. End users see dramatic improvements in response times, and the  implementation is completely transparent to them.
• Ease of use---The Cache Engine is designed to be installed in minutes by even a novice. Only five commands on the Cache Engine are required and only one command is needed on the accompanying Cisco router for initial deployment. All subsequent configuration and management tasks can be performed using any standard Web browser from anywhere within the network.
• Content control---The Cache Engine provides network administrators with a simple, secure method to enforce a  site  wide access policy through Universal Resource Locator (URL) filtering.

Technology Overview

The solution comprises the Web Cache  Control Protocol (a standard feature of Cisco IOS software) and one  or more Cisco Cache Engines that store and retrieve cached data  locally.

• The Web Cache Control Protocol defines the communication between Cache Engines and routers. Using the Web Cache Control Protocol, a router redirects Web requests to a Cache Engine (rather than to  the  intended Web server). The router also determines Cache  Engine availability and redirects requests to new  Cache Engines as  they are added to a cache farm.
• The Cache Engine uses a high-performance file system designed solely for caching systems, eliminating the file fragmentation and long directory searches associated with general-purpose file-system software. The Cache Engine's secure, real time, embedded operating system avoids the  relatively high process context overhead of general- purpose operating systems. The result is an  extremely high-performance, scalable Cache Engine.

Operation

Figure 1 shows a solution that incorporates a  four-Cache Engine cache farm. When customers add Cache Engines to scale a  cache farm, each additional engine takes on  an equal portion of the stored data. For example, a single Cache Engine provides 24 GB of storage and 2000 concurrent sessions; two Cache Engines provide 48  GB of storage and  4000 concurrent sessions. A single cache farm can scale to 32 Cache Engines, providing 768 GB of  cache storage and  64,000 concurrent sessions.
Figure 1: The Cache Engine is connected directly to the router

Applications

Small and medium-sized businesses and branch offices can use the  Cache Engine to cache Internet and intranet Web  servers at both a central site and remote offices. (See  Figure  3.) This hierarchical implementation reduces congestion at central servers and frees bandwidth on intersite  links.
Figure 3: Enterprise Deployment of Cache Engines

Service and Support Options

Availability and Orderability

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