Section A: Overview of Global Request Manager

What is the Global Request Manager?

GRM is the NetCache appliance request redirection feature used to redirect client requests to the cache, or caches, closest to them. Whether a CDN exists within an enterprise network or a telco, it requires a number of components specifically geared toward providing premium service to users--including routing, caching, content management, and network management and reporting services.

The NetCache GRM feature works seamlessly with other products in the Network Appliance^TM content delivery suite to build robust CDNs. See How GRM obtains content for a description of how the Network Appliance ContentDirector^TM application can be used in a GRM deployment for pushing content to NetCache appliances and how ContentReporter can be used to track that information.

Advantages of directing requests to caches close to clients

A request routing scheme is necessary so that clients can find the content. In traditional caching deployments, L4 switches or WCCP routers are deployed on the network, or client browsers are manually configured to direct requests to NetCache appliances. These solutions are not ideal for CDNs, however, for the following reasons:

CDNs want to provide premium service.
In order to provide premium service, CDNs want to serve content as close to clients as possible. The reason is that the closer the device that serves the content is to the client, the faster the delivery. Additionally, the quality of the content served is likely to be higher. The content is less vulnerable to network problems because it travels a shorter distance.
Enterprises and telcos typically do not want to reconfigure their networks to deploy CDN service.
GRM provides an alternative to using L4 switches, WCCP routers, or manual configuration of client browsers to direct content requests to NetCache appliances--an alternative that is especially suited to the needs of CDNs. Often, NetCache appliances configured as GRM agent caches can be "dropped" into the customer environment; typically, reconfiguration of a customer's network environment is not necessary to support GRM. Reconfiguration might be necessary if your GRM deployment is not typical, for example, if you configure GRM agent caches to fetch content from random origin servers on the Internet, as well as from the CDN data centers (not the recommended approach).

Importance of serving content close to users

With the growing demand for streaming media in particular, serving content stored close to users is especially important because network congestion significantly degrades the quality of streaming media. Additionally, streaming media files, which are very large, consume a great amount of network bandwidth. NetCache appliances deployed close to users, working on behalf of the CDN content servers, can store and serve CDN content to clients. A significant amount of bandwidth is saved because the cache can fulfill multiple requests for the same content instead of the content servers at the other end of the WAN.