The following table summarizes the strategies discussed in this chapter. Each strategy in the table is discussed in detail later in this chapter. An important consideration when determining your strategy for client access to a NetCache appliance is whether you want users to have to configure their Web browsers and media players to access the NetCache appliance.
Strategy
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Summary
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Transparent client access method
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Transparent proxying
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- This strategy is available for DNS, HTTP, FTP, NNTP, MMS, and RTSP. (DNS caching can also be deployed nontransparently.)
- Transparent proxying is the only strategy you can use that does not require users to configure their Web browsers or media players for client access to a NetCache appliance.
- You add a Layer 4 (L4) switch, a Layer 7 (L7) switch, a policy-based router, or a WCCP 2.0-based router and configure your NetCache appliance for transparency.
- Automatic failover to other NetCache appliances, third-party proxy-cache servers, and the Internet is standard.
- This strategy has good request distribution capabilities. Request distribution is based on IP address or URL (L7 switch only), which is desirable because this method results in a higher hit rate than methods such as DNS round robin.
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Nontransparent (direct) client access methods
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Pointing client Web browsers to an automatic proxy configuration file
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- This strategy can be used for access to a Web cache only.
- Users must configure their Web browsers to point to this file.
- You do not need to add hardware to the network.
- Automatic failover to other NetCache appliances, third-party proxy-cache servers, and the Internet is available. However, this strategy relies on the browser to detect failover. Not all Web browsers detect failover well.
- This strategy has good request distribution capabilities. This file lists proxy cache-servers over which requests are to be distributed. Request distribution is based on IP address. Distribution is static.
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Pointing client Web browsers to the NetCache appliance
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- Users must configure their Web browsers to point to a single NetCache appliance.
- You do not need to add hardware to the network.
- No failover is available. If the NetCache appliance goes down, news and Web access is not available because the NetCache appliance cannot fail over to another appliance.
- No request distribution is available.
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Pointing a client media player to the NetCache appliance
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- Users of a RealNetworks® RTSP-based media player, QuickTimeTM media player from Apple® Corporation, and Windows MediaTM 7 player from Microsoft® can point the media player to a NetCache appliance.
- For Windows Media players prior to WMP 7, you must use NetCache Windows metafile rewriting.
- No failover is available.
- No request distribution is available.
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Pointing client Web browsers to the NetCache appliance that is functioning as a DNS proxy cache
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- If DNS caching will be nontransparent, some client setup is required.
- You do not need to add hardware to the network.
- No failover is available.
- No request distribution is available.
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Request routing for CDNs
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NetCache Global Request Manager (GRM)
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GRM directs content requests from clients in a Content Delivery Network (CDN) to the NetCache appliances that are closest to the clients. GRM supports two different redirection methods:
- DNS-based redirection services
- L7 redirection services
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