Coyote Point Systems Equalizer GX Series, Руководство администратора

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Working with Clusters and Match Rules
Configuring Direct Server Return
In a typical load balancing scenario, server responses to client requests are routed through
Equalizer on their way back to the client. Equalizer examines the headers of each response and
may insert a cookie, before sending the server response on to the client.
In a Direct Server Return (DSR) configuration, the server receiving a client request responds
directly to the client IP, bypassing Equalizer. Because Equalizer only processes incoming
requests, cluster performance is dramatically improved when using DSR in high bandwidth
applications, especially those that deliver a significant amount of streaming content. In such
applications, it is not necessary for Equalizer to receive and examine the server’s responses: the
client makes a request and the server simply streams a large amount of data to the client.
DSR is supported on Layer 4 TCP and UDP clusters only, and is not supported for FTP clusters
(Layer 4 TCP clusters with a start port of 21). Port translation or port mapping is not supported in
DSR configurations.
DSR configurations are usually configured in single network mode, where the cluster IP and the
server IPs are all on the internal interface. An example single network mode DSR configuration is
shown below:
DSR can also be used in dual network mode, although this is a less common configuration than
single network mode. Cluster IPs are on the external interface, and server IPs are on the internal
interface. An example of a dual network mode DSR configuration is shown below.
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