Coyote Point Systems Equalizer GX Series, Руководство администратора

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Working with Clusters and Match Rules
Using Match Rules
Note - Match Rules are not supported on E250GX model Equalizers.
The ability to make load balancing decisions based on the content of a client request is what
separates Layer 7 processing from the processing options available at Layer 4. For Layer 7 HTTP
and HTTPS clusters, Match Rules provide fine-grained control over load balancing decisions based
on the content of the client request. If you need to be able to route requests to the servers in a
cluster based on the content of the request, Match Rules are the answer.
Layer 7 HTTP and HTTPS clusters can use logical constructs called “Match Rules” to control the
processing of the incoming data stream from clients. Match rules extend the Layer 7 load
balancing capabilities of HTTP and HTTPS clusters by allowing you to define a set of logical
conditions which, when met by the contents of the request, trigger the load balancing behavior
specified in the match rule.
Typically, a match rule selects the subset of servers that the load balancing algorithms will use for
a particular request. By default, a request is load balanced over all the available non-spare
servers in a cluster. Match rules allow you to select the group of servers, or server pools, that will
be used to load balance the request.
For each virtual cluster, you can specify any number of match rules. For each match rule, you
specify the subset of servers or server pools that can handle requests that meet the rule criteria.
A match rule provides custom processing of requests within connections. Equalizer provides
common and protocol-specific match functions that enable dynamic matching based on a
request’s contents. Protocol-specific match functions typically test for the presence of particular
attributes in the current request.
For example, a Layer 7 HTTP virtual cluster can specify matching on specific path name attributes
to direct requests to subsets of servers or server pools so that all requests for images are sent to
the image servers. The difference between load balancing with and without match rules in such a
situation is illustrated in the following figure.
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