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Configure rules to manage traffic to busy or unavailable servers

Use rules-based load balancing to fine tune when and why packets are sent to which servers. Load Balancer reviews any rules you add from first priority to last priority, stopping on the first rule that it finds to be true, then load balancing the traffic between any servers associated with the rule. It already balances the load based on the destination and port, but using rules expands your ability to distribute connections.

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In most cases when configuring rules, you should configure a default always true rule in order to catch any request that is passed by other higher priority rules. This default can be a "Sorry, the site is currently down, try again later" response when all other servers fail for the client request.

All rules have a name, type, priority, and might have a begin range and end range, along with a set of servers. Rules are evaluated in priority order. A rule with a priority of 1 (lower number) is evaluated before a rule with a priority of 2 (higher number). The first rule that is satisfied will be used. When a rule has been satisfied, no further rules are evaluated. For a rule to be satisfied, it must meet two conditions:
  1. The predicate of the rule must be true. That is, the value it is evaluating must be between the begin and end ranges, or the content must match the regular expression that is specified in the rule's pattern. For rules of type "true," the predicate is always satisfied, regardless of the begin and end ranges. If a rule has no servers that are associated with it, the rule only needs to meet this first condition to be satisfied. In this case, Load Balancer will drop the connection request.
  2. If there are servers associated with the rule, at least one server must have a weight greater than 0 to forward packets so Load Balancer will have a server to which connections can be forwarded.
If a connection request does not satisfy any rules, Load Balancer will select a server from the full set of servers available on the port.

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Tuning Load Balancer
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Last updatedLast updated: Jun 20, 2011 4:04:37 PM EDT
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