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Load balancing

100 bytes added, 09:39, 9 January 2014
Check and distribution methods
Traffic is distributed over the active hosts using one of the following methods. Persistence is sometimes provided by the distribution method, and otherwise (in case of for example least states) by the source tracking mechanism (if [[#Redirect sticky address|sticky address]] is enabled).
{| class="wikitable"
! Syntax !! Supported by !! Comment
|-
| <tt>loadbalance</tt>|| Relays || Source IP address of the client, and the IP address and port of the relay
|-
| <tt>source-hash</tt> || Relays || Source IP address of the client
|-
| <tt>hash</tt> || Relays || Input fed from the protocol specification, for example HTTP headers and GET variables
|-
| <tt>least-states</tt> || Redirections || The host with the fewest active connections (firewall states)
|-
| <tt>roundrobin</tt> || Relays, Redirections ||
|-
| <tt>random</tt> || Redirections ||
|}
 
=== Layer 3 (redirects) ===
Layer 3 load balancing is implemented as a firewall port forward, which is very efficient, and therefore gives layer 3 load balancing a performance advantage over layer 4+. Because of its implementation, it '''requires the firewall to be started''' (simply check if there are any firewall rules in the configuration). Also because if this, it's normally not necessary to add any additional firewall rules. Further, it's necessary that the load balancer is the default route (gateway) of the servers being load balanced, since the source packets of the incoming traffic is maintained. In order words, the topology would look something like:
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