Intergraph WebScale User Manual page 34

WebScale™
port's network traffic is handled is called its filtering mode. There are three possible
filtering modes:
Multiple hosts filtering mode. This mode lets WebScale automatically distribute
the port's network traffic to multiple hosts within the cluster according to a load
percentage that you specify. This balances the network load among the hosts
within the cluster and scales the performance of your Internet server application.
Network traffic is distributed among the hosts on a per-connection basis for TCP
(or a per-datagram basis for UDP), where the combination of source and
destination IP address and port numbers determines a unique client request. If
the host fails, WebScale automatically re-distributes network traffic among the
surviving hosts.
You can control the precise load balancing behavior of this filtering mode by
indicating that all hosts should maintain an equal load distribution or by setting
the load percentage for each host. When you specify load percentages, WebScale
adds up the load percentages for all participating cluster hosts and directs the
proportional amounts to each host; the total load percentage for the cluster need
not add up to 100 percent. For example, if the cluster has two hosts with load
percentages of 30 and 60 percent, WebScale will direct one-third (30/90) of the
traffic to one host and two-thirds (60/90) to the other.
In addition, you can select one of three options for client affinity. This is used in
handling client sessions to ensure that all network traffic from a particular client
be directed to the same cluster host. When you select None, WebScale load
balances all network requests across the cluster without respect to their source to
maximize the scaled performance achieved by load balancing. You can select
Single affinity to direct all client requests from the same IP address to the same
cluster host. You can also select Class C affinity to direct all client requests from
the same Class C address range to the same cluster host. Increased affinity
enhances the cluster's ability to support client sessions, although it may
somewhat reduce scaled performance.
Single host filtering mode. This mode directs all of the port's network traffic to
the host with the highest handling priority. In this mode, you specify a set of
priorities for handling the port's network traffic in the event of a host failure.
This lets you assign the network traffic for different host ports to different servers
in the cluster and customize the failover policy for each port.
Disabled filtering mode. This mode blocks all traffic to a port to provide a
firewall against unwanted network access to your cluster.
For your convenience, you can specify that a filtering mode apply to a numerical range
of ports. You do this by defining a port rule with a set of configuration parameters that
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User's Guide