About Multicast Communication
In a multiple-server enterprise, Netscape Application Servers communicate with each other, for purposes of load balancing and administration, using a multicast wide area network (WAN) service. The multicast service provides a virtual server to which all messages can be posted and distributed. The Netscape Application Servers use a N-Way multicast configuration that allows each server to send or receive the broadcast information. The following illustration depicts how this network looks:
Multicast services are handled by the network hardware for all servers within a local area network (LAN). For these servers, you do not have to register or change the default multicast address. When you are implementing an enterprise in a wide area network, you should use a publicly registered multicast address that allows only your Netscape Application Servers to communicate with each other.
How Multicast Services Apply to Administration
For administration purposes, all Administrative Server processes within each server in the enterprise should use the same multicast address. This allows you to administer each server in the enterprise from one location.
In addition, once servers are registered, they are dynamically added and removed from the enterprise view. For example, if a server is brought down locally, you, as the remote administrator, can see that it is not currently part of the enterprise view. When the server comes back up, it is returned to the enterprise view automatically. You do not have to register it again.
For information about changing the administrative multicast address, see "Changing the Administrative Multicast Address."
How Multicast Services Apply to Load Balancing
For load balancing, you can have all servers communicate with each other, or you can create islands of servers that only balance application loads between themselves. For example, an application in New York does not need to load balance with the same application in Los Angeles. However, an application in Newton, Brighton, and downtown Boston probably would share load responsibilities for all the users in the Boston area.
For load balancing, multicast communication is determined by the Executive Server multicast address.
For information about changing the load balancing multicast address, see "Changing the Multicast Host Address for Load Balancing."
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