MACROMEDIA COLDFUSION MX-CLUSTERCATS Manuel d'utilisateur télécharger pdf (Page 48)

38 Chapter 3 Installing ClusterCATS

Round-robin DNS distributes the initial domain-level requests across all four servers.

Thereafter, ClusterCATS distributes load to avoid failed or overloaded servers.

Configuring server failover

ClusterCATS protects clusters from server hardware and software failures. When a server

is no longer sending or receiving packets from the network, its IP address (and, therefore,

its HTTP requests) are assumed by another cluster member, which picks up HTTP

traffic originally addressed to the failed server. Server failover services are provided per

subnet.

Server failover is an option to select during the installation process. If you do not do so,

you must reinstall ClusterCATS and select that option. On Windows systems, preparing

your site for ClusterCATS Server failover can require uninstalling your web server

software. For more information, see “Using server failover” on page 137.

Using ClusterCATS dynamic IP addressing

You can set up your website so ClusterCATS dynamically assigns IP addresses to your

web servers. This addressing scheme includes a static maintenance address for each server

that lets you and ClusterCATS contact the server at any time, even during a web server

failure.

The setup for ClusterCATS dynamic IP addressing varies depending on your cluster’s

operating system:

• Windows — If your IP address for the local system is the same as the IP of your web

server, setting up your site for ClusterCATS dynamic IP addressing can involve

reinstalling your web server software and resetting your TCP/IP settings. Consider

this carefully before installing ClusterCATS. For more information, see

“ClusterCATS dynamic IP addressing (Windows only)” on page 132.

• UNIX — It is not necessary to configure a UNIX system for dynamic IP addressing

because it is set up by default if you select that option during installation.

Configuring firewalls

Many corporate environments today rely on firewalls to securely control access to

proprietary knowledge that resides on public Internet sites, internal intranet sites, or

private extranet sites. You can configure ClusterCATS to work seamlessly across one or

more firewalls.

A common technique is to use NAT as a security precaution on your firewall. This

configuration segregates internal and external resources and facilitates extra control and

monitoring of web traffic. For more information, see Macromedia Knowledge Base

Article 15339.

If multiple, distributed server clusters support a domain, you must open appropriate

ports on each firewall to ensure that the server clusters’ load-balancing and failover

features work. For example, if you cluster multiple, distributed web servers that have a

firewall between them, you must open ports 9123 and 9129 on the firewall that separates

them to enable server-to-server communications. Also, if you will manage your cluster

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MACROMEDIA COLDFUSION MX-CLUSTERCATS Manuel d'utilisateur Page 48