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High Availability and Load
8
Balancing
The following sections contain more information:
Section 8.1, "High Availability," on page 225
Section 8.2, "Load Balancing," on page 228
8.1 High Availability
High availability occurs when one or more ESs takes over for an ES that has become unavailable in
a multiple-server installation.
Once an ES becomes unavailable, the other ESs take over enforcement from the ES that is now
unavailable. All ESs participate in enforcement. The MS provides notification in the user interface
at the top of the Home window. For example, if an ES is unavailable, the notification indicates that
at the top of the Home window.
When Novell ZENworks Network Access Control is installed inline in a multiple-server
configuration
(Figure 8-1 on page
condition). The Spanning Tree Protocol (STP) detects the loop and closes one of the offending ports
on the switch based on the switch configuration. If an ES becomes unavailable, the switch
reconnects so that there is always a path from the VPN to an ES. All of the ES firewalls
continuously stay in sync with each other.
226), the multiple ESs form a network loop (an undesired
High Availability and Load Balancing
8
225
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