High Availability - HP ProCurve NAC 800 User Manual

High Availability and Load Balancing

High Availability

8-2
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 NAC 800 is installed inline in a multiple-server configuration (figure 8-
1), the multiple ESs form a network loop (an undesired condition). The
Spanning Tree Protocol (STP) detects the loop and closes one of the offending