High Availability - HP 800 User Manual

High Availability and Load Balancing

High Availability

8-2
High Availability
High availability occurs when one or more Enforcement servers takes over
for an Enforcement server 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 console 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 Enforcement servers (ESs) form a network loop (an undesired
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