Instruction manual

Chapter 3: High Availability
NetScaler 9000 Series Installation and Configuration Guide - Volume 1 3-1
NSICG60_JAN05
Chapter 3
High Availability
This chapter introduces you to the NetScaler 9000 system High availability
configuration setup. It also provides the steps to configure the NetScaler 9000
system in high availability mode.
Topics included are
z Overview
z Considerations for High Availability Setup
z Configuring two NetScaler 9000 systems in High Availability Mode
z Changing to a High Availability Configuration
z Verifying Configuration Propagation
z Force Failover of the Primary NetScaler 9000 System
z Forcing the Secondary Device to Stay Secondary
z Troubleshooting HA Issues
3.1 Overview
If the NetScaler 9000 system deployed in a stand alone mode stops
functioning due to unexpected network error then your network will be
unavailable to traffic till the network error is resolved. To avoid this problem
you can deploy two NetScaler 9000 systems in the network; on failure of one
system the other NetScaler 9000 system acts as a backup and keeps the
network alive for the traffic. This mode of having one NetScaler 9000 system
as a backup for the other is called the High Availability mode.
In this mode, one NetScaler 9000 system is configured as the Primary (active)
and the other is configured as Secondary (passive). The secondary NetScaler
9000 system sends periodic ‘hello’ messages to the primary NetScaler 9000
system to check whether it is operating. If the secondary does not receive a
reply, it sends successive “hello” messages. If there is no response for a