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CHAPTER
12-1
Cisco NAC Guest Server Installation and Configuration Guide
OL-15986-01
12
Replication and High Availability
To provide high availability, the Cisco NAC Guest Server solution can be configured so that a pair of
units synchronize their databases between one another. This provides the ability for the solution to carry
on working in the event of loss of connectivity or failure to a single unit.
High availability is provided in an active/active scenario, where both Cisco NAC Guest Servers can
service requests from sponsors or network devices at the same time. This capability also allows you to
load balance the requests between the boxes.
Note For load balancing external load balancers must be used to load balance the web interface. RADIUS
requests can also be load balanced via external load balancers or by configuration.
This chapter includes the following sections:
• Setting up replication
• Configuring Provisioning
• Replication Status
• Recovering from Failures
• Deployment Considerations
Setting up replication
Initial replication is configured by setting one of the Cisco NAC Guest Servers to copy all of the data
from the other Guest Server. The Guest Server that is configured to copy the data from the other device
will be first set to delete all its own data. This ensures that no conflicts exist. Cisco recommends setting
up replication at initial install time of Cisco NAC Guest Server, or when adding a new Guest Server to
an existing implementation.
Warning
All Data on one of the Guest Servers will be overwritten. If you have data that is needed on both Guest
Servers then you should not configure replication as you will loose data.
Once one of the Guest Servers has received a copy of the data from the other device they are
synchronized and replication is turned on. Any data that is updated on one Guest Server is then
automatically replicated to the other Guest Server.
All communication between the Cisco NAC Guest Servers is encrypted using SSL and runs over TCP
destination port 5432.