Administrator Guide

146 | Deploying W-ClearPass Clusters Dell Networking W-ClearPass Deployment Guide
Virtual IPAddress Considerations
Using a virtual IP address allows for the deployment of a highly available pair of servers. This reduces the
amount of down-time in the event of a server failure. If one of the servers in a high-availability pair fails, the
other server can take over the virtual IP address and continue providing service to clients. This is particularly
useful if the network access server (NAS) devices are processing basic RADIUS authentications to a CPPM node.
The Standby Publisher node cannot take over immediately as the failure may be transient and the minimum
time for a Standby Publisher to become active is about eight minutes. This duration is due to five attempts
(one per minute) to connect to the active Publisher’s database, then about four minutes for the node to
promote itself to an active state.
Thus, there will always be a delay before the virtual IP address on the transitioning active Publisher the NAS
clients are communicating with is back in service and able to process RADIUS authentication requests.
During this eight-minute window, requests from subscribers to write to the Publisher's database will fail as
there will be no Publisher available that can write to the database.
Functions Lost When the Publisher Is Down
When the active Publisher goes out of service, the following W-ClearPass Policy Manager functions are
temporarily lost:
l AirGroup and MACTrac enrollment
l Certificate creation and revocation
l Certificate revocation list updates
l W-ClearPass Exchange outbound enforcement
l General W-ClearPass Policy Manager and W-ClearPass Guest configuration changes
l W-ClearPass Guest account creation
l Mobile device management endpoint polling and ingestion
l Onboarding functionality
Adding a Subscriber Node to the Publisher
This section contains the following information:
l Introduction
l Using the WebUI to Add a Subscriber Node
l Using the CLIto Create a Subscriber Node
Introduction
In the Policy Manager cluster environment, the Publisher node acts as the cluster master. A Policy Manager
cluster can contain only one Publisher node. Administration, configuration, and database write operations can
occur only on the Publisher node.
The Policy Manager hardware or virtual appliance defaults to a Publisher node unless it is made a Subscriber
node. You can demote the Publisher to Subscriber status.
When the current node is a Subscriber, the Make Subscriber link isn't displayed.