NetScaler Application Delivery Management service

Configure agents for multisite deployment

Agents work as an intermediary between the NetScaler ADM and the discovered instances across different data centers and public clouds. NetScaler ADM supports agent failover within a data center or a public cloud.

The following are the benefits of installing agents:

  • The configured instances to an agent send the unprocessed data directly to the agent instead of NetScaler ADM. Agent does the first level of data processing and sends the processed data in compressed format to the NetScaler ADM for storage.

  • Agents and instances are co-located in the same data center or cloud so that the data processing is faster.

  • Clustering the agents provides redistribution of NetScaler instances on agent failover. When one agent in a site fails, traffic from NetScaler instances switches to another available agent in the same site.

Architecture

The following figure illustrates NetScaler instances configured on multiple agents in a data center and public cloud to achieve agent failover:

NetScaler ADM agents configured for multisite deployment

The public cloud has four ADC instances and two NetScaler ADM agents. The enterprise data center also have four ADC instances and two NetScaler ADM agents. Each agent is configured with two ADC instances.

The agents receive data directly from the configured instances. After agent receives the data, agent processes the data and sends to the NetScaler ADM in a compressed format. Agents communicate with the NetScaler ADM server over a secure channel.

On public cloud, when NetScaler ADM Agent 1 becomes inactive (DOWN state), agent failover occurs. NetScaler ADM redistributes the ADC instances of NetScaler ADM Agent 1 with NetScaler ADM Agent 2. The instance redistribution occurs on an enterprise data center if one of the agents fails in the data center.

To install a NetScaler ADM agent, see Install the NetScaler ADM Agent.

NetScaler ADM Agent failover

The agent failover can occur in a site that has two or more registered agents. When an agent becomes inactive (DOWN state) in the site, the NetScaler ADM redistributes the ADC instances of the inactive agent with other active agents.

Important

  • NetScaler ADM agent failover does not consider CPX instances.

  • Ensure Agent Failover feature is enabled on your account. To enable this feature, see Enable or disable NetScaler ADM features.

  • If an agent is running a script, ensure that script is present on all the agents in the site. Therefore, the changed agent can run the script after agent failover.

To attach a site to an agent in the NetScaler ADM GUI:

  1. Navigate to Infrastructure > Instances > Agents.

  2. Select an agent that you want to attach to a site.

  3. Specify the site from the list. If you want to add a new site, click Add.

  4. Click Save.

To achieve an agent failover, select NetScaler ADM agents one by one and attach to the same site.

For example, two agents 10.106.1xx.2x and 10.106.1xx.7x are attached and operational in the Bangalore site. If one agent becomes inactive, NetScaler ADM detects it and displays the state as down.

When a NetScaler ADM agent becomes inactive (Down state) in a site, NetScaler ADM waits for few minutes for the agent to become active (Up state). If the agent remains inactive, NetScaler ADM automatically redistributes the instances among available agents in the same site. This redistribution may take approximately 10-15 minutes.

NetScaler ADM triggers instance redistribution every 30 minutes to balance the load among active agents in the site.

The instances attached and automatically reconfigured to agents in the same site for trap destination, syslog server, and analytics.

Configure agents for multisite deployment