NetScaler Console service

NetScaler agent behavior for Flexed or Pooled licensing

March 14, 2024

Contributed by:

R S C

The NetScaler agent works as an intermediary between NetScaler Console and the discovered instances across different data centers and public clouds. NetScaler Console service requires a minimum of one agent per tenant for Flexed or Pooled licensing to work. Multiple NetScaler agents can be deployed per site or multi-site, but only one agent can have the License Server Agent (LSA) role for the entire tenant deployment.

The following example shows two agents deployed and one of them has the LSA role:

Agent designated as LSA

An LSA is an agent that works as a license server in NetScaler Console service based pooled licensing deployment. If the LSA goes down, the service waits for 24 hours to elect a new LSA.

Until then, the NetScaler instances using pooled or flexed license go in grace period. As an administrator, you can also manually elect an LSA.

Manually select a NetScaler Console agent as LSA

Admins can manually select a NetScaler Console agent as the LSA for NetScaler Pooled licensing or NetScaler Flexed licensing. When the LSA is down, the NetScaler Console service waits for 24 hours before auto-electing the next LSA. The admin can manually elect the new LSA in the interim by using this feature. However, the admin must ensure that the status of the new LSA being elected is UP and its diagnostic status is OK.

When the admin manually selects a new LSA, it might take up to 5 minutes for the licensing functionality to work correctly. During this time, the NetScaler instances are in grace and any fresh checkout for a license fails.

To select an LSA:

Navigate to Infrastructure > Instances Dashboard > Agents and select an agent.
In the Select Action list, select Set as LSA.
Click Yes to confirm. The selected agent assumes the LSA role.

Multiple NetScaler agents behavior

In a deployment with a combination of multiple agents and multiple sites, the NetScaler agents follow the client/server architecture.

The first/oldest agent registered in an UP state is assigned the LSA role. Any other agents added later act as a proxy and communicate with the agent hosting the main LSA role for license allocation. Each agent hosting the proxy role communicates to the agent with the current LSA role through the NetScaler Console service.

LSA agent to non-LSA agent connectivity

Note

There is no direct communication between the agent holding the LSA role and the other (non-LSA) agents. All the connections go through the NetScaler Console service only.

NetScaler agent failover behavior

The agent failover works in a multi-agent deployment in the following way.

Assume that there are two agents, AG1 and AG2, in the same data center.

AG1 is configured to use ADC11, ADC12, ADC13 as the remote license host or LSA.
AG2 is configured to use ADC21, ADC22, ADC23 as the remote license host or LSA.
AG2 is acting as the license server.
- If AG1 fails, ADC11, ADC12, and ADC13 automatically connect through AG2 for license reconciliation.
  - ADC11, ADC12, and ADC13 might still notice a small period of grace if a few heartbeats are missed, while this reconnection happens.
- If AG2 fails, all ADCs continue to stay in grace until:
  - Either AG2 comes back up/is brought back up, or AG1 is selected as the new LSA either automatically after 24 hours by NetScaler Console service or manually by admin.
  - Or AG2 is deleted from the NetScaler Console service. Once deregistered, the NetScaler Console service designates AG1 as the agent with the LSA role.
  - After the election has completed, AG1 starts allocating and reconciling resources to the configured instances.

For questions related to LSA, see FAQs on License Server Agent.

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NetScaler agent behavior for Flexed or Pooled licensing

March 14, 2024

Contributed by:

R S C

March 14, 2024

Contributed by:

R S C

NetScaler agent behavior for Flexed or Pooled licensing

Manually select a NetScaler Console agent as LSA

Multiple NetScaler agents behavior

NetScaler agent failover behavior

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