Automatic MID Server selection

  • Release version: Washingtondc
  • Updated February 1, 2024
  • 2 minutes to read
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    Summary of Automatic MID Server Selection

    Automatic MID Server selection allows agents to efficiently connect with the best available MID Server based on connectivity tests, ensuring optimal performance. This feature is disabled by default and requires careful consideration before implementation.

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    Key Features

    • Improved Efficiency: The agent tests connectivity to available MID Servers, selecting the one with the lowest latency and fewest connected agents.
    • Dynamic Updates: The configuration list for back-end URLs is kept current without additional workflows.
    • Fail-Over Mechanism: While it provides some load balancing, it primarily serves as a fail-over option rather than a true load balancer.
    • Security Considerations: Agents may attempt to connect to MID Servers in restricted areas, potentially triggering security alerts.
    • DNS Configuration: Proper DNS setup is crucial as it can affect connectivity, especially in environments with varying network contexts.

    Key Outcomes

    When automatic selection is enabled, agents receive regular updates from the ServiceNow instance, allowing them to maintain a list of primary and secondary MID Servers. This enhances fail-over protection and ensures seamless connectivity even if the agent's network environment changes. For secure communication, utilize the MID Server's unified key store.

    Automatic selection of MID Servers ensures that each agent uses the most efficient available MID Server.

    The Agent Client Collector automatic MID Server selection feature set is disabled by default. There are several factors to consider before determining if automatic MID Server selection is right for your use cases.

    Use case considerations

    Automatic MID Server selection provides several benefits. MID Server capabilities can narrow the list of MID Servers an agent can potential connect to. Automatic MID Server selection keeps the back-end URL configuration list up to date on the agent host without additional work flows.

    When automatic MID Server selection is enabled, the agent performs a connectivity test against the list of available MID Servers and determines the best connection based on latency and number of currently connected agents.

    However, there are several additional considerations that may make automatic MID Server selection wrong for your use case.

    The ACC automatic MID Server selection is not a true load balancer and should be considered a fail-over mechanism. There is higher complexity for choosing a back-end URL as it is derived from multiple input sources. If, instead, an application load balancer is used only one back-end URL needs to be specified. See Enable the Agent Client Collector load balancer for more information.

    By default, each agent is sent the list of all MID Servers listening for ACC connections. Since that list includes MID Servers running in restricted areas, the agents can try to connect to them which can generate security alerts.

    Your DNS configuration should be considered before using automatic MID Server selection because the resolution can lead to unexpected results. The DNS resolution is done periodically. End User Compute systems that alternate between internal corporate, Wi-Fi, VPN, or external networks may not be able to reconnect if the network context has changed.

    Automatic selection process

    When automatic selection is enabled, the ServiceNow instance sends periodic MID Server updates to existing agents. The agent selects a MID Server based on information it receives from the ServiceNow instance.

    During automatic MID Server selection, the agent selects a primary MID and a secondary MID list, and writes them to the agent’s config file. The agent uses this list for fail-over protection when the primary MID/secondary MID in the list loses connection.

    When an agent detects that its IP address has changed, it automatically connects with the most efficient MID Server available from the agent's list of MID Servers.

    To secure communication between the MID Server and the agent, use the MID Server's unified key store. For details on using the MID Server unified key store, see MID Server unified key store.