MID Server configuration for Service Mapping in upgraded deployments

  • Release version: Zurich
  • Updated July 31, 2025
  • 2 minutes to read
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    Summary of MID Server configuration for Service Mapping in upgraded deployments

    When upgrading ServiceNow deployments to the Istanbul release, Service Mapping continues to use a legacy algorithm to select MID Servers for discovery requests. Proper MID Server configuration is essential to ensure Service Mapping operates efficiently and discovery processes succeed.

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    Key Features

    • Application Parameter: Determines which application the MID Server supports. Setting it to ServiceMapping reserves it exclusively for Service Mapping discovery requests, whereas ALL allows any ServiceNow application to utilize the MID Server. During upgrades, existing MID Servers configured with the legacy Capability parameter are automatically updated to have their application parameter set to ServiceMapping.
    • IP Range: Restricts the MID Server’s operational scope to a specific IP address range. Service Mapping only selects MID Servers whose IP range includes the discovery request’s endpoint.
    • Default MID Server: You can configure one MID Server as the default to handle discovery requests that do not match any MID Server’s IP range.

    MID Server Selection Algorithm in Upgraded Deployments

    • Service Mapping first attempts to select a MID Server with an application parameter set to ServiceMapping or ALL.
    • It then prefers MID Servers whose IP range matches the discovery request’s IP.
    • If no matching IP range is found, the default MID Server is assigned.
    • If there is no default MID Server and no IP range matches, Service Mapping either selects a random MID Server or cannot start discovery if no IP ranges are configured.
    • The legacy algorithm does not consider the network protocol.

    New MID Server Selection Algorithm

    A new selection algorithm is available that adds capability as a criterion, allowing Service Mapping to consider network protocols when choosing a MID Server. Although the legacy algorithm remains the default for upgraded deployments, you can enable the new algorithm if needed to improve MID Server selection.

    Practical Implications for ServiceNow Customers

    • Review and adjust the application and IP range parameters on your MID Servers after upgrading to Istanbul to ensure Service Mapping selects the appropriate MID Servers for discovery.
    • Configure a default MID Server to handle discovery requests outside configured IP ranges and avoid discovery failures.
    • Consider enabling the new MID Server selection algorithm if your environment benefits from capability-based selection, especially for network protocol considerations.

    For ServiceNow deployments upgraded from earlier versions to Istanbul, Service Mapping uses the legacy algorithm to choose a MID Server for a discovery request.

    MID Servers have the following selection criteria that Service Mapping in upgraded deployments uses to choose a MID Server for a discovery request:
    • Application — defines what application a MID Server works with. Set it to Service Mapping to reserve this MID Server exclusively to Service Mapping discovery requests. Alternatively, set it to ALL to allow any ServiceNow application to use this MID Server.

      In earlier releases, you could configure MID Servers to work only with Service Mapping by using the Capability parameter. If you had MID Servers with this configuration, during the upgrade to Istanbul the application parameter is automatically set to ServiceMapping for them.

    • IP range — limits operation of this MID Server to this IP range. Service Mapping does not choose this MID Server for a discovery request whose endpoint is outside this IP range.

    In addition to the IP range, you can configure one of the MID Servers as the default server that Service Mapping uses. For operational information, see Configure a default MID Server for Service Mapping for upgraded deployments.

    In upgraded deployments, Service Mapping selects a MID Server using a legacy algorithm:
    • Service Mapping chooses the MID Server whose application criteria is set to ServiceMapping or to ALL.
    • By default, Service Mapping selects the MID Server whose IP range matches the IP in the discovery request.
    • If Service Mapping cannot find a MID Server with the matching IP range and matching application, it assigns the discovery request to the default MID Server.
    • If there is no default MID Server and none of the MID Servers have IP ranges configured for them, Service Mapping uses a random MID Server.
    • If there is no default MID Server and no IP range matches the IP in the discovery request, Service Mapping cannot start the discovery process.

    The new algorithm for selecting MID Servers uses an extra selection criteria: capability. It allows Service Mapping to take a network protocol into consideration. For information about updated selection criteria and the new MID Server selection algorithm, see Choose MID Server selection algorithm.

    While by default Service Mapping uses the legacy algorithm in upgraded deployments, it can support both new and legacy algorithms for selecting a MID Server. If necessary, you can enable the new MID Server selection algorithm for your upgraded deployment. For more information, see Choose MID Server selection algorithm.