MID Server configuration for Service Mapping in upgraded deployments

  • Release version: Xanadu
  • Updated August 1, 2024
  • 2 minutes to read
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    Summary of MID Server configuration for Service Mapping in upgraded deployments

    In ServiceNow deployments upgraded from earlier versions to Istanbul, Service Mapping continues to use a legacy algorithm to select a MID Server for discovery requests. This selection process is based on specific criteria including the application assigned to the MID Server and IP address ranges. Understanding these criteria helps ensure proper configuration and optimal discovery performance in upgraded environments.

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    Key Features

    • Application Parameter: Determines which application the MID Server supports. It should be set to ServiceMapping to reserve the MID Server exclusively for Service Mapping discovery requests or to ALL to allow use by any ServiceNow application. Upgraded MID Servers previously configured via the Capability parameter have this automatically set to ServiceMapping.
    • IP Range: Limits the operational scope of the MID Server. Service Mapping selects MID Servers whose IP range encompasses the discovery request’s endpoint IP.
    • Default MID Server: You can designate one MID Server as the default to handle discovery requests when no matching IP range is found.
    • Legacy Selection Algorithm: Service Mapping first attempts to select a MID Server based on application and IP range. If no match is found, it uses the default MID Server or chooses a random MID Server if no default or IP range exists. Without a default MID Server or matching IP range, discovery cannot proceed.
    • New Selection Algorithm (Optional): Incorporates an additional capability parameter, considering network protocols for MID Server selection. This algorithm can be enabled in upgraded deployments if desired.

    Practical Implications for ServiceNow Customers

    • Verify and configure the application parameter on MID Servers to ensure they are correctly assigned for Service Mapping or other uses.
    • Define appropriate IP ranges for MID Servers to restrict their usage to relevant network segments, facilitating accurate MID Server selection.
    • Configure a default MID Server to ensure discovery requests are handled when no IP range matches exist.
    • Consider enabling the new MID Server selection algorithm to leverage enhanced selection capabilities based on network protocols, especially for complex network environments.
    • Understanding these configurations helps maintain discovery reliability and performance in upgraded ServiceNow deployments.

    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.