---
sourceDocument: Yokohama IT Operations Management
sourceDocumentLink: https://servicenow-prod.fluidtopics.net/r/yokohama/it-operations-management

 Release :

    - yokohama

ft:locale :

    - en-US

ft:publication_title :

    - Yokohama IT Operations Management

ft:clusterId :

    - itom

bundleId :

    - itom

workflow :

    - Technology


---

# Choose MID Server selection algorithm

# Choose MID Server selection algorithm {#ariaid-title1}

* Release version: Yokohama
* 
* Updated January 30, 2025
* 
* ![](https://www.servicenow.com/docs/portal-asset/ico-clock) 1 minute to read

Service Mapping supports the new
and the legacy algorithms for selecting a MID Server for a discovery request.
Depending on your organization needs, you can choose which algorithm to enable.

## Before you begin

Role required: admin or service_mapping_admin

## About this task

Service Mapping selects a MID Server using the following algorithm:

* Service Mapping chooses the MID Server whose selection criteria best match the parameters of the discovery request.
* If there are no MID Servers with matching selection criteria, Service Mapping chooses the default MID Server.
* If there are no MID Servers with matching selection criteria or default MID Server, Service Mapping cannot start the discovery process.
{#choose-mid-selection-algorithm__ul_avl_fyp_gv}

By default, Service Mapping uses
this algorithm in all fresh installs and deployments upgraded from Istanbul or Jakarta.  
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.
{#choose-mid-selection-algorithm__ul_hfy_fns_xw}

By default, Service Mapping uses
the legacy algorithm in all deployments upgraded to Istanbul and earlier.

## Procedure

1. Navigate to Service MappingAdministrationProperties.
2. To enable the new algorithm for deployments upgraded to Istanbul and earlier:
   1. Clear the Enable Legacy MID selection algorithm check box.
   2. Click Save.
   3. Configure MID Server selection criteria as described in [MID Server configuration for Service Mapping](https://servicenow-prod.fluidtopics.net/zWlPCWfb7dE865TT7wtHHA "Configure Service Mapping and MID Servers to work together.").
   {#choose-mid-selection-algorithm__substeps_rlk_rxm_1x}
3. To enable the legacy algorithm for the Yokohama deployment:
   1. Select the Enable Legacy MID selection algorithm check box.
   2. Click Save.
   3. Configure MID Server selection criteria as described in [MID Server configuration for Service Mapping in upgraded deployments](https://servicenow-prod.fluidtopics.net/CRNh9QNlXwLT0rTy6hA6Rg "For ServiceNow deployments upgraded from earlier versions to Istanbul, Service Mapping uses the legacy algorithm to choose a MID Server for a discovery request.").
   {#choose-mid-selection-algorithm__substeps_jlk_zxm_1x}

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