CSM provides two types of SLA models: Time-Based Model and Hierarchy-Based Model.
Changing the SLA model only affects Incidents and Service Requests created after the model is selected, so we recommend choosing a model during initial implementation.
In OOTB content, SLAs select based on the Time-Based Model, which takes the soonest deadline for any SLAs associated to the ticket.
If you use the Time-Based model, CSM calculates, in real time, which SLA results in the earliest resolution deadline and uses that in the event there are multiple SLAs present. The shortest SLA is then applied to the resolution and response deadlines.
In the event of multiple SLAs, CSM chooses the SLA type that is highest in the following hierarchy (provided the necessary overrides are in place):
- Config Item: SLAs for Configuration Items (CIs), typically based on criticality (example: Primary Server). A Config Item SLA overrides every other SLA.
- Service: SLAs for a Service, typically based on criticality (example: Email service is really important). A Service SLA overrides a Customer and Corporate SLA. Not many Services require a special SLA. In the OOTB system, only Desktop Management and E-mail Calendaring have their own SLAs.
- Customer: SLAs for customer levels, typically based on employee status (Platinum, Gold, Silver, Bronze). A Customer SLA overrides a Corporate SLA.
- Corporate (default): Default SLA. Many organizations use only this SLA type.
See SLA and Priority for Response/Resolve Target Times by Work Hours and Priority.