Service types enable an application to specify service quality requirements for a QOS-enabled connection. The availability of different service types enables the RSVP SP to categorize the quality of service required by the application, and thereby decide the type of requests it (the RSVP SP) should make to complementary components on behalf of the requesting application.
There are four primary service types included in the RSVP SP. Applications must choose which service type is most appropriate for their transmission requirements, based on traffic characteristics, performance requirements, user preferences, or any other criterion that influences how data should be transmitted. Also note that when an application invokes the RSVP SP to initiate quality of service for a given connection, the ServiceType member of the FLOWSPEC structure (where the service type is specified) for both the SendingFlowspec and ReceivingFlowspec members of the QOS structure must be specified.
In addition to the primary service types, the RSVP SP provides secondary service types that enable application programmers and the RSVP SP to monitor or modify service provisions under certain circumstances, and on an ongoing basis.