The HRN uses Query messages to request a price quotation from the NRN for one or more services, for a flow or group of flows belonging to the customer. The message consists of a set of Flow Ids, and one or more service fields accompanying each Flow Id. The HRN specifies a set of requirements (such as service time and QoS) with each service, by setting appropriate service sub-fields. When the HRN sends a Query for the first time, the NRN also sets up state information for a new RNAP session.
Upon receiving a Query message, the NRN determines the price for each service for which quotations were requested, and returns a list of Service and Price pairs inside a Quotation message. When a Query message has null Service list, the NRN returns quotations for all available services using default values of unspecified service parameters; it does not return quotations for services which have one or more mandatory parameters to be specified by the customer. In addition to asynchronously sending Quotation messages, the NRN also sends out Quotation messages periodically. A Quotation message sent periodically contains price quotations for all services requested by the customer.
The HRN sends a Reserve message to apply for services with specified service parameters for a flow or group of flow. A Reserve message is sent at the beginning of a session to request services for the first time, and thereafter, periodically at Negotiation Intervals, and also asynchronously at any time. In general, each Reserve message carries one or more Flow Id-Service-Price triples.
The Commit message is generated by the NRN in response to a Reserve message, and consist of a set of Flow Id, Service, Status and Price 4-tuples. The reservation request indicates the desired and minimum acceptable QoS. The Reserve message keeps track of the currently allocated resources, which fall within that range. For each Flow Id , the NRN determines the admissibility of the flow, and returns this information in the Status field, as Admit_Complete, Admit_Incomplete or Reject. The admission policy is specific to the service, and need not be administered by the NRN. The Status is Admit_Incomplete if network resources are scarce and the provider admits the service request with a lower QoS or sending rate than requested. If the flows are admitted, the NRN returns the price for providing the service in the Price field (normally the same as the price quoted in the preceding Quotation message). If the Commit is in response to a re-negotiation Reserve request in an ongoing session, the NRN also returns the amount charged for each service in the preceding negotiation period, and the accumulated charge since the beginning of the session.
If a Service is set as preemptable, the NRN may send a Preempt message to the HRN to unilaterally change the service parameters or price, or even terminate the service, at any time during a Negotiation Interval. This allows the provider to make room for other more important flows urgently, without waiting for the end of a Negotiation Interval. A preemptable service would be expected to cost less than an equivalent non-preemptable service.
Close and Release:
A Close message is sent from the HRN to the NRN to signal the end of an RNAP session. The NRN sends a Release message in acknowledgment.

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Next: RNAP Messaging Scenarios Up: Protocol Messages and Message Previous: Message Fields
Xin Wang