Connected: An Internet Encyclopedia
3.1.4 Resv Messages

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3.1.4 Resv Messages

3.1.4 Resv Messages

Resv messages carry reservation requests hop-by-hop from receivers to senders, along the reverse paths of data flows for the session. The IP destination address of a Resv message is the unicast address of a previous-hop node, obtained from the path state. The IP source address is an address of the node that sent the message. The Resv message format is as follows:

           <Resv Message> ::= <Common Header> [ <INTEGRITY> ]

                                   <SESSION>  <RSVP_HOP>


                                   [ <RESV_CONFIRM> ]  [ <SCOPE> ]

                                   [ <POLICY_DATA> ... ]

                                   <STYLE> <flow descriptor list>

           <flow descriptor list> ::=  <empty> |

                            <flow descriptor list> <flow descriptor>

If the INTEGRITY object is present, it must immediately follow the common header. The STYLE object followed by the flow descriptor list must occur at the end of the message, and objects within the flow descriptor list must follow the BNF given below. There are no other requirements on transmission order, although the above order is recommended.

The NHOP (i.e., the RSVP_HOP) object contains the IP address of the interface through which the Resv message was sent and the LIH for the logical interface on which the reservation is required.

The appearance of a RESV_CONFIRM object signals a request for a reservation confirmation and carries the IP address of the receiver to which the ResvConf should be sent. Any number of POLICY_DATA objects may appear.

The BNF above defines a flow descriptor list as simply a list of flow descriptors. The following style-dependent rules specify in more detail the composition of a valid flow descriptor list for each of the reservation styles.

The reservation scope, i.e., the set of senders towards which a particular reservation is to be forwarded (after merging), is determined as follows:

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Connected: An Internet Encyclopedia
3.1.4 Resv Messages