Editing Resource Reservation Protocol (section)

===Filterspec===
The ''filterspec'' defines the set of packets that shall be affected by a ''flowspec'' (i.e. the data packets to receive the QoS defined by the flowspec). A ''filterspec'' typically selects a subset of all the packets processed by a node. The selection can depend on any attribute of a packet (e.g. the sender IP address and port).

The currently defined RSVP reservation styles are:
#Fixed filter - reserves resources for a specific flow.
#Shared explicit - reserves resources for several flows and all share the resources
#Wildcard filter - reserves resources for a general type of flow without specifying the flow; all flows share the resources

An RSVP reservation request consists of a ''flowspec'' and a ''filterspec'' and the pair is called a ''flowdescriptor''. The ''flowspec'' sets the parameters of the packet scheduler at a node and the ''filterspec'' sets the parameters at the packet classifier.