Editing Resource Reservation Protocol (section)

==Messages==
There are two primary types of messages:
*Path messages (''path'')
:The ''path'' message is sent from the sender host along the data path and stores the ''path state'' in each node along the path.
:The ''path state'' includes the IP address of the previous node, and some data objects:
::#''sender template'' to describe the format of the sender data in the form of a Filterspec<ref>{{cite IETF |rfc=2205 |date=September 1997 |url=https://tools.ietf.org/html/rfc2205#section-2 |page=19 |title=Resource ReSerVation Protocol (RSVP) -- Version 1 Functional Specification |first1=Zhang |last1=Lixia |first2=Berson |last2=Steve |first3=Herzog |last3=Shai |first4=Jamin |last4=Sugih}}</ref>
::#''sender tspec'' to describe the traffic characteristics of the data flow
::#''adspec'' that carries advertising data (see RFC 2210 for more details).
*Reservation messages (''resv'')
:The ''resv'' message is sent from the receiver to the sender host along the reverse data path. At each node the IP destination address of the ''resv'' message will change to the address of the next node on the reverse path and the IP source address to the address of the previous node address on the reverse path.
:The ''resv'' message includes the ''flowspec'' data object that identifies the resources that the flow needs.

The data objects on RSVP messages can be transmitted in any order. For the complete list of RSVP messages and data objects see RFC 2205.