RSVP Session Overview

RSVP creates independent sessions to handle each data flow. It is important to note that each session is simplex, even though bidirectional messages (Path and Resv) create the simplex session. A session is identified by a combination of the destination address, an optional destination port, and a protocol. Within a session, there can be one or more senders. Each sender is identified by a combination of its source address and source port. Figure 7 shows a simplified overview of an RSVP point-to-point session. For information on point-to-multipoint LSPs, see the JUNOS MPLS Applications Configuration Guide.

Figure 7: RSVP Session

A typical RSVP session involves the following sequence of events:

• A potential sender (ingress router) starts sending RSVP Path messages to the session address (egress router).
• The receiver receives the Path messages.
• The receiver sends appropriate Resv messages toward the sender. These messages carry a flow descriptor, which is used by routers along the path to make reservations in their link-layer media.
• The sender receives the Resv message, then starts sending application data.