Configuring RSVP and MPLS
The primary purpose of the Junos RSVP software is to support dynamic signaling within label-switched paths (LSPs). When you enable both MPLS and RSVP on a router, MPLS becomes a client of RSVP. No additional configuration is required to bind MPLS and RSVP.
You can configure MPLS to set up signaled paths by using the label-switched-path statement at the [edit protocols mpls] hierarchy level. Each LSP translates into a request for RSVP to initiate an RSVP session. This request is passed through the internal interface between label switching and RSVP. After examining the request information, checking RSVP states, and checking the local routing tables, RSVP initiates one session for each LSP. The session is sourced from the local router and is destined for the target of the LSP.
When an RSVP session is successfully created, the LSP is set up along the paths created by the RSVP session. If the RSVP session is unsuccessful, RSVP notifies MPLS of its status. It is up to MPLS to initiate backup paths or continue retrying the initial path.
To pass label-switching signaling information, RSVP supports four additional objects: Label Request object, Label object, Explicit Route object, and Record Route object. For an LSP to be set up successfully, all routers along the path must support MPLS, RSVP, and the four objects. Of the four objects, the Record Route object is not mandatory.
To configure MPLS and make it a client of RSVP, do the following:
- Enable MPLS on all routers that will participate in the label switching (this is, on all routers that might be part of a label-switching path).
- Enable RSVP on all routers and on all router interfaces that form the LSP.
- Configure the routers at the beginning of the LSP.
Example: Configuring RSVP and MPLS
The following shows a sample configuration for a router at the beginning of an LSP:
The following shows a sample configuration for all the other routers that form the LSP:
