Folks, I am starting some work on MPLS and I see that RSVP is enabled on backbone MPLS routers.
In the past I learned that the Diff Services advantage when compared to Int Services (i.e., RSVP) is that RSVP does allocate resources from end to end along all the network path it is supposed to traverse. For that reason Diff Services QoS mechanisms were preferable.
In a MPLS enabled backbone, what is the rationale to deploy RSVP (Int. Services) then?
In an MPLS network, the RSVP is used to set up MPLS-TE tunnels - more precisely, it is used to provide reservations for individual tunnels' bandwidth requirements, and it is also responsible for conveying the label bindings for a particular tunnel. If you do not use MPLS-TE, you do not need to run or enable the RSVP in your MPLS network. The RSVP here is not used for user's flows and reservations, rather only for traffic engineering purposes.