Preferred Path Routing (PPR) Graphs - Beyond Signaling Of Paths To Networks

Preferred Path Routing (PPR) is an innovative architecture to signal explicit paths and per-hop processing including QoS from computation engines to network nodes leveraging distribution mechanisms of existing network routing protocols. PPR supports a wide range of existing forwarding planes including IP and Segment Routing. Through these mechanisms, PPR supports more lightweight, scalable and widely applicable support for high precision network services than prior signaling mechanisms including the ReSource ReserVation Protocol with Traffic Engineering (RSVP-TE). This paper describes the next fundamental step for the PPR architecture, with the signaling of PPR Graphs instead of only point to point PPR Paths. This extension provides better scalability and efficiency both for signaling, but even more so for the resulting forwarding and QoS processing entries created in network nodes. For any-to-any connectivity of N nodes, PPR Graphs can achieve the same O(N) scalability of forwarding entries as distributed routing protocols (IGPs), compared to O(N
₂
) in RSVP-TE or PPR point to point Paths. PPR Graphs therefore enable future networks to support high precision services much more broadly - independent of the chosen forwarding plane.