RSVP-TE Scalability - Protocol Extension - Neighbor Compatibility

RSVP Traffic Engineering (TE) protocol extensions to support Refresh-interval Independent RSVP (RI-RSVP) defined in RFC 8370 for fast reroute (FRR) facility protection allows for greater scalability of label-switched paths (LSPs), faster convergence times, and decreased RSVP signaling message overhead from periodic refreshes. On Juniper devices, RSVP-TE runs in enhanced FRR mode, also known as RI-RSVP mode, by default, which includes protocol extensions to support RI-RSVP for FRR facility bypass originally specified in RFC 4090. The implemented RI-RSVP protocol extensions are fully backward compatible. In mixed environments, where a subset of LSPs traverse nodes that do not include this feature, RSVP-TE running in enhanced FRR mode automatically turns off the new protocol extensions in its signaling exchanges with nodes that do not support the new extensions. Specifically, this feature introduces following measures to determine whether the neighbor supports RI-RSVP extensions: * Previous Hop (PHOP), in case of link-protection (LP), or Previous-Previous Hop (PPHOP), in case of node-protection (NP), sets the "enhanced facility protection" flag in Record Route Object (RRO) carried in the Path message, and in Capability object in Hello message * Next Hop (NHOP), in case of LP, or Next-Next Hop (NNHOP), in case of NP, sets the "enhanced facility protection" flag in RRO carried in the Resv message, and in Capability object in Hello message