IETF RFC 8149 PDF

The reoptimization of a Point-to-Multipoint (P2MP) Traffic Engineering (TE) Label Switched Path (LSP) may be triggered based on the need to reoptimize an individual source-to-leaf (S2L) sub-LSP or a set of S2L sub-LSPs, both using the Sub-Group-based reoptimization method, or the entire P2MP-TE LSP tree using the Make-Before-Break (MBB) method. This document discusses the application of the existing mechanisms for path reoptimization of loosely routed Pointto- Point (P2P) TE LSPs to the P2MP-TE LSPs, identifies issues in doing so, and defines procedures to address them. When reoptimizing a large number of S2L sub-LSPs in a tree using the Sub-Group-based reoptimization method, the S2L sub-LSP descriptor list may need to be semantically fragmented. This document defines the notion of a fragment identifier to help recipient nodes unambiguously reconstruct the fragmented S2L sub-LSP descriptor list.