The Hierarchical Path Computation Element (H-PCE) architecture,
defined in the companion framework document [RFC6805], provides a
mechanism to allow the optimum sequence of domains to be selected,
and the optimum end-to-end path to be derived through the use of a
hierarchical relationship between domains.
This document defines the Path Computation Element Protocol (PCEP)
extensions for the purpose of implementing Hierarchical PCE
procedures which are described in the aforementioned document. These
extensions are experimental and published for examination,
discussion, implementation, and evaluation.