IETF RFC 5711 PDF

Introduction

The aim of this document is to describe a common practice with regard to the behavior of a node sending a Resource Reservation Protocol (RSVP) Traffic Engineering (TE) Path Error message and to the behavior of a node receiving an RSVP Path Error message for a preempted Multiprotocol Label Switching (MPLS) and Generalized MPLS (GMPLS) Traffic Engineering Label Switched Path (TE LSP). (For reference to the notion of TE LSP preemption, see [RFC3209]).

[RFC2205] defines two RSVP error message types: PathErr and ResvErr that are generated when an error occurs. Path Error messages (PathErr) are used to report errors and travel upstream toward the head-end of the flow. Resv Error messages (ResvErr) travel downstream toward the tail-end of the flow.

This document describes only PathErr message processing for the specific case of a preempted TE LSP, where the term preemption is defined in [RFC3209].