Performance-Based Path Selection for Explicitly Routed Label Switched Paths (LSPs) Using TE Metric Extensions
RFC 7823

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Internet Engineering Task Force (IETF)                          A. Atlas
Request for Comments: 7823                                      J. Drake
Category: Informational                                 Juniper Networks
ISSN: 2070-1721                                             S. Giacalone
                                                               Microsoft
                                                              S. Previdi
                                                           Cisco Systems
                                                                May 2016

                  Performance-Based Path Selection for
Explicitly Routed Label Switched Paths (LSPs) Using TE Metric Extensions

Abstract

   In certain networks, it is critical to consider network performance
   criteria when selecting the path for an explicitly routed RSVP-TE
   Label Switched Path (LSP).  Such performance criteria can include
   latency, jitter, and loss or other indications such as the
   conformance to link performance objectives and non-RSVP TE traffic
   load.  This specification describes how a path computation function
   may use network performance data, such as is advertised via the OSPF
   and IS-IS TE metric extensions (defined outside the scope of this
   document) to perform such path selections.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Not all documents
   approved by the IESG are a candidate for any level of Internet
   Standard; see Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc7823.

Atlas, et al.                 Informational                     [Page 1]
RFC 7823        Path Selection with TE Metric Extensions        May 2016

Copyright Notice

   Copyright (c) 2016 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Basic Requirements  . . . . . . . . . . . . . . . . . . .   4
     1.2.  Oscillation and Stability Considerations  . . . . . . . .   4
   2.  Using Performance Data Constraints  . . . . . . . . . . . . .   5
     2.1.  End-to-End Constraints  . . . . . . . . . . . . . . . . .   5
     2.2.  Link Constraints  . . . . . . . . . . . . . . . . . . . .   6
     2.3.  Links out of Compliance with Link Performance Objectives    6
       2.3.1.  Use of Anomalous Links for New Paths  . . . . . . . .   7
       2.3.2.  Links Entering the Anomalous State  . . . . . . . . .   7
       2.3.3.  Links Leaving the Anomalous State . . . . . . . . . .   8
   3.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   4.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   8
     4.1.  Normative References  . . . . . . . . . . . . . . . . . .   8
     4.2.  Informative References  . . . . . . . . . . . . . . . . .   8
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .   9
   Contributors  . . . . . . . . . . . . . . . . . . . . . . . . . .  10
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

   In certain networks, such as financial information networks, network
   performance information is becoming as critical to data-path
   selection as other existing metrics.  Network performance information
   can be obtained via either the TE Metric Extensions in OSPF [RFC7471]
   or IS-IS [RFC7810] or via a management system.  As with other TE
   information flooded via OSPF or IS-IS, the TE metric extensions have
   a flooding scope limited to the local area or level.  This document
   describes how a path computation function, whether in an ingress LSR
   or a PCE [RFC4655], can use that information for path selection for
   explicitly routed LSPs.  The selected path may be signaled via RSVP-
   TE [RFC3209] [RFC3473] or simply used by the ingress with segment

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