Signaling RSVP-TE Tunnels on a Shared MPLS Forwarding Plane
RFC 8577

Document Type RFC - Proposed Standard (April 2019; No errata)
Last updated 2019-04-30
Replaces draft-sitaraman-mpls-rsvp-shared-labels
Stream IETF
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Stream WG state Submitted to IESG for Publication
Document shepherd Loa Andersson
Shepherd write-up Show (last changed 2018-11-05)
IESG IESG state RFC 8577 (Proposed Standard)
Consensus Boilerplate Yes
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Responsible AD Deborah Brungard
Send notices to Loa Andersson <loa@pi.nu>
IANA IANA review state Version Changed - Review Needed
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Internet Engineering Task Force (IETF)                      H. Sitaraman
Request for Comments: 8577                                     V. Beeram
Category: Standards Track                               Juniper Networks
ISSN: 2070-1721                                                T. Parikh
                                                                 Verizon
                                                                 T. Saad
                                                           Cisco Systems
                                                              April 2019

      Signaling RSVP-TE Tunnels on a Shared MPLS Forwarding Plane

Abstract

   As the scale of MPLS RSVP-TE networks has grown, the number of Label
   Switched Paths (LSPs) supported by individual network elements has
   increased.  Various implementation recommendations have been proposed
   to manage the resulting increase in the amount of control-plane state
   information.

   However, those changes have had no effect on the number of labels
   that a transit Label Switching Router (LSR) has to support in the
   forwarding plane.  That number is governed by the number of LSPs
   transiting or terminated at the LSR and is directly related to the
   total LSP state in the control plane.

   This document defines a mechanism to prevent the maximum size of the
   label space limit on an LSR from being a constraint to control-plane
   scaling on that node.  It introduces the notion of preinstalled
   'per-TE link labels' that can be shared by MPLS RSVP-TE LSPs that
   traverse these TE links.  This approach significantly reduces the
   forwarding-plane state required to support a large number of LSPs.
   This couples the feature benefits of the RSVP-TE control plane with
   the simplicity of the Segment Routing (SR) MPLS forwarding plane.

Status of This Memo

   This is an Internet Standards Track document.

   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).  Further information on
   Internet Standards is available in Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc8577.

Sitaraman, et al.            Standards Track                    [Page 1]
RFC 8577                  RSVP-TE Shared Labels               April 2019

Copyright Notice

   Copyright (c) 2019 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
   (https://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
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Sitaraman, et al.            Standards Track                    [Page 2]
RFC 8577                  RSVP-TE Shared Labels               April 2019

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   4
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   5
     2.1.  Requirements Language . . . . . . . . . . . . . . . . . .   6
   3.  Allocation of TE Link Labels  . . . . . . . . . . . . . . . .   6
   4.  Segment Routed RSVP-TE Tunnel Setup . . . . . . . . . . . . .   6
   5.  Delegating Label Stack Imposition . . . . . . . . . . . . . .   8
     5.1.  Stacking at the Ingress . . . . . . . . . . . . . . . . .   8
       5.1.1.  Stack to Reach Delegation Hop . . . . . . . . . . . .   9
       5.1.2.  Stack to Reach Egress . . . . . . . . . . . . . . . .  10
     5.2.  Explicit Delegation . . . . . . . . . . . . . . . . . . .  11
     5.3.  Automatic Delegation  . . . . . . . . . . . . . . . . . .  11
       5.3.1.  Effective Transport Label-Stack Depth (ETLD)  . . . .  11
   6.  Mixing TE Link Labels and Regular Labels in an RSVP-TE Tunnel  13
   7.  Construction of Label Stacks  . . . . . . . . . . . . . . . .  14
   8.  Facility Backup Protection  . . . . . . . . . . . . . . . . .  14
     8.1.  Link Protection . . . . . . . . . . . . . . . . . . . . .  14
   9.  Protocol Extensions . . . . . . . . . . . . . . . . . . . . .  15
     9.1.  Requirements  . . . . . . . . . . . . . . . . . . . . . .  15
     9.2.  Attribute Flags TLV: TE Link Label  . . . . . . . . . . .  16
     9.3.  RRO Label Sub-object Flag: TE Link Label  . . . . . . . .  16
     9.4.  Attribute Flags TLV: LSI-D  . . . . . . . . . . . . . . .  16
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