Signaling RSVP-TE tunnels on a shared MPLS forwarding plane
draft-ietf-mpls-rsvp-shared-labels-02
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MPLS Working Group H. Sitaraman
Internet-Draft V. Beeram
Intended status: Standards Track Juniper Networks
Expires: December 30, 2018 T. Parikh
Verizon
T. Saad
Cisco Systems
June 28, 2018
Signaling RSVP-TE tunnels on a shared MPLS forwarding plane
draft-ietf-mpls-rsvp-shared-labels-02.txt
Abstract
As the scale of MPLS RSVP-TE networks has grown, so 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 control plane state.
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. That is, it allows many more LSPs to be
supported than there are forwarding plane labels available.
This work introduces the notion of pre-installed 'per Traffic
Engineering (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 MPLS forwarding plane.
This document also introduces the ability to mix different types of
label operations along the path of an LSP, thereby allowing the
ingress router or an external controller to influence how to
optimally place a LSP in the network.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
Sitaraman, et al. Expires December 30, 2018 [Page 1]
Internet-Draft RSVP-TE Shared Labels June 2018
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on December 30, 2018.
Copyright Notice
Copyright (c) 2018 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
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.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Allocation of TE Link Labels . . . . . . . . . . . . . . . . 5
4. Segment Routed RSVP-TE Tunnel Setup . . . . . . . . . . . . . 5
5. Delegating Label Stack Imposition . . . . . . . . . . . . . . 7
5.1. Stacking at the Ingress . . . . . . . . . . . . . . . . . 8
5.1.1. Stack to Reach Delegation Hop . . . . . . . . . . . . 8
5.1.2. Stack to Reach Egress . . . . . . . . . . . . . . . . 9
5.2. Explicit Delegation . . . . . . . . . . . . . . . . . . . 10
5.3. Automatic Delegation . . . . . . . . . . . . . . . . . . 10
5.3.1. Effective Transport Label-Stack Depth (ETLD) . . . . 11
Sitaraman, et al. Expires December 30, 2018 [Page 2]
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