MPLS-TP Shared-Ring Protection (MSRP) Mechanism for Ring Topology
RFC 8227
Internet Engineering Task Force (IETF) W. Cheng
Request for Comments: 8227 L. Wang
Category: Standards Track H. Li
ISSN: 2070-1721 China Mobile
H. van Helvoort
Hai Gaoming BV
J. Dong
Huawei Technologies
August 2017
MPLS-TP Shared-Ring Protection (MSRP) Mechanism for Ring Topology
Abstract
This document describes requirements, architecture, and solutions for
MPLS-TP Shared-Ring Protection (MSRP) in a ring topology for point-
to-point (P2P) services. The MSRP mechanism is described to meet the
ring protection requirements as described in RFC 5654. This document
defines the Ring Protection Switching (RPS) protocol that is used to
coordinate the protection behavior of the nodes on an MPLS ring.
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
http://www.rfc-editor.org/info/rfc8227.
Cheng, et al. Standards Track [Page 1]
RFC 8227 MSRP Protection Mechanism for Ring Topology August 2017
Copyright Notice
Copyright (c) 2017 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
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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.
Cheng, et al. Standards Track [Page 2]
RFC 8227 MSRP Protection Mechanism for Ring Topology August 2017
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 4
2. Terminology and Notation . . . . . . . . . . . . . . . . . . 4
3. MPLS-TP Ring Protection Criteria and Requirements . . . . . . 5
4. Shared-Ring Protection Architecture . . . . . . . . . . . . . 6
4.1. Ring Tunnel . . . . . . . . . . . . . . . . . . . . . . . 6
4.1.1. Establishment of the Ring Tunnel . . . . . . . . . . 8
4.1.2. Label Assignment and Distribution . . . . . . . . . . 9
4.1.3. Forwarding Operation . . . . . . . . . . . . . . . . 9
4.2. Failure Detection . . . . . . . . . . . . . . . . . . . . 10
4.3. Ring Protection . . . . . . . . . . . . . . . . . . . . . 11
4.3.1. Wrapping . . . . . . . . . . . . . . . . . . . . . . 12
4.3.2. Short-Wrapping . . . . . . . . . . . . . . . . . . . 14
4.3.3. Steering . . . . . . . . . . . . . . . . . . . . . . 17
4.4. Interconnected Ring Protection . . . . . . . . . . . . . 21
4.4.1. Interconnected Ring Topology . . . . . . . . . . . . 21
4.4.2. Interconnected Ring Protection Mechanisms . . . . . . 22
4.4.3. Ring Tunnels in Interconnected Rings . . . . . . . . 23
4.4.4. Interconnected Ring-Switching Procedure . . . . . . . 25
4.4.5. Interconnected Ring Detection Mechanism . . . . . . . 26
5. Ring Protection Coordination Protocol . . . . . . . . . . . . 27
5.1. RPS and PSC Comparison on Ring Topology . . . . . . . . . 27
5.2. RPS Protocol . . . . . . . . . . . . . . . . . . . . . . 28
5.2.1. Transmission and Acceptance of RPS Requests . . . . . 30
5.2.2. RPS Protocol Data Unit (PDU) Format . . . . . . . . . 31
5.2.3. Ring Node RPS States . . . . . . . . . . . . . . . . 32
5.2.4. RPS State Transitions . . . . . . . . . . . . . . . . 34
5.3. RPS State Machine . . . . . . . . . . . . . . . . . . . . 36
5.3.1. Switch Initiation Criteria . . . . . . . . . . . . . 36
5.3.2. Initial States . . . . . . . . . . . . . . . . . . . 39
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