An Architecture for IP/LDP Fast Reroute Using Maximally Redundant Trees (MRT-FRR)
RFC 7812
Internet Engineering Task Force (IETF) A. Atlas
Request for Comments: 7812 C. Bowers
Category: Standards Track Juniper Networks
ISSN: 2070-1721 G. Enyedi
Ericsson
June 2016
An Architecture for IP/LDP Fast Reroute
Using Maximally Redundant Trees (MRT-FRR)
Abstract
This document defines the architecture for IP and LDP Fast Reroute
using Maximally Redundant Trees (MRT-FRR). MRT-FRR is a technology
that gives link-protection and node-protection with 100% coverage in
any network topology that is still connected after the failure.
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/rfc7812.
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
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Atlas, et al. Standards Track [Page 1]
RFC 7812 MRT Unicast FRR Architecture June 2016
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Importance of 100% Coverage . . . . . . . . . . . . . . . 4
1.2. Partial Deployment and Backwards Compatibility . . . . . 5
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 5
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
4. Maximally Redundant Trees (MRT) . . . . . . . . . . . . . . . 7
5. MRT and Fast Reroute . . . . . . . . . . . . . . . . . . . . 9
6. Unicast Forwarding with MRT Fast Reroute . . . . . . . . . . 9
6.1. Introduction to MRT Forwarding Options . . . . . . . . . 10
6.1.1. MRT LDP Labels . . . . . . . . . . . . . . . . . . . 10
6.1.1.1. Topology-Scoped FEC Encoded Using a Single Label
(Option 1A) . . . . . . . . . . . . . . . . . . . 10
6.1.1.2. Topology and FEC Encoded Using a Two-Label Stack
(Option 1B) . . . . . . . . . . . . . . . . . . . 11
6.1.1.3. Compatibility of MRT LDP Label Options 1A and 1B 12
6.1.1.4. Required Support for MRT LDP Label Options . . . 12
6.1.2. MRT IP Tunnels (Options 2A and 2B) . . . . . . . . . 12
6.2. Forwarding LDP Unicast Traffic over MRT Paths . . . . . . 13
6.2.1. Forwarding LDP Traffic Using MRT LDP Label Option 1A 13
6.2.2. Forwarding LDP Traffic Using MRT LDP Label Option 1B 14
6.2.3. Other Considerations for Forwarding LDP Traffic Using
MRT LDP Labels . . . . . . . . . . . . . . . . . . . 14
6.2.4. Required Support for LDP Traffic . . . . . . . . . . 14
6.3. Forwarding IP Unicast Traffic over MRT Paths . . . . . . 14
6.3.1. Tunneling IP Traffic Using MRT LDP Labels . . . . . . 15
6.3.1.1. Tunneling IP Traffic Using MRT LDP Label Option
1A . . . . . . . . . . . . . . . . . . . . . . . 15
6.3.1.2. Tunneling IP Traffic Using MRT LDP Label Option
1B . . . . . . . . . . . . . . . . . . . . . . . 15
6.3.2. Tunneling IP Traffic Using MRT IP Tunnels . . . . . . 16
6.3.3. Required Support for IP Traffic . . . . . . . . . . . 16
7. MRT Island Formation . . . . . . . . . . . . . . . . . . . . 16
7.1. IGP Area or Level . . . . . . . . . . . . . . . . . . . . 17
7.2. Support for a Specific MRT Profile . . . . . . . . . . . 17
7.3. Excluding Additional Routers and Interfaces from the MRT
Island . . . . . . . . . . . . . . . . . . . . . . . . . 18
7.3.1. Existing IGP Exclusion Mechanisms . . . . . . . . . . 18
7.3.2. MRT-Specific Exclusion Mechanism . . . . . . . . . . 19
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