No Further Fast Reroute
draft-kompella-mpls-nffrr-01
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Active Internet-Draft (individual)
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Kireeti Kompella
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Wen Lin
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2020-11-02
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MPLS WG K. Kompella
Internet-Draft W. Lin
Intended status: Standards Track Juniper Networks
Expires: May 6, 2021 November 02, 2020
No Further Fast Reroute
draft-kompella-mpls-nffrr-01
Abstract
There are several cases where, once Fast Reroute has taken place (for
MPLS protection), a second fast reroute is undesirable, even
detrimental. This memo gives several examples of this, and proposes
a mechanism to prevent further fast reroutes.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on May 6, 2021.
Copyright Notice
Copyright (c) 2020 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
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Kompella & Lin Expires May 6, 2021 [Page 1]
Internet-Draft NFFRR November 2020
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Other Approaches . . . . . . . . . . . . . . . . . . . . 3
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. EVPN (VPN/VPLS) Active-active Multihoming . . . . . . . . 3
2.2. RMR Protection . . . . . . . . . . . . . . . . . . . . . 4
2.3. General MPLS forwarding . . . . . . . . . . . . . . . . . 5
3. Solution . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.1. NFFRR for MPLS forwarding . . . . . . . . . . . . . . . . 6
3.2. Proposal . . . . . . . . . . . . . . . . . . . . . . . . 8
3.2.1. NFFRR and SPRING . . . . . . . . . . . . . . . . . . 10
3.3. NFFRR for MPLS Services . . . . . . . . . . . . . . . . . 10
3.4. NFFRR for RMR . . . . . . . . . . . . . . . . . . . . . . 11
4. Signaling NFFRR Capability . . . . . . . . . . . . . . . . . 12
4.1. Signaling NFFRR Capability for MPLS Services with BGP . . 12
4.2. Signaling NFFRR Capability for MPLS Services with
Targeted LDP . . . . . . . . . . . . . . . . . . . . . . 12
4.3. Signaling NFFRR Capability for MPLS Forwarding . . . . . 12
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
6. Security Considerations . . . . . . . . . . . . . . . . . . . 13
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
7.1. Normative References . . . . . . . . . . . . . . . . . . 13
7.2. Informative References . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15
1. Introduction
MPLS Fast Reroute (FRR) [RFC4090] [RFC5286] [RFC7490] is a useful and
widely deployed tool for minimizing packet loss in the case of a link
or node failure. This has not only proven to be very effective, it
is often the reason for using MPLS as a data plane. FRR works for a
variety of control plane protocols, including LDP, RSVP-TE, and
SPRING. Furthermore, FRR is often used to protect MPLS services such
as IP VPN and EVPN.
Having said this, there are case where, once FRR has taken place, if
the packet encounters a second failure, a second FRR is not helpful,
perhaps even disruptive. For example, the packet may loop until TTL
expires. This can lead to link congestion and further packet loss.
Thus, the attempt to prevent a packet from being dropped may instead
affect many other packets. Note that the "second" failure may simply
be another manifestation of the same failure; see Figure 1.
This memo proposes a mechanism for preventing further FRR once in
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