Bidirectional Forwarding Detection (BFD) for EVPN Ethernet Segment Failover Use Case
draft-zwm-bess-es-failover-00

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BESS WG                                                         Z. Zhang
Internet-Draft                                                   Y. Wang
Intended status: Standards Track                               G. Mirsky
Expires: September 6, 2019                               ZTE Corporation
                                                           March 5, 2019

   Bidirectional Forwarding Detection (BFD) for EVPN Ethernet Segment
                           Failover Use Case
                   draft-zwm-bess-es-failover-00.txt

Abstract

   This document introduces a method for fast switchover of Designated
   Forwarder for Ethernet Segment failover by using Bidirectional
   Forwarding Detection protocol.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
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   This Internet-Draft will expire on September 6, 2019.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Proposal  . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Specification . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   6.  Normative References  . . . . . . . . . . . . . . . . . . . .   4
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   4

1.  Introduction

   [RFC7432] introduces Ethernet Virtual Private Network (EVPN)
   technology.  Designated Forwarder (DF) election procedures for multi-
   homing Ethernet Segments has been described in it.  When PE (provider
   edge) receives BUM (Broadcast, Unknown Unicast and Multicast) flows,
   only DF forwards the BUM flows to CE (customer edge).  Non-DFs do not
   forward the BUM flows in order to avoid duplication.  If the link
   between DF and CE fails, another PE will forward the BUM flows after
   it is elected as DF.

   [I-D.ietf-bess-evpn-df-election-framework] defines the DF election
   framework, including that Backup Designated Forwarder (BDF) can be
   elected as the next best for the role.  But before the BDF is elected
   as DF, the BUM flows are discarded after the link between DF and CE
   fails.

                                          +-----+
                               +-----X----+ PE1 |
                               |          +--+--+
                               |
                             +-+--+
                             | CE |
                             +-+--+
                               |
                               |          +--+--+
                               +----------+ PE2 |
                                          +-----+

   For example, CE is multihomed to PE1 and PE2.  PE1 is elected as DF.
   All BUM flows are forwarded by PE1 when the link between PE1 and CE
   is operational.  When the link between PE1 and CE fails, the BUM
   flows are discarded until PE2 is elected as DF.

   This document will use terminology defined in [RFC7432] and
   [I-D.jain-bess-evpn-lsp-ping].

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2.  Proposal

   In order to avoid the BUM packet loss on BDF after the link between
   DF and CE fails, a data-plane detection function is needed for DF
   fast switchover.  [RFC5884] provides mechanisms for using LSP Ping to
   bootstrap a BFD session.  [I-D.jain-bess-evpn-lsp-ping] introduces
   four new Target FEC Stack sub-TLVs that are included in the LSP-Ping