INTERNET-DRAFT                                               Samer Salam
Intended Status: Informational                               Ali Sajassi
                                                                   Cisco
                                                              Sam Aldrin
                                                                  Google
                                                           John E. Drake
                                                                 Juniper
                                                         Donald Eastlake
                                                               Futurewei
Expires: October 5, 11, 2021                                 April 6, 12, 2021

            EVPN Operations, Administration and Maintenance
                       Requirements and Framework
                 draft-ietf-bess-evpn-oam-req-frmwk-08
                 draft-ietf-bess-evpn-oam-req-frmwk-09

Abstract

   This document specifies the requirements and reference framework for
   Ethernet VPN (EVPN) Operations, Administration and Maintenance (OAM).
   The requirements cover the OAM aspects of EVPN and PBB-EVPN (Provider
   Backbone Bridge EVPN).  The framework defines the layered OAM model
   encompassing the EVPN service layer, network layer, underlying Packet
   Switched Network (PSN) transport layer, and link layer but focuses on
   the service and network layers.

Status of this Memo

   This Internet-Draft is submitted to IETF in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as Internet-
   Drafts.

   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."

   The list of current Internet-Drafts can be accessed at
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   https://www.ietf.org/1id-abstracts.html. The list of Internet-Draft
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   https://www.ietf.org/shadow.html

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Copyright and License Notice

   Copyright (c) 2021 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
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   described in the Simplified BSD License.

INTERNET-DRAFT                           EVPN OAM Requirements/Framework

Table of Contents

      1. Introduction............................................4
      1.1 Relationship to Other OAM Work.........................4
      1.2 Specification of Requirements..........................5
      1.3 Terminology............................................5

      2. EVPN OAM Framework......................................7
      2.1 OAM Layering...........................................7
      2.2 EVPN Service OAM.......................................8
      2.3 EVPN Network OAM.......................................9
      2.4 Transport OAM for EVPN................................10
      2.5 Link OAM..............................................11
      2.6 OAM Inter-working.....................................11

      3. EVPN OAM Requirements..................................12
      3.1 Fault Management Requirements.........................12
      3.1.1 Proactive Fault Management Functions................12
      3.1.1.1 Fault Detection (Continuity Check)................12
      3.1.1.2 Defect Indication.................................13
      3.1.1.2.1 Forward Defect Indication.......................13
      3.1.1.2.2 Reverse Defect Indication (RDI).................14
      3.1.2 On-Demand Fault Management Functions................14
      3.1.2.1 Connectivity Verification.........................14
      3.1.2.2 Fault Isolation...................................15
      3.2 Performance Management................................15
      3.2.1 Packet Loss.........................................16
      3.2.2 Packet Delay and Jitter.............................16

      4. Security Considerations................................17
      5. IANA Considerations....................................17

      6. Acknowledgements.......................................17

      Normative References......................................18
      Informative References....................................19

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1. Introduction

   This document specifies the requirements and defines a reference
   framework for Ethernet VPN (EVPN) Operations, Administration and
   Maintenance (OAM, [RFC6291]). In this context, we use the term EVPN
   OAM to loosely refer to the OAM functions required for and/or
   applicable to [RFC7432] and [RFC7623].

   EVPN is an a Layer 2 VPN (L2VPN) solution for multipoint Ethernet
   services, with advanced multi-homing capabilities, using BGP for
   distributing customer/client MAC address reachability information
   over the core MPLS/IP network.

   PBB-EVPN combines Provider Backbone Bridging (PBB) [802.1Q] with EVPN
   in order to reduce the number of BGP MAC advertisement routes,
   provide client MAC address mobility using C-MAC (Client MAC
   [RFC7623]) aggregation and B-MAC
   sub-netting, (Backbone MAC [RFC7623]) sub-
   netting, confine the scope of C-MAC learning to only active flows,
   offer per site policies, and avoid C-MAC address flushing on topology
   changes.

   This document focuses on the fault management and performance
   management aspects of EVPN OAM. It defines the layered OAM model
   encompassing the EVPN service layer, network layer, underlying Packet
   Switched Network (PSN) transport layer, and link layer but focuses on
   the service and network layers.

1.1 Relationship to Other OAM Work

   This document leverages concepts and draws upon elements defined
   and/or used in the following documents:

   [RFC6136] specifies the requirements and a reference model for OAM as
   it relates to L2VPN services, pseudowires and associated Packet
   Switched Network (PSN) tunnels. This document focuses on VPLS and
   VPWS solutions and services.

   [RFC8029] defines mechanisms for detecting data plane failures in
   MPLS LSPs, including procedures to check the correct operation of the
   data plane, as well as mechanisms to verify the data plane against
   the control plane.

   [802.1Q] specifies the Ethernet Connectivity Fault Management (CFM)
   protocol, which defines the concepts of Maintenance Domains,
   Maintenance Associations, Maintenance End Points, and Maintenance
   Intermediate Points.

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   [Y.1731] extends Connectivity Fault Management in the following
   areas: it defines fault notification and alarm suppression functions

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   for Ethernet.  It also specifies mechanisms for Ethernet performance
   management, including loss, delay, jitter, and throughput
   measurement.

1.2 Specification of Requirements

   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
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

1.3 Terminology

   This document uses the following terminology much of which is defined
   in [RFC6136]:

   CE    Customer Edge device, e.g., a host, router, or switch.

   CFM  Connectivity Fault Management [802.1Q].

   DF    Designated Forwarder [RFC7432].

   Down MEP  A MEP that originates traffic away from and terminates
         traffic towards the core of the device in whose port it is
         logically located.

   EVI   An EVPN instance spanning the Provider Edge (PE) devices
         participating in that EVPN. EVPN [RFC7432].

   L2VPN Layer 2 VPN.

   MA    Maintenance Association is a set of MEPs belonging to the same
         Maintenance Domain, Domain (MD), established to verify the integrity of
         a single service instance. instance [802.1Q].

   MD    Maintenance Domain, an OAM Domain that represents a region over
         which OAM frames can operate unobstructed [802.1Q].

   MEP   Maintenance End Point is responsible for origination and
         termination of OAM frames for a given MA. A MEP is logically
         located in a device's port. port [802.1Q].

   MIP   Maintenance Intermediate Point is located between peer MEPs and

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         can process and respond to certain OAM frames but does not
         initiate them. A MIP is logically located in a device's port.

   MD    Maintenance Domain, an OAM Domain that represents a region over
         which OAM frames can operate unobstructed. port
         [802.1Q].

   MP2P  Multipoint to Point.

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   NMS   Network Management Station [RFC6632].

   P     Provider network interior (non-edge) device. node.

   P2MP  Point to Multipoint.

   PBB   Provider Backbone Bridge. Bridge [RFC7623].

   PE    Provider network Edge device.

   Up MEP  A MEP that originates traffic towards and terminates traffic
         from the core of the device in whose port it is logically
         located.

   VPN   Virtual Private Network

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2. EVPN OAM Framework

2.1 OAM Layering

   Multiple layers come into play for implementing an L2VPN service
   using the EVPN family of solutions as listed below. The focus of this
   document is the Service and Network layers.

   - The Service Layer runs end to end between the sites or Ethernet
     Segments that are being interconnected by the EVPN solution.

   - The Network Layer extends between the EVPN PE (Provider Edge) nodes
     and is mostly transparent to the core P (Provider) (Provider network interior)
     nodes (except where Flow Entropy comes into play). It leverages
     MPLS for service (i.e., EVI) multiplexing and Split-Horizon
     functions.

   - The Transport Layer is dictated by the networking technology of the
     PSN. It may be either based on MPLS LSPs or IP.

   - The Link Layer is dependent upon the physical technology used.
     Ethernet is a popular choice for this layer, but other alternatives
     are deployed (e.g., POS, DWDM etc.).

   This layering extends to the set of OAM protocols that are involved
   in the ongoing maintenance and diagnostics of EVPN networks. Figure 1
   below depicts the OAM layering, and shows which devices have
   visibility into what OAM layer(s).

           +---+                               +---+
   +--+    |   |    +---+    +---+    +---+    |   |    +--+
   |CE|----|PE1|----|
   |CE|----|PE |----| P |----| P |----| P |----|PE2|----|CE| |----|PE |----|CE|
   +--+    |   |    +---+    +---+    +---+    |   |    +--+
           +---+                               +---+

    o--------o----------

     o-------o----------- Service OAM ------------o--------o -----------o-------o

             o----------- Network OAM -----------o

             o--------o--------o--------o--------o  Transport OAM

      o----o   o----o   o----o   o----o   o----o   o----o  Link OAM

                          Figure 1: OAM Layering

   Service OAM and Network OAM mechanisms only have visibility to the PE
   (Provider Edge) nodes but not the P nodes (Provider network interior
   nodes). interior) nodes. As
   such, they can be used to deduce whether the fault is in the

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   customer's own network, the local CE-PE segment, the PE-PE

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   the remote CE-PE segment(s). EVPN Transport OAM mechanisms can be
   used for fault isolation between the PEs and P nodes.

   Figure 2 below shows an example network where native Ethernet domains
   are interconnected via EVPN using MPLS and gives the OAM mechanisms
   applicable at each layer. The details of the layers are described in
   the sections below.

           +---+                               +---+
   +--+    |   |    +---+    +---+    +---+    |   |    +--+
   |CE|----|PE1|----|
   |CE|----|PE |----| P |----| P |----| P |----|PE2|----|CE| |----|PE |----|CE|
   +--+    |   |    +---+    +---+    +---+    |   |    +--+
           +---+                               +---+

    o--------o---------- Service

      o----o---------- CFM ------------o--------o (Service OAM) ----------o----o

             o-------- EVPN Network OAM ---------o

             o--------o--------o--------o--------o MPLS OAM

      o----o   o----o   o----o   o----o   o----o   o----o  802.3 [802.3] OAM

                        Figure 2: EVPN OAM Example

2.2 EVPN Service OAM

   The EVPN Service OAM protocol depends on what service layer
   technology is being interconnected by the EVPN solution. In case of
   [RFC7432] and [RFC7623], the service layer is Ethernet; hence, the
   corresponding service OAM protocol is Ethernet Connectivity Fault
   Management (CFM) [802.1Q].

   EVPN service OAM is visible to the CEs and EVPN PEs, but not to the
   core (P) P
   nodes. This is because the PEs operate at the Ethernet MAC layer in
   [RFC7432] [RFC7623] whereas the P nodes do not.

   The EVPN PE MUST support MIP functions in the applicable service OAM
   protocol, for example Ethernet CFM. The EVPN PE SHOULD support MEP
   functions in the applicable service OAM protocol. This includes both
   Up and Down MEP functions.

   As shown in Figure 3, the MIP and MEP functions being referred to are
   logically located within the device's port operating at the customer
   level. (There could be MEPs/MIPs within PE ports facing the provider
   network but they would not be relevant to EVPN Service OAM as the
   traffic passing through them will be encapsulated/tunneled so any
   customer level OAM messages will just be treated as data.)  Down MEP

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   functions are away from the core of the device while up MEP functions
   are towards

INTERNET-DRAFT                           EVPN OAM Requirements/Framework the core of the device (towards the PE forwarding
   mechanism in the case of a PE). OAM messages between the PE Up MEPs
   shown are a type of EVPN Network OAM while such messages between the
   CEs or from a PE to its local CE or to the remote CE are Service OAM.

    +-------+   +----------------+       +----------------+   +-------+
    |+-----+|   |+--------------+|       |+--------------+|   |+-----+|
    ||  CE ||   ||     PE1     PE       ||  ...  ||      PE2       PE     ||   || CE  ||
    |+--+--+|   |+---+--------+-+|       |+-+--------+---+|   |+--+--+|
    |   |   |   |    |        |  |       |  |        |    |   |   |   |
    |+--+--+|   |+---+-----+  .  |       |  .  +-----+---+|   |+--+--+|
    || MEP ||   ||   | Up^ | Up ^|  .  |  ...  |  .  |Up^  | Up ^|   ||   || MEP ||
    ||DownV||   ||MIP|MEP  |  .  |       |  .  |MEP  |MIP||   ||downV||   ||DownV||
    |+--+--+|   ||   |DownV|  .  |       |  .  |DownV|   ||   |+--+--+|
    |   |   |   |+---+-----+  |  |       |  |  +-----+---+|   |   |   |
    +---|---+   +----|--------|--+       +--|--------|----+   +---|---+
        |            |        |             |        |            |
        +------------+        +---  ...  ---+        +------------+

                           Figure 3: CFM Details

   The EVPN PE MUST MUST, by default, learn the MAC address of locally
   attached CE MEPs by snooping on CFM frames and advertising them to
   remote PEs as a MAC/IP Advertisement route. Some means to limit the
   number of MAC addresses that a PE will learn SHOULD be implemented.

   The EVPN PE SHOULD advertise any MEP/MIP local to the PE as a MAC/IP
   Advertisement route. Since these are not subject to mobility, they
   SHOULD be advertised with the static (sticky) bit set (see Section
   15.2 of [RFC7432]).

2.3 EVPN Network OAM

   EVPN Network OAM is visible to the PE nodes only. This OAM layer is
   analogous to VCCV [RFC5085] in the case of VPLS/VPWS. It provides
   mechanisms to check the correct operation of the data plane, as well
   as a mechanism to verify the data plane against the control plane.
   This includes the ability to perform fault detection and diagnostics
   on:

   - the MP2P tunnels used for the transport of unicast traffic between
     PEs. EVPN allows for three different models of unicast label
     assignment: label per EVI, label per <ESI, Ethernet Tag> and label
     per MAC address. In all three models, the label is bound to an EVPN
     Unicast FEC.  EVPN Network OAM MUST provide mechanisms to check the
     operation of the data plane and verify that operation against the
     control plane view.

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   - the MP2P tunnels used for aliasing unicast traffic destined to a

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     multi-homed Ethernet Segment. The three label assignment models,
     discussed above, apply here as well. In all three models, the label
     is bound to an EVPN Aliasing FEC. EVPN Network OAM MUST provide
     mechanisms to check the operation of the data plane and verify that
     operation against the control plane view.

   - the multicast tunnels (either MP2P or P2MP) used for the transport
     of broadcast, unknown unicast and multicast traffic between PEs. In
     the case of ingress replication, a label is allocated per EVI or
     per <EVI, Ethernet Tag> and is bound to an EVPN Multicast FEC. In
     the case of LSM (Label Switched Multicast), and more specifically
     aggregate inclusive trees, again a label may be allocated per EVI
     or per <EVI, Ethernet Tag> and is bound to the tunnel FEC.

   - the correct operation of the ESI split-horizon filtering function.
     In EVPN, a label is allocated per multi-homed Ethernet Segment for
     the purpose of performing the access split-horizon enforcement. The
     label is bound to an EVPN Ethernet Segment.

   - the correct operation of the DF (Designated Forwarder) Forwarder [RFC7432])
     filtering function.  EVPN Network OAM MUST provide mechanisms to
     check the operation of the data plane and verify that operation
     against the control plane view for the DF filtering function.

   EVPN Network OAM mechanisms MUST provide in-band monitoring
   capabilities. As such, OAM messages MUST SHOULD be encoded so that they exhibit identical
   similar entropy characteristics to data traffic in order
   that they share to maximize
   the same fate. fate sharing between OAM and data.

   EVPN Network OAM SHOULD provide both proactive and on-demand
   mechanisms of monitoring the data plane operation and data plane
   conformance to the state of the control plane.

2.4 Transport OAM for EVPN

   The transport OAM protocol depends on the nature of the underlying
   transport technology in the PSN. MPLS OAM mechanisms [RFC8029]
   [RFC6425] as well as ICMP [RFC792] / ICMPv6 [RFC4443] are applicable,
   depending on whether the PSN employs MPLS or IP transport,
   respectively.  Furthermore, BFD mechanisms per [RFC5880], [RFC5881],
   [RFC5883] and [RFC5884] apply. Also, the BFD mechanisms pertaining to
   MPLS-TP LSPs per [RFC6428] are applicable.

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2.5 Link OAM

   Link OAM depends on the data link technology being used between the
   PE and P nodes. For example, if Ethernet links are employed, then
   Ethernet Link OAM ([802.3] Clause 57) may be used.

2.6 OAM Inter-working

   When inter-working two networking domains, such as native Ethernet
   and EVPN to provide an end-to-end emulated service, there is a need
   to identify the failure domain and location, even when a PE supports
   both the Service OAM mechanisms and the EVPN Network OAM mechanisms.
   In addition, scalability constraints may not allow running proactive
   monitoring, such as Ethernet Continuity Check Messages (CCMs), (CCMs
   [802.1Q]), at a PE to detect the failure of an EVI across the EVPN
   domain. Thus, the mapping of alarms generated upon failure detection
   in one domain (e.g., native Ethernet or EVPN network domain) to the
   other domain is needed. There are also cases where a PE may not be
   able to process Service OAM messages received from a remote PE over
   the PSN even when such messages are defined, as in the Ethernet case,
   thereby necessitating support for fault notification message mapping
   between the EVPN Network domain and the Service domain.

   OAM inter-working is not limited though to scenarios involving
   disparate network domains. It is possible to perform OAM inter-
   working across different layers in the same network domain. In
   general, alarms generated within an OAM layer, as a result of
   proactive fault detection mechanisms, may be injected into its client
   layer OAM mechanisms. This allows the client layer OAM to trigger
   event-driven (i.e., asynchronous) fault notifications. For example,
   alarms generated by the Link OAM mechanisms may be injected into the
   Transport OAM layer, and alarms generated by the Transport OAM
   mechanism may be injected into the Network OAM mechanism, and so on.

   EVPN OAM MUST support inter-working between the Network OAM and
   Service OAM mechanisms. EVPN OAM MAY support inter-working among
   other OAM layers.

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3. EVPN OAM Requirements

   This section discusses the EVPN OAM requirements pertaining to Fault
   Management and Performance Management.

3.1 Fault Management Requirements

3.1.1 Proactive Fault Management Functions

   The network operator configures proactive fault management functions
   to run periodically without a time bound. Certain actions, for
   example protection switchover or alarm indication signaling, can be
   associated with specific events, such as entering or clearing fault
   states.

3.1.1.1 Fault Detection (Continuity Check)

   Proactive fault detection is performed by periodically monitoring the
   reachability between service endpoints, i.e., MEPs in a given MA,
   through the exchange of Continuity Check messages. Messages [802.1Q]. The
   reachability between any two arbitrary MEPs may be monitored for:

   - in-band per-flow monitoring. This enables per flow monitoring
     between MEPs. EVPN Network OAM MUST support fault detection with
     per user flow granularity. EVPN Service OAM MAY support fault
     detection with per user flow granularity.

   - a representative path. This enables liveness check of the nodes
     hosting the MEPs assuming that the loss of continuity to the MEP is
     interpreted as a failure of the hosting node. This, however, does
     not conclusively indicate liveness of the path(s) taken by user
     data traffic. This enables node failure detection but not path
     failure detection, through the use of a test flow. EVPN Network OAM
     and Service OAM MUST support fault detection using test flows.

   - all paths. For MPLS/IP networks with ECMP, monitoring of all
     unicast paths between MEPs (on non-adjacent nodes) may not be
     possible, since the per-hop ECMP hashing behavior may yield
     situations where it is impossible for a MEP to pick flow entropy
     characteristics that result in exercising the exhaustive set of
     ECMP paths. Monitoring of all ECMP paths between MEPs (on non-
     adjacent nodes) is not a requirement for EVPN OAM.

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   The fact that MPLS/IP networks do not enforce congruency between

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   unicast and multicast paths means that the proactive fault detection
   mechanisms for EVPN networks MUST provide procedures to monitor the
   unicast paths independently of the multicast paths. This applies to
   EVPN Service OAM and Network OAM.

3.1.1.2 Defect Indication

   Defect indications can be categorized into two types: forward and
   reverse defect indications as described below. EVPN Service OAM MUST
   support at least one of these types of event-driven defect indication
   upon the detection of a connectivity defect.

3.1.1.2.1 Forward Defect Indication

   This is used to signal a failure that is detected by a lower layer
   OAM mechanism. A server MEP (i.e., an actual or virtual MEP)
   transmits a Forward Defect Indication in a direction that is away
   from the direction of the failure (refer to Figure 4 below).

                              Failure
                                 |
          +-----+      +-----+   V   +-----+      +-----+
          |  A  |------|  B  |--XXX--|  C  |------|  D  |
          +-----+      +-----+       +-----+      +-----+

              <===========|             |============>
                Forward                    Forward
                Defect                     Defect
                Indication                 Indication

                    Figure 4: Forward Defect Indication

   Forward defect indication may be used for alarm suppression and/or
   for purpose of inter-working with other layer OAM protocols. Alarm
   suppression is useful when a transport/network level fault translates
   to multiple service or flow level faults. In such a scenario, it is
   enough to alert a network management station (NMS) of the single
   transport/network level fault in lieu of flooding that NMS with a
   multitude of Service or Flow granularity alarms. EVPN PEs SHOULD
   support Forward Defect Indication in the Service OAM mechanisms.

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3.1.1.2.2 Reverse Defect Indication (RDI)

   RDI is used to signal that the advertising MEP has detected a loss of
   continuity (LoC) defect. RDI is transmitted in the direction of the
   failure (refer to Figure 5).

                              Failure
                                 |
          +-----+      +-----+   V   +-----+      +-----+
          |  A  |------|  B  |--XXX--|  C  |------|  D  |
          +-----+      +-----+       +-----+      +-----+

              |===========>             <============|
                Reverse                    Reverse
                Defect                     Defect
                Indication                 Indication

                    Figure 5: Reverse Defect Indication

   RDI allows single-sided management, where the network operator can
   examine the state of a single MEP and deduce the overall health of a
   monitored service. EVPN PEs SHOULD support Reverse Defect Indication
   in the Service OAM mechanisms. This includes both the ability to
   signal LoC defect to a remote MEP, as well as the ability to
   recognize RDI from a remote MEP. Note that, in a multipoint MA, RDI
   is not a useful indicator of unidirectional fault.  This is because
   RDI carries no indication of the affected MEP(s) with which the
   sender had detected a LoC defect.

3.1.2 On-Demand Fault Management Functions

   On-demand fault management functions are initiated manually by the
   network operator and continue for a time bound period. These
   functions enable the operator to run diagnostics to investigate a
   defect condition.

3.1.2.1 Connectivity Verification

   EVPN Network OAM MUST support on-demand connectivity verification
   mechanisms for unicast and multicast destinations. The connectivity
   verification mechanisms SHOULD provide a means for specifying and
   carrying in the messages:

   - variable length payload/padding to test MTU (Maximum Transmission
     Unit) related connectivity problems.

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   - test frame formats as defined in Appendix C of [RFC2544] to detect
     potential packet corruption.

   EVPN Network OAM MUST support connectivity verification at per flow
   granularity. This includes both user flows (to test a specific path
   between PEs) as well as test flows (to test a representative path
   between PEs).

   EVPN Service OAM MUST support connectivity verification on test flows
   and MAY support connectivity verification on user flows.

   For multicast connectivity verification, EVPN Network OAM MUST
   support reporting on:

   - the DF filtering status of specific port(s) or all the ports in a
     given bridge-domain.

   - the Split Horizon filtering status of specific port(s) or all the
     ports in a given bridge-domain.

3.1.2.2 Fault Isolation

   EVPN OAM MUST support an on-demand fault localization function. This
   involves the capability to narrow down the locality of a fault to a
   particular port, link or node. The characteristic of forward/reverse
   path asymmetry, in MPLS/IP, makes fault isolation a direction-
   sensitive operation. That is, given two PEs A and B, localization of
   continuity failures between them requires running fault isolation
   procedures from PE A to PE B as well as from PE B to PE A.

   EVPN Service OAM mechanisms only have visibility to the PEs but not
   the MPLS/IP MPLS or IP P nodes. As such, they can be used to deduce whether
   the fault is in the customer's own network, the local CE-PE segment
   or remote CE-PE segment(s). EVPN Network and Transport OAM mechanisms
   can be used for fault isolation between the PEs and P nodes.

3.2 Performance Management

   Performance Management functions can be performed both proactively
   and on-demand. Proactive management involves a recurring function,
   where the performance management probes are run continuously without
   a trigger. We cover both proactive and on-demand functions in this
   section.

INTERNET-DRAFT                           EVPN OAM Requirements/Framework

3.2.1 Packet Loss

   EVPN Network OAM SHOULD provide mechanisms for measuring packet loss
   for a given service service, for example [RFC7680] [RFC6673].

   Given that EVPN provides inherent support for multipoint-to-
   multipoint connectivity, then packet loss cannot be accurately
   measured by means of counting user data packets. This is because user
   packets can be delivered to more PEs or more ports than are necessary
   (e.g., due to broadcast, un-pruned multicast or unknown unicast
   flooding). As such, a statistical means of approximating packet loss
   rate is required.  This can be achieved by sending "synthetic" OAM
   packets that are counted only by those ports (MEPs) that are required
   to receive them.  This provides a statistical approximation of the
   number of data frames lost, even with multipoint-to-multipoint
   connectivity.

3.2.2 Packet Delay and Jitter

   EVPN Service OAM SHOULD support measurement of one-way and two-way
   packet delay and delay variation (jitter) across the EVPN network.
   Measurement of one-way delay requires clock synchronization between
   the probe source and target devices. Mechanisms for clock
   synchronization are outside the scope of this document. Note that
   Service OAM performance management mechanisms defined in [Y.1731] can
   be used. See also [RFC7679], [RFC2681], and [RFC3393]

   EVPN Network OAM MAY support measurement of one-way and two-way
   packet delay and delay variation (jitter) across the EVPN network.

INTERNET-DRAFT                           EVPN OAM Requirements/Framework

4. Security Considerations

   EVPN OAM MUST prevent OAM packets from leaking outside of the EVPN
   network or outside their corresponding Maintenance Domain. This can
   be done for CFM, for example, by having MEPs implement a filtering
   function based on the Maintenance Level associated with received OAM
   packets.

   EVPN OAM SHOULD provide mechanisms for implementation and optional
   use to:

   - Prevent denial of service attacks caused by exploitation of the OAM
     message channel (for example by forging messages to exceed a
     maintenance end point's capacity to maintain state).

   - Authenticate communicating endpoints (for example MEPs and MIPs).

5. IANA Considerations

   This document requires no IANA actions.

6. Acknowledgements

   The authors would like to thank the following for their review of
   this work and valuable comments:

      David Black, Martin Duke, Xiao Min, Gregory Mirsky,
      Zaheduzzaman Sarker, Dave Schinazi, John Scudder, Melinda Shore,
      Robert Wilton, Alexander Vainshtein, and Stig Venaas. Venaas, and Eric Vyncke.

INTERNET-DRAFT                           EVPN OAM Requirements/Framework

Normative References

   [RFC792]  Postel, J., "Internet Control Message Protocol", STD 5, RFC
             792, DOI 10.17487/RFC0792, September 1981,
             <https://www.rfc-editor.org/info/rfc792>.

   [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
             Requirement Levels", BCP 14, RFC 2119, DOI
             10.17487/RFC2119, March 1997, <https://www.rfc-
             editor.org/info/rfc2119>.

   [RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet
             Control Message Protocol (ICMPv6) for the Internet Protocol
             Version 6 (IPv6) Specification", STD 89, RFC 4443, DOI
             10.17487/RFC4443, March 2006, <https://www.rfc-
             editor.org/info/rfc4443>.

   [RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection
             (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010,
             <https://www.rfc-editor.org/info/rfc5880>.

   [RFC5881] Katz, D. and D. Ward, "Bidirectional Forwarding Detection
             (BFD) for IPv4 and IPv6 (Single Hop)", RFC 5881, DOI
             10.17487/RFC5881, June 2010, <https://www.rfc-
             editor.org/info/rfc5881>.

   [RFC5883] Katz, D. and D. Ward, "Bidirectional Forwarding Detection
             (BFD) for Multihop Paths", RFC 5883, DOI 10.17487/RFC5883,
             June 2010, <https://www.rfc-editor.org/info/rfc5883>.

   [RFC5884] Aggarwal, R., Kompella, K., Nadeau, T., and G. Swallow,
             "Bidirectional Forwarding Detection (BFD) for MPLS Label
             Switched Paths (LSPs)", RFC 5884, DOI 10.17487/RFC5884,
             June 2010, <https://www.rfc-editor.org/info/rfc5884>.<

   [RFC6291] Andersson, L., van Helvoort, H., Bonica, R., Romascanu, D.,
             and S. Mansfield, "Guidelines for the Use of the "OAM"
             Acronym in the IETF", BCP 161, RFC 6291, DOI
             10.17487/RFC6291, June 2011, <https://www.rfc-
             editor.org/info/rfc6291>.

   [RFC6425] Saxena, S., Ed., Swallow, G., Ali, Z., Farrel, A.,
             Yasukawa, S., and T. Nadeau, "Detecting Data-Plane Failures
             in Point-to-Multipoint MPLS - Extensions to LSP Ping", RFC
             6425, DOI 10.17487/RFC6425, November 2011,
             <https://www.rfc-editor.org/info/rfc6425>.

   [RFC6428] Allan, D., Ed., Swallow, G., Ed., and J. Drake, Ed.,
             "Proactive Connectivity Verification, Continuity Check, and
             Remote Defect Indication for the MPLS Transport Profile",

INTERNET-DRAFT                           EVPN OAM Requirements/Framework

             RFC 6428, DOI 10.17487/RFC6428, November 2011,
             <https://www.rfc-editor.org/info/rfc6428>.

   [RFC7432] Sajassi, A., Ed., Aggarwal, R., Bitar, N., Isaac, A.,
             Uttaro, J., Drake, J., and W. Henderickx, "BGP MPLS-Based
             Ethernet VPN", RFC 7432, DOI 10.17487/RFC7432, February
             2015, <https://www.rfc-editor.org/info/rfc7432>.

   [RFC7623] Sajassi, A., Ed., Salam, S., Bitar, N., Isaac, A., and W.
             Henderickx, "Provider Backbone Bridging Combined with
             Ethernet VPN (PBB-EVPN)", RFC 7623, DOI 10.17487/RFC7623,
             September 2015, <https://www.rfc-editor.org/info/rfc7623>.

   [RFC8029] Kompella, K., Swallow, G., Pignataro, C., Ed., Kumar, N.,
             Aldrin, S., and M. Chen, "Detecting Multiprotocol Label
             Switched (MPLS) Data-Plane Failures", RFC 8029, DOI
             10.17487/RFC8029, March 2017, <https://www.rfc-
             editor.org/info/rfc8029>.

   [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119
             Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May
             2017, <http://www.rfc-editor.org/info/rfc8174>

Informative References

   [802.1Q]  IEEE, "IEEE Standard for Local and metropolitan area
             networks - Media Access Control (MAC) Bridges and Virtual
             Bridge Local Area Networks", IEEE Std 802.1Q-2014, 2014.

   [Y.1731]  "ITU-T Recommendation Y.1731 (02/08) - OAM functions and
             mechanisms

   [802.3]   IEEE, "IEEE Standard for Ethernet based networks", February 2008. Ethernet", IEEE Std 802.3-2015,
             2015.

   [RFC2544] Bradner, S. and J. McQuaid, "Benchmarking Methodology for
             Network Interconnect Devices", RFC 2544, DOI
             10.17487/RFC2544, March 1999, <https://www.rfc-
             editor.org/info/rfc2544>.

   [RFC2681] Almes, G., Kalidindi, S., and M. Zekauskas, "A Round-trip
             Delay Metric for IPPM", RFC 2681, DOI 10.17487/RFC2681,
             September 1999, <https://www.rfc-editor.org/info/rfc2681>.

   [RFC3393] Demichelis, C. and P. Chimento, "IP Packet Delay Variation
             Metric for IP Performance Metrics (IPPM)", RFC 3393, DOI
             10.17487/RFC3393, November 2002, <https://www.rfc-
             editor.org/info/rfc3393>.

   [RFC5085] Nadeau, T., Ed., and C. Pignataro, Ed., "Pseudowire Virtual
             Circuit Connectivity Verification (VCCV): A Control Channel

INTERNET-DRAFT                           EVPN OAM Requirements/Framework

             for Pseudowires", RFC 5085, DOI 10.17487/RFC5085, December
             2007, <https://www.rfc-editor.org/info/rfc5085>.

   [RFC6136] Sajassi, A., Ed., and D. Mohan, Ed., "Layer 2 Virtual
             Private Network (L2VPN) Operations, Administration, and
             Maintenance (OAM) Requirements and Framework", RFC 6136,
             DOI 10.17487/RFC6136, March 2011, <https://www.rfc-
             editor.org/info/rfc6136>.

   [RFC6632] Ersue, M., Ed., and B. Claise, "An Overview of the IETF
             Network Management Standards", RFC 6632, DOI
             10.17487/RFC6632, June 2012, <https://www.rfc-
             editor.org/info/rfc6632>.

   [RFC6673] Morton, A., "Round-Trip Packet Loss Metrics", RFC 6673, DOI
             10.17487/RFC6673, August 2012, <https://www.rfc-
             editor.org/info/rfc6673>.

   [RFC7679] Almes, G., Kalidindi, S., Zekauskas, M., and A. Morton,
             Ed., "A One-Way Delay Metric for IP Performance Metrics
             (IPPM)", STD 81, RFC 7679, DOI 10.17487/RFC7679, January
             2016, <https://www.rfc-editor.org/info/rfc7679>.

   [RFC7680] Almes, G., Kalidindi, S., Zekauskas, M., and A. Morton,
             Ed., "A One-Way Loss Metric for IP Performance Metrics
             (IPPM)", STD 82, RFC 7680, DOI 10.17487/RFC7680, January
             2016, <https://www.rfc-editor.org/info/rfc7680>.

   [Y.1731]  "ITU-T Recommendation Y.1731 (02/08) - OAM functions and
             mechanisms for Ethernet based networks", February 2008.

INTERNET-DRAFT                           EVPN OAM Requirements/Framework

Authors' Addresses

      Samer Salam
      Cisco

      Email: ssalam@cisco.com

      Ali Sajassi
      Cisco
      170 West Tasman Drive
      San Jose, CA 95134, USA

      Email: sajassi@cisco.com

      Sam Aldrin
      Google, Inc.
      1600 Amphitheatre Parkway
      Mountain View, CA 94043 USA

      Email: aldrin.ietf@gmail.com

      John E. Drake
      Juniper Networks
      1194 N. Mathilda Ave.
      Sunnyvale, CA 94089, USA

      Email: jdrake@juniper.net

      Donald E. Eastlake, 3rd
      Futurewei Technologies
      2386 Panoramic Circle
      Apopka, FL 32703 USA

      Tel: +1-508-333-2270
      Email: d3e3e3@gmail.com