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Versions: (draft-tissa-lime-yang-oam-model) 00 01 02 03 04 05 06 07 08 09 10 draft-ietf-lime-yang-connection-oriented-oam-model

Network Working Group                                           D. Kumar
Internet-Draft                                                     Cisco
Intended status: Standards Track                                   Q. Wu
Expires: October 11, 2017                                        M. Wang
                                                                  Huawei
                                                           April 9, 2017


      Generic YANG Data Model for Connection Oriented Operations,
             Administration, and Maintenance(OAM) protocols
                   draft-ietf-lime-yang-oam-model-10

Abstract

   This document presents a base YANG Data model for connection oriented
   OAM protocols.  It provides a technology-independent abstraction of
   key OAM constructs for such protocols.  The model presented here can
   be extended to include technology specific details.  This guarantees
   uniformity in the management of OAM protocols and provides support
   for nested OAM workflows (i.e., performing OAM functions at different
   levels through a unified interface)

Status of This Memo

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

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   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."

   This Internet-Draft will expire on October 11, 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
   publication of this document.  Please review these documents



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   carefully, as they describe your rights and restrictions with respect
   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.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Conventions used in this document . . . . . . . . . . . . . .   4
     2.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   5
   3.  Architecture of Generic YANG Model for OAM  . . . . . . . . .   6
   4.  Overview of the OAM Model . . . . . . . . . . . . . . . . . .   7
     4.1.  Maintenance Domain (MD) configuration . . . . . . . . . .   8
     4.2.  Maintenance Association (MA) configuration  . . . . . . .   9
     4.3.  Maintenance Endpoint (MEP) configuration  . . . . . . . .   9
     4.4.  RPC definitions . . . . . . . . . . . . . . . . . . . . .  10
     4.5.  Notifications . . . . . . . . . . . . . . . . . . . . . .  13
     4.6.  Monitor statistics  . . . . . . . . . . . . . . . . . . .  13
     4.7.  OAM data hierarchy  . . . . . . . . . . . . . . . . . . .  13
   5.  OAM YANG Module . . . . . . . . . . . . . . . . . . . . . . .  18
   6.  Base Mode . . . . . . . . . . . . . . . . . . . . . . . . . .  40
     6.1.  MEP Address . . . . . . . . . . . . . . . . . . . . . . .  40
     6.2.  MEP ID for Base Mode  . . . . . . . . . . . . . . . . . .  41
     6.3.  Maintenance Association . . . . . . . . . . . . . . . . .  41
   7.  Connection-oriented OAM YANG model applicability  . . . . . .  41
     7.1.  Generic YANG Model extension for TRILL OAM  . . . . . . .  42
       7.1.1.  MD Configuration Extension  . . . . . . . . . . . . .  42
       7.1.2.  MA Configuration Extension  . . . . . . . . . . . . .  43
       7.1.3.  MEP Configuration Extension . . . . . . . . . . . . .  43
       7.1.4.  RPC extension . . . . . . . . . . . . . . . . . . . .  44
     7.2.  Generic YANG Model extension for MPLS-TP OAM  . . . . . .  45
       7.2.1.  MD Configuration Extension  . . . . . . . . . . . . .  45
       7.2.2.  MA Configuration Extension  . . . . . . . . . . . . .  47
       7.2.3.  MEP Configuration Extension . . . . . . . . . . . . .  47
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  48
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  48
   10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  49
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .  49
     11.1.  Normative References . . . . . . . . . . . . . . . . . .  49
     11.2.  Informative References . . . . . . . . . . . . . . . . .  50
   Appendix A.  Contributors' Addresses  . . . . . . . . . . . . . .  51
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  52








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1.  Introduction

   Operations, Administration, and Maintenance (OAM) are important
   networking functions that allow operators to:

   1.  Monitor networks connections (Connectivity Verification,
       Continuity Check).

   2.  Troubleshoot failures (Fault verification and localization).

   3.  Monitor Performance

   An overview of OAM tools is presented in [RFC7276].  Over the years,
   many technologies have developed similar tools for fault and
   performance management.

   [IEEE802.1ag] Connectivity Fault Management is a well-established OAM
   standard that is widely adopted for Ethernet networks.  ITU-T
   [G.8013], MEF Service OAM, MPLS-TP [RFC6371], TRILL [RFC7455] all
   define OAM mechanisms based on the manageability frame work of CFM
   [IEEE802.1ag].

   Given the wide adoption of the underlying OAM concepts defined in CFM
   [IEEE802.1ag], it is a reasonable choice to develop the unified
   management framework for connection oriented OAM based on those
   concepts.  In this document, we take the CFM [IEEE802.1ag] model and
   extend it to a technology independent framework and define the
   corresponding YANG model accordingly.  The YANG model presented in
   this document is the base model for connection oriented OAM protocols
   and supports generic continuity check, connectivity verification and
   path discovery (traceroute).  The generic YANG model for connection
   oriented OAM is designed to be extensible to other connection
   oriented technologies.  Technology dependent nodes and remote process
   call (RPC) commands are defined in technology specific YANG models,
   which use and extend the base model defined here.  As an example,
   VXLAN uses source UDP port number for flow entropy, while TRILL uses
   either MAC addresses, the VLAN tag or fine grain label, and/or IP
   addresses for flow entropy in the hashing for multipath selection.
   To capture this variation, corresponding YANG models would define the
   applicable structures as augmentation to the generic base model
   presented here.  This accomplishes three goals: First it keeps each
   YANG model smaller and more manageable.  Second, it allows
   independent development of corresponding YANG models.  Third,
   implementations can limit support to only the applicable set of YANG
   models. (e.g.  TRILL RBridge may only need to implement Generic model
   and the TRILL YANG model).





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   All implementations that follow the YANG framework presented in this
   document MUST implement the generic connection oriented YANG model
   presented here.

   The YANG data model presented in this document is generated at the
   management layer.  Encapsulations and state machines may differ
   according to each OAM protocol.  A user who wishes to issues a
   Continuity Check command or a Loopback or initiate a performance
   monitoring session can do so in the same manner regardless of the
   underlying protocol or technology or specific vendor implementation.

   As an example, consider a scenario where Loopback from device A to
   Device B fails.  Between device A and B there are IEEE 802.1 bridges
   a, b and c.  Let's assume a,b and c are using CFM [IEEE802.1ag].
   Upon detecting the Loopback failures, a user may decide to drill down
   to the lower level at different segments of the path and issue the
   corresponding fault verification (LBM) and fault isolation (LTM)
   tools, using the same API.  This ability to drill down to a lower
   layer of the protocol stack at a specific segment within a path for
   fault localization and troubleshooting is referred to as "nested OAM
   workflow".  It is a useful concept that leads to efficient network
   troubleshooting and maintenance workflows.  The connection oriented
   OAM YANG model presented in this document facilitates that without
   needing changes to the underlying protocols.

2.  Conventions used in this document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].  In this
   document, these words will appear with that interpretation only when
   in ALL CAPS.  Lower case uses of these words are not to be
   interpreted as carrying [RFC2119] significance.

   The following notations are used within the data tree and carry the
   meaning as below.

   Each node is printed as:













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   <status> <flags> <name> <opts> <type>

   <status> is one of:
        +  for current


   <flags> is one of:

       rw for configuration data
       ro for non-configuration data
       -x for rpcs
       -n for notifications
           -w for writable


   <name> is the name of the node

   If the node is augmented into the tree from another module, its name
   is printed as <prefix>:<name>.

   <opts> is one of:

        ?  for an optional leaf or choice
        !  for a presence container
        *  for a leaf-list or list
        [<keys>] for a list's keys
        (choice)/:(case) Parentheses enclose choice and case nodes,
            and case nodes are also marked with a colon (":")
   <type> is the name of the type for leafs and leaf-lists

2.1.  Terminology

   CCM   - Continuity Check Message [IEEE802.1ag].

   ECMP  - Equal Cost Multipath.

   LBM   - Loopback Message [IEEE802.1ag].

   MP    - Maintenance Point [IEEE802.1ag].

   MEP   - Maintenance End Point [RFC7174] (Maintenance association End
         Point [IEEE802.1ag], MEG End Points [RFC6371]).

   MIP   - Maintenance Intermediate Point [RFC7174] (Maintenance domain
         Intermediate Point [IEEE802.1ag], MEG Intermediate Point
         [RFC6371]).

   MA    - Maintenance Association [IEEE802.1ag] [RFC7174].



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   MD    - Maintenance Domain [IEEE802.1ag]

   MEG   - Maintenance Entity Group [RFC6371]

   MTV   - Multi-destination Tree Verification Message.

   OAM   - Operations, Administration, and Maintenance [RFC6291].

   TRILL - Transparent Interconnection of Lots of Links [RFC6325].

   CFM   - Connectivity Fault Management [RFC7174] [IEEE802.1ag].

   RPC   - Remote Process Call.

   CC    - Continuity Check [RFC7276].  Continuity Checks are used to
         verify that a destination is reachable and therefore also
         referred to as reachability verification.

   CV    - Connectivity Verification [RFC7276].Connectivity Verification
         are used to verify that a destination is connected.  It are
         also referred to as path verification and used to verify not
         only that the two MPs are connected, but also that they are
         connected through the expected path, allowing detection of
         unexpected topology changes.

   Proactive OAM  - The proactive OAM refers to OAM actions which are
         carried out continuously to permit proactive reporting of
         fault.  Proactive OAM method requires persistent configuration.

   On-demand OAM  - The on-demand OAM refers to OAM actions which are
         initiated via manual intervention for a limited time to carry
         out diagnostics.  On-demand OAM method requires only transient
         configuration.

3.  Architecture of Generic YANG Model for OAM

   In this document we define a generic YANG model for connection
   oriented OAM protocols.  The YANG model defined here is generic in a
   sense that other technologies can extend it for technology specific
   needs.  The Generic YANG model acts as the root for other OAM YANG
   models.  This allows users to traverse between different OAM
   protocols with ease through a uniform API set.  This also enables a
   nested OAM workflow.  Figure 1 depicts the relationship of different
   OAM YANG models to the Generic YANG Model for connection oriented
   OAM.  The Generic YANG model for OAM provides a framework where
   technology- specific YANG models can inherit constructs from the base
   YANG models without needing to redefine them within the sub-
   technology.



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   Figure 1 depicts relationship of different YANG modules.

                            +----------+
                            |Connection|
                            | Oriented |
                            |  gen     |
                            |OAM YANG  |
                            +-+-+-+-+-++
                                 |
                                 |
                                 |
         +------------------------------------------+
         |                       |                  |
     +-+-+-+-+-+          +-+-+-+-+-+          +-+-+-+-+-+
     | TRILL   |          | MPLS-TP |     . . .|  foo    |
     |OAM YANG |          |OAM YANG |          |OAM YANG |
     +-+-+-+-+-+          +-+-+-+-+-+          +-+-+-+-+-+
           |                    |                  |
           |                    |              +-+-+-+-+-+
           |                    |         . . .|  foo    |
           |                    |              |sub tech |
           |                    |              +-+-+-+-+-+
           |                    |                  |
           |                    |                  |
    +-------------------------------------------------------+
    |                      Uniform API                      |
    +-------------------------------------------------------+

        Relationship of OAM YANG model to generic (base) YANG model

4.  Overview of the OAM Model

   In this document we adopt the concepts of the CFM [IEEE802.1ag] model
   and structure it such that it can be adapted to different connection
   oriented OAM protocols.

   At the top of the Model is the Maintenance Domain.  Each Maintenance
   Domain is associated with a Maintenance Name and a Domain Level.

   Under each Maintenance Domain there is one or more Maintenance
   Association (MA).  In TRILL this can be per Fine-Grained Label or for
   VPLS this can be per VPLS instance [RFC6136].

   Under each MA, there can be two or more MEPs (Maintenance End
   Points).  MEPs are addressed by their respective technology specific
   address identifiers.  The YANG model presented here provides
   flexibility to accommodate different addressing schemes.




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   In the vertical direction orthogonal to the Maintenance Domain,
   presented are the commands.  Those, in YANG terms, are the RPC
   commands.  These RPC commands provide uniform APIs for continuity
   check, connectivity verification, path discovery(traceroute) and
   their equivalents as well as other OAM commands.

   The OAM entities in the generic YANG model defined here will be
   either explicitly or implicitly configured using any of the OAM
   tools.  The OAM tools used here are limited to OAM toolset specified
   in section 5.1 of [RFC7276].  In order to facilitate zero-touch
   experience, this document defines a default mode of OAM.  The default
   mode of OAM is referred to as the Base Mode and specifies default
   values for each of model parameters, such as Maintenance Domain
   Level, Name of the Maintenance Association, Addresses of MEPs and so
   on.  The default values of these depend on the technology.  Base Mode
   for TRILL is defined in [RFC7455].  Base mode for other technologies
   and future extensions developed in IETF will be defined in their
   corresponding documents.

   It is important to note that, no specific enhancements are needed in
   the YANG model to support Base Mode.  Implementations that comply
   with this document, by default implement the data nodes of the
   applicable technology.  Data nodes of the Base Mode are read-only
   nodes.

4.1.  Maintenance Domain (MD) configuration

   The container "domains" is the top level container within the gen-oam
   module.  Within the container "domains", separate list is maintained
   per MD.  The MD list uses the key MD-name-string for indexing.  MD-
   name-string is a leaf and derived from type string.  Additional name
   formats as defined in [IEEE802.1ag] or other standards can be
   included by association of the MD-name-format with an identity-ref.
   MD-name-format indicates the format of the augmented MD-names.  MD-
   name is presented as choice/case construct.  Thus, it is easily
   augmentable by derivative work.















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       module: ietf-conn-oam
      +--rw domains
         +--rw domain* [technology MD-name-string]
            +--rw technology        identityref
            +--rw MD-name-string    MD-name-string
            +--rw MD-name-format?   identityref
            +--rw (MD-name)?
            |  +--:(MD-name-null)
            |     +--rw MD-name-null?     empty
            +--rw md-level?         MD-level

             Snippet of data hierarchy related to OAM domains

4.2.  Maintenance Association (MA) configuration

   Within a given Maintenance Domain there can be one or more
   Maintenance Associations (MA).  MAs are represented as a list and
   indexed by the MA-name-string.  Similar to MD-name defined
   previously, additional name formats can be added by augmenting the
   name-format identity-ref and adding applicable case statements to MA-
   name.

      module: ietf-conn-oam
         +--rw domains
            +--rw domain* [technology MD-name-string]
               .
               .
               +--rw MAs
                  +--rw MA* [MA-name-string]
                     +--rw MA-name-string       MA-name-string
                     +--rw MA-name-format?      identityref
                     +--rw (MA-name)?
                     |  +--:(MA-name-null)
                     |     +--rw MA-name-null?        empty

    Snippet of data hierarchy related to Maintenance Associations (MA)

4.3.  Maintenance Endpoint (MEP) configuration

   Within a given Maintenance Association (MA), there can be one or more
   Maintenance End Points (MEP).  MEPs are represented as a list within
   the data hierarchy and indexed by the key MEP-name.









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      module: ietf-conn-oam
         +--rw domains
            +--rw domain* [technology MD-name-string]
               +--rw technology        identityref
               .
               .
               +--rw MAs
                  +--rw MA* [MA-name-string]
                     +--rw MA-name-string       MA-name-string
                     .
                     .
                     +--rw MEP* [mep-name]
                     |  +--rw mep-name             MEP-name
                     |  +--rw (MEP-ID)?
                     |  |  +--:(MEP-ID-int)
                     |  |     +--rw MEP-ID-int?          int32
                     |  +--rw MEP-ID-format?       identityref
                     |  +--rw (mep-address)?
                     |  |  +--:(mac-address)
                     |  |  |  +--rw mac-address?   yang:mac-address
                     |  |  +--:(ipv4-address)
                     |  |  |  +--rw ipv4-address?  inet:ipv4-address
                     |  |  +--:(ipv6-address)
                     |  |     +--rw ipv6-address?  inet:ipv6-address
                     .          .
                     .          .
                     .          .

      Snippet of data hierarchy related to Maintenance Endpoint (MEP)

4.4.  RPC definitions

   The RPC model facilitates issuing commands to a NETCONF server (in
   this case to the device that need to execute the OAM command) and
   obtain a response.  RPC model defined here abstracts OAM specific
   commands in a technology independent manner.

   There are several RPC commands defined for the purpose of OAM.  In
   this section we present a snippet of the continuity check command for
   illustration purposes.  Please refer to Section 4.5 for the complete
   data hierarchy and Section 5 for the YANG model.

   module: ietf-conn-oam
      +--rw domains
            +--rw domain* [technology MD-name-string]
            +--rw technology        identityref
      .
      .



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  rpcs:
    +---x continuity-check {continuity-check}?
    |  +---w input
    |  |  +---w technology?             identityref
    |  |  +---w MD-name-string  -> /domains/domain/MD-name-string
    |  |  +---w md-level?       -> /domains/domain/md-level
    |  |  +---w MA-name-string  -> /domains/domain/MAs/MA/MA-name-string
    |  |  +---w cos-id?                 uint8
    |  |  +---w ttl?                    uint8
    |  |  +---w sub-type?               identityref
    |  |  +---w source-mep?     -> /domains/domain/MAs/MA/MEP/mep-name
    |  |  +---w destination-mep
    |  |  |  +---w (mep-address)?
    |  |  |  |  +--:(mac-address)
    |  |  |  |  |  +---w mac-address?     yang:mac-address
    |  |  |  |  +--:(ipv4-address)
    |  |  |  |  |  +---w ipv4-address?    inet:ipv4-address
    |  |  |  |  +--:(ipv6-address)
    |  |  |  |     +---w ipv6-address?    inet:ipv6-address
    |  |  |  +---w (MEP-ID)?
    |  |  |  |  +--:(MEP-ID-int)
    |  |  |  |     +---w MEP-ID-int?      int32
    |  |  |  +---w MEP-ID-format?   identityref
    |  |  +---w count?                  uint32
    |  |  +---w cc-transmit-interval?   Interval
    |  |  +---w packet-size?            uint32
    |  +--ro output
    |     +--ro (monitor-stats)?
    |        +--:(monitor-null)
    |           +--ro monitor-null?   empty
    +---x continuity-verification {connectivity-verification}?
    |  +---w input
    |  |  +---w MD-name-string  -> /domains/domain/MD-name-string
    |  |  +---w md-level?       -> /domains/domain/md-level
    |  |  +---w MA-name-string  -> /domains/domain/MAs/MA/MA-name-string
    |  |  +---w cos-id?            uint8
    |  |  +---w ttl?               uint8
    |  |  +---w sub-type?          identityref
    |  |  +---w source-mep?     -> /domains/domain/MAs/MA/MEP/mep-name
    |  |  +---w destination-mep
    |  |  |  +---w (mep-address)?
    |  |  |  |  +--:(mac-address)
    |  |  |  |  |  +---w mac-address?     yang:mac-address
    |  |  |  |  +--:(ipv4-address)
    |  |  |  |  |  +---w ipv4-address?    inet:ipv4-address
    |  |  |  |  +--:(ipv6-address)
    |  |  |  |     +---w ipv6-address?    inet:ipv6-address
    |  |  |  +---w (MEP-ID)?



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    |  |  |  |  +--:(MEP-ID-int)
    |  |  |  |     +---w MEP-ID-int?      int32
    |  |  |  +---w MEP-ID-format?   identityref
    |  |  +---w count?             uint32
    |  |  +---w interval?          Interval
    |  |  +---w packet-size?       uint32
    |  +--ro output
    |     +--ro (monitor-stats)?
    |        +--:(monitor-null)
    |           +--ro monitor-null?   empty
    +---x traceroute {traceroute}?
       +---w input
       |  +---w MD-name-string  -> /domains/domain/MD-name-string
       |  +---w md-level?       -> /domains/domain/md-level
       |  +---w MA-name-string  -> /domains/domain/MAs/MA/MA-name-string
       |  +---w cos-id?             uint8
       |  +---w ttl?                uint8
       |  +---w command-sub-type?   identityref
       |  +---w source-mep?     -> /domains/domain/MAs/MA/MEP/mep-name
       |  +---w destination-mep
       |  |  +---w (mep-address)?
       |  |  |  +--:(mac-address)
       |  |  |  |  +---w mac-address?     yang:mac-address
       |  |  |  +--:(ipv4-address)
       |  |  |  |  +---w ipv4-address?    inet:ipv4-address
       |  |  |  +--:(ipv6-address)
       |  |  |     +---w ipv6-address?    inet:ipv6-address
       |  |  +---w (MEP-ID)?
       |  |  |  +--:(MEP-ID-int)
       |  |  |     +---w MEP-ID-int?      int32
       |  |  +---w MEP-ID-format?   identityref
       |  +---w count?              uint32
       |  +---w interval?           Interval
       +--ro output
          +--ro response* [response-index]
             +--ro response-index     uint8
             +--ro ttl?               uint8
             +--ro destination-mep
             |  +--ro (mep-address)?
             |  |  +--:(mac-address)
             |  |  |  +--ro mac-address?     yang:mac-address
             |  |  +--:(ipv4-address)
             |  |  |  +--ro ipv4-address?    inet:ipv4-address
             |  |  +--:(ipv6-address)
             |  |     +--ro ipv6-address?    inet:ipv6-address
             |  +--ro (MEP-ID)?
             |  |  +--:(MEP-ID-int)
             |  |     +--ro MEP-ID-int?      int32



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             |  +--ro MEP-ID-format?   identityref
             +--ro mip {mip}?
             |  +--ro interface?      if:interface-ref
             |  +--ro (mip-address)?
             |     +--:(mac-address)
             |     |  +--ro mac-address?    yang:mac-address
             |     +--:(ipv4-address)
             |     |  +--ro ipv4-address?   inet:ipv4-address
             |     +--:(ipv6-address)
             |        +--ro ipv6-address?   inet:ipv6-address
             +--ro (monitor-stats)?
                +--:(monitor-null)
                   +--ro monitor-null?      empty

      Snippet of data hierarchy related to RPC call continuity-check

4.5.  Notifications

   Notification is sent on defect condition and defect clears with
   Maintenance Domain Name, MA Name, defect-type (The currently active
   defects), generating-mepid, and defect-message to indicate more
   details.

4.6.  Monitor statistics

   Grouping for monitoring statistics is to be used by Yang modules
   which Augment Yang to provide statistics due to pro-active OAM like
   CCM Messages.  For example CCM Transmit, CCM Receive, CCM Errors,
   etc.

4.7.  OAM data hierarchy

   The complete data hierarchy related to the connection oriented OAM
   YANG model is presented below.

module: ietf-conn-oam
    +--rw domains
       +--rw domain* [technology MD-name-string]
          +--rw technology        identityref
          +--rw MD-name-string    MD-name-string
          +--rw MD-name-format?   identityref
          +--rw (MD-name)?
          |  +--:(MD-name-null)
          |     +--rw MD-name-null?     empty
          +--rw md-level?         MD-level
          +--rw MAs
             +--rw MA* [MA-name-string]
                +--rw MA-name-string    MA-name-string



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                +--rw MA-name-format?   identityref
                +--rw (MA-name)?
                |  +--:(MA-name-null)
                |     +--rw MA-name-null?     empty
                +--rw (connectivity-context)?
                |  +--:(context-null)
                |     +--rw context-null?     empty
                +--rw cos-id?           uint8
                +--rw cc-enable?        boolean
                +--rw MEP* [mep-name]
                |  +--rw mep-name         MEP-name
                |  +--rw (MEP-ID)?
                |  |  +--:(MEP-ID-int)
                |  |     +--rw MEP-ID-int?      int32
                |  +--rw MEP-ID-format?   identityref
                |  +--rw (mep-address)?
                |  |  +--:(mac-address)
                |  |  |  +--rw mac-address?     yang:mac-address
                |  |  +--:(ipv4-address)
                |  |  |  +--rw ipv4-address?    inet:ipv4-address
                |  |  +--:(ipv6-address)
                |  |     +--rw ipv6-address?    inet:ipv6-address
                |  +--rw cos-id?          uint8
                |  +--rw cc-enable?       boolean
                |  +--rw session* [session-cookie]
                |     +--rw session-cookie             uint32
                |     +--rw destination-mep
                |     |  +--rw (MEP-ID)?
                |     |  |  +--:(MEP-ID-int)
                |     |  |     +--rw MEP-ID-int?      int32
                |     |  +--rw MEP-ID-format?   identityref
                |     +--rw destination-mep-address
                |     |  +--rw (mep-address)?
                |     |     +--:(mac-address)
                |     |     |  +--rw mac-address?    yang:mac-address
                |     |     +--:(ipv4-address)
                |     |     |  +--rw ipv4-address?   inet:ipv4-address
                |     |     +--:(ipv6-address)
                |     |        +--rw ipv6-address?   inet:ipv6-address
                |     +--rw cos-id?                    uint8
                +--rw MIP* [interface] {mip}?
                   +--rw interface       if:interface-ref
                   +--rw (mip-address)?
                      +--:(mac-address)
                      |  +--rw mac-address?    yang:mac-address
                      +--:(ipv4-address)
                      |  +--rw ipv4-address?   inet:ipv4-address
                      +--:(ipv6-address)



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                         +--rw ipv6-address?   inet:ipv6-address

  rpcs:
    +---x continuity-check {continuity-check}?
    |  +---w input
    |  |  +---w technology?             identityref
    |  |  +---w MD-name-string  -> /domains/domain/MD-name-string
    |  |  +---w md-level?       -> /domains/domain/md-level
    |  |  +---w MA-name-string  -> /domains/domain/MAs/MA/MA-name-string
    |  |  +---w cos-id?                 uint8
    |  |  +---w ttl?                    uint8
    |  |  +---w sub-type?               identityref
    |  |  +---w source-mep?     -> /domains/domain/MAs/MA/MEP/mep-name
    |  |  +---w destination-mep
    |  |  |  +---w (mep-address)?
    |  |  |  |  +--:(mac-address)
    |  |  |  |  |  +---w mac-address?     yang:mac-address
    |  |  |  |  +--:(ipv4-address)
    |  |  |  |  |  +---w ipv4-address?    inet:ipv4-address
    |  |  |  |  +--:(ipv6-address)
    |  |  |  |     +---w ipv6-address?    inet:ipv6-address
    |  |  |  +---w (MEP-ID)?
    |  |  |  |  +--:(MEP-ID-int)
    |  |  |  |     +---w MEP-ID-int?      int32
    |  |  |  +---w MEP-ID-format?   identityref
    |  |  +---w count?                  uint32
    |  |  +---w cc-transmit-interval?   Interval
    |  |  +---w packet-size?            uint32
    |  +--ro output
    |     +--ro (monitor-stats)?
    |        +--:(monitor-null)
    |           +--ro monitor-null?   empty
    +---x continuity-verification {connectivity-verification}?
    |  +---w input
    |  |  +---w MD-name-string  -> /domains/domain/MD-name-string
    |  |  +---w md-level?       -> /domains/domain/md-level
    |  |  +---w MA-name-string  -> /domains/domain/MAs/MA/MA-name-string
    |  |  +---w cos-id?            uint8
    |  |  +---w ttl?               uint8
    |  |  +---w sub-type?          identityref
    |  |  +---w source-mep?     -> /domains/domain/MAs/MA/MEP/mep-name
    |  |  +---w destination-mep
    |  |  |  +---w (mep-address)?
    |  |  |  |  +--:(mac-address)
    |  |  |  |  |  +---w mac-address?     yang:mac-address
    |  |  |  |  +--:(ipv4-address)
    |  |  |  |  |  +---w ipv4-address?    inet:ipv4-address
    |  |  |  |  +--:(ipv6-address)



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    |  |  |  |     +---w ipv6-address?    inet:ipv6-address
    |  |  |  +---w (MEP-ID)?
    |  |  |  |  +--:(MEP-ID-int)
    |  |  |  |     +---w MEP-ID-int?      int32
    |  |  |  +---w MEP-ID-format?   identityref
    |  |  +---w count?             uint32
    |  |  +---w interval?          Interval
    |  |  +---w packet-size?       uint32
    |  +--ro output
    |     +--ro (monitor-stats)?
    |        +--:(monitor-null)
    |           +--ro monitor-null?   empty
    +---x traceroute {traceroute}?
       +---w input
       |  +---w MD-name-string -> /domains/domain/MD-name-string
       |  +---w md-level?      -> /domains/domain/md-level
       |  +---w MA-name-string -> /domains/domain/MAs/MA/MA-name-string
       |  +---w cos-id?             uint8
       |  +---w ttl?                uint8
       |  +---w command-sub-type?   identityref
       |  +---w source-mep?    -> /domains/domain/MAs/MA/MEP/mep-name
       |  +---w destination-mep
       |  |  +---w (mep-address)?
       |  |  |  +--:(mac-address)
       |  |  |  |  +---w mac-address?     yang:mac-address
       |  |  |  +--:(ipv4-address)
       |  |  |  |  +---w ipv4-address?    inet:ipv4-address
       |  |  |  +--:(ipv6-address)
       |  |  |     +---w ipv6-address?    inet:ipv6-address
       |  |  +---w (MEP-ID)?
       |  |  |  +--:(MEP-ID-int)
       |  |  |     +---w MEP-ID-int?      int32
       |  |  +---w MEP-ID-format?   identityref
       |  +---w count?              uint32
       |  +---w interval?           Interval
       +--ro output
          +--ro response* [response-index]
             +--ro response-index     uint8
             +--ro ttl?               uint8
             +--ro destination-mep
             |  +--ro (mep-address)?
             |  |  +--:(mac-address)
             |  |  |  +--ro mac-address?     yang:mac-address
             |  |  +--:(ipv4-address)
             |  |  |  +--ro ipv4-address?    inet:ipv4-address
             |  |  +--:(ipv6-address)
             |  |     +--ro ipv6-address?    inet:ipv6-address
             |  +--ro (MEP-ID)?



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             |  |  +--:(MEP-ID-int)
             |  |     +--ro MEP-ID-int?      int32
             |  +--ro MEP-ID-format?   identityref
             +--ro mip {mip}?
             |  +--ro interface?      if:interface-ref
             |  +--ro (mip-address)?
             |     +--:(mac-address)
             |     |  +--ro mac-address?    yang:mac-address
             |     +--:(ipv4-address)
             |     |  +--ro ipv4-address?   inet:ipv4-address
             |     +--:(ipv6-address)
             |        +--ro ipv6-address?   inet:ipv6-address
             +--ro (monitor-stats)?
                +--:(monitor-null)
                   +--ro monitor-null?      empty

  notifications:
    +---n defect-condition-notification
    |  +--ro technology?         identityref
    |  +--ro MD-name-string -> /domains/domain/MD-name-string
    |  +--ro MA-name-string -> /domains/domain/MAs/MA/MA-name-string
    |  +--ro mep-name?      -> /domains/domain/MAs/MA/MEP/mep-name
    |  +--ro defect-type?        identityref
    |  +--ro generating-mepid
    |  |  +--ro (MEP-ID)?
    |  |  |  +--:(MEP-ID-int)
    |  |  |     +--ro MEP-ID-int?      int32
    |  |  +--ro MEP-ID-format?   identityref
    |  +--ro (defect)?
    |     +--:(defect-null)
    |     |  +--ro defect-null?        empty
    |     +--:(defect-code)
    |        +--ro defect-code?        int32
    +---n defect-cleared-notification
       +--ro technology?         identityref
       +--ro MD-name-string -> /domains/domain/MD-name-string
       +--ro MA-name-string -> /domains/domain/MAs/MA/MA-name-string
       +--ro mep-name?      -> /domains/domain/MAs/MA/MEP/mep-name
       +--ro defect-type?        identityref
       +--ro generating-mepid
       |  +--ro (MEP-ID)?
       |  |  +--:(MEP-ID-int)
       |  |     +--ro MEP-ID-int?      int32
       |  +--ro MEP-ID-format?   identityref
       +--ro (defect)?
          +--:(defect-null)
          |  +--ro defect-null?        empty
          +--:(defect-code)



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             +--ro defect-code?        int32

                           data hierarchy of OAM

5.  OAM YANG Module

   <CODE BEGINS> file "ietf-conn-oam.yang"

module ietf-conn-oam {
  namespace "urn:ietf:params:xml:ns:yang:ietf-conn-oam";
  prefix goam;

  import ietf-yang-types {
    prefix yang;
  }
  import ietf-inet-types {
    prefix inet;
  }
  import ietf-interfaces {
    prefix if;
  }

  organization "IETF LIME Working Group";
  contact
    "WG Web:    http://tools.ietf.org/wg/lime
     WG List:   mailto:lime@ietf.org
     WG Chair:  Carlos Pignataro cpignata@cisco.com
     WG Chair:  Ron Bonica rbonica@juniper.net
     Editor:    Deepak Kumar dekumar@cisco.com
     Editor:    Qin Wu bill.wu@huawei.com
     Editor:    Zitao Wang wangzitao@huawei.com";
  description
    "This YANG module defines the generic configuration,
  statistics and rpc for connection oriented OAM
  to be used within IETF in a protocol indpendent manner.
  Functional level abstraction is indendent
  with YANG modeling. It is assumed that each protocol
  maps corresponding abstracts to its native format.
  Each protocol may extend the YANG model defined
  here to include protocol specific extensions";

  revision 2017-04-10 {
    description
      "Initial revision. - 08 version";

    reference "draft-ietf-lime-yang-oam-model";
  }




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  /* features */
  feature connectivity-verification {
    description
      "This feature indicates that the server supports
    executing connectivity verification OAM command and
    returning a response. Servers that do not advertise
    this feature will not support executing
    connectivity verification command or rpc model for
    connectivity verification command.";
  }
  feature continuity-check{
    description
      "This feature indicates that the server supports
    executing continuity check OAM command and
    returning a response. Servers that do not advertise
    this feature will not support executing
    continuity check command or rpc model for
    continuity check command.";
  }

  feature traceroute{
    description
      "This feature indicates that the server supports
    executing traceroute OAM command and
    returning a response. Servers that do not advertise
    this feature will not support executing
    traceroute command or rpc model for
    traceroute command.";
   }
  feature mip {
   description
   "This feature indicates that the MIP (Maintenance Intermediate Point)
   need to
   be explicit configured";
  }
  /* Identities */

  identity technology-types {
    description
    "This is the base identy of technology types which are
    TRILL,MPLS-TP,vpls etc";
  }

  identity command-sub-type {
    description
      "Defines different rpc command subtypes,
    e.g rfc6905 trill OAM, this is optional for most cases";
  }



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  identity on-demand {
   base command-sub-type;
   description
   "On demand activation - indicates that the tool is activated
    manually to detect a specific anomaly.
    On-demand OAM method requires only transient configuration.";
  }

  identity proactive {
   base command-sub-type;
   description
   "Proactive activation - indicates that the tool is activated on a
    continual basis, where messages are sent periodically, and errors
    are detected when a certain number of expected messages are not
    received. Proactive OAM method requires persistent configuration.";
  }

  identity name-format {

    description
    "This defines the name format, IEEE 8021ag CFM defines varying
    styles of names. It is expected name format as an identity ref
    to be extended with new types.";
  }

  identity name-format-null {
    base name-format;
    description
    "Defines name format as null";
  }

  identity identifier-format {
    description
    "Identifier-format identity can be augmented to define other
     format identifiers used in MEP-ID etc";
  }

  identity identifier-format-integer {
    base identifier-format;
    description
    "Defines identifier-format to be integer";

  }

  identity defect-types {
    description
    "Defines different defect types, e.g. rdi
    (Remote Defect Indication), loss of continuity";



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  }
  identity rdi {
    base defect-types;
    description
      "Indicates the aggregate health of the remote MEPs. ";
  }

  identity remote-mep-defect{
    base defect-types;
    description
        "Indicates that one or more of the remote MEPs is
    reporting a failure ";
  }

  identity loss-of-continuity{
    base defect-types;
    description
    "If no proactive CC OAM packets from the source
    MEP (and in the case of CV, this includes the
    requirement to have the expected unique,
    technology dependent source MEP identifier)
    are received within the interval. ";
   }

   identity cv-defect {
    base defect-types;
    description
    "This function should support monitoring between the MEPs and,
    in addition, between a MEP and MIP.[RFC6371] highlights,
    when performing Connectivity Verification, the need for the
    Continuity Check and Connectivity Verification (CC-V) messages
    to include unique identification of the MEG that is being
    monitored and the MEP that originated the message.";
   }


  identity invalid-oam-defect{
    base defect-types;
    description
    "Indicates that one or more invalid OAM messages has been
    received and that 3.5 times that OAM message transmission
    interval has not yet expired.";
  }

  identity cross-connect-defect{
    base defect-types;
    description
    "Indicates that one or more cross-connect defect



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    (for example, a service ID does not match the VLAN.)
     messages has been received and that 3.5 times that OAM message
     transmission interval has not yet expired.";
  }

  /* typedefs */

  typedef MEP-name {
    type string;
    description
      "Generic administrative name for a MEP";
  }

  typedef Interval{
    type decimal64{
    fraction-digits 2;
   }
   units "milliseconds";
    description
    "Interval between packets in milliseconds.
    0 means no packets are sent.";
  }

  typedef MD-name-string {
    type string;
    description
      "Generic administrative name for an MD";
  }

  typedef MA-name-string {
    type string;
    description
      "Generic administrative name for an MA";
  }

  typedef oam-counter32 {
    type yang:zero-based-counter32;
    description
      "Defines 32 bit counter for OAM";
  }

  typedef MD-level {
    type uint32 {
      range "0..255";
    }
    description
      "Maintenance Domain level.  The level may be restricted in
       certain protocols (eg to 0-7)";



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  }

  /* groupings */

  grouping maintenance-domain-reference {
  description
     "This grouping uniquely identifies a maintenance domain.";
  leaf maintenance-domain {
     type leafref {
       path "/goam:domains/goam:domain/goam:MD-name-string";
    }
  description
    "A reference to a specific Maintenance Domain.";
}
}

grouping maintenance-association-reference {
  description
    "This grouping uniquely identifies a
     maintenance association. It consists
     of a maintence-domain-reference and
     a maintenance-association leafref";
  uses maintenance-domain-reference;
  leaf maintenance-association {
    type leafref {
      path "/goam:domains/goam:domain"
          +"[goam:MD-name-string = current()/"
          +"../maintenance-domain]/goam:MAs"
          +"/goam:MA/goam:MA-name-string";
    }
  description
      "A reference to a specific Maintenance Association.";
  }
}

grouping maintenance-association-end-point-reference {
  description
  "This grouping uniquely identifies
   a maintenance association. It consists
   of a maintence-association-reference and
   a maintenance-association-end-point leafref";
  uses maintenance-association-reference;
  leaf maintenance-association-end-point {
    type leafref {
      path "/goam:domains/goam:domain"
          +"[goam:MD-name-string = current()/"
          +"../maintenance-domain]/goam:MAs"
          +"/goam:MA[goam:MA-name-string = "



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          +"current()/../maintenance-association]"
          +"/goam:MEP/goam:mep-name";
     }
    description
      "A reference to a specific Maintenance
          association End Point.";
  }
 }

  grouping time-to-live {
    leaf ttl{
     type uint8;
     description
       "Time to Live.";
    }
    description
      "Time to Live grouping.";
  }
  grouping defect-message {
    choice defect {
      case defect-null {
        description
          "This is a placeholder when no defect status is needed";
        leaf defect-null {
           type empty;
           description
             "there is no defect define, it will be defined in
              technology specific model.";
        }
      }
      case defect-code {
        description
          "This is a placeholder to display defect code.";
        leaf defect-code {
           type int32;
           description
             "Defect code is integer value specific to technology.";
        }
      }

      description
        "Defect Message choices.";
    }

    description
      "Defect Message.";
  }




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  grouping mep-address {
    choice mep-address {
      case mac-address {
        leaf mac-address {
          type yang:mac-address;
          description
          "MAC Address";
        }
      description
      "MAC Address based MEP Addressing.";
      }
      case ipv4-address {
        leaf ipv4-address {
          type inet:ipv4-address;
          description
          "IPv4 Address";
        }
      description
      "IP Address based MEP Addressing.";
      }
      case ipv6-address {
        leaf ipv6-address {
          type inet:ipv6-address;
          description
          "IPv6 Address";
        }
        description
        "IPv6 Address based MEP Addressing.";
      }
      description
       "MEP Addressing.";
    }
    description
     "MEP Address";
  }
  grouping mip-address {
    choice mip-address {
      case mac-address {
        leaf mac-address {
          type yang:mac-address;
          description
          "MAC Address";
        }
      description
      "MAC Address based MIP Addressing.";
      }
      case ipv4-address {
        leaf ipv4-address {



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          type inet:ipv4-address;
          description
          "IPv4 Address";
        }

      description
      "IP Address based MIP Addressing.";
      }
      case ipv6-address {
        leaf ipv6-address {
          type inet:ipv6-address;
          description
          "IPv6 Address";
        }
        description
        "IPv6 Address based MIP Addressing.";
      }
      description
       "MIP Addressing.";
    }
    description
     "MIP Address";
  }
  grouping maintenance-domain-id {
    description
      "Grouping containing leaves sufficient to identify an MD";
    leaf technology {
      type identityref {
        base technology-types;
      }
      mandatory true;
      description
        "Defines the technology";
    }
    leaf MD-name-string {
      type MD-name-string;
      mandatory true;
      description
        "Defines the generic administrative maintenance domain name";
    }
  }

  grouping MD-name {
    leaf MD-name-format {
      type identityref {
        base name-format;
      }
      description



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        "Name format.";
    }
    choice MD-name {
      case MD-name-null {
        leaf MD-name-null {
        when "'../../../MD-name-format' = 'name-format-null'" {
        description
        "MD name format is equal to null format.";
        }
        type empty;
        description
        "MD name Null.";
        }
      }
      description
        "MD name.";
    }
    description
      "MD name";
  }

  grouping ma-identifier {
    description
      "Grouping containing leaves sufficient to identify an MA";
    leaf MA-name-string {
      type MA-name-string;

      description

        "MA name string.";
    }
  }

  grouping MA-name {
    description
      "MA name";
    leaf MA-name-format {
      type identityref {
        base name-format;
      }
      description
        "Ma name format";
    }
    choice MA-name {
     case MA-name-null {
      leaf MA-name-null {
       when "'../../../MA-name-format' = 'name-format-null'" {
       description



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         "MA";
      }
        type empty;

        description
        "Empty";
        }
      }
      description
        "MA name";
    }
  }

  grouping MEP-ID {
    choice MEP-ID {
      default "MEP-ID-int";
      case MEP-ID-int {
        leaf MEP-ID-int {
          type int32;
  description
    "MEP ID in integer format";
        }
      }
      description
        "MEP-ID";
    }

    leaf MEP-ID-format {

      type identityref {
        base identifier-format;
      }
      description
        "MEP ID format.";
    }
    description
      "MEP-ID";
  }

  grouping MEP {
    description
      "Defines elements within the MEP";
    leaf mep-name {
      type MEP-name;
      mandatory true;
      description
        "Generic administrative name of the MEP";
    }



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    uses MEP-ID;
    uses mep-address;
  }

 grouping monitor-stats {
   description
    "grouping for monitoring statistics, this will be augmented
    by others who use this component";
    choice monitor-stats {

     default "monitor-null";
      case monitor-null {
       description
        "This is a place holder when
         no monitoring statistics is needed";
         leaf monitor-null {
          type empty;
          description
          "There is no monitoring statistics to be defined";
              }
            }
          description
          "Define the monitor stats";
          }
        }

  grouping connectivity-context {
    description
      "Grouping defining the connectivity context for an MA; for
       example, a VRF for VPLS, or an LSP for MPLS-TP.  This will be
       augmented by each protocol who use this component";
    choice connectivity-context {
      default "context-null";
      case context-null {
        description
          "This is a place holder when no context is needed";
        leaf context-null {
          type empty;
          description
            "There is no context define";
        }
      }
      description
        "Connectivity context";
    }
  }
  grouping cos {
    description



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    "Priority used in transmitted packets; for example, in the
    EXP field in MPLS-TP.";

    leaf cos-id {
     type uint8;
     description
     "Class of service";
    }
  }
  grouping MIP-grouping {
   uses mip-address;
   description
   "Grouping for MIP configuration";
  }

  container domains {
    description
      "Contains configuration related data. Within the container
       is list of fault domains. Within each domian has List of MA.";
    list domain {
      key "technology MD-name-string";
      ordered-by system;
      description
        "Define the list of Domains within the IETF-OAM";
      uses maintenance-domain-id;
      uses MD-name;
      leaf md-level {
        type MD-level;
        description
          "Defines the MD-Level";
      }
      container MAs {
        description
          "This container defines MA, within that have multiple MA
           and within MA have MEP";
        list MA {
          key "MA-name-string";
          ordered-by system;
          uses ma-identifier;
          uses MA-name;
          uses connectivity-context;
          uses cos {
          description
          "Default class of service for this MA,
           which may be overridden
           for particular MEPs,
           sessions or operations.";
          }



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             leaf cc-enable{
              type boolean;
              description
              "Indicate whether the CC enable.";
             }
          list MEP {
            key "mep-name";

            ordered-by system;
            description
            "Contain list of MEPS";
            uses MEP;
            uses cos;
            leaf cc-enable{
             type boolean;
             description
             "Indicate whether the CC enable.";
            }
            list session {
              key "session-cookie";
              ordered-by user;
              description
                "Monitoring session to/from a particular remote MEP.
                 Depending on the protocol, this could represent CC
                 messages received from a single remote MEP (if the
                 protocol uses multicast CCs) or a target to which
                 unicast echo request CCs are sent and from which
                 responses are received (if the protocol uses a
                 unicast request/response mechanism).";
              leaf session-cookie {
                type uint32;
                description
                "Cookie to identify different sessions, when there
                 are multiple remote MEPs or multiple sessions to
                 the same remote MEP.";
              }
              container destination-mep {
                uses MEP-ID;
                description
                "Destination MEP";
              }
              container destination-mep-address {
                uses mep-address;
                description
                "Destination MEP Address";
              }
              uses cos;
            }



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          }
          list MIP {
           if-feature mip;
           key "interface";
           leaf interface {
            type if:interface-ref;
            description
            "Interface";
           }
           uses MIP-grouping;
           description
           "List for MIP";
          }
          description
          "Maintenance Association list";
         }
        }
      }

  }

  notification defect-condition-notification {
    description
      "When defect condition is met this notification is sent";
    leaf technology {
      type identityref {
        base technology-types;
      }
      description
      "The technology";
    }
    leaf MD-name-string {
      type leafref{
      path "/domains/domain/MD-name-string";
      }
      mandatory true;
      description
      "Indicate which MD is seeing the defect";
    }
    leaf MA-name-string{
     type leafref{
     path "/domains/domain/MAs/MA/MA-name-string";
     }
      mandatory true;
      description
      "Indicate which MA is seeing the defect";
        }
    leaf mep-name {



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      type leafref{
       path "/domains/domain/MAs/MA/MEP/mep-name";
      }
      description
       "Indicate which MEP is seeing the defect";
    }
    leaf defect-type {
      type identityref {
        base defect-types;
      }
      description
      "The currently active defects on the specific MEP.";
    }
    container generating-mepid {

      uses MEP-ID;
      description
      "Who is generating the defect (if known) if
       unknown make it 0.";
    }
    uses defect-message {
      description
      "Defect message to indicate more details.";
    }
  }

  notification defect-cleared-notification {
    description
      "When defect cleared is met this notification is sent";
    leaf technology {
      type identityref {
        base technology-types;
      }
      description
        "The technology";
    }
    leaf MD-name-string {
      type leafref{
      path "/domains/domain/MD-name-string";
      }
      mandatory true;
      description
      "Indicate which MD is seeing the defect";
    }
    leaf MA-name-string{
      type leafref{
      path "/domains/domain/MAs/MA/MA-name-string";
      }



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      mandatory true;
      description
      "Indicate which MA is seeing the defect";
        }
    leaf mep-name {
      type leafref{
      path "/domains/domain/MAs/MA/MEP/mep-name";
      }
      description
        "Indicate which MEP is seeing the defect";
    }

    leaf defect-type {
      type identityref {
        base defect-types;
      }
      description
      "The currently active defects on the specific MEP.";
    }
    container generating-mepid {
      uses MEP-ID;
      description
      "Who is generating the defect (if known) if
       unknown make it 0.";
    }
    uses defect-message {
      description
      "Defect message to indicate more details.";
    }
  }

  rpc continuity-check {
    if-feature "continuity-check";
    description
      "Generates continuity-check as per RFC7276 Table 4.";
    input {
    leaf technology {
      type identityref {
        base technology-types;
      }
      description
        "The technology";
    }
    leaf MD-name-string {
      type leafref{
       path "/domains/domain/MD-name-string";
      }
      mandatory true;



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      description
      "Indicate which MD is seeing the defect";
    }
    leaf md-level {
     type leafref {
     path "/domains/domain/md-level";
     }
     description
     "The maintenance domain level.";
    }
    leaf MA-name-string{
     type leafref{
     path "/domains/domain/MAs/MA/MA-name-string";
     }
     mandatory true;
     description
     "Indicate which MA is seeing the defect";
    }
      uses cos;
      uses time-to-live;
      leaf sub-type {
        type identityref {
          base command-sub-type;
        }
        description
        "Defines different command types";
      }
      leaf source-mep {
       type leafref{
       path "/domains/domain/MAs/MA/MEP/mep-name";
       }
       description
       "Source MEP";
      }
      container destination-mep {
        uses mep-address;
        uses MEP-ID {
        description
        "Only applicable if the destination is a MEP";
        }
        description
        "Destination MEP";

      }
      leaf count {
        type uint32;
        default "3";
        description



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         "Number of continuity-check message to send";
      }
      leaf cc-transmit-interval {
        type Interval;
        description
          "Interval between echo requests";
      }
      leaf packet-size {
        type uint32 {
          range "0..10000";
        }
        default "64";
        description
          "Size of continuity-check packets, in octets";
      }
    }
    output {
      uses monitor-stats {
        description
          "Stats of continuity check.";
      }

    }
  }

  rpc continuity-verification {
    if-feature connectivity-verification;
    description
      "Generates continuity-verification as per RFC7276 Table 4.";
    input {
     leaf MD-name-string {
      type leafref{
       path "/domains/domain/MD-name-string";
      }
      mandatory true;
      description
      "Indicate which MD is seeing the defect";
     }

     leaf md-level {
      type leafref {
      path "/domains/domain/md-level";
      }
      description
      "The maintenance domain level.";
     }

     leaf MA-name-string{



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      type leafref{
      path "/domains/domain/MAs/MA/MA-name-string";
      }
      mandatory true;
      description
      "Indicate which MA is seeing the defect";
     }
      uses cos;
      uses time-to-live;
      leaf sub-type {
        type identityref {
          base command-sub-type;
        }
        description
         "Defines different command types";
      }
      leaf source-mep {
       type leafref{
        path "/domains/domain/MAs/MA/MEP/mep-name";
       }
       description
       "Source MEP";
      }
      container destination-mep {
        uses mep-address;
        uses MEP-ID {
          description "Only applicable if the destination is a MEP";
        }
        description
        "Destination MEP";

      }
      leaf count {
        type uint32;
        default "3";
        description
          "Number of continuity-verification message to send";
      }
      leaf interval {
        type Interval;
        description
          "Interval between echo requests";
      }
      leaf packet-size {
        type uint32 {
          range "64..10000";
        }
        default "64";



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        description
          "Size of continuity-verification packets, in octets";
      }
    }

    output {
      uses monitor-stats {
        description
          "Stats of continuity check.";
      }
    }
  }
  rpc traceroute {
    if-feature traceroute;
    description
      "Generates Traceroute or Path Trace and return response.
       Referencing RFC7276 for common Toolset name, for
       MPLS-TP OAM it's Route Tracing, and for TRILL OAM It's
       Path Tracing tool. Starts with TTL of one and increment
       by one at each hop. Untill destination reached or TTL
       reach max value";
    input {
     leaf MD-name-string {
      type leafref{
       path "/domains/domain/MD-name-string";
      }
      mandatory true;
      description
      "Indicate which MD is seeing the defect";
     }

     leaf md-level {
      type leafref {
      path "/domains/domain/md-level";
      }
      description
      "The maintenance domain level.";
     }

     leaf MA-name-string{
      type leafref{
       path "/domains/domain/MAs/MA/MA-name-string";
      }
      mandatory true;
      description
      "Indicate which MA is seeing the defect";
         }
      uses cos;



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      uses time-to-live;
      leaf command-sub-type {
        type identityref {
          base command-sub-type;
        }
        description
         "Defines different command types";
      }
      leaf source-mep {
       type leafref{
        path "/domains/domain/MAs/MA/MEP/mep-name";
       }
       description
       "Source MEP";
      }
      container destination-mep {
        uses mep-address;
        uses MEP-ID {
         description
         "Only applicable if the destination is a MEP";
        }
        description
        "Destination MEP";
      }
      leaf count {
        type uint32;
        default "1";
        description
        "Number of traceroute probes to send.  In protocols where a
         separate message is sent at each TTL, this is the number
         of packets to send at each TTL.";
      }
      leaf interval {
        type Interval;
        description
        "Interval between echo requests";
      }
    }
    output {
      list response {
        key "response-index";

        leaf response-index {
         type uint8;
          description
          "Arbitrary index for the response.  In protocols that
           guarantee there is only a single response at each TTL,
                   the TTL can be used as the response index.";



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        }
        uses time-to-live;
        container destination-mep {
          description "MEP from which the response has been received";
          uses mep-address;
          uses MEP-ID {
            description
            "Only applicable if the destination is a MEP";
          }
        }
        container mip {
         if-feature mip;
         leaf interface {
         type if:interface-ref;
         description
         "MIP interface";
         }
         uses mip-address;
         description
         "MIP responding with traceroute";
         }
        uses monitor-stats {
         description
         "Stats of traceroute.";
        }
      description
        "List of response.";
      }
    }
  }
}


   <CODE ENDS>

6.  Base Mode

   The Base Mode ('default mode' described in section 4) defines default
   configuration that MUST be present in the devices that comply with
   this document.  Base Mode allows users to have "zero-touch"
   experience.  Several parameters require technology specific
   definition.

6.1.  MEP Address

   In the Base Mode of operation, the MEP Address is by default the IP
   address of the interface on which the MEP is located.




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6.2.  MEP ID for Base Mode

   In the Base Mode of operation, each device creates a single MEP
   associated with a virtual OAM port with no physical layer (NULL PHY).
   The MEP-ID associated with this MEP is zero (0).  The choice of MEP-
   ID zero is explained below.

   MEP-ID is 2 octet field by default.  It is never used on the wire
   except when using CCM.  It is important to have method that can
   derive MEP-ID of base mode in an automatic manner with no user
   intervention.  IP address cannot be directly used for this purpose as
   the MEP-ID is much smaller field.  For Base Mode of operation we
   propose to use MEP-ID zero (0) as the default MEP-ID.

   CCM packet use MEP-ID on the payload.  CCM MUST NOT be used in the
   Base Mode.  Hence CCM MUST be disabled on the Maintenance Association
   of the Base Mode.

   If CCM is required, users MUST configure a separate Maintenance
   association and assign unique value for the corresponding MEP IDs.

   CFM [IEEE802.1ag] defines MEP ID as an unsigned integer in the range
   1 to 8191.  In this document we propose extend the range to 0 to
   65535.  Value 0 is reserved for MEP-ID of Base Mode operation and
   MUST NOT be used for other purposes.

6.3.  Maintenance Association

   The ID of the Maintenance Association (MA-ID) [IEEE802.1ag] has a
   flexible format and includes two parts: Maintenance Domain Name and
   Short MA name.  In the Based Mode of operation, the value of the
   Maintenance Domain Name must be the character string
   "GenericBaseMode" (excluding the quotes ").  In Base Mode operation
   Short MA Name format is set to 2-octet integer format (value 3 in
   Short MA Format field [IEEE802.1ag]) and Short MA name set to 65532
   (0xFFFC).

7.  Connection-oriented OAM YANG model applicability

   "ietf-conn-oam" model defined in this document provides technology-
   independent abstraction of key OAM constructs for connection oriented
   protocols.  This model can be further extended to include technology
   specific details, e.g., adding new data nodes with technology
   specific functions and parameters into proper anchor points of the
   base model, so as to develop a technology-specific connection-
   oriented OAM model.





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   This section demonstrates the usability of the connection-oriented
   YANG OAM data model to various connection-oriented OAM technologies,
   e.g., TRILL and MPLS-TP.  Note that, in this section, we only present
   several snippets of technology-specific model extensions for
   illustrative purposes.  The complete model extensions should be
   worked on in respective protocol working groups.

7.1.  Generic YANG Model extension for TRILL OAM

   The TRILL YANG module is augmenting connection oriented OAM module
   for both configuration and RPC commands.

   The TRILL YANG module requires the base TRILL module ([I-D.ietf-
   trill-yang]) to be supported as there is a strong relationship
   between those modules.

   The configuration extensions for connection oriented OAM include MD
   configuration extension, Technology type extension, MA configuration
   extension, Connectivity-Context Extension, MEP Configuration
   Extension, ECMP extension.  In the RPC extension, the continuity-
   check and path-discovery RPC are extended with TRILL specific.

7.1.1.  MD Configuration Extension

   MD level configuration parameters are management information which
   can be inherited in the TRILL OAM model and set by connection
   oriented base model as default values.  For example domain name can
   be set to area-ID in the TRILL OAM case.  In addition, at the
   Maintenance Domain level, domain data node at root level can be
   augmented with technology type.

   Note that MD level configuration parameters provides context
   information for management system to correlate faults, defects,
   network failures with location information, which helps quickly
   identify root causes of network failures.

7.1.1.1.  Technology Type Extension

   No TRILL technology type has been defined in the connection oriented
   base model.  Therefore a technology type extension is required in the
   TRILL OAM model.  The technology type "trill" is defined as an
   identity that augments the base "technology-types" defined in the
   connection oriented base model:








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      identity trill{
       base goam:technology-types;
       description
        "trill type";
      }

7.1.2.  MA Configuration Extension

   MA level configuration parameters are management information which
   can be inherited in the TRILL OAM model and set by connection
   oriented base model as default values.  In addition, at the
   Maintenance Association(MA) level, MA data node at the second level
   can be augmented with connectivity-context extension.

   Note that MA level configuration parameters provides context
   information for management system to correlate faults, defects,
   network failures with location information, which helps quickly
   identify root causes of network failures.

7.1.2.1.  Connectivity-Context Extension

   In TRILL OAM, one example of connectivity-context is either a 12 bit
   VLAN ID or a 24 bit Fine Grain Label.  The connection oriented base
   model defines a placeholder for context-id.  This allows other
   technologies to easily augment that to include technology specific
   extensions.  The snippet below depicts an example of augmenting
   connectivity-context to include either VLAN ID or Fine Grain Label.

      augment /goam:domains/goam:domain/goam:MAs
      /goam:MA /goam:connectivity-context:
            +--:(connectivity-context-vlan)
            |  +--rw connectivity-context-vlan?   vlan
            +--:(connectivity-context-fgl)
               +--rw connectivity-context-fgl?    fgl

7.1.3.  MEP Configuration Extension

   The MEP configuration definition in the connection oriented base
   model already supports configuring the interface of MEP with either
   MAC address or IP address.  In addition, the MEP address can be
   represented using a 2 octet RBridge Nickname in TRILL OAM . Hence,
   the TRILL OAM model augments the MEP configuration in base model to
   add a nickname case into the MEP address choice node as follows:

   augment /goam:domains/goam:domain/goam:MAs
      /goam:MA/ goam:MEP/goam:mep-address:
            +--:( mep-address-trill)
            |  +--rw mep-address-trill?  tril-rb-nickname



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   In addition, at the Maintenance Association Endpoint(MEP) level, MEP
   data node at the third level can be augmented with ECMP extension.

7.1.3.1.  ECMP Extension

   Since TRILL supports ECMP path selection, flow-entropy in TRILL is
   defined as a 96 octet field in the LIME model extension for TRILL
   OAM.  The snippet below illustrates its extension.

    augment /goam:domains/goam:domain/goam:MAs/goam:MA/goam:MEP:
               +--rw flow-entropy-trill?   flow-entropy-trill
      augment /goam:domains/goam:domain/goam:MAs/goam:MA/goam:MEP
      /goam:session:
               +--rw flow-entropy-trill?   flow-entropy-trill

7.1.4.  RPC extension

   In the TRILL OAM YANG model, the continuity-check and path-discovery
   RPC commands are extended with TRILL specific requirements.  The
   snippet below depicts an example of illustrates the TRILL OAM RPC
   extension.






























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      augment /goam:continuity-check/goam:input:
            +--ro (out-of-band)?
            |  +--:(ipv4-address)
            |  |  +--ro ipv4-address?      inet:ipv4-address
            |  +--:(ipv6-address)
            |  |  +--ro ipv6-address?      inet:ipv6-address
            |  +--:(trill-nickname)
            |     +--ro trill-nickname?    tril-rb-nickname
            +--ro diagnostic-vlan?   boolean
      augment /goam:continuity-check/goam:input:
               +--ro flow-entropy-trill?   flow-entropy-trill
      augment /goam:continuity-check/goam:output:
            +--ro upstream-rbridge?   tril-rb-nickname
            +--ro next-hop-rbridge*   tril-rb-nickname
      augment /goam:path-discovery/goam:input:
            +--ro (out-of-band)?
            |  +--:(ipv4-address)
            |  |  +--ro ipv4-address?      inet:ipv4-address
            |  +--:(ipv6-address)
            |  |  +--ro ipv6-address?      inet:ipv6-address
            |  +--:(trill-nickname)
            |     +--ro trill-nickname?    tril-rb-nickname
            +--ro diagnostic-vlan?   boolean
      augment /goam:path-discovery/goam:input:
               +--ro flow-entropy-trill?   flow-entropy-trill
      augment /goam:path-discovery/goam:output/goam:response:
            +--ro upstream-rbridge?   tril-rb-nickname
            +--ro next-hop-rbridge*   tril-rb-nickname

7.2.  Generic YANG Model extension for MPLS-TP OAM

   The MPLS-TP OAM YANG module can augment connection oriented OAM
   Module with some technology-specific details.  And the
   [mpls-tp-oam-yang] presents the YANG Data model for MPLS-TP OAM.

   The configuration extensions for connection oriented OAM include MD
   configuration extension, Technology type extension, Sub Technology
   Type Extension ,MA configuration extension, MEP Configuration
   Extension.

7.2.1.  MD Configuration Extension

   MD level configuration parameters are management information which
   can be inherited in the MPLS-TP OAM model and set by LIME base model
   as default values.  For example domain name can be set to area-ID or
   the provider's Autonomous System Number(ASN) [RFC6370] in the MPLS-TP
   OAM case.  In addition, at the Maintenance Domain level, domain data




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   node at root level can be augmented with technology type and sub-
   technology type.

   Note that MD level configuration parameters provides context
   information for management system to correlate faults, defects,
   network failures with location information, which helps quickly
   identify root causes of network failures

7.2.1.1.  Technology Type Extension

   No MPLS-TP technology type has been defined in the connection
   oriented base model, hence it is required in the MPLS OAM model.  The
   technology type "mpls-tp" is defined as an identity that augments the
   base "technology-types" defined in the connection oriented base
   model:

       identity mpls-tp{
             base goam:technology-types;
             description
              "mpls-tp type";
            }

7.2.1.2.  Sub Technology Type Extension

   In MPLS-TP, since different encapsulation types such as IP/UDP
   Encapsulation, PW-ACH encapsulation can be employed, the "technology-
   sub-type" data node is defined and added into the MPLS OAM model to
   further identify the encapsulation types within the MPLS-TP OAM
   model.  Based on it, we also define a technology sub-type for IP/UDP
   encapsulation and PW-ACH encapsulation.  Other Encapsulation types
   can be defined in the same way.  The snippet below depicts an example
   of several encapsulation types.



















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   identity technology-sub-type {
         description
         "certain implementations can have different
          encapsulation types such as ip/udp, pw-ach and so on.
          Instead of defining separate models for each
          encapsulation, we define a technology sub-type to
       further identify different encapsulations.
       Technology sub-type is associated at the MA level"; }

              identity technology-sub-type-udp {
                base technology-sub-type;
                description
                  "technology sub-type is IP/UDP encapsulation";
              }

              identity technology-sub-type-ach {
                base technology-sub-type;
                description
                  "technology sub-type is PW-ACH encapsulation";
              }
              }

         augment "/goam:domains/goam:domain/goam:MAs/goam:MA" {
                leaf technology-sub-type {
                  type identityref {
                    base technology-sub-type;
                  }
                }
              }

7.2.2.  MA Configuration Extension

   MA level configuration parameters are management information which
   can be inherited in the MPLS-TP OAM model and set by Connection
   Oriented base model as default values.  One example of MA Name could
   be MEG LSP ID or MEG Section ID or MEG PW ID[RFC6370].

   Note that MA level configuration parameters provides context
   information for management system to correlate faults, defects,
   network failures with location information, which helps quickly
   identify root causes of network failures.

7.2.3.  MEP Configuration Extension

   In MPLS-TP, MEP-ID is either a variable length label value in case of
   G-ACH encapsulation or a 2 octet unsigned integer value in case of
   IP/UDP encapsulation.  One example of MEP-ID is MPLS-TP LSP_MEP_ID
   [RFC6370].  In the connection-oriented base model, MEP-ID is defined



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   as a choice/case node which can supports an int32 value, and the same
   definition can be used for MPLS-TP with no further modification.  In
   addition, at the Maintenance Association Endpoint(MEP) level, MEP
   data node at the third level can be augmented with Session extension
   and interface extension.

8.  Security Considerations

   The YANG module defined in this memo is designed to be accessed via
   the NETCONF protocol [RFC6241] [RFC6241].  The lowest NETCONF layer
   is the secure transport layer and the mandatory-to-implement secure
   transport is SSH [RFC6242] [RFC6242].  The NETCONF access control
   model [RFC6536] [RFC6536] provides the means to restrict access for
   particular NETCONF users to a pre-configured subset of all available
   NETCONF protocol operations and content.

   There are a number of data nodes defined in the YANG module which are
   writable/creatable/deletable (i.e., config true, which is the
   default).  These data nodes may be considered sensitive or vulnerable
   in some network environments.  Write operations (e.g., <edit-config>)
   to these data nodes without proper protection can have a negative
   effect on network operations.

   The vulnerable "config true" subtrees and data nodes are the
   following:

   /goam:domains/goam:domain/

   /goam:domains/goam:domain/goam:MAs/goam:MA/

   /goam:domains/goam:domain/goam:MAs/goam:MA/goam:MEP

   /goam:domains/goam:domain/goam:MAs/goam:MA/goam:MEP/goam:session/

   Unauthorized access to any of these lists can adversely affect OAM
   management system handling of end-to-end OAM and coordination of OAM
   within underlying network layers This may lead to inconsistent
   configuration, reporting, and presentation for the OAM mechanisms
   used to manage the network.

9.  IANA Considerations

   This document registers a URI in the IETF XML registry [RFC3688]
   [RFC3688].  Following the format in RFC 3688, the following
   registration is requested to be made:






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   URI: urn:ietf:params:xml:ns:yang:ietf-gen-oam

   Registrant Contact: The IESG.

   XML: N/A, the requested URI is an XML namespace.

   This document registers a YANG module in the YANG Module Names
   registry [RFC6020].

  name: ietf-gen-oam namespace: urn:ietf:params:xml:ns:yang:ietf-gen-oam
     prefix: goam reference: RFC XXXX

10.  Acknowledgments

   Giles Heron came up with the idea of developing a YANG model as a way
   of creating a unified OAM API set (interface), work in this document
   is largely an inspiration of that.  Alexander Clemm provided many
   valuable tips, comments and remarks that helped to refine the YANG
   model presented in this document.

   Carlos Pignataro, David Ball,Mahesh Jethanandani,Benoit
   Claise,Ladislav Lhotka,GUBALLA JENS,Yuji Tochio,Gregory Mirsky, Huub
   van Helvoort, Tom Taylor, Dapeng Liu,Mishael Wexler, Adi Molkho
   participated and contributed to this document.

11.  References

11.1.  Normative References

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

   [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
              DOI 10.17487/RFC3688, January 2004,
              <http://www.rfc-editor.org/info/rfc3688>.

   [RFC6020]  Bjorklund, M., Ed., "YANG - A Data Modeling Language for
              the Network Configuration Protocol (NETCONF)", RFC 6020,
              DOI 10.17487/RFC6020, October 2010,
              <http://www.rfc-editor.org/info/rfc6020>.

   [RFC6241]  Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
              and A. Bierman, Ed., "Network Configuration Protocol
              (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
              <http://www.rfc-editor.org/info/rfc6241>.




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   [RFC6242]  Wasserman, M., "Using the NETCONF Protocol over Secure
              Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011,
              <http://www.rfc-editor.org/info/rfc6242>.

   [RFC6370]  Bocci, M., Swallow, G., and E. Gray, "MPLS Transport
              Profile (MPLS-TP) Identifiers", RFC 6370,
              DOI 10.17487/RFC6370, September 2011,
              <http://www.rfc-editor.org/info/rfc6370>.

   [RFC6536]  Bierman, A. and M. Bjorklund, "Network Configuration
              Protocol (NETCONF) Access Control Model", RFC 6536,
              DOI 10.17487/RFC6536, March 2012,
              <http://www.rfc-editor.org/info/rfc6536>.

11.2.  Informative References

   [G.8013]   "OAM functions and mechanisms for Ethernet based
              networks", ITU-T Recommendation G.8013/Y.1731, 2013.

   [IEEE802.1ag]
              "Connectivity Fault Management", IEEE Std 802.1ag-2011,
              August 2011.

   [mpls-tp-oam-yang]
              Zhang, L., Zheng, L., Aldrin, S., and G. Mirsky, "YANG
              Data Model for MPLS-TP Operations, Administration, and
              Maintenance", draft-zhang-mpls-tp-yang-oam (work in
              progress), 2016.

   [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,
              <http://www.rfc-editor.org/info/rfc6136>.

   [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,
              <http://www.rfc-editor.org/info/rfc6291>.

   [RFC6325]  Perlman, R., Eastlake 3rd, D., Dutt, D., Gai, S., and A.
              Ghanwani, "Routing Bridges (RBridges): Base Protocol
              Specification", RFC 6325, DOI 10.17487/RFC6325, July 2011,
              <http://www.rfc-editor.org/info/rfc6325>.






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   [RFC6371]  Busi, I., Ed. and D. Allan, Ed., "Operations,
              Administration, and Maintenance Framework for MPLS-Based
              Transport Networks", RFC 6371, DOI 10.17487/RFC6371,
              September 2011, <http://www.rfc-editor.org/info/rfc6371>.

   [RFC7174]  Salam, S., Senevirathne, T., Aldrin, S., and D. Eastlake
              3rd, "Transparent Interconnection of Lots of Links (TRILL)
              Operations, Administration, and Maintenance (OAM)
              Framework", RFC 7174, DOI 10.17487/RFC7174, May 2014,
              <http://www.rfc-editor.org/info/rfc7174>.

   [RFC7276]  Mizrahi, T., Sprecher, N., Bellagamba, E., and Y.
              Weingarten, "An Overview of Operations, Administration,
              and Maintenance (OAM) Tools", RFC 7276,
              DOI 10.17487/RFC7276, June 2014,
              <http://www.rfc-editor.org/info/rfc7276>.

   [RFC7455]  Senevirathne, T., Finn, N., Salam, S., Kumar, D., Eastlake
              3rd, D., Aldrin, S., and Y. Li, "Transparent
              Interconnection of Lots of Links (TRILL): Fault
              Management", RFC 7455, DOI 10.17487/RFC7455, March 2015,
              <http://www.rfc-editor.org/info/rfc7455>.

Appendix A.  Contributors' Addresses

      Tissa Senevirathne
      Consultant

      Email: tsenevir@gmail.com


      Norman Finn
      CISCO Systems
      510 McCarthy Blvd
      Milpitas, CA  95035
      USA

      Email: nfinn@cisco.com

      Samer Salam
      CISCO Systems
      595 Burrard St. Suite 2123
      Vancouver, BC  V7X 1J1
      Canada

      Email: ssalam@cisco.com





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Authors' Addresses

   Deepak Kumar
   CISCO Systems
   510 McCarthy Blvd
   Milpitas, CA  95035
   USA

   Email: dekumar@cisco.com


   Qin Wu
   Huawei
   101 Software Avenue, Yuhua District
   Nanjing, Jiangsu  210012
   China

   Email: bill.wu@huawei.com


   Michael Wang
   Huawei Technologies,Co.,Ltd
   101 Software Avenue, Yuhua District
   Nanjing  210012
   China

   Email: wangzitao@huawei.com
























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