I2RS Working Group                                             Y. Zhuang
Internet-Draft                                                    D. Shi
Intended status: Standards Track                                  Huawei
Expires: June 25, July 13, 2018                                             R. Gu
                                                            China Mobile
                                                      H. Ananthakrishnan
                                                           Packet Design
                                                       December 22, 2017
                                                         January 9, 2018

     A YANG Data Model for Fabric Topology in Data Center Network
           draft-ietf-i2rs-yang-dc-fabric-network-topology-03 Networks
           draft-ietf-i2rs-yang-dc-fabric-network-topology-04

Abstract

   This document defines a YANG data model for fabric topology in Data
   Center Network.

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 https://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 June 25, July 13, 2018.

Copyright Notice

   Copyright (c) 2017 2018 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   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  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Definitions an Acronyms . . . . . . . . . . . . . . . . . . .   3
     2.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   3
     2.2.  Tree diagram  . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Model Overview  . . . . . . . . . . . . . . . . . . . . . . .   4
     3.1.  Topology Model structure  . . . . . . . . . . . . . . . .   4
     3.2.  Fabric Topology Model . . . . . . . . . . . . . . . . . .   5   4
       3.2.1.  Fabric Topology . . . . . . . . . . . . . . . . . . .   5
       3.2.2.  Fabric node extension . . . . . . . . . . . . . . . .   6
       3.2.3.  Fabric termination-point extension  . . . . . . . . .   7
   4.  Fabric YANG Module  . . . . . . . . . . . . . . . . . . . . .   8   7
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  20  19
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  21  20
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  22  21
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  22  21
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .  22  21
     8.2.  Informative References  . . . . . . . . . . . . . . . . .  23  22
   Appendix A.  Non NMDA -state modules  . . . . . . . . . . . . . .  23  22
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  29  28

1.  Introduction

   Normally, a data center (DC) network is composed of single or
   multiple fabrics which are also known as PODs (a Point (Points Of Delivery).
   These fabrics may be heterogeneous due to implementation of different
   technologies while when a DC network upgrading is upgraded or enrolling new techniques and features.
   features are enrolled.  For example, Fabric A may use VXLAN while
   Fabric B may use VLAN within a DC network.  Likewise, a legacy Fabric an existing
   fabric may use VXLAN while a new Fabric B implemented fabric, for example a fabric
   introduced for DC upgrade and expansion, may implement a technique
   discussed in NVO3 WG WG, such as GPE[I-D. draft-ietf-nvo3-vxlan-gpe] may be built due to DC
   expansion and upgrading. GPE [I-D. draft-ietf-nvo3-vxlan-gpe].
   The configuration and management of such DC networks with
   heterogeneous fabrics will be sophisticated and
   complex. result in considerable complexity,
   requiring a fair amount of sophistication.

   Luckily, for a DC network, a fabric can be considered as an atomic
   structure to provide network services and management, as well as
   expand network capacity. for management purposes.  From this point of view, the miscellaneous
   management of the DC network management can be decomposed to task into a set of managing tasks to
   manage each fabric respectively along with their connections, which can make separately, as well as the
   entire fabric
   interconnections.  This way, the overall management much concentrated task becomes very
   flexible and flexible, also makes it easy to
   expand.

   With this purpose, expand and adopt to DC networks that
   evolve over time.

   As a basis for DC fabric management, this document defines a YANG
   data model [6020][7950] for the
   Fabric-based Data fabric-based data center topology by using YANG [6020][7950]. topology.  To do
   so, it augments the generic network and network topology data models
   defined in [I-D.ietf-i2rs-yang-network-topo] with information that is
   specific to Data Center fabric network.

   This networks.

   The model defines the generic configuration and operational state for
   a fabric-based network topology, which can subsequently be extended
   by vendors with specific information.  This vendor-specific information as needed.  The model can then
   be used by a network controller to represent its view of the fabric
   topology that it controls and expose it this view to network
   administrators or applications for DC network management.

   With

   Within the context of topology architecture defined in [I-D.ietf-i2rs-
   yang-network-topo] [I-D.ietf-
   i2rs-yang-network-topo] and [I.D. draft-ietf-i2rs-usecase-reqs-summary], draft-ietf-i2rs-usecase-reqs-
   summary], this model can also be treated as an application of the
   I2RS network topology model [I-D.ietf-i2rs-yang-network-topo] in the
   scenario of Data center network management.  It can also act as a
   service topology when mapping network elements at the fabric layer to
   elements to of other topologies, such as L3 topology topologies as defined in
   [I.D. draft-ietf-
   i2rs-yang-l3-topology-01. draft-ietf-i2rs-yang-l3-topology].

   By using this the fabric topology model, model defined in this document, people
   can treat a fabric as an a holistic entity and focus on characteristics
   of fabrics a fabric (such as encapsulation type, gateway type, etc.) as well
   as their interconnections its connections to other fabrics while putting the underlay
   topology aside.  As such, clients can consume the topology
   information at the fabric level, while level with no need to be aware of the
   entire set of links and nodes in the corresponding underlay networks.  The
   configuration of a
   A fabric topology can be made configured by a network
   administractor to administrator using
   the controller by adding physical devices and links
   of a fabric into a fabric network. fabric.
   Alternatively, the fabric topology can also learnt be learned from the underlay
   network infrastructure.

2.  Definitions an Acronyms

   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].

2.1.  Terminology

   DC Fabric: also known as POD, is a module of network, compute,
   storage, and application components that work together to deliver
   networking services.  It is a repeatable design pattern, and its
   components maximize the modularity, scalability, and manageability of
   data centers.

2.2.  Tree diagram

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

  Each node is printed as:
    <status> <flags> <name> <opts> <type>

    <status> is one of:
         +  for current
         x  for deprecated
         o  for obsolete
    <flags> is one of:
        rw for configuration data
        ro for non-configuration data
        -x for rpcs
        -n for notifications
    <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
    <type> is the name of the type for leafs "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and leaf-lists "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 RFC-2119 significance.

2.1.  Terminology

   Fabric: also known as a POD, is a module of network, compute,
   storage, and application components that work together to deliver
   networking services.  It represents a repeatable design pattern.  Its
   components maximize the modularity, scalability, and manageability of
   data centers.

3.  Model Overview

   This section provides an overview of the DC Fabric data center fabric topology
   model and its relationship with other topology models.

3.1.  Topology Model structure

   The relationship of the DC fabric topology model and other topology
   models is shown in the following figure (dotted lines in the figure
   denote augmentations). figure.

             +------------------------+
             |      network model     |
             +------------------------+
                          |
                          |
             +------------V-----------+
             | network topology model |
             +------------------------+
                          |
        +-----------+-----+------+-------------+
        |           |            |             |
    +---V----+  +---V----+   +---V----+   +----V---+
    |   L1   |  |   L2   |   |   L3   |   | Fabric |
    |topology|  |topology|   |topology|   |topology|
    |  model |  |  model |   |  model |   |  model |
    +--------+  +--------+   +--------+   +--------+
       Figure 1: The network data model structure

   From the perspective of resource management and service provisioning
   for a Data Center data center network, the fabric topology model augments the
   basic network topology model with definitions and features specific
   to a DC fabric, to provide common configuration and operations for
   heterogeneous fabrics.

3.2.  Fabric Topology Model

   The fabric topology model module is designed to be generic and can be
   applied to data center fabrics built with different technologies,
   such as VLAN, VXLAN etc.  The main purpose of this module is to
   configure and manage fabrics and their connections. provide  It provides a fabric-
   based
   fabric-based topology view for data center network applications.

3.2.1.  Fabric Topology

   In the fabric topology module, a fabric is modeled as a node in the of a
   network, while as such the fabric-based Data data center network consists of a
   set of fabric nodes and their connections known as "fabric port". connections.  The following is the snip depicts a
   snippet of the definition definitions to show the main structure of the model: model.
   The notation syntax follows [I-D.draft-ietf-netmod-yang-tree-
   diagrams].

        module: ietf-fabric-topology
        augment /nw:networks/nw:network/nw:network-types:
           +--rw fabric-network!
        augment /nw:networks/nw:network/nw:node:
           +--rw fabric-attributes
                  +--rw fabric-id?              fabric-id
                  +--rw name?           string
                  +--rw type?           fabrictype:underlay-network-type
                  +--rw description?    string
                  +--rw options
                  +--...
        augment /nw:networks/nw:network/nw:node/nt:termination-point:
           +--ro fport-attributes
                  +--ro name?          string
                  +--ro role?          fabric-port-role
                  +--ro type?          fabric-port-type

   The fabric topology module augments the generic ietf-network and
   ietf-network-topology modules as follows:

   o  A new topology type "ietf-fabric-topology" is introduced and added
      under the "network-types" container of the ietf-network module.

   o  Fabric is defined as a node under the network/node container.  A
      new container of "fabric-attributes" is defined to carry attributes
      for a fabric network such as gateway mode, fabric types, involved device nodes
      nodes, and links etc. links.

   o  Termination points (in network topology module) are augmented with
      fabric port attributes defined in a container.  The "termination-
      point" here can is used to represent the "port" of a fabric "port" that provides
      connections to other nodes, such as device internally, an internal device, another
      fabric externally and also externally, or end hosts.

   Details of the fabric node and the fabric termination point extension
   will be explained in the following sections.

3.2.2.  Fabric node extension

   As a an atomic network, a fabric itself is composed of a set of network
   elements i.e. devices, and related links.  As stated previously, the  The configuration of a
   fabric is contained under the "fabric-attributes" container depicted
   as follows: follows.  The notation syntax follows [I-D.draft-ietf-netmod-yang-
   tree-diagrams].

                +--rw fabric-attributes
                   +--rw fabric-id?      fabric-id
                   +--rw name?           string
                   +--rw type?           fabrictype:underlay-network-type
                   +--rw vni-capacity
                   |  +--rw min?   int32
                   |  +--rw max?   int32
                   +--rw description?    string
                   +--rw options
                   |  +--rw gateway-mode?           enumeration
                   |  +--rw traffic-behavior?       enumeration
                   |  +--rw capability-supported*   fabrictype:service-capabilities
                   +--rw device-nodes* [device-ref]
                   |  +--rw device-ref    fabrictype:node-ref
                   |  +--rw role?         fabrictype:device-role
                   +--rw device-links* [link-ref]
                   |  +--rw link-ref    fabrictype:link-ref
                   +--rw device-ports* [port-ref]
                          +--rw port-ref     fabrictype:tp-ref
                          +--rw port-type?   fabrictypes:port-type
                          +--rw bandwidth?   fabrictypes:bandwidth

   As in

   In the module, additional data objects for fabric nodes are
   introduced by augmenting the "node" list of the network module.  New
   objects include fabric name, type of the fabric, descriptions of the
   fabric as well as a set of options defined in an "options" container.
   The
   options "options" container includes type of the gateway-mode type (centralized
   or distributed) and traffic-behavior (whether acl an Access Control Lists
   (ACLs) is needed for the traffic).  Also, it defines includes a list of
   device-nodes and related links as supporting-nodes to form a fabric
   network.  These device nodes and links are leaf-ref represented as leaf-refs
   of existing nodes and links in the underlay topology.  For the
   device-node, the "role" object is defined to
   represents represent the role of the a
   device within the fabric, such as "SPINE" or "LEAF", which should
   work together with the gateway-mode.

3.2.3.  Fabric termination-point extension

   Since the a fabric can be considered as a node, in this concept, "termination-points" can
   represent "ports" of a fabric "ports" that connects connect to other fabrics or fabrics, end hosts, besides representing ports that
   connect as
   well as devices inside the fabric itself. fabric.

   As such, the "termination-point" in the fabric topology has three
   roles, that are internal TP that connects to devices within a fabric,
   external TP that connects to outside network, and access TP to end
   hosts.

   The set of "termination-point" "termination-points" of a fabric indicates indicate all
   connections of the fabric, including its internal connections,
   interconnections with other fabrics fabrics, and also connections to end hosts for a DC
   network. hosts.

   The structure of fabric ports is as follows.  The notation syntax
   follows [I-D.draft-ietf-netmod-yang-tree-diagrams].

   The structure of fabric ports is as follows:

           augment /nw:networks/nw:network/nw:node/nt:termination-point:
                 +--ro fport-attributes
                    +--ro name?          string
                    +--ro role?          fabric-port-role
                    +--ro type?          fabric-port-type
                    +--ro device-port?   tp-ref
                    +--ro (tunnel-option)?

   It augments the termination points (in network topology module) with
   fabric port attributes defined in a container.

   New nodes are defined for fabric ports which include including fabric name, role of
   the port within the fabric (internal port, external port to outside
   network, access port to end hosts), port type (l2 interface, l3
   interface
   interface, etc).  By defining the device-port as a tp-ref, a fabric
   port can be mapped to a device node in the underlay network.

   Also, a new container for tunnel-options is introduced to present the
   tunnel configuration on the a port.

   The termination points point information are all learnt is learned from the underlay
   networks but
   networks, not configured by the fabric topology layer.

4.  Fabric YANG Module

<CODE BEGINS> file "ietf-dc-fabric-types@2017-12-21.yang"
    module ietf-dc-fabric-types {

    yang-version 1.1;
    namespace "urn:ietf:params:xml:ns:yang:ietf-dc-fabric-types";
    prefix fabrictypes;
        organization
    "IETF I2RS (Interface to the Routing System) Working Group";

        contact
    "WG Web:    <http://tools.ietf.org/wg/i2rs/ >
     WG List:   <mailto:i2rs@ietf.org>

     Editor:    Yan Zhuang
                <mailto:zhuangyan.zhuang@huawei.com>

     Editor:    Danian Shi
                <mailto:shidanian@huawei.com>";

     description
        "This module contains a collection of YANG definitions for Fabric.
        Copyright (c) 2016 IETF Trust and the persons identified as
        authors of the code.  All rights reserved.

        Redistribution and use in source and binary forms, with or
        without modification, is permitted pursuant to, and subject
        to the license terms contained in, the Simplified BSD License
        set forth in Section 4.c of the IETF Trust's Legal Provisions
        Relating to IETF Documents
        (http://trustee.ietf.org/license-info).

        This version of this YANG module is part of
        draft-ietf-i2rs-yang-dc-fabric-network-topology;
        see the RFC itself for full legal notices.

        NOTE TO RFC EDITOR: Please replace above reference to
        draft-ietf-i2rs-yang-dc-fabric-network-topology-03 with RFC
        number when published (i.e. RFC xxxx).";

    revision "2017-12-21"{
        description
            "Initial revision.
             NOTE TO RFC EDITOR: Please replace the following reference to
             draft-ietf-i2rs-yang-dc-fabric-network-topology-03 with RFC
             number when published (i.e. RFC xxxx).";
        reference
            "draft-ietf-i2rs-yang-dc-fabric-network-topology-03";
        }

    identity fabric-type {
        description
           "Base type for fabric networks";
    }
    identity vxlan-fabric {
        base fabric-type;
        description "Vxlan fabric";
    }

    identity vlan-fabric {
        base fabric-type;
        description
           "Vlan fabric";
    }

    identity trill-fabric {
        base fabric-type;
        description "Trill fabric";
    }
    identity port-type {
        description
           "Base type for fabric port";
        }
    identity eth {
        base port-type;
        description "ETH";
    }
    identity serial {
        base port-type;
        description "Serial";
    }

    identity bandwidth {
        description "Base for bandwidth";
    }
    identity bw-1M {
        base bandwidth;
        description "1M";
    }
    identity bw-10M {
        base bandwidth;
        description "10M";
    }
    identity bw-100M {
        base bandwidth;
        description "100M";
    }
    identity bw-1G {
        base bandwidth;
        description "1G";
    }
    identity bw-10G {
        base bandwidth;
        description "10G";
    }
    identity bw-40G {
        base bandwidth;
        description "40G";
    }
    identity bw-100G{
        base bandwidth;
        description "100G";
    }

    identity device-role {
        description "Base for the device role in a fabric.";
    }
    identity spine {
        base device-role;
        description "This is a spine node in a fabric.";
    }
    identity leaf {
        base device-role;
        description "This is a leaf node in a fabric. ";
    }
    identity border {
        base device-role;
        description "This is a border node to connect to
        other fabric/network.";
    }
    identity fabric-port-role {
        description "Base for the port's role in a fabric.";
    }
    identity internal {
        base fabric-port-role;
        description "The port is used for devices to access
        each other within a fabric.";
    }
    identity external {
        base fabric-port-role;
        description "The port is used for a fabric to connect
        to outside network.";
    }
    identity access {
        base fabric-port-role;
        description "The port is used for an endpoint to
        connect to a fabric.";
    }

    /*
     * Typedefs
     */
    typedef service-capabilities {
        type enumeration {
            enum ip-mapping {
                description "NAT";
                        }
            enum acl-redirect{
                description "Acl redirect, which can provide
                SFC function";
                        }
            enum dynamic-route-exchange{
                description "Dynamic route exchange";
                        }
        }
        description
            "Capability of the device";
    }

    typedef port-type {
        type identityref {
             base port-type;
        }
        description "Port type: ethernet or serial or others.";
    }
    typedef bandwidth {
        type identityref {
             base bandwidth;
        }
        description "Bandwidth of the port.";
    }
    typedef node-ref {
        type instance-identifier;
        description "A reference to a node in topology";
    }

    typedef tp-ref {
        type instance-identifier;
        description "A reference to a termination point in topology";
    }

    typedef link-ref {
        type instance-identifier;
        description "A reference to a link in topology";
    }

    typedef underlay-network-type {
        type identityref {
             base fabric-type;
        }
        description "The type of physical network that implements this
        fabric.Examples are vlan, and trill.";
    }
    typedef device-role {
         type identityref {
             base device-role;
        }
        description "Role of the device node.";
    }
    typedef fabric-port-role {
        type identityref {
             base fabric-port-role;
        }
        description "Role of the port in a fabric.";
    }

    typedef fabric-port-type {
        type enumeration {
            enum layer2interface {
                description "L2 interface";
            }
            enum layer3interface {
                description "L3 interface";
            }
            enum layer2Tunnel {
                description "L2 tunnel";
            }
            enum layer3Tunnel {
                description "L3 tunnel";
            }
        }
                description
            "Fabric port type";
    }

    grouping fabric-port {
        description
            "Attributes of a fabric port.";
        leaf name {
            type string;
            description "Name of the port.";
        }
        leaf role {
            type fabric-port-role;
            description "Role of the port in a fabric.";
        }
        leaf type {
            type fabric-port-type;
            description "Type of the port";
        }
        leaf device-port {
            type tp-ref;
            description "The device port it mapped to.";
        }
        choice tunnel-option {
            description "Tunnel options to connect two fabrics.
            It could be L2 Tunnel or L3 Tunnel.";
        }
    }
}
<CODE ENDS>

<CODE BEGINS> file "ietf-dc-fabric-topology@2017-12-21.yang"
    module ietf-dc-fabric-topology {

    yang-version 1.1;
    namespace "urn:ietf:params:xml:ns:yang:ietf-dc-fabric-topology";
    prefix fabric;

    import ietf-network {
        prefix nw;

        reference
        "draft-ietf-i2rs-yang-network-topo-20
        NOTE TO RFC EDITOR:
        (1) Please replace above reference to
        draft-ietf-i2rs-yang-network-topo-20 with RFC
        number when published (i.e. RFC xxxx).
        (2) Please replace the date in the revision statement with the
         date of publication when published.";
    }

    import ietf-network-topology {
        prefix nt;

        reference
        "draft-ietf-i2rs-yang-network-topo-20
        NOTE TO RFC EDITOR:
        (1) Please replace above reference to
        draft-ietf-i2rs-yang-network-topo-20 with RFC
        number when published (i.e. RFC xxxx).
        (2) Please replace the date in the revision statement with the
         date of publication when published.";
    }
    import ietf-dc-fabric-types {
        prefix fabrictypes;

        reference
        "draft-ietf-i2rs-yang-dc-fabric-network-topology-03
        NOTE TO RFC EDITOR:
         (1) Please replace above reference to draft-ietf-i2rs-yang-dc
         -fabric-network-topology-03 with RFC number when publised
         (i.e. RFC xxxx).
         (2) Please replace the data in the revision statement with the
         data of publication when published.";
    }

    organization
    "IETF I2RS (Interface to the Routing System) Working Group";

    contact
    "WG Web:    <http://tools.ietf.org/wg/i2rs/ >
     WG List:   <mailto:i2rs@ietf.org>

     Editor:    Yan Zhuang
                <mailto:zhuangyan.zhuang@huawei.com>

     Editor:    Danian Shi
                <mailto:shidanian@huawei.com>";

    description
       "This module contains a collection of YANG definitions for Fabric.

        Copyright (c) 2016 IETF Trust and the persons identified as
        authors of the code.  All rights reserved.

        Redistribution and use in source and binary forms, with or
        without modification, is permitted pursuant to, and subject
        to the license terms contained in, the Simplified BSD License
        set forth in Section 4.c of the IETF Trust's Legal Provisions
        Relating to IETF Documents
        (http://trustee.ietf.org/license-info).

        This version of this YANG module is part of
        draft-ietf-i2rs-yang-dc-fabric-network-topology;see the RFC
        itself for full legal notices.

        NOTE TO RFC EDITOR: Please replace above reference to
        draft-ietf-i2rs-yang-dc-fabric-network-topology-03 with RFC
        number when published (i.e. RFC xxxx).";
        revision "2017-12-21"{
        description
             "Initial revision.
              NOTE TO RFC EDITOR: Please replace the following reference
              to draft-ietf-i2rs-yang-dc-fabric-network-topology-03 with
              RFC number when published (i.e. RFC xxxx).";
        reference
            "draft-ietf-i2rs-yang-dc-fabric-network-topology-03";
    }

    identity fabric-context {
        description
           "Identity of fabric context";
    }

    typedef fabric-id {
        type nw:node-id;
        description
            "An identifier for a fabric in a topology.
            The identifier is generated by compose-fabric RPC.";
    }

    //grouping statements
    grouping fabric-network-type {
        description "Identify the topology type to be fabric.";
        container fabric-network {
            presence "indicates fabric Network";
        description
          "The presence of the container node indicates fabric topology";
      }
    }

    grouping fabric-options {
        description "Options for a fabric";

        leaf gateway-mode {
            type enumeration {
                enum centralized {
                    description "The Fabric uses centerilized gateway, in
                    which gateway is deployed on SPINE node.";
                }
                enum distributed {
                    description "The Fabric uses distributed gateway, in
                    which gateway is deployed on LEAF node.";
                }
            }
            default "distributed";
            description "Gateway mode of the fabric";

        }

        leaf traffic-behavior {
            type enumeration {
                enum normal {
                    description "Normal";
                }
                enum policy-driven {
                    description "Policy driven";
                }
            }
            default "normal";
            description "Traffic behavior of the fabric";
        }

        leaf-list capability-supported {
            type fabrictypes:service-capabilities;
            description
               "Supported services of the fabric";
        }
    }

    grouping device-attributes {
        description "device attributes";
        leaf device-ref {
            type fabrictypes:node-ref;
            description
                "The device the fabric includes.";
        }
        leaf role {
            type fabrictypes:device-role;
            default fabrictypes:leaf;
            description
                "Role of the device node";
        }
    }

    grouping link-attributes {
                description "Link attributes";
        leaf link-ref {
            type fabrictypes:link-ref;
            description
                "The link it includes";
        }
    }

    grouping port-attributes {
        description "Port attributes";
        leaf port-ref {
            type fabrictypes:tp-ref;
            description
                "The port it refers to.";
        }
        leaf port-type {
            type fabrictypes:port-type;
            description
                "Port type: ethernet or serial or others.";
        }
        leaf bandwidth {
            type fabrictypes:bandwidth;
            description
                "Bandwidth of the port.";
        }
    }

    grouping fabric-attributes {
        description "Attributes of a fabric";

        leaf fabric-id {
            type fabric-id;
            description
                "Fabric id";
        }

        leaf name {
            type string;
            description
                "Name of the fabric";
        }

        leaf type {
            type fabrictypes:underlay-network-type;
            description
                "The type of physical network that implements this
                 fabric.Examples are vlan, and trill.";
        }

        container vni-capacity {
            description "Number of vnis that the fabric has";
            leaf min {
                type int32;
                description
                    "Vni min capacity";
            }

            leaf max {
                type int32;
                description
                    "Vni max capacity";
            }
        }

        leaf description {
            type string;
            description
                "Description of the fabric";
        }

        container options {
            description "Options of the fabric";
            uses fabric-options;
        }

        list device-nodes {
            key device-ref;
            description "Device nodes that include in a fabric.";
            uses device-attributes;
        }

        list device-links {
            key link-ref;
            description "Links that include within a fabric.";
            uses link-attributes;
        }

        list device-ports {
            key port-ref;
            description "Ports that include in the fabric.";
            uses port-attributes;
        }

    }

        // augment statements

    augment "/nw:networks/nw:network/nw:network-types" {
    description
        "Introduce new network type for Fabric-based logical topology";

        uses fabric-network-type;
        }

    augment "/nw:networks/nw:network/nw:node" {
        when "/nw:networks/nw:network/nw:network-types/fabric:fabric-network" {
        description
          "Augmentation parameters apply only for networks
           with fabric topology";
      }
        description "Augmentation for fabric nodes created by faas.";

        container fabric-attributes {
                        description
                        "Attributes for a fabric network";

            uses fabric-attributes;
        }
    }

    augment "/nw:networks/nw:network/nw:node/nt:termination-point" {
        when "/nw:networks/nw:network/nw:network-types/fabric:fabric-network" {
        description
          "Augmentation parameters apply only for networks
           with fabric topology";
      }
        description "Augmentation for port on fabric.";

        container fport-attributes {
            config false;
            description
               "Attributes for fabric ports";
            uses fabrictypes:fabric-port;
        }
    }
}
<CODE ENDS>

5.  IANA Considerations

   This document registers the following namespace URIs in the "IETF XML
   Registry" [RFC3688]:

   URI: urn:ietf:params:xml:ns:yang:ietf-dc-fabric-types Registrant
   Contact: The IESG.  XML: N/A; the requested URI is an XML namespace.

   URI: urn:ietf:params:xml:ns:yang:ietf-dc-fabric-topology Registrant
   Contact: The IESG.  XML: N/A; the requested URI is an XML namespace.

   URI: urn:ietf:params:xml:ns:yang:ietf-dc-fabric-topology-state
   Registrant Contact: The IESG.  XML: N/A; the requested URI is an XML
   namespace.

   This document registers the following YANG modules in the "YANG
   Module Names" registry [RFC6020]:

   NOTE TO THE RFC EDITOR: In the list below, please replace references
   to "draft-ietf-i2rs-yang-dc-fabric-network-topology-03 (RFC form)"
   with RFC number when published (i.e.  RFC xxxx).

   Name: ietf-dc-fabric-types Namespace:
   urn:ietf:params:xml:ns:yang:ietf-dc-fabric-types Prefix: fabrictypes
   Reference: draft-ietf-i2rs-yang-dc-fabric-network-topology-03.txt
   (RFC form)

   Name: ietf-dc-fabric-topology Namespace:
   urn:ietf:params:xml:ns:yang:ietf-dc-fabric-topology Prefix: fabric
   Reference: draft-ietf-i2rs-yang-dc-fabric-network-topology-03.txt
   (RFC form)

   Name: ietf-dc-fabric-topology-state Namespace:
   urn:ietf:params:xml:ns:yang:ietf-dc-fabric-topology-state Prefix:
   sfabric Reference: draft-ietf-i2rs-yang-dc-fabric-network-topology-
   03.txt (RFC form)

6.  Security Considerations

   The YANG module defined in this document is designed to be accessed
   via network management protocols such as NETCONF [RFC6241] or
   RESTCONF [RFC8040].  The lowest NETCONF layer is the secure transport
   layer, and the mandatory-to-implement secure transport is Secure
   Shell (SSH) [RFC6242].  The lowest RESTCONF layer is HTTPS, and the
   mandatory-to-implement secure transport is TLS [RFC5246].

   The NETCONF access control model [RFC6536] provides the means to
   restrict access for particular NETCONF or RESTCONF users to a
   preconfigured subset of all available NETCONF or RESTCONF protocol
   operations and content.These are the content.  The subtrees and data nodes and their
   sensitivity/vulnerability in the ietf-dc-fabric-topology
   module: module are
   as follows:

   fabric-attributes: A malicious client could attempt to sabotage the
   configuration of important fabric attributes, such as device-nodes, device-nodes or
   type.

   Some of the readable data nodes in this YANG module may be considered
   sensitive or vulnerable in some network environments.  It is thus
   important to control read access (e.g., via get, get-config, or
   notification) to these data nodes.  These are the  The subtrees and data nodes and
   their sensitivity/vulnerability in the ietf-dc-fabric-
   topology module: ietf-dc-fabric-topology module
   are as follows:

   fport-attributes: A malicious client could attempt to read the
   connections of fabrics without permission, such as device-port, name.

7.  Acknowledgements

   We wish to acknowledge the helpful contributions, comments, and
   suggestions that were received from Alexander Clemm, Donald E.
   Eastlake, Xufeng Liu, Susan Hares, Wei Song, Luis M.  Contreras and
   Benoit Claise.

8.  References

8.1.  Normative References

   [I-D.draft-ietf-i2rs-yang-l3-topology]
              Clemm, A., Medved, J., Tkacik, T., Liu, X., Bryskin, I.,
              Guo, A., Ananthakrishnan, H., Bahadur, N., and V. Beeram,
              "A YANG Data Model for Layer 3 Topologies", I-D draft-
              ietf-i2rs-yang-l3-topology-04, September 2016.

   [I-D.draft-ietf-i2rs-yang-network-topo]
              Clemm, A., Medved, J., Tkacik, T., Varga, R., Bahadur, N.,
              and H. Ananthakrishnan, "A YANG Data Model for Network
              Topologies", I-D draft-ietf-i2rs-yang-network-topo-06,
              September 2016.

   [I-D.draft-ietf-netmod-revised-datastores-06]
              Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K.,
              and R. Wilton, "A Revised Conceptual Model for YANG
              Datastores", I-D draft-ietf-netmod-revised-datastores-06,
              October 2017.

   [I-D.draft-ietf-nvo3-vxlan-gpe]
              Maino, F., Kreeger, L., and U. Elzur, "Generic Protocol
              Extension for VXLAN", I-D draft-ietf-i2rs-yang-network-
              topo-02, October 2016.

   [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>.

   [RFC5246]  Dierks, T. and E. Rescorla, "Transport Layer Security
              (TLS) Protocol Version 1.2", August 2008,
              <http://www.rfc-editor.org/info/rfc5246>.

   [RFC6020]  Bjorklund, M., "YANG - A Data Modeling Language for the
              Network Configuration Protocol (NETCONF)", RFC 6020,
              October 2010.

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

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

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

   [RFC6991]  Schoenwaelder, J., "Common YANG Data Types", RFC 6991,
              July 2013.

   [RFC7950]  Bjorklund, M., "The YANG 1.1 Data Modeling Language",
              RFC 7950, DOI 10.17487/RFC7950, Auguest 2016.

   [RFC8040]  Bierman, A., Bjorklund, B., and K. Watsen, "RESTCONF
              Protocol", Jan 2017,
              <http://www.rfc-editor.org/info/rfc8040>.

8.2.  Informative References

   [I-D.draft-ietf-i2rs-usecase-reqs-summary]
              Hares, S. and M. Chen, "Summary of I2RS Use Case
              Requirements", I-D draft-ietf-i2rs-usecase-reqs-summary-
              01, draft-ietf-netmod-yang-tree-diagrams,
              May 2015.

   [I-D.draft-ietf-netmod-yang-tree-diagrams]
              Bjorklund, M. and L. Berger, "YANG Tree Diagrams", I-D
              draft-ietf-netmod-yang-tree-diagrams, October 2017.

Appendix A.  Non NMDA -state modules

   The YANG module ietf-fabric-toplogy defined in this document augments
   two modules, ietf-network and ietf-network-topology, that are
   designed to be used in conjunction with implementations that support
   the Network Management Datastore Architecture (NMDA) defined in [I-
   D.draft-ietf-netmod-revised-datastores].  In order to allow
   implementations to use the model even in case when NMDA is not
   supported, a set of companion modules have been defined that
   represent a state model of networks and network topologies, ietf-
   network-state and ietf-network-topology-state, respectively.

   In order to be able to use the model for fabric topologies defined in
   this in this document in conjunction with non-NMDA compliant
   implementations, a corresponding companion module needs to be
   introduced as well.  This companion module, ietf-fabric-topology-
   state, mirrors ietf-fabric-topology.  However, the module augments
   ietf-network-state (instead of ietf-network and ietf-network-
   topology) and all of its data nodes are non-configurable.

   Like ietf-network-state and ietf-network-topology-state, ietf-fabric-
   topology-state SHOULD NOT be supported by implementations that
   support NMDA.  It is for this reason that the module is defined in
   the Appendix.

   The definition of the module follows below.  As the structure of the
   module mirrors that of its underlying module, the YANG tree is not
   depicted separately.

    <CODE BEGINS> file "ietf-dc-fabric-topology-state@2017-12-21.yang"
    module ietf-dc-fabric-topology-state {

    yang-version 1.1;
    namespace "urn:ietf:params:xml:ns:yang:ietf-dc-fabric-topology-state";
    prefix sfabric;

    import ietf-network-state {
        prefix nws;
        reference
        "draft-ietf-i2rs-yang-network-topo-20
        NOTE TO RFC EDITOR:
        (1) Please replace above reference to
        draft-ietf-i2rs-yang-network-topo-20 with RFC
        number when published (i.e. RFC xxxx).
        (2) Please replace the date in the revision statement with the
         date of publication when published.";
    }
    import ietf-dc-fabric-types {
        prefix fabrictypes;

        reference
        "draft-ietf-i2rs-yang-dc-fabric-network-topology-03
        NOTE TO RFC EDITOR:
        (1) Please replace above reference to draft-ietf-i2rs-yang-dc
        -fabric-network-topology-03 with RFC number when published
        (i.e. RFC xxxx).
        (2) Please replace the data in the revision statement with the
        data of publication when published.";
    }
    import ietf-dc-fabric-topology {
        prefix fabric;

        reference
        "draft-ietf-i2rs-yang-dc-fabric-network-topology-03
         NOTE TO RFC EDITOR:
         (1) Please replace above reference to draft-ietf-i2rs-yang-dc
         -fabric-network-topology-03 with RFC number when published
         (i.e. RFC xxxx).
         (2) Please replace the data in the revision statement with the
         data of publication when published.";
    }

    organization
    "IETF I2RS (Interface to the Routing System) Working Group";

    contact
    "WG Web:    <http://tools.ietf.org/wg/i2rs/ >
     WG List:   <mailto:i2rs@ietf.org>

     Editor:    Yan Zhuang
                <mailto:zhuangyan.zhuang@huawei.com>

     Editor:    Danian Shi
                <mailto:shidanian@huawei.com>";

    description
        "This module contains a collection of YANG definitions
        for Fabric state, representing topology that is either
        learned, or topology that results from applying toplogy
        that has been configured per the ietf-dc-fabric-topology
        model, mirroring the corresponding data nodes in this model.

        This model mirrors the configuration tree of
        ietf-dc-fabric-topology, but contains only read-only state
        data. The model is not needed when the implemtation
        infrastructure supports the Network Management Datastore
        Architecture(NMDA).

        Copyright (c) 2016 IETF Trust and the persons identified
        as authors of the code.  All rights reserved.

        Redistribution and use in source and binary forms, with or
        without modification, is permitted pursuant to, and subject
        to the license terms contained in, the Simplified BSD License
        set forth in Section 4.c of the IETF Trust's Legal Provisions
        Relating to IETF Documents(http://trustee.ietf.org/license-info).
        This version of this YANG module is part of
        draft-ietf-i2rs-yang-dc-fabric-network-topology;see the RFC
        itself for full legal notices.

        NOTE TO RFC EDITOR: Please replace above reference to
        draft-ietf-i2rs-yang-dc-fabric-network-topology-03 with RFC number
        when published (i.e. RFC xxxx).";

    revision "2017-12-21" {
        description
            "Initial revision.
             NOTE TO RFC EDITOR: Please replace the following reference to
             draft-ietf-i2rs-yang-dc-fabric-network-topology-03 with RFC
             number when published (i.e. RFC xxxx).";
        reference
            "draft-ietf-i2rs-yang-dc-fabric-network-topology-03";
    }

    //grouping statements
    grouping fabric-network-type {
      description "Identify the topology type to be fabric.";
      container fabric-network {
         presence "indicates fabric Network";
         description
          "The presence of the container node indicates fabric Topology";
        }
    }

    grouping fabric-options {
      description "Options for a fabric";
      leaf gateway-mode {
        type enumeration {
          enum centralized {
            description "The Fabric uses centerilized gateway, in which
            gateway is deployed on SPINE node.";
          }
          enum distributed {
            description "The Fabric uses distributed gateway, in which
            gateway is deployed on LEAF node.";
          }
        }
        default "distributed";
        description "Gateway mode of the fabric";
      }

      leaf traffic-behavior {
        type enumeration {
          enum normal {
            description "Normal";
          }
          enum policy-driven {
            description "Policy driven";
          }
        }
        default "normal";
        description "Traffic behavior of the fabric";
      }

      leaf-list capability-supported {
        type fabrictypes:service-capabilities;
        description
          "Supported services of the fabric";
      }
    }

    grouping device-attributes {
      description "device attributes";
      leaf device-ref {
        type fabrictypes:node-ref;
        description "The device the fabric includes.";
      }
      leaf role {
        type fabrictypes:device-role;
        default fabrictypes:leaf;
        description "Role of the node";
      }
    }

    grouping link-attributes {
      description "Link attributes";
      leaf link-ref {
        type fabrictypes:link-ref;
        description "The link it includes";
      }
    }

    grouping port-attributes {
      description "Port attributes";
      leaf port-ref {
        type fabrictypes:tp-ref;
        description "The port it refers to.";
      }
      leaf port-type {
        type fabrictypes:port-type;
        description
          "Port type: ethernet or serial or others";

        }
      leaf bandwidth {
        type fabrictypes:bandwidth;
        description "Bandwidth of the port";
      }
    }

    grouping fabric-attributes {
      description "Attributes of a fabric";
      leaf fabric-id {
        type fabric:fabric-id;
        description "Fabric id";
      }
      leaf name {
        type string;
        description     "Name of the fabric";
      }
      leaf type {
        type fabrictypes:underlay-network-type;
         description
          "The type of physical network that implements this
          fabric.Examples are vlan, and trill.";
        }
      container vni-capacity {
        description "Number of vnis the fabric has";
          leaf min {
            type int32;
            description "Vni min capacity";
          }
          leaf max {
            type int32;
            description "Vni max capacity";
          }
      }
      leaf description {
        type string;
        description "Description of the fabric";
      }
      container options {
        description "Options of the fabric";
        uses fabric-options;
      }
      list device-nodes {
        key device-ref;
        description "Device nodes that include in a fabric.";
        uses device-attributes;
      }
      list device-links {
        key link-ref;
        description "Links that include within a fabric.";
        uses link-attributes;
      }
      list device-ports {
        key port-ref;
        description "Ports that include in the fabric.";
        uses port-attributes;
      }
    }

    // augment statements

    augment "/nws:networks/nws:network/nws:network-types" {
      description
        "Introduce new network type for Fabric-based logical topology";
      uses fabric-network-type;
    }

    augment "/nws:networks/nws:network/nws:node" {
      when "/nws:networks/nws:network/nws:network-types/sfabric:fabric-network" {
        description "Augmentation parameters apply only for networks with
        fabric topology.";
      }
      description "Augmentation for fabric nodes.";
      container fabric-attributes-state {
        description
          "Attributes for a fabric network";
        uses fabric-attributes;
      }
    }
}
<CODE ENDS>

Authors' Addresses

   Yan Zhuang
   Huawei
   101 Software Avenue, Yuhua District
   Nanjing, Jiangsu  210012
   China

   Email: zhuangyan.zhuang@huawei.com
   Danian Shi
   Huawei
   101 Software Avenue, Yuhua District
   Nanjing, Jiangsu  210012
   China

   Email: shidanian@huawei.com

   Rong Gu
   China Mobile
   32 Xuanwumen West Ave, Xicheng District
   Beijing, Beijing  100053
   China

   Email: gurong_cmcc@outlook.com

   Hariharan Ananthakrishnan
   Packet Design

   Email: hari@packetdesign.com