path: root/doc/rfc/rfc8431.txt

Internet Engineering Task Force (IETF)                           L. Wang
Request for Comments: 8431                                    Individual
Category: Standards Track                                        M. Chen
ISSN: 2070-1721                                                   Huawei
                                                                 A. Dass
                                                                Ericsson
                                                      H. Ananthakrishnan
                                                                 Netflix
                                                                 S. Kini
                                                              Individual
                                                              N. Bahadur
                                                                    Uber
                                                          September 2018


        A YANG Data Model for the Routing Information Base (RIB)

Abstract

   This document defines a YANG data model for the Routing Information
   Base (RIB) that aligns with the Interface to the Routing System
   (I2RS) RIB information model.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc8431.















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Copyright Notice

   Copyright (c) 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  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
     1.2.  Definitions and Abbreviations . . . . . . . . . . . . . .   3
     1.3.  Tree Diagrams . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Model Structure . . . . . . . . . . . . . . . . . . . . . . .   3
     2.1.  RIB Capability  . . . . . . . . . . . . . . . . . . . . .   8
     2.2.  Routing Instance and RIB  . . . . . . . . . . . . . . . .   8
     2.3.  Route . . . . . . . . . . . . . . . . . . . . . . . . . .   9
     2.4.  Nexthop . . . . . . . . . . . . . . . . . . . . . . . . .  11
     2.5.  RPC Operations  . . . . . . . . . . . . . . . . . . . . .  15
     2.6.  Notifications . . . . . . . . . . . . . . . . . . . . . .  20
   3.  YANG Module . . . . . . . . . . . . . . . . . . . . . . . . .  22
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  67
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .  67
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  68
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .  68
     6.2.  Informative References  . . . . . . . . . . . . . . . . .  69
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .  70
   Contributors  . . . . . . . . . . . . . . . . . . . . . . . . . .  70
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  71














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1.  Introduction

   The Interface to the Routing System (I2RS) [RFC7921] provides read
   and write access to the information and state within the routing
   process that exists inside the routing elements; this is achieved via
   protocol message exchange between I2RS clients and I2RS agents
   associated with the routing system.  One of the functions of I2RS is
   to read and write data of the Routing Information Base (RIB).
   [I2RS-REQS] introduces a set of RIB use cases.  The RIB information
   model is defined in [RFC8430].

   This document defines a YANG data model [RFC7950] [RFC6991] for the
   RIB that satisfies the RIB use cases and aligns with the RIB
   information model.

1.1.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

1.2.  Definitions and Abbreviations

   RIB: Routing Information Base

   FIB: Forwarding Information Base

   RPC: Remote Procedure Call

   IM: Information Model.  An abstract model of a conceptual domain,
   which is independent of a specific implementation or data
   representation.

1.3.  Tree Diagrams

   Tree diagrams used in this document follow the notation defined in
   [RFC8340].

2.  Model Structure

   The following figure shows an overview of the structure tree of the
   ietf-i2rs-rib module.  To give a whole view of the structure tree,
   some details of the tree are omitted.  The relevant details are
   introduced in the subsequent subsections.





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   module: ietf-i2rs-rib
      +--rw routing-instance
         +--rw name              string
         +--rw interface-list* [name]
         |  +--rw name if:interface-ref
         +--rw router-id?        yang:dotted-quad
         +--rw lookup-limit?     uint8
         +--rw rib-list* [name]
            +--rw name              string
            +--rw address-family address-family-definition
            +--rw ip-rpf-check?     boolean
            +--rw route-list* [route-index]
            |  +--rw route-index                uint64
            |  +--rw match
            |  |  +--rw (route-type)?
            |  |     +--:(ipv4)
            |  |     |  ...
            |  |     +--:(ipv6)
            |  |     |  ...
            |  |     +--:(mpls-route)
            |  |     |  ...
            |  |     +--:(mac-route)
            |  |     |  ...
            |  |     +--:(interface-route)
            |  |        ...
            |  +--rw nexthop
            |  |  +--rw nexthop-id?           uint32
            |  |  +--rw sharing-flag?         boolean
            |  |  +--rw (nexthop-type)?
            |  |     +--:(nexthop-base)
            |  |     |  ...
            |  |     +--:(nexthop-chain) {nexthop-chain}?
            |  |     |  ...
            |  |     +--:(nexthop-replicate) {nexthop-replicate}?
            |  |     |  ...
            |  |     +--:(nexthop-protection) {nexthop-protection}?
            |  |     |  ...
            |  |     +--:(nexthop-load-balance) {nexthop-load-balance}?
            |  |        ...
            |  +--rw route-status
            |  |  ...
            |  +--rw route-attributes
            |  |  ...
            |  +--rw route-vendor-attributes
            +--rw nexthop-list* [nexthop-member-id]
               +--rw nexthop-member-id uint32





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   rpcs:
      +---x rib-add
      |  +---w input
      |  |  +---w name        string
      |  |  +---w address-family      address-family-definition
      |  |  +---w ip-rpf-check?   boolean
      |  +--ro output
      |     +--ro result boolean
      |     +--ro reason? string
      +---x rib-delete
      |  +---w input
      |  |  +---w name string
      |  +--ro output
      |     +--ro result boolean
      |     +--ro reason? string
      +---x route-add
      |  +---w input
      |  |  +---w return-failure-detail?   boolean
      |  |  +---w rib-name                 string
      |  |  +---w routes
      |  |     +---w route-list* [route-index]
      |  |        ...
      |  +--ro output
      |     +--ro success-count     uint32
      |     +--ro failed-count      uint32
      |     +--ro failure-detail
      |        +--ro failed-routes* [route-index]
      |           +--ro route-index uint32
      |           +--ro error-code? uint32
      +---x route-delete
      |  +---w input
      |  |  +---w return-failure-detail?   boolean
      |  |  +---w rib-name                 string
      |  |  +---w routes
      |  |     +---w route-list* [route-index]
      |  |        ...
      |  +--ro output
      |     +--ro success-count     uint32
      |     +--ro failed-count      uint32
      |     +--ro failure-detail
      |        +--ro failed-routes* [route-index]
      |           +--ro route-index uint32
      |           +--ro error-code? uint32
      +---x route-update
      |  +---w input
      |  |  +---w return-failure-detail?           boolean
      |  |  +---w rib-name                         string




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      |  |  +---w (match-options)?
      |  |     +--:(match-route-prefix)
      |  |     |  ...
      |  |     +--:(match-route-attributes)
      |  |     |  ...
      |  |     +--:(match-route-vendor-attributes) {...}?
      |  |     |  ...
      |  |     +--:(match-nexthop)
      |  |        ...
      |  +--ro output
      |     +--ro success-count uint32
      |     +--ro failed-count uint32
      |     +--ro failure-detail
      |        +--ro failed-routes* [route-index]
      |           +--ro route-index uint32
      |           +--ro error-code? uint32
      +---x nh-add
      |  +---w input
      |  |  +---w rib-name              string
      |  |  +---w nexthop-id?           uint32
      |  |  +---w sharing-flag?         boolean
      |  |  +---w (nexthop-type)?
      |  |     +--:(nexthop-base)
      |  |     |  ...
      |  |     +--:(nexthop-chain) {nexthop-chain}?
      |  |     |  ...
      |  |     +--:(nexthop-replicate) {nexthop-replicate}?
      |  |     |  ...
      |  |     +--:(nexthop-protection) {nexthop-protection}?
      |  |     |  ...
      |  |     +--:(nexthop-load-balance) {nexthop-load-balance}?
      |  |        ...
      |  +--ro output
      |     +--ro result        boolean
      |     +--ro reason?       string
      |     +--ro nexthop-id?   uint32
      +---x nh-delete
         +---w input
         |  +---w rib-name              string
         |  +---w nexthop-id?           uint32
         |  +---w sharing-flag?         boolean
         |  +---w (nexthop-type)?
         |     +--:(nexthop-base)
         |     |  ...
         |     +--:(nexthop-chain) {nexthop-chain}?
         |     |  ...
         |     +--:(nexthop-replicate) {nexthop-replicate}?
         |     |  ...



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         |     +--:(nexthop-protection) {nexthop-protection}?
         |     |  ...
         |     +--:(nexthop-load-balance) {nexthop-load-balance}?
         |        ...
         +--ro output
            +--ro result boolean
            +--ro reason? string
   notifications:
      +---n nexthop-resolution-status-change
      |  +--ro nexthop
      |  |  +--ro nexthop-id?           uint32
      |  |  +--ro sharing-flag?         boolean
      |  |  +--ro (nexthop-type)?
      |  |     +--:(nexthop-base)
      |  |     |  ...
      |  |     +--:(nexthop-chain) {nexthop-chain}?
      |  |     |  ...
      |  |     +--:(nexthop-replicate) {nexthop-replicate}?
      |  |     |  ...
      |  |     +--:(nexthop-protection) {nexthop-protection}?
      |  |     |  ...
      |  |     +--:(nexthop-load-balance) {nexthop-load-balance}?
      |  |        ...
      |  +--ro nexthop-state nexthop-state-definition
      +---n route-change
         +--ro rib-name                 string
         +--ro address-family               address-family-definition
         +--ro route-index              uint64
         +--ro match
         |  +--ro (route-type)?
         |     +--:(ipv4)
         |     |  ...
         |     +--:(ipv6)
         |     |  ...
         |     +--:(mpls-route)
         |     |  ...
         |     +--:(mac-route)
         |     |  ...
         |     +--:(interface-route)
         |        ...
         +--ro route-installed-state route-installed-state-definition
         +--ro route-state         route-state-definition
         +--ro route-change-reasons* [route-change-reason]
            +--ro route-change-reason    route-change-reason-definition

              Figure 1: Overview of I2RS RIB Module Structure





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2.1.  RIB Capability

   RIB capability negotiation is very important because not all of the
   hardware will be able to support all kinds of nexthops, and there
   might be a limitation on how many levels of lookup can be practically
   performed.  Therefore, a RIB data model needs to specify a way for an
   external entity to learn about the functional capabilities of a
   network device.

   At the same time, nexthop chains can be used to specify multiple
   headers over a packet before that particular packet is forwarded.
   Not every network device will be able to support all kinds of nexthop
   chains along with the arbitrary number of headers that are chained
   together.  The RIB data model needs a way to expose the nexthop
   chaining capability supported by a given network device.

   This module uses the feature and if-feature statements to achieve
   above capability advertisement.

2.2.  Routing Instance and RIB

   A routing instance, in the context of the RIB information model, is a
   collection of RIBs, interfaces, and routing protocol parameters.  A
   routing instance creates a logical slice of the router and can allow
   multiple different logical slices, across a set of routers, to
   communicate with each other.  The routing protocol parameters control
   the information available in the RIBs.  More details about a routing
   instance can be found in Section 2.2 of [RFC8430].

   For a routing instance, there can be multiple RIBs.  Therefore, this
   model uses "list" to express the RIBs.  The structure tree is shown
   below:

   +--rw routing-instance
      +--rw name              string
      +--rw interface-list* [name]
      |  +--rw name if:interface-ref
      +--rw router-id?        yang:dotted-quad
      +--rw lookup-limit?     uint8
      +--rw rib-list* [name]
         +--rw name            string
         +--rw address-family      address-family-definition
         +--rw ip-rpf-check?   boolean
         +--rw route-list* [route-index]
            ... // refer to Section 2.3

                   Figure 2: Routing Instance Structure




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2.3.  Route

   A route is essentially a match condition and an action following that
   match.  The match condition specifies the kind of route (e.g., IPv4,
   MPLS, Media Access Control (MAC), Interface, etc.) and the set of
   fields to match on.

   A route MUST contain the ROUTE_PREFERENCE attribute (see Section 2.3
   of [RFC8430]).

   In addition, a route MUST associate with the following status
   attributes in responses to a RIB writing/reading operation:

   o  Active: Indicates whether a route has at least one fully resolved
      nexthop and is therefore eligible for installation in the FIB.

   o  Installed: Indicates whether the route got installed in the FIB.

   o  Reason: Indicates the specific reason that caused the failure,
      e.g., "Not authorized".

   In addition, a route can be associated with one or more optional
   route-attributes (e.g., route-vendor-attributes).

   A RIB will have a number of routes, so the routes are expressed as a
   list under a specific RIB.  Each RIB has its own route list.

























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   +--rw route-list* [route-index]
      +--rw route-index                uint64
      +--rw match
      |  +--rw (route-type)?
      |     +--:(ipv4)
      |     |  +--rw ipv4
      |     |     +--rw (ip-route-match-type)?
      |     |        +--:(dest-ipv4-address)
      |     |        |  ...
      |     |        +--:(src-ipv4-address)
      |     |        |  ...
      |     |        +--:(dest-src-ipv4-address)
      |     |           ...
      |     +--:(ipv6)
      |     |  +--rw ipv6
      |     |     +--rw (ip-route-match-type)?
      |     |        +--:(dest-ipv6-address)
      |     |        |  ...
      |     |        +--:(src-ipv6-address)
      |     |        |  ...
      |     |        +--:(dest-src-ipv6-address)
      |     |           ...
      |     +--:(mpls-route)
      |     |  +--rw mpls-label              uint32
      |     +--:(mac-route)
      |     |  +--rw mac-address             uint32
      |     +--:(interface-route)
      |        +--rw interface-identifier if:interface-ref
      +--rw nexthop
      |  ...(refer to Section 2.4)

                        Figure 3: Routes Structure



















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2.4.  Nexthop

   A nexthop represents an object resulting from a route lookup.  As
   illustrated in Figure 4 of [RFC8430], to support various use cases
   (e.g., load-balancing, protection, multicast, or a combination of
   them), the nexthop is modeled as a multilevel structure and supports
   recursion.  The first level of the nexthop includes the following
   four types:

   o  Base: The "base" nexthop is the foundation of all other nexthop
      types.  It includes the following basic nexthops:

      *  nexthop-id

      *  IPv4 address

      *  IPv6 address

      *  egress-interface

      *  egress-interface with IPv4 address

      *  egress-interface with IPv6 address

      *  egress-interface with MAC address

      *  logical-tunnel

      *  tunnel-encapsulation

      *  tunnel-decapsulation

      *  rib-name

   o  Chain: The "chain" nexthop provides a way to perform multiple
      operations on a packet by logically combining them.

   o  Load-Balance: The "load-balance" nexthop is designed for a load-
      balance case where it normally will have multiple weighted
      nexthops.

   o  Protection: The "protection" nexthop is designed for a protection
      scenario where it normally will have primary and standby nexthop.

   o  Replicate: The "replicate" nexthop is designed for multiple
      destinations forwarding.





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   The structure tree of nexthop is shown in the following figures.

   +--rw nexthop
   |  +--rw nexthop-id?           uint32
   |  +--rw sharing-flag?         boolean
   |  +--rw (nexthop-type)?
   |     +--:(nexthop-base)
   |     |  ...(refer to Figure 5)
   |     +--:(nexthop-chain) {nexthop-chain}?
   |     |  +--rw nexthop-chain
   |     |     +--rw nexthop-list* [nexthop-member-id]
   |     |        +--rw nexthop-member-id uint32
   |     +--:(nexthop-replicate) {nexthop-replicate}?
   |     |  +--rw nexthop-replicate
   |     |     +--rw nexthop-list* [nexthop-member-id]
   |     |        +--rw nexthop-member-id uint32
   |     +--:(nexthop-protection) {nexthop-protection}?
   |     |  +--rw nexthop-protection
   |     |     +--rw nexthop-list* [nexthop-member-id]
   |     |        +--rw nexthop-member-id uint32
   |     |        +--rw nexthop-preference nexthop-preference-definition
   |     +--:(nexthop-load-balance) {nexthop-load-balance}?
   |        +--rw nexthop-lb
   |           +--rw nexthop-list* [nexthop-member-id]
   |              +--rw nexthop-member-id uint32
   |              +--rw nexthop-lb-weight nexthop-lb-weight-definition

                        Figure 4: Nexthop Structure

   Figure 5 (as shown below) is a subtree of nexthop.  It's under the
   nexthop base node and shows the structure of the "base" nexthop.

+--:(nexthop-base)
|  +--rw nexthop-base
|     +--rw (nexthop-base-type)?
|        +--:(special-nexthop)
|        |  +--rw special? special-nexthop-definition
|        +--:(egress-interface-nexthop)
|        |  +--rw outgoing-interface if:interface-ref
|        +--:(ipv4-address-nexthop)
|        |  +--rw ipv4-address inet:ipv4-address
|        +--:(ipv6-address-nexthop)
|        |  +--rw ipv6-address inet:ipv6-address
|        +--:(egress-interface-ipv4-nexthop)
|        |  +--rw egress-interface-ipv4-address
|        |     +--rw outgoing-interface if:interface-ref
|        |     +--rw ipv4-address       inet:ipv4-address




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|        +--:(egress-interface-ipv6-nexthop)
|        |  +--rw egress-interface-ipv6-address
|        |     +--rw outgoing-interface if:interface-ref
|        |     +--rw ipv6-address       inet:ipv6-address
|        +--:(egress-interface-mac-nexthop)
|        |  +--rw egress-interface-mac-address
|        |     +--rw outgoing-interface if:interface-ref
|        |     +--rw ieee-mac-address yang:mac-address
|        +--:(tunnel-encapsulation-nexthop) {nexthop-tunnel}?
|        |  +--rw tunnel-encapsulation
|        |     +--rw (tunnel-type)?
|        |        +--:(ipv4) {ipv4-tunnel}?
|        |        |  +--rw ipv4-header
|        |        |     +--rw src-ipv4-address inet:ipv4-address
|        |        |     +--rw dest-ipv4-address inet:ipv4-address
|        |        |     +--rw protocol          uint8
|        |        |     +--rw ttl?              uint8
|        |        |     +--rw dscp?             uint8
|        |        +--:(ipv6) {ipv6-tunnel}?
|        |        |  +--rw ipv6-header
|        |        |     +--rw src-ipv6-address inet:ipv6-address
|        |        |     +--rw dest-ipv6-address inet:ipv6-address
|        |        |     +--rw next-header       uint8
|        |        |     +--rw traffic-class? uint8
|        |        |     +--rw flow-label?
|        |        |             inet:ipv6-flow-label
|        |        |     +--rw hop-limit?        uint8
|        |        +--:(mpls) {mpls-tunnel}?
|        |        |  +--rw mpls-header
|        |        |     +--rw label-operations* [label-oper-id]
|        |        |        +--rw label-oper-id uint32
|        |        |        +--rw (label-actions)?
|        |        |           +--:(label-push)
|        |        |           |  +--rw label-push
|        |        |           |     +--rw label        uint32
|        |        |           |     +--rw s-bit?       boolean
|        |        |           |     +--rw tc-value? uint8
|        |        |           |     +--rw ttl-value? uint8
|        |        |           +--:(label-swap)
|        |        |              +--rw label-swap
|        |        |                 +--rw out-label     uint32
|        |        |                 +--rw ttl-action?
|        |        |                         ttl-action-definition
|        |        +--:(gre) {gre-tunnel}?
|        |        |  +--rw gre-header
|        |        |     +--rw (dest-address-type)?





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|        |        |     |  +--:(ipv4)
|        |        |     |  |  +--rw ipv4-dest inet:ipv4-address
|        |        |     |  +--:(ipv6)
|        |        |     |     +--rw ipv6-dest inet:ipv6-address
|        |        |     +--rw protocol-type uint16
|        |        |     +--rw key?          uint64
|        |        +--:(nvgre) {nvgre-tunnel}?
|        |        |  +--rw nvgre-header
|        |        |     +--rw (nvgre-type)?
|        |        |     |  +--:(ipv4)
|        |        |     |  |  +--rw src-ipv4-address inet:ipv4-address
|        |        |     |  |  +--rw dest-ipv4-address inet:ipv4-address
|        |        |     |  |  +--rw protocol          uint8
|        |        |     |  |  +--rw ttl?              uint8
|        |        |     |  |  +--rw dscp?             uint8
|        |        |     |  +--:(ipv6)
|        |        |     |     +--rw src-ipv6-address inet:ipv6-address
|        |        |     |     +--rw dest-ipv6-address inet:ipv6-address
|        |        |     |     +--rw next-header       uint8
|        |        |     |     +--rw traffic-class?    uint8
|        |        |     |     +--rw flow-label?
|        |        |     |             inet:ipv6-flow-label
|        |        |     |     +--rw hop-limit?        uint8
|        |        |     +--rw virtual-subnet-id uint32
|        |        |     +--rw flow-id?          uint8
|        |        +--:(vxlan) {vxlan-tunnel}?
|        |           +--rw vxlan-header
|        |              +--rw (vxlan-type)?
|        |              |  +--:(ipv4)
|        |              |  |  +--rw src-ipv4-address inet:ipv4-address
|        |              |  |  +--rw dest-ipv4-address inet:ipv4-address
|        |              |  |  +--rw protocol             uint8
|        |              |  |  +--rw ttl?                 uint8
|        |              |  |  +--rw dscp?                uint8
|        |              |  +--:(ipv6)
|        |              |     +--rw src-ipv6-address inet:ipv6-address
|        |              |     +--rw dest-ipv6-address inet:ipv6-address
|        |              |     +--rw next-header          uint8
|        |              |     +--rw traffic-class?       uint8
|        |              |     +--rw flow-label? inet:ipv6-flow-label
|        |              |     +--rw hop-limit?           uint8
|        |              +--rw vxlan-identifier     uint32
|        +--:(tunnel-decapsulation-nexthop) {nexthop-tunnel}?
|        |  +--rw tunnel-decapsulation
|        |     +--rw (tunnel-type)?






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|        |        +--:(ipv4) {ipv4-tunnel}?
|        |        |  +--rw ipv4-decapsulation
|        |        |     +--rw ipv4-decapsulation
|        |        |             tunnel-decapsulation-action-definition
|        |        |     +--rw ttl-action?   ttl-action-definition
|        |        +--:(ipv6) {ipv6-tunnel}?
|        |        |  +--rw ipv6-decapsulation
|        |        |     +--rw ipv6-decapsulation
|        |        |             tunnel-decapsulation-action-definition
|        |        |     +--rw hop-limit-action?
|        |        |             hop-limit-action-definition
|        |        +--:(mpls) {mpls-tunnel}?
|        |           +--rw label-pop
|        |              +--rw label-pop     mpls-label-action-definition
|        |              +--rw ttl-action?   ttl-action-definition
|        +--:(logical-tunnel-nexthop) {nexthop-tunnel}?
|        |  +--rw logical-tunnel
|        |     +--rw tunnel-type tunnel-type-definition
|        |     +--rw tunnel-name string
|        +--:(rib-name-nexthop)
|        |  +--rw rib-name?                        string
|        +--:(nexthop-identifier)
|           +--rw nexthop-ref                      nexthop-ref

                     Figure 5: Nexthop Base Structure

2.5.  RPC Operations

   This module defines the following RPC operations:

   o  rib-add: Add a RIB to a routing instance.  The following are
      passed as the input parameters: the name of the RIB, the address
      family of the RIB, and (optionally) whether the RPF check is
      enabled.  The output is the result of the add operation:

      *  true - success

      *  false - failed (when failed, the I2RS agent may return the
         specific reason that caused the failure)












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   o  rib-delete: Delete a RIB from a routing instance.  When a RIB is
      deleted, all routes installed in the RIB will be deleted.  A rib-
      name is passed as the input parameter.  The output is the result
      of the delete operation:

      *  true - success

      *  false - failed (when failed, the I2RS agent may return the
         specific reason that caused the failure)

   o  route-add: Add a route or a set of routes to a RIB.  The following
      are passed as the input parameters: the name of the RIB, the route
      prefix(es), the route-attributes, the route-vendor-attributes, the
      nexthop, and the "whether to return failure details" indication.
      Before calling the route-add rpc, it is required to call the nh-
      add rpc to create and/or return the nexthop identifier.  However,
      in situations when the nexthop already exists and the nexthop-id
      is known, this action is not expected.  The output is a
      combination of the route operation states while querying the
      appropriate node in the data tree, which includes:

      *  success-count: the number of routes that were successfully
         added;

      *  failed-count: the number of the routes that failed to be added;
         and,

      *  failure-detail: this shows the specific routes that failed to
         be added.

   o  route-delete: Delete a route or a set of routes from a RIB.  The
      following are passed as the input parameters: the name of the RIB,
      the route prefix(es), and the "whether to return failure details"
      indication.  The output is a combination of route operation
      states, which includes:

      *  success-count: the number of routes that were successfully
         deleted;

      *  failed-count: the number of the routes that failed to be
         deleted; and,

      *  failure-detail: this shows the specific routes that failed to
         be deleted.







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   o  route-update: Update a route or a set of routes.  The following
      are passed as the input parameters: the name of the RIB, the route
      prefix(es), the route-attributes, the route-vendor-attributes, or
      the nexthop.  The match conditions can be either route prefix(es),
      route-attributes, route-vendor-attributes, or nexthops.  The
      update actions include the following: update the nexthops, update
      the route-attributes, and update the route-vendor-attributes.  The
      output is a combination of the route operation states, which
      includes:

      *  success-count: the number of routes that were successfully
         updated;

      *  failed-count: the number of the routes that failed to be
         updated; and,

      *  failure-detail: this shows the specific routes that failed to
         be updated.

   o  nh-add: Add a nexthop to a RIB.  The following are passed as the
      input parameters: the name of the RIB and the nexthop.  The
      network node is required to allocate a nexthop identifier to the
      nexthop.  The outputs include the result of the nexthop add
      operation.

      *  true - success (when success, a nexthop identifier will be
         returned to the I2RS client)

      *  false - failed (when failed, the I2RS agent may return the
         specific reason that caused the failure)

   o  nh-delete: Delete a nexthop from a RIB.  The following are passed
      as the input parameters: the name of the RIB and a nexthop or
      nexthop identifier.  The output is the result of the delete
      operation:

      *  true - success

      *  false - failed (when failed, the I2RS agent may return the
         specific reason that caused the failure)











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   The structure tree of rpcs is shown in following figure.

   rpcs:
      +---x rib-add
      |  +---w input
      |  |  +---w rib-name        string
      |  |  +---w address-family      address-family-definition
      |  |  +---w ip-rpf-check?   boolean
      |  +--ro output
      |     +--ro result uint32
      |     +--ro reason? string
      +---x rib-delete
      |  +---w input
      |  |  +---w rib-name string
      |  +--ro output
      |     +--ro result uint32
      |     +--ro reason? string
      +---x route-add
      |  +---w input
      |  |  +---w return-failure-detail?   boolean
      |  |  +---w rib-name                 string
      |  |  +---w routes
      |  |     +---w route-list* [route-index]
      |  |        ...
      |  +--ro output
      |     +--ro success-count     uint32
      |     +--ro failed-count      uint32
      |     +--ro failure-detail
      |        +--ro failed-routes* [route-index]
      |           +--ro route-index uint32
      |           +--ro error-code? uint32
      +---x route-delete
      |  +---w input
      |  |  +---w return-failure-detail?   boolean
      |  |  +---w rib-name                 string
      |  |  +---w routes
      |  |     +---w route-list* [route-index]
      |  |        ...
      |  +--ro output
      |     +--ro success-count     uint32
      |     +--ro failed-count      uint32
      |     +--ro failure-detail
      |        +--ro failed-routes* [route-index]
      |           +--ro route-index uint32
      |           +--ro error-code? uint32






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      +---x route-update
      |  +---w input
      |  |  +---w return-failure-detail?           boolean
      |  |  +---w rib-name                         string
      |  |  +---w (match-options)?
      |  |     +--:(match-route-prefix)
      |  |     |  ...
      |  |     +--:(match-route-attributes)
      |  |     |  ...
      |  |     +--:(match-route-vendor-attributes) {...}?
      |  |     |  ...
      |  |     +--:(match-nexthop)
      |  |        ...
      |  +--ro output
      |     +--ro success-count uint32
      |     +--ro failed-count uint32
      |     +--ro failure-detail
      |        +--ro failed-routes* [route-index]
      |           +--ro route-index uint32
      |           +--ro error-code? uint32
      +---x nh-add
      |  +---w input
      |  |  +---w rib-name              string
      |  |  +---w nexthop-id?           uint32
      |  |  +---w sharing-flag?         boolean
      |  |  +---w (nexthop-type)?
      |  |     ...
      |  +--ro output
      |     +--ro result        uint32
      |     +--ro reason?       string
      |     +--ro nexthop-id?   uint32
      +---x nh-delete
         +---w input
         |  +---w rib-name              string
         |  +---w nexthop-id?           uint32
         |  +---w sharing-flag?         boolean
         |  +---w (nexthop-type)?
         |     ...
         +--ro output
            +--ro result uint32
            +--ro reason? string

                         Figure 6: RPCs Structure








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2.6.  Notifications

   Asynchronous notifications are sent by the RIB manager of a network
   device to an external entity when some event triggers on the network
   device.  An implementation of this RIB data model MUST support
   sending two kinds of asynchronous notifications.

   1.  Route change notification:

   o Installed (indicates whether the route got installed in the FIB)

   o Active (indicates whether a route has at least one fully resolved
   nexthop and is therefore eligible for installation in the FIB)

   o Reason (e.g., "Not authorized")

   2.  Nexthop resolution status notification

   Nexthops can be fully resolved or unresolved.

   A resolved nexthop has an adequate level of information to send the
   outgoing packet towards the destination by forwarding it on an
   interface to a directly connected neighbor.

   An unresolved nexthop is something that requires the RIB manager to
   determine the final resolved nexthop.  In one example, a nexthop
   could be an IP address.  The RIB manager would resolve how to reach
   that IP address, e.g., by checking if that particular IP address is
   reachable by regular IP forwarding, by an MPLS tunnel, or by both.
   If the RIB manager cannot resolve the nexthop, then the nexthop
   remains in an unresolved state and is NOT a suitable candidate for
   installation in the FIB.

   An implementation of this RIB data model MUST support sending route-
   change notifications whenever a route transitions between the
   following states:

   o  from the active state to the inactive state

   o  from the inactive state to the active state

   o  from the installed state to the uninstalled state

   o  from the uninstalled state to the installed state

   A single notification MAY be used when a route transitions from
   inactive/uninstalled to active/installed or in the other direction.




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   The structure tree of notifications is shown in the following figure.

   notifications:
        +---n nexthop-resolution-status-change
        |  +--ro nexthop
        |  |  +--ro nexthop-id            uint32
        |  |  +--ro sharing-flag          boolean
        |  |  +--ro (nexthop-type)?
        |  |     +--:(nexthop-base)
        |  |     |  ...
        |  |     +--:(nexthop-chain) {nexthop-chain}?
        |  |     |  ...
        |  |     +--:(nexthop-replicate) {nexthop-replicate}?
        |  |     |  ...
        |  |     +--:(nexthop-protection) {nexthop-protection}?
        |  |     |  ...
        |  |     +--:(nexthop-load-balance) {nexthop-load-balance}?
        |  |        ...
        |  +--ro nexthop-state nexthop-state-definition
        +---n route-change
           +--ro rib-name                 string
           +--ro address-family           address-family-definition
           +--ro route-index              uint64
           +--ro match
           |  +--ro (route-type)?
           |     +--:(ipv4)
           |     |  ...
           |     +--:(ipv6)
           |     |  ...
           |     +--:(mpls-route)
           |     |  ...
           |     +--:(mac-route)
           |     |  ...
           |     +--:(interface-route)
           |        ...
           +--ro route-installed-state route-installed-state-definition
           +--ro route-state              route-state-definition
           +--ro route-change-reason      route-change-reason-definition

                     Figure 7: Notifications Structure











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3.  YANG Module

   This YANG module references [RFC2784], [RFC7348], [RFC7637], and
   [RFC8344].

   <CODE BEGINS> file "ietf-i2rs-rib@2018-09-13.yang"

   module ietf-i2rs-rib {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:ietf-i2rs-rib";
     prefix iir;

     import ietf-inet-types {
       prefix inet;
       reference "RFC 6991";
     }
     import ietf-interfaces {
       prefix if;
       reference "RFC 8344";
     }
     import ietf-yang-types {
       prefix yang;
       reference "RFC 6991";
     }

     organization
       "IETF I2RS (Interface to Routing System) Working Group";
     contact
       "WG Web:   <https://datatracker.ietf.org/wg/i2rs/>
        WG List:  <mailto:i2rs@ietf.org>

        Editor:   Lixing Wang
                  <mailto:wang_little_star@sina.com>

        Editor:   Mach(Guoyi) Chen
                  <mailto:mach.chen@huawei.com>

        Editor:   Amit Dass
                  <mailto:dass.amit@gmail.com>

        Editor:   Hariharan Ananthakrishnan
                  <mailto:hari@netflix.com>

        Editor:   Sriganesh Kini
                  <mailto:sriganeshkini@gmail.com>

        Editor:   Nitin Bahadur
                  <mailto:nitin_bahadur@yahoo.com>";



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     description
       "This module defines a YANG data model for
        Routing Information Base (RIB) that aligns
        with the I2RS RIB information model.

        Copyright (c) 2018 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 RFC 8341; see
        the RFC itself for full legal notices.";

     revision 2018-09-13 {
       description
         "initial revision";
       reference "RFC 8431";
     }

     //Features

     feature nexthop-tunnel {
       description
         "This feature means that a node supports
          tunnel nexthop capability.";
     }

     feature nexthop-chain {
       description
         "This feature means that a node supports
          chain nexthop capability.";
     }

     feature nexthop-protection {
       description
         "This feature means that a node supports
          protection nexthop capability.";
     }

     feature nexthop-replicate {
       description
         "This feature means that a node supports
          replicate nexthop capability.";



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     }

     feature nexthop-load-balance {
       description
         "This feature means that a node supports
          load-balance nexthop capability.";
     }

     feature ipv4-tunnel {
       description
         "This feature means that a node supports
          IPv4 tunnel encapsulation capability.";
     }

     feature ipv6-tunnel {
       description
         "This feature means that a node supports
          IPv6 tunnel encapsulation capability.";
     }

     feature mpls-tunnel {
       description
         "This feature means that a node supports
          MPLS tunnel encapsulation capability.";
     }

     feature vxlan-tunnel {
       description
         "This feature means that a node supports
          Virtual eXtensible Local Area Network
          (VXLAN) tunnel encapsulation capability.";
       reference "RFC 7348";
     }

     feature gre-tunnel {
       description
         "This feature means that a node supports
          GRE tunnel encapsulation capability.";
       reference "RFC 2784";
     }

     feature nvgre-tunnel {
       description
         "This feature means that a node supports
          Network Virtualization Using GRE (NVGRE)
          tunnel encapsulation capability.";
       reference "RFC 7637";
     }



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     feature route-vendor-attributes {
       description
         "This feature means that a node supports
          route vendor attributes.";
     }

     //Identities and Type Definitions

     identity mpls-label-action {
       description
         "Base identity from which all MPLS label
          operations are derived.

          The MPLS label stack operations include:
          push - to add a new label to a label stack
          pop -  to pop the top label from a label stack
          swap - to exchange the top label of a label
                 stack with a new label";
     }

     identity label-push {
       base mpls-label-action;
       description
         "MPLS label stack operation: push.";
     }

     identity label-pop {
       base mpls-label-action;
       description
         "MPLS label stack operation: pop.";
     }

     identity label-swap {
       base mpls-label-action;
       description
         "MPLS label stack operation: swap.";
     }

     typedef mpls-label-action-definition {
       type identityref {
         base mpls-label-action;
       }
       description
         "MPLS label action definition.";
     }

     identity tunnel-decapsulation-action {
       description



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         "Base identity from which all tunnel decapsulation
          actions are derived.
          Tunnel decapsulation actions include
          ipv4-decapsulation (to decapsulate an IPv4 tunnel)
          ipv6-decapsulation (to decapsulate an IPv6 tunnel)";
     }

     identity ipv4-decapsulation {
       base tunnel-decapsulation-action;
       description
         "IPv4 tunnel decapsulation.";
     }

     identity ipv6-decapsulation {
       base tunnel-decapsulation-action;
       description
         "IPv6 tunnel decapsulation.";
     }

     typedef tunnel-decapsulation-action-definition {
       type identityref {
         base tunnel-decapsulation-action;
       }
       description
         "Tunnel decapsulation definition.";
     }

     identity ttl-action {
       description
         "Base identity from which all TTL
          actions are derived.";
     }

     identity no-action {
       base ttl-action;
       description
         "Do nothing regarding the TTL.";
     }

     identity copy-to-inner {
       base ttl-action;
       description
         "Copy the TTL of the outer header
          to the inner header.";
     }

     identity decrease-and-copy-to-inner {
       base ttl-action;



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       description
         "Decrease TTL by one and copy the TTL
          to the inner header.";
     }

     identity decrease-and-copy-to-next {
       base ttl-action;
       description
         "Decrease TTL by one and copy the TTL
          to the next header; for example, when
          MPLS label swapping, decrease the TTL
          of the in_label and copy it to the
          out_label.";
     }

     typedef ttl-action-definition {
       type identityref {
         base ttl-action;
       }
       description
         "TTL action definition.";
     }

     identity hop-limit-action {
       description
         "Base identity from which all hop limit
          actions are derived.";
     }

     identity hop-limit-no-action {
       base hop-limit-action;
       description
         "Do nothing regarding the hop limit.";
     }

     identity hop-limit-copy-to-inner {
       base hop-limit-action;
       description
         "Copy the hop limit of the outer header
          to the inner header.";
     }

     typedef hop-limit-action-definition {
       type identityref {
         base hop-limit-action;
       }
       description
         "IPv6 hop limit action definition.";



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     }

     identity special-nexthop {
       description
         "Base identity from which all special
          nexthops are derived.";
     }

     identity discard {
       base special-nexthop;
       description
         "This indicates that the network
          device should drop the packet and
          increment a drop counter.";
     }

     identity discard-with-error {
       base special-nexthop;
       description
         "This indicates that the network
          device should drop the packet,
          increment a drop counter, and send
          back an appropriate error message
          (like ICMP error).";
     }

     identity receive {
       base special-nexthop;
       description
         "This indicates that the traffic is
          destined for the network device, e.g.,
          protocol packets or Operations,
          Administration, and Maintenance (OAM) packets.
          All locally destined traffic SHOULD be
          throttled to avoid a denial-of-service
          attack on the router's control plane.  An
          optional rate-limiter can be specified
          to indicate how to throttle traffic
          destined for the control plane.";
     }

     identity cos-value {
       base special-nexthop;
       description
         "Cos-value special nexthop.";
     }

     typedef special-nexthop-definition {



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       type identityref {
         base special-nexthop;
       }
       description
         "Special nexthop definition.";
     }

     identity ip-route-match-type {
       description
         "Base identity from which all route
          match types are derived.
          The route match type could be:
          match source, or
          match destination, or
          match source and destination.";
     }

     identity match-ip-src {
       base ip-route-match-type;
       description
         "Source route match type.";
     }

     identity match-ip-dest {
       base ip-route-match-type;
       description
         "Destination route match type";
     }

     identity match-ip-src-dest {
       base ip-route-match-type;
       description
         "Source and Destination route match type";
     }

     typedef ip-route-match-type-definition {
       type identityref {
         base ip-route-match-type;
       }
       description
         "IP route match type definition.";
     }

     identity address-family {
       description
         "Base identity from which all RIB
          address families are derived.";
     }



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     identity ipv4-address-family {
       base address-family;
       description
         "IPv4 RIB address family.";
     }

     identity ipv6-address-family {
       base address-family;
       description
         "IPv6 RIB address family.";
     }

     identity mpls-address-family {
       base address-family;
       description
         "MPLS RIB address family.";
     }

     identity ieee-mac-address-family {
       base address-family;
       description
         "MAC RIB address family.";
     }

     typedef address-family-definition {
       type identityref {
         base address-family;
       }
       description
         "RIB address family definition.";
     }

     identity route-type {
       description
         "Base identity from which all route types
          are derived.";
     }

     identity ipv4-route {
       base route-type;
       description
         "IPv4 route type.";
     }

     identity ipv6-route {
       base route-type;
       description
         "IPv6 route type.";



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     }

     identity mpls-route {
       base route-type;
       description
         "MPLS route type.";
     }

     identity ieee-mac {
       base route-type;
       description
         "MAC route type.";
     }

     identity interface {
       base route-type;
       description
         "Interface route type.";
     }

     typedef route-type-definition {
       type identityref {
         base route-type;
       }
       description
         "Route type definition.";
     }

     identity tunnel-type {
       description
         "Base identity from which all tunnel
          types are derived.";
     }

     identity ipv4-tunnel {
       base tunnel-type;
       description
         "IPv4 tunnel type";
     }

     identity ipv6-tunnel {
       base tunnel-type;
       description
         "IPv6 tunnel type";
     }

     identity mpls-tunnel {
       base tunnel-type;



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       description
         "MPLS tunnel type";
     }

     identity gre-tunnel {
       base tunnel-type;
       description
         "GRE tunnel type";
     }

     identity vxlan-tunnel {
       base tunnel-type;
       description
         "VXLAN tunnel type";
     }

     identity nvgre-tunnel {
       base tunnel-type;
       description
         "NVGRE tunnel type";
     }

     typedef tunnel-type-definition {
       type identityref {
         base tunnel-type;
       }
       description
         "Tunnel type definition.";
     }

     identity route-state {
       description
         "Base identity from which all route
          states are derived.";
     }

     identity active {
       base route-state;
       description
         "Active state.";
     }

     identity inactive {
       base route-state;
       description
         "Inactive state.";
     }




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     typedef route-state-definition {
       type identityref {
         base route-state;
       }
       description
         "Route state definition.";
     }

     identity nexthop-state {
       description
         "Base identity from which all nexthop
          states are derived.";
     }

     identity resolved {
       base nexthop-state;
       description
         "Resolved nexthop state.";
     }

     identity unresolved {
       base nexthop-state;
       description
         "Unresolved nexthop state.";
     }

     typedef nexthop-state-definition {
       type identityref {
         base nexthop-state;
       }
       description
         "Nexthop state definition.";
     }

     identity route-installed-state {
       description
         "Base identity from which all route
          installed states are derived.";
     }

     identity uninstalled {
       base route-installed-state;
       description
         "Uninstalled state.";
     }

     identity installed {
       base route-installed-state;



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       description
         "Installed state.";
     }

     typedef route-installed-state-definition {
       type identityref {
         base route-installed-state;
       }
       description
         "Route installed state definition.";
     }

     //Route Change Reason Identities

     identity route-change-reason {
       description
         "Base identity from which all route change
          reasons are derived.";
     }

     identity lower-route-preference {
       base route-change-reason;
       description
         "This route was installed in the FIB because it had
          a lower route preference value (and thus was more
          preferred) than the route it replaced.";
     }

     identity higher-route-preference {
       base route-change-reason;
       description
         "This route was uninstalled from the FIB because it had
          a higher route preference value (and thus was less
          preferred) than the route that replaced it.";
     }

     identity resolved-nexthop {
       base route-change-reason;
       description
         "This route was made active because at least
          one of its nexthops was resolved.";
     }

     identity unresolved-nexthop {
       base route-change-reason;
       description
         "This route was made inactive because all of
          its nexthops are unresolved.";



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     }

     typedef route-change-reason-definition {
       type identityref {
         base route-change-reason;
       }
       description
         "Route change reason definition.";
     }

     typedef nexthop-preference-definition {
       type uint8 {
         range "1..99";
       }
       description
         "Nexthop-preference is used for protection schemes.
          It is an integer value between 1 and 99.  Lower
          values are preferred.  To download N
          nexthops to the FIB, the N nexthops with the lowest
          value are selected.  If there are more than N
          nexthops that have the same preference, an
          implementation of the I2RS client should select N
          nexthops and download them.  As for how to select
          the nexthops, this is left to the implementations.";
     }

     typedef nexthop-lb-weight-definition {
       type uint8 {
         range "1..99";
       }
       description
         "Nexthop-lb-weight is used for load-balancing.
          Each list member SHOULD be assigned a weight
          between 1 and 99.  The weight determines the
          proportion of traffic to be sent over a nexthop
          used for forwarding as a ratio of the weight of
          this nexthop divided by the sum of the weights
          of all the nexthops of this route that are used
          for forwarding.  To perform equal load-balancing,
          one MAY specify a weight of 0 for all the member
          nexthops.  The value 0 is reserved for equal
          load-balancing and, if applied, MUST be applied
          to all member nexthops.
          Note that the weight of 0 is special because of
          historical reasons.  It's typically used in
          hardware devices to signify ECMP.";
     }




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     typedef nexthop-ref {
       type leafref {
         path  "/iir:routing-instance" +
               "/iir:rib-list" +
               "/iir:route-list" +
               "/iir:nexthop" +
               "/iir:nexthop-id";
       }
       description
         "A nexthop reference that provides
          an indirection reference to a nexthop.";
     }

     //Groupings

     grouping route-prefix {
       description
         "The common attributes used for all types of route prefixes.";
       leaf route-index {
         type uint64;
         mandatory true;
         description
           "Route index.";
       }
       container match {
         description
           "The match condition specifies the
            kind of route (IPv4, MPLS, etc.)
            and the set of fields to match on.";
         choice route-type {
           description
             "Route types: IPv4, IPv6, MPLS, MAC, etc.";
           case ipv4 {
             description
               "IPv4 route case.";
             container ipv4 {
               description
                 "IPv4 route match.";
               choice ip-route-match-type {
                 description
                   "IP route match type options:
                    match source, or
                    match destination, or
                    match source and destination.";
                 case dest-ipv4-address {
                   leaf dest-ipv4-prefix {
                     type inet:ipv4-prefix;
                     mandatory true;



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                     description
                       "An IPv4 destination address as the match.";
                   }
                 }
                 case src-ipv4-address {
                   leaf src-ipv4-prefix {
                     type inet:ipv4-prefix;
                     mandatory true;
                     description
                       "An IPv4 source address as the match.";
                   }
                 }
                 case dest-src-ipv4-address {
                   container dest-src-ipv4-address {
                     description
                       "A combination of an IPv4 source and
                        an IPv4 destination address as the match.";
                     leaf dest-ipv4-prefix {
                       type inet:ipv4-prefix;
                       mandatory true;
                       description
                         "The IPv4 destination address of the match.";
                     }
                     leaf src-ipv4-prefix {
                       type inet:ipv4-prefix;
                       mandatory true;
                       description
                         "The IPv4 source address of the match.";
                     }
                   }
                 }
               }
             }
           }
           case ipv6 {
             description
               "IPv6 route case.";
             container ipv6 {
               description
                 "IPv6 route match.";
               choice ip-route-match-type {
                 description
                   "IP route match type options:
                    match source,
                    match destination, or
                    match source and destination.";
                 case dest-ipv6-address {
                   leaf dest-ipv6-prefix {



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                     type inet:ipv6-prefix;
                     mandatory true;
                     description
                       "An IPv6 destination address as the match.";
                   }
                 }
                 case src-ipv6-address {
                   leaf src-ipv6-prefix {
                     type inet:ipv6-prefix;
                     mandatory true;
                     description
                       "An IPv6 source address as the match.";
                   }
                 }
                 case dest-src-ipv6-address {
                   container dest-src-ipv6-address {
                     description
                       "A combination of an IPv6 source and
                        an IPv6 destination address as the match.";
                     leaf dest-ipv6-prefix {
                       type inet:ipv6-prefix;
                       mandatory true;
                       description
                         "The IPv6 destination address of the match.";
                     }
                     leaf src-ipv6-prefix {
                       type inet:ipv6-prefix;
                       mandatory true;
                       description
                         "The IPv6 source address of the match.";
                     }
                   }
                 }
               }
             }
           }
           case mpls-route {
             description
               "MPLS route case.";
             leaf mpls-label {
               type uint32;
               mandatory true;
               description
                 "The label used for matching.";
             }
           }
           case mac-route {
             description



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               "MAC route case.";
             leaf mac-address {
               type yang:mac-address;
               mandatory true;
               description
                 "The MAC address used for matching.";
             }
           }
           case interface-route {
             description
               "Interface route case.";
             leaf interface-identifier {
               type if:interface-ref;
               mandatory true;
               description
                 "The interface used for matching.";
             }
           }
         }
       }
     }

     grouping route {
       description
         "The common attributes used for all types of routes.";
       uses route-prefix;
       container nexthop {
         description
           "The nexthop of the route.";
         uses nexthop;
       }
       //In the information model, it is called route-statistic
       container route-status {
         description
           "The status information of the route.";
         leaf route-state {
           type route-state-definition;
           config false;
           description
             "Indicate a route's state: active or inactive.";
         }
         leaf route-installed-state {
           type route-installed-state-definition;
           config false;
           description
             "Indicate that a route's installed states:
              installed or uninstalled.";
         }



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         leaf route-reason {
           type route-change-reason-definition;
           config false;
           description
             "Indicate the reason that caused the route change.";
         }
       }
       container route-attributes {
         description
           "Route attributes.";
         uses route-attributes;
       }
       container route-vendor-attributes {
         description
           "Route vendor attributes.";
         uses route-vendor-attributes;
       }
     }

     grouping nexthop-list {
       description
         "A generic nexthop list.";
       list nexthop-list {
         key "nexthop-member-id";
         description
           "A list of nexthops.";
         leaf nexthop-member-id {
           type uint32;
           mandatory true;
           description
             "A nexthop identifier that points
              to a nexthop list member.
              A nexthop list member is a nexthop.";
         }
       }
     }

     grouping nexthop-list-p {
       description
         "A nexthop list with preference parameter.";
       list nexthop-list {
         key "nexthop-member-id";
         description
           "A list of nexthop.";
         leaf nexthop-member-id {
           type uint32;
           mandatory true;
           description



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             "A nexthop identifier that points
              to a nexthop list member.
              A nexthop list member is a nexthop.";
         }
         leaf nexthop-preference {
           type nexthop-preference-definition;
           mandatory true;
           description
             "Nexthop-preference is used for protection schemes.
              It is an integer value between 1 and 99.  Lower
              values are more preferred.  To download a
              primary/standby/tertiary group to the FIB, the
              nexthops that are resolved and are most preferred
              are selected.";
         }
       }
     }

     grouping nexthop-list-w {
       description
         "A nexthop list with a weight parameter.";
       list nexthop-list {
         key "nexthop-member-id";
         description
           "A list of nexthop.";
         leaf nexthop-member-id {
           type uint32;
           mandatory true;
           description
             "A nexthop identifier that points
              to a nexthop list member.
              A nexthop list member is a nexthop.";
         }
         leaf nexthop-lb-weight {
           type nexthop-lb-weight-definition;
           mandatory true;
           description
             "The weight of a nexthop of
              the load-balance nexthops.";
         }
       }
     }

     grouping nexthop {
       description
         "The nexthop structure.";
       leaf nexthop-id {
         type uint32;



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         description
           "An identifier that refers to a nexthop.";
       }
       leaf sharing-flag {
         type boolean;
         description
           "To indicate whether a nexthop is sharable
            or non-sharable:
            true  - sharable (which means the nexthop can be
                    shared with other routes)
            false - non-sharable (which means the nexthop can
                    not be shared with other routes)";
       }
       choice nexthop-type {
         description
           "Nexthop type options.";
         case nexthop-base {
           container nexthop-base {
             description
               "The base nexthop.";
             uses nexthop-base;
           }
         }
         case nexthop-chain {
           if-feature "nexthop-chain";
           container nexthop-chain {
             description
               "A chain nexthop.";
             uses nexthop-list;
           }
         }
         case nexthop-replicate {
           if-feature "nexthop-replicate";
           container nexthop-replicate {
             description
               "A replicate nexthop.";
             uses nexthop-list;
           }
         }
         case nexthop-protection {
           if-feature "nexthop-protection";
           container nexthop-protection {
             description
               "A protection nexthop.";
             uses nexthop-list-p;
           }
         }
         case nexthop-load-balance {



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           if-feature "nexthop-load-balance";
           container nexthop-lb {
             description
               "A load-balance nexthop.";
             uses nexthop-list-w;
           }
         }
       }
     }

     grouping nexthop-base {
       description
         "The base nexthop.";
       choice nexthop-base-type {
         description
           "Nexthop base type options.";
         case special-nexthop {
           leaf special {
             type special-nexthop-definition;
             description
               "A special nexthop.";
           }
         }
         case egress-interface-nexthop {
           leaf outgoing-interface {
             type if:interface-ref;
             mandatory true;
             description
               "The nexthop is an outgoing interface.";
           }
         }
         case ipv4-address-nexthop {
           leaf ipv4-address {
             type inet:ipv4-address;
             mandatory true;
             description
               "The nexthop is an IPv4 address.";
           }
         }
         case ipv6-address-nexthop {
           leaf ipv6-address {
             type inet:ipv6-address;
             mandatory true;
             description
               "The nexthop is an IPv6 address.";
           }
         }
         case egress-interface-ipv4-nexthop {



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           container egress-interface-ipv4-address {
             leaf outgoing-interface {
               type if:interface-ref;
               mandatory true;
               description
                 "Name of the outgoing interface.";
             }
             leaf ipv4-address {
               type inet:ipv4-address;
               mandatory true;
               description
                 "The nexthop points to an interface with
                  an IPv4 address.";
             }
             description
               "The nexthop is an egress-interface and an IP
                address.  This can be used in cases where, e.g.,
                the IP address is a link-local address.";
           }
         }
         case egress-interface-ipv6-nexthop {
           container egress-interface-ipv6-address {
             leaf outgoing-interface {
               type if:interface-ref;
               mandatory true;
               description
                 "Name of the outgoing interface.";
             }
             leaf ipv6-address {
               type inet:ipv6-address;
               mandatory true;
               description
                 "The nexthop points to an interface with
                  an IPv6 address.";
             }
             description
               "The nexthop is an egress-interface and an IP
                address.  This can be used in cases where, e.g.,
                the IP address is a link-local address.";
           }
         }
         case egress-interface-mac-nexthop {
           container egress-interface-mac-address {
             leaf outgoing-interface {
               type if:interface-ref;
               mandatory true;
               description
                 "Name of the outgoing interface.";



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             }
             leaf ieee-mac-address {
               type yang:mac-address;
               mandatory true;
               description
                 "The nexthop points to an interface with
                  a specific MAC address.";
             }
             description
               "The egress-interface must be an Ethernet
                interface.  Address resolution is not required
                for this nexthop.";
           }
         }
         case tunnel-encapsulation-nexthop {
           if-feature "nexthop-tunnel";
           container tunnel-encapsulation {
             uses tunnel-encapsulation;
             description
               "This can be an encapsulation representing an IP
                tunnel, MPLS tunnel, or others as defined in the info
                model.  An optional egress-interface can be chained
                to the tunnel encapsulation to indicate which
                interface to send the packet out on.  The
                egress-interface is useful when the network device
                contains Ethernet interfaces and one needs to
                perform address resolution for the IP packet.";
           }
         }
         case tunnel-decapsulation-nexthop {
           if-feature "nexthop-tunnel";
           container tunnel-decapsulation {
             uses tunnel-decapsulation;
             description
               "This is to specify the decapsulation of a tunnel
                header.";
           }
         }
         case logical-tunnel-nexthop {
           if-feature "nexthop-tunnel";
           container logical-tunnel {
             uses logical-tunnel;
             description
               "This can be an MPLS Label Switched Path (LSP)
                or a GRE tunnel (or others as defined in this
                document) that is represented by a unique
                identifier (e.g., name).";
           }



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         }
         case rib-name-nexthop {
           leaf rib-name {
             type string;
             description
               "A nexthop pointing to a RIB indicates that the
                route lookup needs to continue in the specified
                RIB.  This is a way to perform chained lookups.";
           }
         }
         case nexthop-identifier {
           leaf nexthop-ref {
             type nexthop-ref;
             mandatory true;
             description
               "A nexthop reference that points to a nexthop.";
           }
         }
       }
     }

     grouping route-vendor-attributes {
       description
         "Route vendor attributes.";
     }

     grouping logical-tunnel {
       description
         "A logical tunnel that is identified
          by a type and a tunnel name.";
       leaf tunnel-type {
         type tunnel-type-definition;
         mandatory true;
         description
           "A tunnel type.";
       }
       leaf tunnel-name {
         type string;
         mandatory true;
         description
           "A tunnel name that points to a logical tunnel.";
       }
     }

     grouping ipv4-header {
       description
         "The IPv4 header encapsulation information.";
       leaf src-ipv4-address {



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         type inet:ipv4-address;
         mandatory true;
         description
           "The source IP address of the header.";
       }
       leaf dest-ipv4-address {
         type inet:ipv4-address;
         mandatory true;
         description
           "The destination IP address of the header.";
       }
       leaf protocol {
         type uint8;
         mandatory true;
         description
           "The protocol id of the header.";
       }
       leaf ttl {
         type uint8;
         description
           "The TTL of the header.";
       }
       leaf dscp {
         type uint8;
         description
           "The Differentiated Services Code Point
            (DSCP) field of the header.";
       }
     }

     grouping ipv6-header {
       description
         "The IPv6 header encapsulation information.";
       leaf src-ipv6-address {
         type inet:ipv6-address;
         mandatory true;
         description
           "The source IP address of the header.";
       }
       leaf dest-ipv6-address {
         type inet:ipv6-address;
         mandatory true;
         description
           "The destination IP address of the header.";
       }
       leaf next-header {
         type uint8;
         mandatory true;



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         description
           "The next header of the IPv6 header.";
       }
       leaf traffic-class {
         type uint8;
         description
           "The traffic class value of the header.";
       }
       leaf flow-label {
         type inet:ipv6-flow-label;
         description
           "The flow label of the header.";
       }
       leaf hop-limit {
         type uint8 {
           range "1..255";
         }
         description
           "The hop limit of the header.";
       }
     }

     grouping nvgre-header {
       description
         "The NVGRE header encapsulation information.";
       choice nvgre-type {
         description
           "NVGRE can use either an IPv4
            or an IPv6 header for encapsulation.";
         case ipv4 {
           uses ipv4-header;
         }
         case ipv6 {
           uses ipv6-header;
         }
       }
       leaf virtual-subnet-id {
         type uint32;
         mandatory true;
         description
           "The subnet identifier of the NVGRE header.";
       }
       leaf flow-id {
         type uint8;
         description
           "The flow identifier of the NVGRE header.";
       }
     }



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     grouping vxlan-header {
       description
         "The VXLAN encapsulation header information.";
       choice vxlan-type {
         description
           "NVGRE can use either an IPv4
            or an IPv6 header for encapsulation.";
         case ipv4 {
           uses ipv4-header;
         }
         case ipv6 {
           uses ipv6-header;
         }
       }
       leaf vxlan-identifier {
         type uint32;
         mandatory true;
         description
           "The VXLAN identifier of the VXLAN header.";
       }
     }

     grouping gre-header {
       description
         "The GRE encapsulation header information.";
       choice dest-address-type {
         description
           "GRE options: IPv4 and IPv6";
         case ipv4 {
           leaf ipv4-dest {
             type inet:ipv4-address;
             mandatory true;
             description
               "The destination IP address of the GRE header.";
           }
         }
         case ipv6 {
           leaf ipv6-dest {
             type inet:ipv6-address;
             mandatory true;
             description
               "The destination IP address of the GRE header.";
           }
         }
       }
       leaf protocol-type {
         type uint16;
         mandatory true;



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         description
           "The protocol type of the GRE header.";
       }
       leaf key {
         type uint64;
         description
           "The GRE key of the GRE header.";
       }
     }

     grouping mpls-header {
       description
         "The MPLS encapsulation header information.";
       list label-operations {
         key "label-oper-id";
         description
           "Label operations.";
         leaf label-oper-id {
           type uint32;
           description
             "An optional identifier that points
              to a label operation.";
         }
         choice label-actions {
           description
             "Label action options.";
           case label-push {
             container label-push {
               description
                 "Label push operation.";
               leaf label {
                 type uint32;
                 mandatory true;
                 description
                   "The label to be pushed.";
               }
               leaf s-bit {
                 type boolean;
                 description
                   "The s-bit ('Bottom of Stack' bit) of the label to be
                    pushed.";
               }
               leaf tc-value {
                 type uint8;
                 description
                   "The traffic class value of the label to be pushed.";
               }
               leaf ttl-value {



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                 type uint8;
                 description
                   "The TTL value of the label to be pushed.";
               }
             }
           }
           case label-swap {
             container label-swap {
               description
                 "Label swap operation.";
               leaf in-label {
                 type uint32;
                 mandatory true;
                 description
                   "The label to be swapped.";
               }
               leaf out-label {
                 type uint32;
                 mandatory true;
                 description
                   "The out MPLS label.";
               }
               leaf ttl-action {
                 type ttl-action-definition;
                 description
                   "The label TTL actions:
                    - No-action
                    - Copy to inner label
                    - Decrease (the in-label)
                      by 1 and copy to the out-label";
               }
             }
           }
         }
       }
     }

     grouping tunnel-encapsulation {
       description
         "Tunnel encapsulation information.";
       choice tunnel-type {
         description
           "Tunnel options for nexthops.";
         case ipv4 {
           if-feature "ipv4-tunnel";
           container ipv4-header {
             uses ipv4-header;
             description



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               "IPv4 header.";
           }
         }
         case ipv6 {
           if-feature "ipv6-tunnel";
           container ipv6-header {
             uses ipv6-header;
             description
               "IPv6 header.";
           }
         }
         case mpls {
           if-feature "mpls-tunnel";
           container mpls-header {
             uses mpls-header;
             description
               "MPLS header.";
           }
         }
         case gre {
           if-feature "gre-tunnel";
           container gre-header {
             uses gre-header;
             description
               "GRE header.";
           }
         }
         case nvgre {
           if-feature "nvgre-tunnel";
           container nvgre-header {
             uses nvgre-header;
             description
               "NVGRE header.";
           }
         }
         case vxlan {
           if-feature "vxlan-tunnel";
           container vxlan-header {
             uses vxlan-header;
             description
               "VXLAN header.";
           }
         }
       }
     }

     grouping tunnel-decapsulation {
       description



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         "Tunnel decapsulation information.";
       choice tunnel-type {
         description
           "Nexthop tunnel type options.";
         case ipv4 {
           if-feature "ipv4-tunnel";
           container ipv4-decapsulation {
             description
               "IPv4 decapsulation.";
             leaf ipv4-decapsulation {
               type tunnel-decapsulation-action-definition;
               mandatory true;
               description
                 "IPv4 decapsulation operations.";
             }
             leaf ttl-action {
               type ttl-action-definition;
               description
                 "The TTL actions:
                  no-action or copy to inner header.";
             }
           }
         }
         case ipv6 {
           if-feature "ipv6-tunnel";
           container ipv6-decapsulation {
             description
               "IPv6 decapsulation.";
             leaf ipv6-decapsulation {
               type tunnel-decapsulation-action-definition;
               mandatory true;
               description
                 "IPv6 decapsulation operations.";
             }
             leaf hop-limit-action {
               type hop-limit-action-definition;
               description
                 "The hop limit actions:
                  no-action or copy to inner header.";
             }
           }
         }
         case mpls {
           if-feature "mpls-tunnel";
           container label-pop {
             description
               "MPLS decapsulation.";
             leaf label-pop {



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               type mpls-label-action-definition;
               mandatory true;
               description
                 "Pop a label from the label stack.";
             }
             leaf ttl-action {
               type ttl-action-definition;
               description
                 "The label TTL action.";
             }
           }
         }
       }
     }

     grouping route-attributes {
       description
         "Route attributes.";
       leaf route-preference {
         type uint32;
         mandatory true;
         description
           "ROUTE_PREFERENCE: This is a numerical value that
            allows for comparing routes from different
            protocols.  Static configuration is also
            considered a protocol for the purpose of this
            field.  It is also known as administrative-distance.
            The lower the value, the higher the preference.";
       }
       leaf local-only {
         type boolean;
         mandatory true;
         description
           "Indicate whether the attribute is local only.";
       }
       container address-family-route-attributes {
         description
           "Address-family-related route attributes.";
         choice route-type {
           description
             "Address-family-related route attributes. Future
              documents should specify these attributes by augmenting
              the cases in this choice.";
           case ip-route-attributes {
           }
           case mpls-route-attributes {
           }
           case ethernet-route-attributes {



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           }
         }
       }
     }

     container routing-instance {
       description
         "A routing instance, in the context of
          the RIB information model, is a collection
          of RIBs, interfaces, and routing parameters.";
       leaf name {
         type string;
         description
           "The name of the routing instance.  This MUST
            be unique across all routing instances in
            a given network device.";
       }
       list interface-list {
         key "name";
         description
           "This represents the list of interfaces associated
            with this routing instance.  The interface list helps
            constrain the boundaries of packet forwarding.
            Packets coming on these interfaces are directly
            associated with the given routing instance.  The
            interface list contains a list of identifiers with
            each identifier uniquely identifying an interface.";
         leaf name {
           type if:interface-ref;
           description
             "A reference to the name of a network-layer interface.";
         }
       }
       leaf router-id {
         type yang:dotted-quad;
         description
           "Router ID: The 32-bit number in the form of a dotted quad.";
       }
       leaf lookup-limit {
         type uint8;
         description
           "A limit on how many levels of a lookup can be performed.";
       }
       list rib-list {
         key "name";
         description
           "A list of RIBs that are associated with the routing
            instance.";



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         leaf name {
           type string;
           mandatory true;
           description
             "A reference to the name of each RIB.";
         }
         leaf address-family {
           type address-family-definition;
           mandatory true;
           description
             "The address family of a RIB.";
         }
         leaf ip-rpf-check {
           type boolean;
           description
             "Each RIB can be optionally associated with a
              ENABLE_IP_RPF_CHECK attribute that enables Reverse
              Path Forwarding (RPF) checks on all IP routes in that
              RIB.   An RPF check is used to
              prevent spoofing and limit malicious traffic.";
         }
         list route-list {
           key "route-index";
           description
             "A list of routes of a RIB.";
           uses route;
         }
         // This is a list that maintains the nexthops added to the RIB.
         uses nexthop-list;
       }
     }

     //RPC Operations

     rpc rib-add {
       description
         "To add a RIB to an instance";
       input {
         leaf name {
           type string;
           mandatory true;
           description
             "A reference to the name of the RIB
              that is to be added.";
         }
         leaf address-family {
           type address-family-definition;
           mandatory true;



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           description
             "The address family of the RIB.";
         }
         leaf ip-rpf-check {
           type boolean;
           description
             "Each RIB can be optionally associated with an
              ENABLE_IP_RPF_CHECK attribute that enables
              RPF checks on all IP routes in that
              RIB.   An RPF check is used to
              prevent spoofing and limit malicious traffic.";
         }
       }
       output {
         leaf result {
           type boolean;
           mandatory true;
           description
             "Return the result of the rib-add operation.
              true  - success;
              false - failed";
         }
         leaf reason {
           type string;
           description
             "The specific reason that caused the failure.";
         }
       }
     }

     rpc rib-delete {
       description
         "To delete a RIB from a routing instance.
          After deleting the RIB, all routes installed
          in the RIB will be deleted as well.";
       input {
         leaf name {
           type string;
           mandatory true;
           description
             "A reference to the name of the RIB
              that is to be deleted.";
         }
       }
       output {
         leaf result {
           type boolean;
           mandatory true;



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           description
             "Return the result of the rib-delete operation.
              true  - success;
              false - failed";
         }
         leaf reason {
           type string;
           description
             "The specific reason that caused failure.";
         }
       }
     }

     grouping route-operation-state {
       description
         "Route operation state.";
       leaf success-count {
         type uint32;
         mandatory true;
         description
           "The numbers of routes that are successfully
            added/deleted/updated.";
       }
       leaf failed-count {
         type uint32;
         mandatory true;
         description
           "The numbers of the routes that fail
            to be added/deleted/updated.";
       }
       container failure-detail {
         description
           "The failure detail reflects the reason why a route
            operation fails.  It is an array that includes the route
            index and error code of the failed route.";
         list failed-routes {
           key "route-index";
           description
             "The list of failed routes.";
           leaf route-index {
             type uint32;
             description
               "The route index of the failed route.";
           }
           leaf error-code {
             type uint32;
             description
               "The error code that reflects the failure reason.



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                0 - Reserved
                1 - Trying to add a repeat route
                2 - Trying to delete or update a route that does not
                  exist
                3 - Malformed route attributes";
           }
         }
       }
     }

     rpc route-add {
       description
         "To add a route or a list of routes to a RIB";
       input {
         leaf return-failure-detail {
           type boolean;
           default "false";
           description
             "Whether to return the failure detail.
              true  - return the failure detail
              false - do not return the failure detail
              The default is false.";
         }
         leaf rib-name {
           type string;
           mandatory true;
           description
             "A reference to the name of a RIB.";
         }
         container routes {
           description
             "The routes to be added to the RIB.";
           list route-list {
             key "route-index";
             description
               "The list of routes to be added.";
             uses route-prefix;
             container route-attributes {
               uses route-attributes;
               description
                 "The route attributes.";
             }
             container route-vendor-attributes {
               if-feature "route-vendor-attributes";
               uses route-vendor-attributes;
               description
                 "The route vendor attributes.";
             }



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             container nexthop {
               uses nexthop;
               description
                 "The nexthop of the added route.";
             }
           }
         }
       }
       output {
         uses route-operation-state;
       }
     }

     rpc route-delete {
       description
         "To delete a route or a list of routes from a RIB";
       input {
         leaf return-failure-detail {
           type boolean;
           default "false";
           description
             "Whether to return the failure detail.
              true  - return the failure detail
              false - do not return the failure detail
              The default is false.";
         }
         leaf rib-name {
           type string;
           mandatory true;
           description
             "A reference to the name of a RIB.";
         }
         container routes {
           description
             "The routes to be added to the RIB.";
           list route-list {
             key "route-index";
             description
               "The list of routes to be deleted.";
             uses route-prefix;
           }
         }
       }
       output {
         uses route-operation-state;
       }
     }




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     grouping route-update-options {
       description
         "Update options:
          1. update the nexthop
          2. update the route attributes
          3. update the route-vendor-attributes";
       choice update-options {
         description
           "Update options:
            1. update the nexthop
            2. update the route attributes
            3. update the route-vendor-attributes";
         case update-nexthop {
           container updated-nexthop {
             uses nexthop;
             description
               "The nexthop used for updating.";
           }
         }
         case update-route-attributes {
           container updated-route-attr {
             uses route-attributes;
             description
               "The route attributes used for updating.";
           }
         }
         case update-route-vendor-attributes {
           container updated-route-vendor-attr {
             uses route-vendor-attributes;
             description
               "The vendor route attributes used for updating.";
           }
         }
       }
     }

     rpc route-update {
       description
         "To update a route or a list of routes of a RIB.
          The inputs:
            1. The match conditions, which could be:
              a. route prefix,
              b. route attributes, or
              c. nexthop.
            2. The update parameters to be used:
              a. new nexthop,
              b. new route attributes, or
              c. nexthop.



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          Actions:
            1. update the nexthop
            2. update the route attributes
          The outputs:
            success-count - the number of routes updated
            failed-count - the number of routes fail to update
            failure-detail - the detail failure info
         ";
       input {
         leaf return-failure-detail {
           type boolean;
           default "false";
           description
             "Whether to return the failure detail.
              true  - return the failure detail
              false - do not return the failure detail
              The default is false.";
         }
         leaf rib-name {
           type string;
           mandatory true;
           description
             "A reference to the name of a RIB.";
         }
         choice match-options {
           description
             "Match options.";
           case match-route-prefix {
             description
               "Update the routes that match the route
                prefix(es) condition.";
             container input-routes {
               description
                 "The matched routes to be updated.";
               list route-list {
                 key "route-index";
                 description
                   "The list of routes to be updated.";
                 uses route-prefix;
                 uses route-update-options;
               }
             }
           }
           case match-route-attributes {
             description
               "Update the routes that match the
                route attributes condition.";
             container input-route-attributes {



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               description
                 "The route attributes are used for matching.";
               uses route-attributes;
             }
             container update-parameters {
               description
                 "Update options:
                  1. update the nexthop
                  2. update the route attributes
                  3. update the route-vendor-attributes";
               uses route-update-options;
             }
           }
           case match-route-vendor-attributes {
             if-feature "route-vendor-attributes";
             description
               "Update the routes that match the
                vendor attributes condition";
             container input-route-vendor-attributes {
               description
                 "The vendor route attributes are used for matching.";
               uses route-vendor-attributes;
             }
             container update-parameters-vendor {
               description
                 "Update options:
                  1. update the nexthop
                  2. update the route attributes
                  3. update the route-vendor-attributes";
               uses route-update-options;
             }
           }
           case match-nexthop {
             description
               "Update the routes that match the nexthop.";
             container input-nexthop {
               description
                 "The nexthop used for matching.";
               uses nexthop;
             }
             container update-parameters-nexthop {
               description
                 "Update options:
                  1. update the nexthop
                  2. update the route attributes
                  3. update the route-vendor-attributes";
               uses route-update-options;
             }



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           }
         }
       }
       output {
         uses route-operation-state;
       }
     }
     rpc nh-add {
       description
         "To add a nexthop to a RIB.
          Inputs parameters:
            1. rib-name
            2. nexthop
          Actions:
            Add the nexthop to the RIB
          Outputs:
            1. Operation result:
               true  - success
               false - failed
            2. nexthop identifier";
       input {
         leaf rib-name {
           type string;
           mandatory true;
           description
             "A reference to the name of a RIB.";
         }
         uses nexthop;
       }
       output {
         leaf result {
           type boolean;
           mandatory true;
           description
             "Return the result of the rib-add operation:
              true  - success
              false - failed";
         }
         leaf reason {
           type string;
           description
             "The specific reason that caused the failure.";
         }
         leaf nexthop-id {
           type uint32;
           description
             "A nexthop identifier that is allocated to the nexthop.";
         }



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       }
     }

     rpc nh-delete {
       description
         "To delete a nexthop from a RIB";
       input {
         leaf rib-name {
           type string;
           mandatory true;
           description
             "A reference to the name of a RIB.";
         }
         uses nexthop;
       }
       output {
         leaf result {
           type boolean;
           mandatory true;
           description
             "Return the result of the rib-add operation:
              true  - success;
              false - failed";
         }
         leaf reason {
           type string;
           description
             "The specific reason that caused the failure.";
         }
       }
     }

     //Notifications

     notification nexthop-resolution-status-change {
       description
         "Nexthop resolution status (resolved/unresolved)
          notification.";
       container nexthop {
         description
           "The nexthop.";
         uses nexthop;
       }
       leaf nexthop-state {
         type nexthop-state-definition;
         mandatory true;
         description
           "Nexthop resolution status (resolved/unresolved)



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            notification.";
       }
     }

     notification route-change {
       description
         "Route change notification.";
       leaf rib-name {
         type string;
         mandatory true;
         description
           "A reference to the name of a RIB.";
       }
       leaf address-family {
         type address-family-definition;
         mandatory true;
         description
           "The address family of a RIB.";
       }
       uses route-prefix;
       leaf route-installed-state {
         type route-installed-state-definition;
         mandatory true;
         description
           "Indicates whether the route got installed in the FIB.";
       }
       leaf route-state {
         type route-state-definition;
         mandatory true;
         description
           "Indicates whether a route is active or inactive.";
       }
       list route-change-reasons {
         key "route-change-reason";
         description
           "The reasons that cause the route change.  A route
            change may result from several reasons; for
            example, a nexthop becoming resolved will make a
            route A active, which is of better preference than
            a currently active route B, which results in the
            route A being installed";
         leaf route-change-reason {
           type route-change-reason-definition;
           mandatory true;
           description
             "The reason that caused the route change.";
         }
       }



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     }
   }

   <CODE ENDS>

4.  IANA Considerations

   This document registers a URI in the "ns" registry within the "IETF
   XML Registry" [RFC3688]:

    -------------------------------------------------------------------
    URI: urn:ietf:params:xml:ns:yang:ietf-i2rs-rib
    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 [RFC7950]:

    -------------------------------------------------------------------
    name:         ietf-i2rs-rib
    namespace:    urn:ietf:params:xml:ns:yang:ietf-i2rs-rib
    prefix:       iir
    reference:    RFC 8431
    -------------------------------------------------------------------

5.  Security Considerations

   The YANG module specified in this document defines a schema for data
   that 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
   [RFC8446].

   The NETCONF access control model [RFC8341] 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.

   The YANG module defines information that can be configurable in
   certain instances, for example, a RIB, a route, a nexthop can be
   created or deleted by client applications; the YANG module also
   defines RPCs that can be used by client applications to add/delete
   RIBs, routes, and nexthops.  In such cases, a malicious client could
   attempt to remove, add, or update a RIB, a route, or a nexthop by
   creating or deleting corresponding elements in the RIB, route, and



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   nexthop lists, respectively.  Removing a RIB or a route could lead to
   disruption or impact in performance of a service; updating a route
   may lead to suboptimal path and degradation of service levels as well
   as possibly disruption of service.  For those reasons, it is
   important that the NETCONF access control model is vigorously applied
   to prevent misconfiguration by unauthorized clients.

   There are a number of data nodes defined in this YANG module that 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.  These are the subtrees and data nodes
   and their sensitivity/vulnerability:

   o  RIB: A malicious client could attempt to remove a RIB from a
      routing instance, for example, in order to sabotage the services
      provided by the RIB or to add a RIB to a routing instance (hence,
      to inject unauthorized traffic into the nexthop).

   o  route: A malicious client could attempt to remove or add a route
      from/to a RIB, for example, in order to sabotage the services
      provided by the RIB.

   o  nexthop: A malicious client could attempt to remove or add a
      nexthop from/to RIB, which may lead to a suboptimal path, a
      degradation of service levels, and a possible disruption of
      service.

6.  References

6.1.  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,
              <https://www.rfc-editor.org/info/rfc2119>.

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

   [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,
              <https://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,
              <https://www.rfc-editor.org/info/rfc6242>.

   [RFC6991]  Schoenwaelder, J., Ed., "Common YANG Data Types",
              RFC 6991, DOI 10.17487/RFC6991, July 2013,
              <https://www.rfc-editor.org/info/rfc6991>.

   [RFC7950]  Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
              RFC 7950, DOI 10.17487/RFC7950, August 2016,
              <https://www.rfc-editor.org/info/rfc7950>.

   [RFC8040]  Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
              Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
              <https://www.rfc-editor.org/info/rfc8040>.

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

   [RFC8341]  Bierman, A. and M. Bjorklund, "Network Configuration
              Access Control Model", STD 91, RFC 8341,
              DOI 10.17487/RFC8341, March 2018,
              <https://www.rfc-editor.org/info/rfc8341>.

   [RFC8344]  Bjorklund, M., "A YANG Data Model for IP Management",
              RFC 8344, DOI 10.17487/RFC8344, March 2018,
              <https://www.rfc-editor.org/info/rfc8344>.

   [RFC8430]  Bahadur, N., Ed., Kini, S., Ed., and J. Medved, "RIB
              Information Model", RFC 8430, DOI 10.17487/RFC8430,
              September 2018, <http://www.rfc-editor.org/info/rfc8430>.

   [RFC8446]  Rescorla, E., "The Transport Layer Security (TLS) Protocol
              Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
              <https://www.rfc-editor.org/info/rfc8446>.

6.2.  Informative References

   [I2RS-REQS]
              Hares, S. and M. Chen, "Summary of I2RS Use Case
              Requirements", Work in Progress, draft-ietf-i2rs-usecase-
              reqs-summary-03, November 2016.

   [RFC2784]  Farinacci, D., Li, T., Hanks, S., Meyer, D., and P.
              Traina, "Generic Routing Encapsulation (GRE)", RFC 2784,
              DOI 10.17487/RFC2784, March 2000,
              <https://www.rfc-editor.org/info/rfc2784>.



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   [RFC7348]  Mahalingam, M., Dutt, D., Duda, K., Agarwal, P., Kreeger,
              L., Sridhar, T., Bursell, M., and C. Wright, "Virtual
              eXtensible Local Area Network (VXLAN): A Framework for
              Overlaying Virtualized Layer 2 Networks over Layer 3
              Networks", RFC 7348, DOI 10.17487/RFC7348, August 2014,
              <https://www.rfc-editor.org/info/rfc7348>.

   [RFC7637]  Garg, P., Ed. and Y. Wang, Ed., "NVGRE: Network
              Virtualization Using Generic Routing Encapsulation",
              RFC 7637, DOI 10.17487/RFC7637, September 2015,
              <https://www.rfc-editor.org/info/rfc7637>.

   [RFC7921]  Atlas, A., Halpern, J., Hares, S., Ward, D., and T.
              Nadeau, "An Architecture for the Interface to the Routing
              System", RFC 7921, DOI 10.17487/RFC7921, June 2016,
              <https://www.rfc-editor.org/info/rfc7921>.

   [RFC8340]  Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams",
              BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018,
              <https://www.rfc-editor.org/info/rfc8340>.

Acknowledgements

   The authors would like to thank Chris Bowers, John Scudder, Tom
   Petch, Mike McBride, and Ebben Aries for their review, suggestions,
   and comments to this document.

Contributors

   The following individuals also contributed to this document.

   o  Zekun He, Tencent Holdings Ltd.

   o  Sujian Lu, Tencent Holdings Ltd.

   o  Jeffery Zhang, Juniper Networks















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Authors' Addresses

   Lixing Wang
   Individual

   Email: wang_little_star@sina.com


   Mach(Guoyi) Chen
   Huawei

   Email: mach.chen@huawei.com


   Amit Dass
   Ericsson

   Email: dass.amit@gmail.com


   Hariharan Ananthakrishnan
   Netflix

   Email: hari@netflix.com


   Sriganesh Kini
   Individual

   Email: sriganeshkini@gmail.com


   Nitin Bahadur
   Uber

   Email: nitin_bahadur@yahoo.com















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