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NETMOD                                                         L. Lhotka
Internet-Draft                                                    CZ.NIC
Intended status: Standards Track                            July 9, 2012
Expires: January 10, 2013


              A YANG Data Model for Routing Configuration
                    draft-ietf-netmod-routing-cfg-04

Abstract

   This document contains a specification of three YANG modules.
   Together they form the core routing data model which serves as a
   framework for configuring a routing subsystem.  It is therefore
   expected that these modules will be augmented by additional YANG
   modules defining data models for individual routing protocols and
   other related functions.  The core routing data model provides common
   building blocks for such configurations - router instances, routes,
   routing tables, routing protocols and route filters.

Status of this Memo

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

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

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on January 10, 2013.

Copyright Notice

   Copyright (c) 2012 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must



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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Terminology and Notation . . . . . . . . . . . . . . . . . . .  4
     2.1.  Glossary of New Terms  . . . . . . . . . . . . . . . . . .  4
     2.2.  Prefixes in Data Node Names  . . . . . . . . . . . . . . .  5
   3.  Objectives . . . . . . . . . . . . . . . . . . . . . . . . . .  6
   4.  The Design of the Core Routing Data Model  . . . . . . . . . .  7
     4.1.  Router . . . . . . . . . . . . . . . . . . . . . . . . . . 10
       4.1.1.  Configuration of IPv6 Router Interfaces  . . . . . . . 10
     4.2.  Route  . . . . . . . . . . . . . . . . . . . . . . . . . . 11
     4.3.  Routing Tables . . . . . . . . . . . . . . . . . . . . . . 12
     4.4.  Routing Protocols  . . . . . . . . . . . . . . . . . . . . 13
       4.4.1.  Routing Pseudo-Protocols . . . . . . . . . . . . . . . 14
       4.4.2.  Defining New Routing Protocols . . . . . . . . . . . . 14
     4.5.  Route Filters  . . . . . . . . . . . . . . . . . . . . . . 17
     4.6.  RPC Operations . . . . . . . . . . . . . . . . . . . . . . 18
       4.6.1.  Operation "active-route" . . . . . . . . . . . . . . . 18
       4.6.2.  Operation "route-count"  . . . . . . . . . . . . . . . 19
   5.  Interactions with Other YANG Modules . . . . . . . . . . . . . 20
     5.1.  Module "ietf-interfaces" . . . . . . . . . . . . . . . . . 20
     5.2.  Module "ietf-ip" . . . . . . . . . . . . . . . . . . . . . 20
   6.  Routing YANG Module  . . . . . . . . . . . . . . . . . . . . . 22
   7.  IPv4 Unicast Routing YANG Module . . . . . . . . . . . . . . . 34
   8.  IPv6 Unicast Routing YANG Module . . . . . . . . . . . . . . . 38
   9.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 47
   10. Security Considerations  . . . . . . . . . . . . . . . . . . . 49
   11. Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 50
   12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 51
     12.1. Normative References . . . . . . . . . . . . . . . . . . . 51
     12.2. Informative References . . . . . . . . . . . . . . . . . . 51
   Appendix A.  Example: Adding a New Routing Protocol  . . . . . . . 52
   Appendix B.  Example: Reply to the NETCONF <get> Message . . . . . 55
   Appendix C.  Change Log  . . . . . . . . . . . . . . . . . . . . . 60
     C.1.  Changes Between Versions -03 and -04 . . . . . . . . . . . 60
     C.2.  Changes Between Versions -02 and -03 . . . . . . . . . . . 60
     C.3.  Changes Between Versions -01 and -02 . . . . . . . . . . . 61
     C.4.  Changes Between Versions -00 and -01 . . . . . . . . . . . 61
   Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 62







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1.  Introduction

   This document contains a specification of the following YANG modules:

   o  Module "ietf-routing" provides generic components of a routing
      data model.

   o  Module "ietf-ipv4-unicast-routing" augments the "ietf-routing"
      module with additional data specific to IPv4 unicast.

   o  Module "ietf-ipv6-unicast-routing" augments the "ietf-routing"
      module with additional data specific to IPv6 unicast, including
      the router configuration variables required by [RFC4861].

   These modules together define the so-called core routing data model,
   which is proposed as a basis for the development of data models for
   more sophisticated routing configurations.  While these three modules
   can be directly used for simple IP devices with static routing, their
   main purpose is to provide essential building blocks for more
   complicated setups involving multiple routing protocols, multicast
   routing, additional address families, and advanced functions such as
   route filtering or policy routing.  To this end, it is expected that
   the core routing data model will be augmented by numerous modules
   developed by other IETF working groups.



























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2.  Terminology and Notation

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

   The following terms are defined in [RFC6241]:

   o  client

   o  message

   o  protocol operation

   o  server

   The following terms are defined in [RFC6020]:

   o  augment

   o  configuration data

   o  container

   o  data model

   o  data node

   o  data type

   o  identity

   o  mandatory node

   o  module

   o  operational state data

   o  prefix

   o  RPC operation

2.1.  Glossary of New Terms








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   active route:  a route which is actually used for sending packets.
      If there are multiple candidate routes with a matching destination
      prefix, then it is up to the routing algorithm to select the
      active route (or several active routes in the case of multi-path
      routing).

   core routing data model:  YANG data model resulting from the
      combination of "ietf-routing", "ietf-ipv4-unicast-routing" and
      "ietf-ipv6-unicast-routing" modules.

   direct route:  a route to a directly connected network.

2.2.  Prefixes in Data Node Names

   In this document, names of data nodes, RPC methods and other data
   model objects are used mostly without a prefix, as long as it is
   clear from the context in which YANG module each name is defined.
   Otherwise, names are prefixed using the standard prefix associated
   with the corresponding YANG module, as shown in Table 1.

           +--------+---------------------------+--------------+
           | Prefix | YANG module               | Reference    |
           +--------+---------------------------+--------------+
           | ianaaf | iana-afn-safi             | [IANA-IF-AF] |
           |        |                           |              |
           | if     | ietf-interfaces           | [YANG-IF]    |
           |        |                           |              |
           | ip     | ietf-ip                   | [YANG-IP]    |
           |        |                           |              |
           | rip    | example-rip               | Appendix A   |
           |        |                           |              |
           | rt     | ietf-routing              | Section 6    |
           |        |                           |              |
           | v4ur   | ietf-ipv4-unicast-routing | Section 7    |
           |        |                           |              |
           | v6ur   | ietf-ipv6-unicast-routing | Section 8    |
           |        |                           |              |
           | yang   | ietf-yang-types           | [RFC6021]    |
           |        |                           |              |
           | inet   | ietf-inet-types           | [RFC6021]    |
           +--------+---------------------------+--------------+

             Table 1: Prefixes and corresponding YANG modules








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3.  Objectives

   The initial design of the core routing data model was driven by the
   following objectives:

   o  The data model should be suitable for the common address families,
      in particular IPv4 and IPv6, and for unicast and multicast
      routing, as well as Multiprotocol Label Switching (MPLS).

   o  Simple routing setups, such as static routing, should be
      configurable in a simple way, ideally without any need to develop
      additional YANG modules.

   o  On the other hand, the core routing framework must allow for
      complicated setups involving multiple routing tables and multiple
      routing protocols, as well as controlled redistributions of
      routing information.

   o  Device vendors will want to map the data models built on this
      generic framework to their proprietary data models and
      configuration interfaces.  Therefore, the framework should be
      flexible enough to facilitate such a mapping and accommodate data
      models with different logic.




























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4.  The Design of the Core Routing Data Model

   The core routing data model consists of three YANG modules.  The
   first module, "ietf-routing", defines the generic components of a
   routing system.  The other two modules, "ietf-ipv4-unicast-routing"
   and "ietf-ipv6-unicast-routing", augment the "ietf-routing" module
   with additional data nodes that are needed for IPv4 and IPv6 unicast
   routing, respectively.  The combined data hierarchy is shown in
   Figure 1, where brackets enclose list keys, "rw" means configuration,
   "ro" operational state data, and "?" means optional node.
   Parentheses enclose choice and case nodes, and case nodes are also
   marked with a colon (":").

   +--rw routing
      +--rw router [name]
      |  +--rw name
      |  +--rw router-id?
      |  +--rw description?
      |  +--rw enabled?
      |  +--rw interfaces
      |  |  +--rw interface [name]
      |  |     +--rw name
      |  |     +--rw v6ur:ipv6-router-advertisements
      |  |        +--rw v6ur:send-advertisements?
      |  |        +--rw v6ur:max-rtr-adv-interval?
      |  |        +--rw v6ur:min-rtr-adv-interval?
      |  |        +--rw v6ur:managed-flag?
      |  |        +--rw v6ur:other-config-flag?
      |  |        +--rw v6ur:link-mtu?
      |  |        +--rw v6ur:reachable-time?
      |  |        +--rw v6ur:retrans-timer?
      |  |        +--rw v6ur:cur-hop-limit?
      |  |        +--rw v6ur:default-lifetime?
      |  |        +--rw v6ur:prefix-list
      |  |           +--rw v6ur:prefix [prefix-spec]
      |  |              +--rw v6ur:prefix-spec
      |  |              +--rw (control-adv-prefixes)?
      |  |                 +--:(no-advertise)
      |  |                 |  +--rw v6ur:no-advertise?
      |  |                 +--:(advertise)
      |  |                    +--rw v6ur:valid-lifetime?
      |  |                    +--rw v6ur:on-link-flag?
      |  |                    +--rw v6ur:preferred-lifetime?
      |  |                    +--rw v6ur:autonomous-flag?
      |  +--rw routing-protocols
      |  |  +--rw routing-protocol [name]
      |  |     +--rw name
      |  |     +--rw description?



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      |  |     +--rw type
      |  |     +--rw connected-routing-tables
      |  |     |  +--rw routing-table [name]
      |  |     |     +--rw name
      |  |     |     +--rw import-filter?
      |  |     |     +--rw export-filter?
      |  |     +--rw static-routes
      |  |        +--rw v4ur:ipv4
      |  |        |  +--rw v4ur:route [id]
      |  |        |     +--rw v4ur:id
      |  |        |     +--rw v4ur:description?
      |  |        |     +--rw v4ur:outgoing-interface?
      |  |        |     +--rw v4ur:dest-prefix
      |  |        |     +--rw v4ur:next-hop?
      |  |        +--rw v6ur:ipv6
      |  |           +--rw v6ur:route [id]
      |  |              +--rw v6ur:id
      |  |              +--rw v6ur:description?
      |  |              +--rw v6ur:outgoing-interface?
      |  |              +--rw v6ur:dest-prefix
      |  |              +--rw v6ur:next-hop?
      |  +--rw routing-tables
      |     +--rw routing-table [name]
      |        +--rw name
      |        +--rw address-family?
      |        +--rw safi?
      |        +--rw description?
      |        +--ro routes
      |        |  +--ro route
      |        |     +--ro outgoing-interface?
      |        |     +--ro source-protocol
      |        |     +--ro age
      |        |     +--ro v4ur:dest-prefix?
      |        |     +--ro v4ur:next-hop?
      |        |     +--ro v6ur:dest-prefix?
      |        |     +--ro v6ur:next-hop?
      |        +--rw recipient-routing-tables
      |           +--rw recipient-routing-table [name]
      |              +--rw name
      |              +--rw filter?
      +--rw route-filters
         +--rw route-filter [name]
            +--rw name
            +--rw description?
            +--rw type?

         Figure 1: Data hierarchy of the core routing data model.




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   As can be seen from Figure 1, the core routing data model introduces
   several generic components of a routing framework: routers, routing
   tables containing routes, routing protocols and route filters.  The
   following subsections describe these components in more detail.

   By combining the components in various ways, and possibly augmenting
   them with appropriate contents defined in other modules, various
   routing setups can be realized.

   +--------+
   | direct |    +---+    +--------------+    +---+    +--------------+
   | routes |--->| F |--->|              |<---| F |<---|              |
   +--------+    +---+    |    main      |    +---+    |  additional  |
                          |   routing    |             |   routing    |
   +--------+    +---+    |    table     |    +---+    |    table     |
   | static |--->| F |--->|              |--->| F |--->|              |
   | routes |    +---+    +--------------+    +---+    +--------------+
   +--------+                 ^      |                     ^      |
                              |      v                     |      v
                            +---+  +---+                 +---+  +---+
                            | F |  | F |                 | F |  | F |
                            +---+  +---+                 +---+  +---+
                              ^      |                     ^      |
                              |      v                     |      v
                            +----------+                 +----------+
                            | routing  |                 | routing  |
                            | protocol |                 | protocol |
                            +----------+                 +----------+

             Figure 2: Example setup of the routing subsystem

   The example in Figure 2 shows a typical (though certainly not the
   only possible) organization of a more complex routing subsystem for a
   single address family.  Several of its features are worth mentioning:

   o  Along with the main routing table, which must always be present,
      an additional routing table is configured.

   o  Each routing protocol instance, including the "static" and
      "direct" pseudo-protocols, is connected to one routing table with
      which it can exchange routes (in both directions, except for the
      "static" and "direct" pseudo-protocols).

   o  Routing tables may also be connected to each other and exchange
      routes in either direction (or both).

   o  Route exchanges along all connections may be controlled by means
      of route filters, denoted by "F" in Figure 2.



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4.1.  Router

   Each router instance in the core routing data model represents a
   logical router.  The exact semantics of this term is left to
   implementations.  For example, router instances may be completely
   isolated virtual routers or, alternatively, they may internally share
   certain information.

   Each network layer interface must be assigned to one or more router
   instances in order to be able to participate in packet forwarding,
   routing protocols and other operations of those router instances.
   The assignment is accomplished by creating a corresponding entry in
   the list of router interfaces ("rt:interface").  The key of the list
   entry MUST be the name of a configured network layer interface, i.e.,
   the value of a node /if:interfaces/if:interface/if:name defined in
   the "ietf-interfaces" module [YANG-IF].

   Implementations MAY specify additional rules for the assignment of
   interfaces to logical routers.  For example, it may be required that
   the sets of interfaces assigned to different logical routers be
   disjoint.

   Apart from the key, each entry of the "rt:interface" list MAY contain
   other configuration or operational state data related to the
   corresponding router interface.

4.1.1.  Configuration of IPv6 Router Interfaces

   The module "ietf-ipv6-unicast-routing" augments the definition of the
   data node "rt:interface" with definitions of the following
   configuration variables as required by [RFC4861], sec. 6.2.1:

   o  send-advertisements,

   o  max-rtr-adv-interval,

   o  min-rtr-adv-interval,

   o  managed-flag,

   o  other-config-flag,

   o  link-mtu,

   o  reachable-time,

   o  retrans-timer,




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   o  cur-hop-limit,

   o  default-lifetime,

   o  prefix-list: a list of prefixes to be advertised.  The following
      parameters are associated with each prefix in the list:

      *  valid-lifetime,

      *  on-link-flag,

      *  preferred-lifetime,

      *  autonomous-flag.

   The definitions and descriptions of the above parameters can be found
   in the text of the module "ietf-ipv6-unicast-routing" (Section 8).

   NOTES:

   1.  The "IsRouter" flag, which is also required by [RFC4861], is
       implemented in the "ietf-ip" module [YANG-IP] (leaf "ip:ip-
       forwarding").

   2.  The original specification [RFC4861] allows the implementations
       to decide whether the "valid-lifetime" and "preferred-lifetime"
       parameters remain the same in consecutive advertisements, or
       decrement in real time.  However, the latter behavior seems
       problematic because the values might be reset again to the
       (higher) configured values after a configuration is reloaded.
       Moreover, no implementation is known to use the decrementing
       behavior.  The "ietf-ipv6-unicast-routing" module therefore
       assumes the former behavior with constant values.

4.2.  Route

   Routes are basic units of information in a routing system.  The core
   routing data model defines only the following minimal set of route
   attributes:

   o  "destination-prefix": IP prefix specifying the set of destination
      addresses for which the route may be used.  This attribute is
      mandatory.

   o  "next-hop": IP address of an adjacent router or host to which
      packets with destination addresses belonging to "destination-
      prefix" should be sent.




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   o  "outgoing-interface": network interface that should be used for
      sending packets with destination addresses belonging to
      "destination-prefix".

   The above list of route attributes suffices for a simple static
   routing configuration.  It is expected that future modules defining
   routing protocols will add other route attributes such as metrics or
   preferences.

   Routes and their attributes are used both in configuration data, for
   example as manually configured static routes, and in operational
   state data, for example as entries in routing tables.

4.3.  Routing Tables

   Routing tables are lists of routes complemented with administrative
   data, namely:

   o  "source-protocol": name of the routing protocol from which the
      route was originally obtained.

   o  "age": number of seconds since the route was created or last
      updated.

   Each routing table may contain only routes of the same address
   family.  Address family information consists of two parameters -
   "address-family" and "safi" (Subsequent Address Family Identifier,
   SAFI).  The permitted values for these two parameters are defined by
   IANA and represented using YANG enumeration types "ianaaf:address-
   family" and "ianaaf:subsequent-address-family" [IANA-IF-AF].

   In the core routing data model, the "routing-table" node represents
   configuration while the descendant list of routes is defined as
   operational state data.  The contents of route lists are controlled
   and manipulated by routing protocol operations which may result in
   route additions, removals and modifications.  This also includes
   manipulations via the "static" and/or "direct" pseudo-protocols, see
   Section 4.4.1.

   One routing table MUST be present for each router instance and each
   address family supported by that router instance.  It is the so-
   called main routing table to which all routing protocol instances
   supporting the given address family SHOULD be connected by default.
   For the two address families that are part of the core routing data
   model, the names of the main routing tables SHOULD be as follows:

   o  "main-ipv4-unicast" for IPv4 unicast,




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   o  "main-ipv6-unicast" for IPv6 unicast.

   Additional routing tables MAY be configured by creating new entries
   in the "routing-table" list, either as a part of factory-default
   configuration, or by a client's action.

   The naming scheme for additional routing tables, as well as
   restrictions on the number and configurability of routing tables are
   implementation-specific.

   The way how the routing system uses information from routing tables
   is outside the scope of this document.  Typically, implementations
   will either use a forwarding table, or perform a direct look-up in
   the main routing table in conjunction with a route cache.

   Every routing table can serve as a source of routes for other routing
   tables.  To achieve this, one or more recipient routing tables may be
   specified in the configuration of the source routing table.  In
   addition, a route filter may be configured for each recipient routing
   table, which selects and/or manipulates the routes that are passed on
   between the source and recipient routing table.

4.4.  Routing Protocols

   The core routing data model provides an open-ended framework for
   defining multiple routing protocol instances.  Each of them is
   identified by a name, which MUST be unique within a router instance.
   Each protocol MUST be assigned a type, which MUST be an identity
   derived from the "rt:routing-protocol" base identity.  The core
   routing data model defines two identities for the direct and static
   pseudo-protocols (Section 4.4.1).

   Each routing protocol instance is connected to exactly one routing
   table for each address family that the routing protocol instance
   supports.  By default, every routing protocol instance SHOULD be
   connected to the main routing table or tables.  An implementation MAY
   allow any or all routing protocol instances to be configured to use a
   different routing table.

   Routes learned from the network by a routing protocol are passed to
   the connected routing table(s) and vice versa - routes appearing in a
   routing table are passed to all routing protocols connected to the
   table (except "direct" and "static" pseudo-protocols) and may be
   advertised by that protocol to the network.

   Two independent route filters (see Section 4.5) may be defined for a
   routing protocol instance to control the exchange of routes in both
   directions between the routing protocol instance and the connected



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   routing table:

   o  import filter controls which routes are passed from a routing
      protocol instance to the routing table,

   o  export filter controls which routes the routing protocol instance
      may receive from the connected routing table.

   Note that, for historical reasons, the terms import and export are
   used from the viewpoint of a routing table.

4.4.1.  Routing Pseudo-Protocols

   The core routing data model defines two special routing protocol
   types - "direct" and "static".  Both are in fact pseudo-protocols,
   which means that they are confined to the local device and do not
   exchange any routing information with neighboring routers.  Routes
   from both "direct" and "static" protocol instances are passed to the
   connected routing table (subject to route filters, if any), but an
   exchange in the opposite direction is not allowed.

   Every router instance MUST contain exactly one instance of the
   "direct" pseudo-protocol type.  The name of this instance MUST also
   be "direct".  It is the source of direct routes for all configured
   address families.  Direct routes are normally supplied by the
   operating system kernel, based on the configuration of network
   interface addresses, see Section 5.2.  Direct routes SHOULD by
   default appear in the main routing table for each configured address
   family.  However, using the framework defined in this document, the
   target routing table for direct routes MAY be changed by connecting
   the "direct" protocol instance to a non-default routing table.
   Direct routes can also be filtered before they appear in the routing
   table.

   A pseudo-protocol of the type "static" allows for specifying routes
   manually.  It MAY be configured in zero or multiple instances,
   although a typical implementation will have exactly one instance per
   logical router.

4.4.2.  Defining New Routing Protocols

   It is expected that future YANG modules will create data models for
   additional routing protocol types.  Such a new module has to define
   the protocol-specific configuration and operational state data, and
   it has to fit it into the core routing framework in the following
   way:





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   o  A new identity MUST be defined for the routing protocol and its
      base identity MUST be set to "rt:routing-protocol", or to an
      identity derived from "rt:routing-protocol".

   o  Additional route attributes MAY be defined, preferably in one
      place by means of defining a YANG grouping.  The new attributes
      have to be inserted as operational state data by augmenting the
      definition of "rt:route" inside "rt:routing-table", and possibly
      to other places in the configuration, operational state data and
      RPC input or output.

   o  Per-interface configuration parameters can be added by augmenting
      the data node "rt:interface" (the list of router interfaces).

   o  Other configuration parameters and operational state data can be
      defined by augmenting the "routing-protocol" data node.  By using
      the "when" statement, this augment SHOULD be made conditional and
      valid only if the value of the "rt:type" child leaf equals to the
      new protocol's identity.

   It is RECOMMENDED that both per-interface and other configuration
   data specific to the new protocol be encapsulated in an appropriately
   named container.

   The above steps are implemented by the example YANG module for the
   RIP routing protocol in Appendix A.  First, the module defines a new
   identity for the RIP protocol:

   identity rip {
     base rt:routing-protocol;
     description "Identity for the RIP routing protocol.";
   }

   New route attributes specific to the RIP protocol ("metric" and
   "tag") are defined in a grouping and then added to the route
   definitions appearing in "routing-table" and in the output part of
   the "active-route" RPC method:














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   grouping route-content {
     description
       "RIP-specific route content.";
     leaf metric {
       type rip-metric;
     }
     leaf tag {
       type uint16;
       default "0";
       description
         "This leaf may be used to carry additional info, e.g. AS
          number.";
     }
   }

   augment "/rt:routing/rt:router/rt:routing-tables/rt:routing-table/"
         + "rt:routes/rt:route" {
     when "../../../../rt:routing-protocols/"
        + "rt:routing-protocol[rt:name=current()/rt:source-protocol]/"
        + "rt:type='rip:rip'" {
       description
         "This augment is only valid if the source protocol from which
          the route originated is RIP.";
     }
     description
       "RIP-specific route components.";
     uses route-content;
   }

   augment "/rt:active-route/rt:output/rt:route" {
     description
       "Add RIP-specific route content.";
     uses route-content;
   }

   Per-interface configuration data are defined by the following
   "augment" statement:














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   augment "/rt:routing/rt:router/rt:interfaces/rt:interface" {
     when "../../rt:routing-protocols/rt:routing-protocol/rt:type  = "
        + "'rip:rip'";
     container rip {
       description
         "Per-interface RIP configuration.";
       leaf enabled {
         type boolean;
         default "true";
       }
       leaf metric {
         type rip-metric;
         default "1";
       }
     }
   }

   Finally, global RIP configuration data are integrated into the "rt:
   routing-protocol" node by using the following "augment" statement,
   which is again valid only for routing protocol instances whose type
   is "rip:rip":

   augment "/rt:routing/rt:router/rt:routing-protocols/"
         + "rt:routing-protocol" {
     when "rt:type = 'rip:rip'";
     container rip {
       leaf update-interval {
         type uint8 {
           range "10..60";
         }
         units "seconds";
         default "30";
         description
           "Time interval between periodic updates.";
       }
     }
   }

4.5.  Route Filters

   The core routing data model provides a skeleton for defining route
   filters that can be used to restrict the set of routes being
   exchanged between a routing protocol instance and a connected routing
   table, or between a source and a recipient routing table.  Route
   filters may also manipulate routes, i.e., add, delete, or modify
   their attributes.

   Route filters are global, which means that a configured route filter



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   may be used by any or all router instances.

   By itself, the route filtering framework defined in this document
   allows for applying only the extreme routing policies which are
   represented by the following pre-defined route filter types:

   o  "deny-all-route-filter": all routes are blocked,

   o  "allow-all-route-filter": all routes are permitted.

   Note that the latter type is equivalent to no route filter.

   It is expected that more comprehensive route filtering frameworks
   will be developed separately.

   Each route filter is identified by a name which MUST be unique within
   the entire configuration.  Its type MUST be specified by the "type"
   identity reference - this opens the space for multiple route
   filtering framework implementations.  The default value for the route
   filter type is the identity "deny-all-route-filter".

4.6.  RPC Operations

   The "ietf-routing" module defines two RPC operations:

   o  active-route,

   o  route-count.

   Their parameters and semantics are described in the following
   subsections.

4.6.1.  Operation "active-route"

   Description:  Retrieve one or more active routes from the forwarding
      information base (FIB) of a router instance, i.e., the route(s)
      that are currently used by that router instance for sending
      datagrams to the destination whose address is provided as an input
      parameter.

   Parameters:

      router-name:  Name of the router instance whose FIB is to be
         queried.







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      destination-address:  Network layer destination address for which
         the active routes are requested.

   Positive Response:  One or more "route" elements containing the
      active route(s).

   Negative Response:

      If the logical router is not found, the server sends an "rpc-
      error" message with "error-tag" set to "data-missing", and "error-
      app-tag" set to "router-not-found".

      If no route exists for the given destination address, the server
      sends an "rpc-error" message with "error-tag" set to "data-
      missing" and "error-app-tag" set to "no-route".

4.6.2.  Operation "route-count"

   Description:  Retrieve the total number of routes in a routing table.

   Parameters:

      router-name:  Name of the logical router containing the routing
         table.

      routing-table:  Name of the routing table.

   Positive Response:  Element "number-of-routes" containing the
      requested nonnegative number.

   Negative Response:  If the logical router or the routing table is not
      found, the server sends an "rpc-error" message with "error-tag"
      set to "data-missing", and "error-app-tag" set to "router-not-
      found" or "routing-table-not-found", respectively.

















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5.  Interactions with Other YANG Modules

   The semantics of the core routing data model also depend on several
   configuration parameters that are defined in other YANG modules.  The
   following subsections describe these interactions.

5.1.  Module "ietf-interfaces"

   The following boolean switch is defined in the "ietf-interfaces" YANG
   module [YANG-IF]:

   /if:interfaces/if:interface/if:enabled

      If this switch is set to "false" for a given network layer
      interface, the device MUST behave exactly as if that interface was
      not assigned to any logical router at all.

5.2.  Module "ietf-ip"

   The following boolean switches are defined in the "ietf-ip" YANG
   module [YANG-IP]:

   /if:interfaces/if:interface/ip:ipv4/ip:enabled

      If this switch is set to "false" for a given interface, then all
      IPv4 routing functions related to that interface MUST be disabled.

   /if:interfaces/if:interface/ip:ipv4/ip:ip-forwarding

      If this switch is set to "false" for a given interface, then the
      forwarding of IPv4 datagrams to and from this interface MUST be
      disabled.  However, the interface may participate in other routing
      functions, such as routing protocols.

   /if:interfaces/if:interface/ip:ipv6/ip:enabled

      If this switch is set to "false" for a given interface, then all
      IPv6 routing functions related to that interface MUST be disabled.

   /if:interfaces/if:interface/ip:ipv6/ip:ip-forwarding

      If this switch is set to "false" for a given interface, then the
      forwarding of IPv6 datagrams to and from this interface MUST be
      disabled.  However, the interface may participate in other routing
      functions, such as routing protocols.

   In addition, the "ietf-ip" module allows for configuring IPv4 and
   IPv6 addresses and subnet masks.  Configuration of these parameters



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   on an enabled interface MUST result in an immediate creation of the
   corresponding direct route (usually in the main routing table).  Its
   destination prefix is set according to the configured IP address and
   subnet mask, and the interface is set as the outgoing interface for
   that route.














































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6.  Routing YANG Module

   RFC Ed.: In this section, replace all occurrences of 'XXXX' with the
   actual RFC number and all occurrences of the revision date below with
   the date of RFC publication (and remove this note).

   <CODE BEGINS> file "ietf-routing@2012-07-09.yang"

   module ietf-routing {

     namespace "urn:ietf:params:xml:ns:yang:ietf-routing";

     prefix "rt";

     import ietf-inet-types {
       prefix "inet";
     }

     import ietf-interfaces {
       prefix "if";
     }

     import iana-afn-safi {
       prefix "ianaaf";
     }

     organization
       "IETF NETMOD (NETCONF Data Modeling Language) Working Group";

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

        WG Chair: David Kessens
        <mailto:david.kessens@nsn.com>

        WG Chair: Juergen Schoenwaelder
        <mailto:j.schoenwaelder@jacobs-university.de>

        Editor: Ladislav Lhotka
        <mailto:lhotka@nic.cz>
       ";

     description
       "This YANG module defines essential components that may be used
        for configuring a routing subsystem.

        Copyright (c) 2012 IETF Trust and the persons identified as



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        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 XXXX; see the
        RFC itself for full legal notices.
       ";

     revision 2012-07-09 {
       description
         "Initial revision.";
       reference
         "RFC XXXX: A YANG Data Model for Routing Configuration";
     }

     /* Identities */

     identity routing-protocol {
       description
         "Base identity from which routing protocol identities are
          derived.";
     }

     identity direct {
       base routing-protocol;
       description
         "Routing pseudo-protocol which provides routes to directly
          connected networks.";
     }

     identity static {
       base routing-protocol;
       description
         "Static routing pseudo-protocol.";
     }

     identity route-filter {
       description
         "Base identity from which all route filters are derived.";
     }

     identity deny-all-route-filter {
       base route-filter;



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       description
         "Route filter that blocks all routes.";
     }

     identity allow-all-route-filter {
       base route-filter;
       description
         "Route filter that permits all routes.
         ";
     }

     /* Type Definitions */

     typedef router-ref {
       type leafref {
         path "/rt:routing/rt:router/rt:name";
       }
       description
         "This type is used for leafs that reference a router
          instance.";
     }

     /* Groupings */

     grouping afn-safi {
       leaf address-family {
         type ianaaf:address-family;
         default "ipv4";
         description
           "Address family of routes in the routing table.";
       }
       leaf safi {
         type ianaaf:subsequent-address-family;
         default "nlri-unicast";
         description
           "Subsequent address family identifier of routes in the
            routing table.";
       }
       description
         "This grouping provides two parameters specifying address
          family and subsequent address family.";
     }

     grouping route-content {
       description
         "Generic parameters of routes.

          A module for an address family should define a specific



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          version of this grouping containing 'uses rt:route-content'.
         ";
       leaf outgoing-interface {
         type if:interface-ref;
         description
           "Outgoing interface.";
       }
     }

     /* RPC Methods */

     rpc active-route {
       description
         "Return the active route (or multiple routes, in the case of
          multi-path routing) to a destination address.

          Parameters

          1. 'router-name',

          2. 'destination-address'.

          If the logical router with 'router-name' doesn't exist, then
          this operation will fail with error-tag 'missing-element' and
          error-app-tag 'router-not-found'.

          If there is no active route for 'destination-address', then
          this operation will fail with error-tag 'data-missing' and
          error-app-tag 'no-route'.
         ";
       input {
         leaf router-name {
           type router-ref;
           mandatory "true";
           description
             "Name of the router instance whose forwarding information
              base is being queried.";
         }
         container destination-address {
           uses afn-safi;
           description
             "Network layer destination address.

              AFN/SAFI-specific modules must augment this container with
              a leaf named 'address'.
             ";
         }
       }



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       output {
         list route {
           min-elements "1";
           uses afn-safi;
           uses route-content;
           description
             "Route contents specific for each address family should be
              defined through augmenting.";
         }
       }
     }

     rpc route-count {
       description
         "Return the current number of routes in a routing table.

          Parameters:

          1. 'router-name',

          2. 'routing-table-name'.

          If the logical router with 'router-name' doesn't exist, then
          this operation will fail with error-tag 'missing-element' and
          error-app-tag 'router-not-found'.

          If the routing table with 'routing-table-name' doesn't exist,
          then this operation will fail with error-tag 'missing-element'
          and error-app-tag 'routing-table-not-found'.
         ";
       input {
         leaf router-name {
           type router-ref;
           mandatory "true";
           description
             "Name of the router instance containing the routing
              table.";
         }
         leaf routing-table {
           type leafref {
             path "/routing/router/routing-tables/routing-table/name";
           }
           mandatory "true";
           description
             "Name of the routing table.";
         }
       }
       output {



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         leaf number-of-routes {
           type uint32;
           mandatory "true";
           description
             "Number of routes in the routing table.";
         }
       }
     }

     /* Data Nodes */

     container routing {
       description
         "Routing parameters.";
       list router {
         key "name";
         unique "router-id";
         description
           'Each list entry is a container for configuration and
            operational state data of a single (logical) router.

            Network layer interfaces assigned to the router must have
            their entries in the "interfaces" list.
           ';
         leaf name {
           type string;
           description
             "The unique router name.";
         }
         leaf router-id {
           type inet:ipv4-address;
           description
             "Global router ID in the form of an IPv4 address.

              An implementation may select a value if this parameter is
              not configured.

              Routing protocols may override this global parameter
              inside their configuration.
             ";
         }
         leaf description {
           type string;
           description
             "Textual description of the router.";
         }
         leaf enabled {
           type boolean;



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           default "true";
           description
             "Enable the router. The default value is 'true'.

              If this parameter is false, the parent router instance is
              disabled, despite any other configuration that might be
              present.
             ";
         }
         container interfaces {
           description
             "Router interface parameters.";
           list interface {
             key "name";
             description
               "List of network layer interfaces assigned to the router
                instance.";
             leaf name {
               type if:interface-ref;
               description
                 "A reference to the name of a configured network layer
                  interface.";
             }
           }
         }
         container routing-protocols {
           description
             "Container for the list of configured routing protocol
              instances.";
           list routing-protocol {
             key "name";
             description
               "An instance of a routing protocol.";
             leaf name {
               type string;
               description
                 "The name of the routing protocol instance.";
             }
             leaf description {
               type string;
               description
                 "Textual description of the routing protocol
                  instance.";
             }
             leaf type {
               type identityref {
                 base routing-protocol;
               }



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               mandatory "true";
               description
                 "Type of the routing protocol - an identity derived
                  from the 'routing-protocol' base identity.";
             }
             container connected-routing-tables {
               description
                 "Container for connected routing tables.";
               list routing-table {
                 must "not(../../../../routing-tables/"
                    + "routing-table[rt:name=current()/"
                    + "preceding-sibling::routing-table/name]/"
                    + "address-family=../../../../routing-tables/"
                    + "routing-table[rt:name=current()/name]/"
                    + "address-family and ../../../../routing-tables/"
                    + "routing-table[rt:name=current()/"
                    + "preceding-sibling::routing-table/name]/safi=../"
                    + "../../../routing-tables/"
                    + "routing-table[rt:name=current()/name]/safi)" {
                   error-message "Each routing protocol may have no "
                               + "more than one connected routing "
                               + "table for each AFN and SAFI.";
                   description
                     "For each AFN/SAFI pair there may be at most one
                      connected routing table.";
                 }
                 key "name";
                 description
                   "List of routing tables to which the routing protocol
                    instance is connected.

                    If no connected routing table is defined for an
                    address family, the routing protocol should be
                    connected by default to the main routing table for
                    that address family.
                   ";
                 leaf name {
                   type leafref {
                     path "../../../../../routing-tables/routing-table/"
                        + "name";
                   }
                   description
                     "Reference to an existing routing table.";
                 }
                 leaf import-filter {
                   type leafref {
                     path "/routing/route-filters/route-filter/name";
                   }



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                   description
                     "Reference to a route filter that is used for
                      filtering routes passed from this routing protocol
                      instance to the routing table specified by the
                      'name' sibling node. If this leaf is not present,
                      the behavior is protocol-specific, but typically
                      it means that all routes are accepted.";
                 }
                 leaf export-filter {
                   type leafref {
                     path "/routing/route-filters/route-filter/name";
                   }
                   description
                     "Reference to a route filter that is used for
                      filtering routes passed from the routing table
                      specified by the 'name' sibling node to this
                      routing protocol instance. If this leaf is not
                      present, the behavior is protocol-specific -
                      typically it means that all routes are accepted,
                      except for the 'direct' and 'static'
                      pseudo-protocols which accept no routes from any
                      routing table.";
                 }
               }
             }
             container static-routes {
               must "../type='rt:static'" {
                 error-message "Static routes may be configured only "
                             + "for 'static' routing protocol.";
                 description
                   "This container is only valid for the 'static'
                    routing protocol.";
               }
               description
                 "Configuration of 'static' pseudo-protocol.";
             }
           }
         }
         container routing-tables {
           description
             "Container for configured routing tables.";
           list routing-table {
             key "name";
             description
               "Each entry represents a routing table identified by the
                'name' key. All routes in a routing table must have the
                same AFN and SAFI.";
             leaf name {



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               type string;
               description
                 "The name of the routing table.";
             }
             uses afn-safi;
             leaf description {
               type string;
               description
                 "Textual description of the routing table.";
             }
             container routes {
               config "false";
               description
                 "Current contents of the routing table (operational
                  state data).";
               list route {
                 description
                   "A routing table entry. This data node must augmented
                    with information specific for routes of each address
                    family.";
                 uses route-content;
                 leaf source-protocol {
                   type leafref {
                     path "/routing/router/routing-protocols/"
                        + "routing-protocol/name";
                   }
                   mandatory "true";
                   description
                     "The name of the routing protocol instance from
                      which the route comes. This routing protocol must
                      be configured (automatically or manually) in the
                      device.";
                 }
                 leaf age {
                   type uint32;
                   units "seconds";
                   mandatory "true";
                   description
                     "The number of seconds since the parent route was
                      created or last updated.";
                 }
               }
             }
             container recipient-routing-tables {
               description
                 "Container for recipient routing tables.";
               list recipient-routing-table {
                 key "name";



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                 description
                   "A list of routing tables that receive routes from
                    this routing table.";
                 leaf name {
                   type leafref {
                     path "/routing/router/routing-tables/"
                        + "routing-table/name";
                   }
                   description
                     "The name of the recipient routing table.";
                 }
                 leaf filter {
                   type leafref {
                     path "/routing/route-filters/route-filter/name";
                   }
                   description
                     "A route filter which is applied to the routes
                      passed on to the recipient routing table.";
                 }
               }
             }
           }
         }
       }
       container route-filters {
         description
           "Container for configured route filters.";
         list route-filter {
           key "name";
           description
             "Route filters are used for filtering and/or manipulating
              routes that are passed between a routing protocol and a
              routing table or vice versa, or between two routing
              tables. It is expected that other modules augment this
              list with contents specific for a particular route filter
              type.";
           leaf name {
             type string;
             description
               "The name of the route filter.";
           }
           leaf description {
             type string;
             description
               "Textual description of the route filter.";
           }
           leaf type {
             type identityref {



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               base route-filter;
             }
             default "rt:deny-all-route-filter";
             description
               "Type of the route-filter - an identity derived from the
                'route-filter' base identity. The default value
                represents an all-blocking filter.";
           }
         }
       }
     }
   }

   <CODE ENDS>





































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7.  IPv4 Unicast Routing YANG Module

   RFC Ed.: In this section, replace all occurrences of 'XXXX' with the
   actual RFC number and all occurrences of the revision date below with
   the date of RFC publication (and remove this note).

   <CODE BEGINS> file "ietf-ipv4-unicast-routing@2012-07-09.yang"

   module ietf-ipv4-unicast-routing {

     namespace "urn:ietf:params:xml:ns:yang:ietf-ipv4-unicast-routing";

     prefix "v4ur";

     import ietf-routing {
       prefix "rt";
     }

     import ietf-inet-types {
       prefix "inet";
     }

     organization
       "IETF NETMOD (NETCONF Data Modeling Language) Working Group";

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

        WG Chair: David Kessens
        <mailto:david.kessens@nsn.com>

        WG Chair: Juergen Schoenwaelder
        <mailto:j.schoenwaelder@jacobs-university.de>

        Editor: Ladislav Lhotka
        <mailto:lhotka@nic.cz>
       ";

     description
       "This YANG module augments the 'ietf-routing' module with basic
        configuration and operational state data for IPv4 unicast
        routing.

        Every implementation must preconfigure a routing table with the
        name 'main-ipv4-unicast', which is the main routing table for
        IPv4 unicast.




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        Copyright (c) 2012 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 XXXX; see the
        RFC itself for full legal notices.
       ";

     revision 2012-07-09 {
       description
         "Initial revision.";
       reference
         "RFC XXXX: A YANG Data Model for Routing Configuration";
     }

     /* Groupings */

     grouping route-content {
       description
         "Parameters of IPv4 unicast routes.";
       leaf dest-prefix {
         type inet:ipv4-prefix;
         description
           "IPv4 destination prefix.";
       }
       leaf next-hop {
         type inet:ipv4-address;
         description
           "IPv4 address of the next hop.";
       }
     }

     /* RPC Methods */

     augment "/rt:active-route/rt:input/rt:destination-address" {
       when "address-family='ipv4' and safi='nlri-unicast'" {
         description
           "This augment is valid only for IPv4 unicast.";
       }
       description
         "The 'address' leaf augments the 'rt:destination-address'
          parameter of the 'rt:active-route' operation.";



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       leaf address {
         type inet:ipv4-address;
         description
           "IPv4 destination address.";
       }
     }

     augment "/rt:active-route/rt:output/rt:route" {
       when "address-family='ipv4' and safi='nlri-unicast'" {
         description
           "This augment is valid only for IPv4 unicast.";
       }
       description
         "Contents of the reply to 'rt:active-route' operation.";
       uses route-content;
     }

     /* Data nodes */

     augment "/rt:routing/rt:router/rt:routing-protocols/"
           + "rt:routing-protocol/rt:static-routes" {
       description
         "This augment defines the configuration of the 'static'
          pseudo-protocol with data specific for IPv4 unicast.";
       container ipv4 {
         description
           "Configuration of a 'static' pseudo-protocol instance
            consists of a list of routes.";
         list route {
           key "id";
           ordered-by "user";
           description
             "A user-ordered list of static routes.";
           leaf id {
             type uint32 {
               range "1..max";
             }
             description
               'Numeric identifier of the route.

                It is not required that the routes be sorted according
                to their "id".
               ';
           }
           leaf description {
             type string;
             description
               "Textual description of the route.";



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           }
           uses rt:route-content;
           uses route-content {
             refine "dest-prefix" {
               mandatory "true";
             }
           }
         }
       }
     }

     augment "/rt:routing/rt:router/rt:routing-tables/rt:routing-table/"
           + "rt:routes/rt:route" {
       when "../../rt:address-family='ipv4' and "
          + "../../rt:safi='nlri-unicast'" {
         description
           "This augment is valid only for IPv4 unicast.";
       }
       description
         "This augment defines the content of IPv4 unicast routes.";
       uses route-content;
     }
   }

   <CODE ENDS>


























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8.  IPv6 Unicast Routing YANG Module

   RFC Ed.: In this section, replace all occurrences of 'XXXX' with the
   actual RFC number and all occurrences of the revision date below with
   the date of RFC publication (and remove this note).

   <CODE BEGINS> file "ietf-ipv6-unicast-routing@2012-07-09.yang"

   module ietf-ipv6-unicast-routing {

     namespace "urn:ietf:params:xml:ns:yang:ietf-ipv6-unicast-routing";

     prefix "v6ur";

     import ietf-routing {
       prefix "rt";
     }

     import ietf-inet-types {
       prefix "inet";
     }

     import ietf-interfaces {
       prefix "if";
     }

     import ietf-ip {
       prefix "ip";
     }

     organization
       "IETF NETMOD (NETCONF Data Modeling Language) Working Group";

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

        WG Chair: David Kessens
        <mailto:david.kessens@nsn.com>

        WG Chair: Juergen Schoenwaelder
        <mailto:j.schoenwaelder@jacobs-university.de>

        Editor: Ladislav Lhotka
        <mailto:lhotka@nic.cz>
       ";

     description



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       "This YANG module augments the 'ietf-routing' module with basic
        configuration and operational state data for IPv6 unicast
        routing.

        Every implementation must preconfigure a routing table with the
        name 'main-ipv6-unicast', which is the main routing table for
        IPv6 unicast.

        Copyright (c) 2012 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 XXXX; see the
        RFC itself for full legal notices.
       ";

     revision 2012-07-09 {
       description
         "Initial revision.";
       reference
         "RFC XXXX: A YANG Data Model for Routing Configuration";
     }

     /* Groupings */

     grouping route-content {
       description
         "Specific parameters of IPv6 unicast routes.";
       leaf dest-prefix {
         type inet:ipv6-prefix;
         description
           "IPv6 destination prefix.";
       }
       leaf next-hop {
         type inet:ipv6-address;
         description
           "IPv6 address of the next hop.";
       }
     }

     /* RPC Methods */




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     augment "/rt:active-route/rt:input/rt:destination-address" {
       when "address-family='ipv6' and safi='nlri-unicast'" {
         description
           "This augment is valid only for IPv6 unicast.";
       }
       description
         "The 'address' leaf augments the 'rt:destination-address'
          parameter of the 'rt:active-route' operation.";
       leaf address {
         type inet:ipv6-address;
         description
           "IPv6 destination address.";
       }
     }

     augment "/rt:active-route/rt:output/rt:route" {
       when "address-family='ipv6' and safi='nlri-unicast'" {
         description
           "This augment is valid only for IPv6 unicast.";
       }
       description
         "Contents of the reply to 'rt:active-route' operation.";
       uses route-content;
     }

     /* Data nodes */

     augment "/rt:routing/rt:router/rt:interfaces/rt:interface" {
       when "/if:interfaces/if:interface[name=current()/name]/ip:ipv6/"
          + "ip:enabled='true'" {
         description
           "This augment is only valid for router interfaces with
            enabled IPv6.

            NOTE: Parameter 'is-router' is not included, it is expected
            that it will be implemented by the 'ietf-ip' module.
           ";
       }
       description
         "IPv6-specific parameters of router interfaces.";
       container ipv6-router-advertisements {
         description
           "Parameters of IPv6 Router Advertisements.";
         reference
           "RFC 4861: Neighbor Discovery for IP version 6 (IPv6).

            RFC 4862: IPv6 Stateless Address Autoconfiguration.
           ";



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         leaf send-advertisements {
           type boolean;
           default "false";
           description
             "A flag indicating whether or not the router sends periodic
              Router Advertisements and responds to Router
              Solicitations.";
         }
         leaf max-rtr-adv-interval {
           type uint16 {
             range "4..1800";
           }
           units "seconds";
           default "600";
           description
             "The maximum time allowed between sending unsolicited
              multicast Router Advertisements from the interface.";
         }
         leaf min-rtr-adv-interval {
           type uint16 {
             range "3..1350";
           }
           units "seconds";
           description
             "The minimum time allowed between sending unsolicited
              multicast Router Advertisements from the interface.

              Must be no greater than 0.75 * max-rtr-adv-interval.

              Its default value is dynamic:

              - if max-rtr-adv-interval >= 9 seconds, the default value
                is 0.33 * max-rtr-adv-interval;

              - otherwise it is 0.75 * max-rtr-adv-interval.
             ";
         }
         leaf managed-flag {
           type boolean;
           default "false";
           description
             "The boolean value to be placed in the 'Managed address
              configuration' flag field in the Router Advertisement.";
         }
         leaf other-config-flag {
           type boolean;
           default "false";
           description



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             "The boolean value to be placed in the 'Other
              configuration' flag field in the Router Advertisement.";
         }
         leaf link-mtu {
           type uint32;
           default "0";
           description
             "The value to be placed in MTU options sent by the router.
              A value of zero indicates that no MTU options are sent.";
         }
         leaf reachable-time {
           type uint32 {
             range "0..3600000";
           }
           units "milliseconds";
           default "0";
           description
             "The value to be placed in the Reachable Time field in the
              Router Advertisement messages sent by the router. The
              value zero means unspecified (by this router).";
         }
         leaf retrans-timer {
           type uint32;
           units "milliseconds";
           default "0";
           description
             "The value to be placed in the Retrans Timer field in the
              Router Advertisement messages sent by the router. The
              value zero means unspecified (by this router).";
         }
         leaf cur-hop-limit {
           type uint8;
           default "64";
           description
             "The default value to be placed in the Cur Hop Limit field
              in the Router Advertisement messages sent by the router.
              The value should be set to the current diameter of the
              Internet. The value zero means unspecified (by this
              router).

              The default should be set to the value specified in IANA
              Assigned Numbers that was in effect at the time of
              implementation.
             ";
           reference
             "IANA: IP Parameters,
              http://www.iana.org/assignments/ip-parameters";
         }



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         leaf default-lifetime {
           type uint16 {
             range "0..9000";
           }
           units "seconds";
           description
             "The value to be placed in the Router Lifetime field of
              Router Advertisements sent from the interface, in seconds.
              MUST be either zero or between max-rtr-adv-interval and
              9000 seconds. A value of zero indicates that the router is
              not to be used as a default router. These limits may be
              overridden by specific documents that describe how IPv6
              operates over different link layers.

              The default value is dynamic and should be set to 3 *
              max-rtr-adv-interval.
             ";
         }
         container prefix-list {
           description
             "A list of prefixes to be placed in Prefix Information
              options in Router Advertisement messages sent from the
              interface.

              By default, all prefixes that the router advertises via
              routing protocols as being on-link for the interface from
              which the advertisement is sent. The link-local prefix
              should not be included in the list of advertised prefixes.
             ";
           list prefix {
             key "prefix-spec";
             description
               "Advertised prefix entry.";
             leaf prefix-spec {
               type inet:ipv6-prefix;
               description
                 "IPv6 address prefix.";
             }
             choice control-adv-prefixes {
               default "advertise";
               description
                 "The prefix either may be explicitly removed from the
                  set of advertised prefixes, or parameters with which
                  it is advertised may be specified (default case).";
               leaf no-advertise {
                 type empty;
                 description
                   "The prefix will not be advertised.



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                    This may be used for removing the prefix from the
                    default set of advertised prefixes.
                   ";
               }
               case advertise {
                 leaf valid-lifetime {
                   type uint32;
                   units "seconds";
                   default "2592000";
                   description
                     "The value to be placed in the Valid Lifetime in
                      the Prefix Information option, in seconds. The
                      designated value of all 1's (0xffffffff)
                      represents infinity.
                     ";
                 }
                 leaf on-link-flag {
                   type boolean;
                   default "true";
                   description
                     "The value to be placed in the on-link flag
                      ('L-bit') field in the Prefix Information
                      option.";
                 }
                 leaf preferred-lifetime {
                   type uint32;
                   units "seconds";
                   must ". <= ../valid-lifetime" {
                     description
                       "This value must not be larger than
                        valid-lifetime.";
                   }
                   default "604800";
                   description
                     "The value to be placed in the Preferred Lifetime
                      in the Prefix Information option, in seconds. The
                      designated value of all 1's (0xffffffff)
                      represents infinity.
                     ";
                 }
                 leaf autonomous-flag {
                   type boolean;
                   default "true";
                   description
                     "The value to be placed in the Autonomous Flag
                      field in the Prefix Information option.";
                 }
               }



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             }
           }
         }
       }
     }

     augment "/rt:routing/rt:router/rt:routing-protocols/"
           + "rt:routing-protocol/rt:static-routes" {
       description
         "This augment defines the configuration of the 'static'
          pseudo-protocol with data specific for IPv6 unicast.";
       container ipv6 {
         description
           "Configuration of a 'static' pseudo-protocol instance
            consists of a list of routes.";
         list route {
           key "id";
           ordered-by "user";
           description
             "A user-ordered list of static routes.";
           leaf id {
             type uint32 {
               range "1..max";
             }
             description
               'Numeric identifier of the route.

                It is not required that the routes be sorted according
                to their "id".
               ';
           }
           leaf description {
             type string;
             description
               "Textual description of the route.";
           }
           uses rt:route-content;
           uses route-content {
             refine "dest-prefix" {
               mandatory "true";
             }
           }
         }
       }
     }

     augment "/rt:routing/rt:router/rt:routing-tables/rt:routing-table/"
           + "rt:routes/rt:route" {



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       when "../../rt:address-family='ipv6' and "
          + "../../rt:safi='nlri-unicast'" {
         description
           "This augment is valid only for IPv6 unicast.";
       }
       description
         "This augment defines the content of IPv6 unicast routes.";
       uses route-content;
     }
   }

   <CODE ENDS>







































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9.  IANA Considerations

   RFC Ed.: In this section, replace all occurrences of 'XXXX' with the
   actual RFC number (and remove this note).

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

   ----------------------------------------------------------
   URI: urn:ietf:params:xml:ns:yang:ietf-routing

   Registrant Contact: The IESG.

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

   ----------------------------------------------------------
   URI: urn:ietf:params:xml:ns:yang:ietf-ipv4-unicast-routing

   Registrant Contact: The IESG.

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

   ----------------------------------------------------------
   URI: urn:ietf:params:xml:ns:yang:ietf-ipv6-unicast-routing

   Registrant Contact: The IESG.

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

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

















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   -------------------------------------------------------------------
   name:         ietf-routing
   namespace:    urn:ietf:params:xml:ns:yang:ietf-routing
   prefix:       rt
   reference:    RFC XXXX
   -------------------------------------------------------------------

   -------------------------------------------------------------------
   name:         ietf-ipv4-unicast-routing
   namespace:    urn:ietf:params:xml:ns:yang:ietf-ipv4-unicast-routing
   prefix:       v4ur
   reference:    RFC XXXX
   -------------------------------------------------------------------

   -------------------------------------------------------------------
   name:         ietf-ipv6-unicast-routing
   namespace:    urn:ietf:params:xml:ns:yang:ietf-ipv6-unicast-routing
   prefix:       v6ur
   reference:    RFC XXXX
   -------------------------------------------------------------------































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10.  Security Considerations

   The YANG modules defined in this document are designed to be accessed
   via the NETCONF protocol [RFC6241].  The lowest NETCONF layer is the
   secure transport layer and the mandatory-to-implement secure
   transport is SSH [RFC6242].

   A number of data nodes defined in the YANG modules are writable/
   creatable/deletable (i.e., "config true" in YANG terms, which is the
   default).  These data nodes may be considered sensitive or vulnerable
   in some network environments.  Write operations to these data nodes,
   such as "edit-config", can have negative effects on the network if
   the protocol operations are not properly protected.

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

   /rt:routing/rt:router/rt:interfaces/rt:interface  This list assigns a
      network layer interface to a router instance and may also specify
      interface parameters related to routing.

   /rt:routing/rt:router/rt:routing-protocols/rt:routing-protocol  This
      list specifies the routing protocols configured on a device.

   /rt:routing/rt:router/rt:route-filters/rt:route-filter  This list
      specifies the configured route filters which represent the
      administrative policies for redistributing and modifying routing
      information.

   Unauthorized access to any of these lists can adversely affect the
   routing subsystem of both the local device and the network.  This may
   lead to network malfunctions, delivery of packets to inappropriate
   destinations and other problems.


















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11.  Acknowledgments

   The author wishes to thank Martin Bjorklund, Joel Halpern, Thomas
   Morin, Tom Petch, Juergen Schoenwaelder, Dave Thaler and Yi Yang for
   their helpful comments and suggestions.














































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12.  References

12.1.  Normative References

   [IANA-IF-AF]
              Bjorklund, M., "IANA Interface Type and Address Family
              YANG Modules", draft-ietf-netmod-iana-if-type-02 (work in
              progress), April 2012.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
              January 2004.

   [RFC4861]  Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
              "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
              September 2007.

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

   [RFC6021]  Schoenwaelder, J., Ed., "Common YANG Data Types",
              RFC 6021, September 2010.

   [RFC6241]  Enns, R., Bjorklund, M., Schoenwaelder, J., and A.
              Bierman, "NETCONF Configuration Protocol", RFC 6241,
              June 2011.

   [YANG-IF]  Bjorklund, M., "A YANG Data Model for Interface
              Configuration", draft-ietf-netmod-interfaces-cfg-04 (work
              in progress), April 2012.

   [YANG-IP]  Bjorklund, M., "A YANG Data Model for IP Configuration",
              draft-ietf-netmod-ip-cfg-03 (work in progress),
              April 2012.

12.2.  Informative References

   [RFC6087]  Bierman, A., "Guidelines for Authors and Reviewers of YANG
              Data Model Documents", RFC 6087, January 2011.

   [RFC6242]  Wasserman, M., "Using the NETCONF Protocol over Secure
              Shell (SSH)", RFC 6242, June 2011.






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Appendix A.  Example: Adding a New Routing Protocol

   This appendix demonstrates how the core routing data model can be
   extended to support a new routing protocol.  The YANG module
   "example-rip" shown below is intended only as an illustration rather
   than a real definition of a data model for the RIP routing protocol.
   For the sake of brevity, we do not follow all the guidelines
   specified in [RFC6087].  See also Section 4.4.2.

   <CODE BEGINS> file "example-rip@2012-07-09.yang"

   module example-rip {

     namespace "http://example.com/rip";

     prefix "rip";

     import ietf-routing {
       prefix "rt";
     }

     identity rip {
       base rt:routing-protocol;
       description
         "Identity for the RIP routing protocol.";
     }

     typedef rip-metric {
       type uint8 {
         range "0..16";
       }
     }

     grouping route-content {
       description
         "RIP-specific route content.";
       leaf metric {
         type rip-metric;
       }
       leaf tag {
         type uint16;
         default "0";
         description
           "This leaf may be used to carry additional info, e.g. AS
            number.";
       }
     }




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     augment "/rt:routing/rt:router/rt:routing-tables/rt:routing-table/"
           + "rt:routes/rt:route" {
       when "../../../../rt:routing-protocols/"
          + "rt:routing-protocol[rt:name=current()/rt:source-protocol]/"
          + "rt:type='rip:rip'" {
         description
           "This augment is only valid if the source protocol from which
            the route originated is RIP.";
       }
       description
         "RIP-specific route components.";
       uses route-content;
     }

     augment "/rt:active-route/rt:output/rt:route" {
       description
         "Add RIP-specific route content.";
       uses route-content;
     }

     augment "/rt:routing/rt:router/rt:interfaces/rt:interface" {
       when "../../rt:routing-protocols/rt:routing-protocol/rt:type = "
          + "'rip:rip'";
       container rip {
         description
           "Per-interface RIP configuration.";
         leaf enabled {
           type boolean;
           default "true";
         }
         leaf metric {
           type rip-metric;
           default "1";
         }
       }
     }

     augment "/rt:routing/rt:router/rt:routing-protocols/"
           + "rt:routing-protocol" {
       when "rt:type = 'rip:rip'";
       container rip {
         leaf update-interval {
           type uint8 {
             range "10..60";
           }
           units "seconds";
           default "30";
           description



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             "Time interval between periodic updates.";
         }
       }
     }
   }

   <CODE ENDS>












































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Appendix B.  Example: Reply to the NETCONF <get> Message

   This section contains a sample reply to the NETCONF <get> message,
   which could be sent by a server supporting (i.e., advertising them in
   the NETCONF <hello> message) the following YANG modules:

   o  ietf-interfaces [YANG-IF],

   o  ietf-ip [YANG-IP],

   o  ietf-routing (Section 6),

   o  ietf-ipv4-unicast-routing (Section 7),

   o  ietf-ipv6-unicast-routing (Section 8).

   We assume a simple network setup as shown in Figure 3: router "A"
   uses static default routes with the "ISP" router as the next hop.
   IPv6 router advertisements are configured only on the "eth1"
   interface and disabled on the upstream "eth0" interface.

                   +-----------------+
                   |                 |
                   |    Router ISP   |
                   |                 |
                   +--------+--------+
                            |2001:db8:0:1::2
                            |192.0.2.2
                            |
                            |
                            |2001:db8:0:1::1
                        eth0|192.0.2.1
                   +--------+--------+
                   |                 |
                   |     Router A    |
                   |                 |
                   +--------+--------+
                        eth1|198.51.100.1
                            |2001:db8:0:2::1
                            |

                  Figure 3: Example network configuration

   A reply to the NETCONF <get> message sent by router "A" would then be
   as follows:

  <?xml version="1.0"?>
  <rpc-reply



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      message-id="101"
      xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"
      xmlns:v4ur="urn:ietf:params:xml:ns:yang:ietf-ipv4-unicast-routing"
      xmlns:v6ur="urn:ietf:params:xml:ns:yang:ietf-ipv6-unicast-routing"
      xmlns:if="urn:ietf:params:xml:ns:yang:ietf-interfaces"
      xmlns:ip="urn:ietf:params:xml:ns:yang:ietf-ip"
      xmlns:rt="urn:ietf:params:xml:ns:yang:ietf-routing">
   <data>
    <if:interfaces>
     <if:interface>
      <if:name>eth0</if:name>
      <if:type>ethernetCsmacd</if:type>
      <if:location>05:00.0</if:location>
      <ip:ipv4>
       <ip:address>
        <ip:ip>192.0.2.1</ip:ip>
        <ip:prefix-length>24</ip:prefix-length>
       </ip:address>
      </ip:ipv4>
      <ip:ipv6>
       <ip:address>
        <ip:ip>2001:0db8:0:1::1</ip:ip>
        <ip:prefix-length>64</ip:prefix-length>
       </ip:address>
       <ip:autoconf>
        <ip:create-global-addresses>false</ip:create-global-addresses>
       </ip:autoconf>
      </ip:ipv6>
     </if:interface>
     <if:interface>
      <if:name>eth1</if:name>
      <if:type>ethernetCsmacd</if:type>
      <if:location>05:00.1</if:location>
      <ip:ipv4>
       <ip:address>
        <ip:ip>198.51.100.1</ip:ip>
        <ip:prefix-length>24</ip:prefix-length>
       </ip:address>
      </ip:ipv4>
      <ip:ipv6>
       <ip:address>
        <ip:ip>2001:0db8:0:2::1</ip:ip>
        <ip:prefix-length>64</ip:prefix-length>
       </ip:address>
       <ip:autoconf>
        <ip:create-global-addresses>false</ip:create-global-addresses>
       </ip:autoconf>
      </ip:ipv6>



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     </if:interface>
    </if:interfaces>
    <rt:routing>
     <rt:router>
      <rt:name>rtr0</rt:name>
      <rt:interfaces>
       <rt:interface>
        <rt:name>eth0</rt:name>
       </rt:interface>
       <rt:interface>
        <rt:name>eth1</rt:name>
        <v6ur:ipv6-router-advertisements>
         <v6ur:send-advertisements>true</v6ur:send-advertisements>
         <v6ur:prefix-list>
          <v6ur:prefix>
           <v6ur:prefix-spec>2001:db8:0:2::/64</v6ur:prefix-spec>
          </v6ur:prefix>
         </v6ur:prefix-list>
        </v6ur:ipv6-router-advertisements>
       </rt:interface>
      </rt:interfaces>
      <rt:routing-protocols>
       <rt:routing-protocol>
        <rt:name>direct</rt:name>
        <rt:type>rt:direct</rt:type>
       </rt:routing-protocol>
       <rt:routing-protocol>
        <rt:name>st0</rt:name>
        <rt:description>
         Static routing is used for the internal network.
        </rt:description>
        <rt:type>rt:static</rt:type>
        <rt:static-routes>
         <v4ur:ipv4>
          <v4ur:route>
           <v4ur:id>1</v4ur:id>
           <v4ur:dest-prefix>0.0.0.0/0</v4ur:dest-prefix>
           <v4ur:next-hop>192.0.2.2</v4ur:next-hop>
          </v4ur:route>
         </v4ur:ipv4>
         <v6ur:ipv6>
          <v6ur:route>
           <v6ur:id>1</v6ur:id>
           <v6ur:dest-prefix>::/0</v6ur:dest-prefix>
           <v6ur:next-hop>2001:db8:0:1::2</v6ur:next-hop>
          </v6ur:route>
         </v6ur:ipv6>
        </rt:static-routes>



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        <rt:connected-routing-tables>
         <rt:routing-table>
          <rt:name>main-ipv4-unicast</rt:name>
         </rt:routing-table>
         <rt:routing-table>
          <rt:name>main-ipv6-unicast</rt:name>
         </rt:routing-table>
        </rt:connected-routing-tables>
       </rt:routing-protocol>
      </rt:routing-protocols>
      <rt:routing-tables>
       <rt:routing-table>
        <rt:name>main-ipv4-unicast</rt:name>
        <rt:routes>
         <rt:route>
          <v4ur:dest-prefix>192.0.2.1/24</v4ur:dest-prefix>
          <rt:outgoing-interface>eth0</rt:outgoing-interface>
          <rt:source-protocol>direct</rt:source-protocol>
          <rt:age>3512</rt:age>
         </rt:route>
         <rt:route>
          <v4ur:dest-prefix>198.51.100.0/24</v4ur:dest-prefix>
          <rt:outgoing-interface>eth1</rt:outgoing-interface>
          <rt:source-protocol>direct</rt:source-protocol>
          <rt:age>3512</rt:age>
         </rt:route>
         <rt:route>
          <v4ur:dest-prefix>0.0.0.0/0</v4ur:dest-prefix>
          <rt:source-protocol>st0</rt:source-protocol>
          <v4ur:next-hop>192.0.2.2</v4ur:next-hop>
          <rt:age>2551</rt:age>
         </rt:route>
        </rt:routes>
       </rt:routing-table>
       <rt:routing-table>
        <rt:name>main-ipv6-unicast</rt:name>
        <rt:address-family>ipv6</rt:address-family>
        <rt:safi>nlri-unicast</rt:safi>
        <rt:routes>
         <rt:route>
          <v6ur:dest-prefix>2001:db8:0:1::/64</v6ur:dest-prefix>
          <rt:outgoing-interface>eth0</rt:outgoing-interface>
          <rt:source-protocol>direct</rt:source-protocol>
          <rt:age>3513</rt:age>
         </rt:route>
         <rt:route>
          <v6ur:dest-prefix>2001:db8:0:2::/64</v6ur:dest-prefix>
          <rt:outgoing-interface>eth1</rt:outgoing-interface>



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          <rt:source-protocol>direct</rt:source-protocol>
          <rt:age>3513</rt:age>
         </rt:route>
         <rt:route>
          <v6ur:dest-prefix>::/0</v6ur:dest-prefix>
          <v6ur:next-hop>2001:db8:0:1::2</v6ur:next-hop>
          <rt:source-protocol>st0</rt:source-protocol>
          <rt:age>2550</rt:age>
         </rt:route>
        </rt:routes>
       </rt:routing-table>
      </rt:routing-tables>
     </rt:router>
    </rt:routing>
   </data>
  </rpc-reply>



































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Appendix C.  Change Log

   RFC Editor: remove this section upon publication as an RFC.

C.1.  Changes Between Versions -03 and -04

   o  Changed "error-tag" for both RPC methods from "missing element" to
      "data-missing".

   o  Removed the decrementing behavior for advertised IPv6 prefix
      parameters "valid-lifetime" and "preferred-lifetime".

   o  Changed the key of the static route lists from "seqno" to "id"
      because the routes needn't be sorted.

   o  Added 'must' constraint saying that "preferred-lifetime" must not
      be greater than "valid-lifetime".

C.2.  Changes Between Versions -02 and -03

   o  Module "iana-afn-safi" moved to I-D "iana-if-type".

   o  Removed forwarding table.

   o  RPC "get-route" changed to "active-route".  Its output is a list
      of routes (for multi-path routing).

   o  New RPC "route-count".

   o  For both RPCs, specification of negative responses was added.

   o  Relaxed separation of router instances.

   o  Assignment of interfaces to router instances needn't be disjoint.

   o  Route filters are now global.

   o  Added "allow-all-route-filter" for symmetry.

   o  Added Section 5 about interactions with "ietf-interfaces" and
      "ietf-ip".

   o  Added "router-id" leaf.

   o  Specified the names for IPv4/IPv6 unicast main routing tables.

   o  Route parameter "last-modified" changed to "age".




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   o  Added container "recipient-routing-tables".

C.3.  Changes Between Versions -01 and -02

   o  Added module "ietf-ipv6-unicast-routing".

   o  The example in Appendix B now uses IP addresses from blocks
      reserved for documentation.

   o  Direct routes appear by default in the FIB table.

   o  Network layer interfaces must be assigned to a router instance.
      Additional interface configuration may be present.

   o  The "when" statement is only used with "augment", "must" is used
      elsewhere.

   o  Additional "must" statements were added.

   o  The "route-content" grouping for IPv4 and IPv6 unicast now
      includes the material from the "ietf-routing" version via "uses
      rt:route-content".

   o  Explanation of symbols in the tree representation of data model
      hierarchy.

C.4.  Changes Between Versions -00 and -01

   o  AFN/SAFI-independent stuff was moved to the "ietf-routing" module.

   o  Typedefs for AFN and SAFI were placed in a separate "iana-afn-
      safi" module.

   o  Names of some data nodes were changed, in particular "routing-
      process" is now "router".

   o  The restriction of a single AFN/SAFI per router was lifted.

   o  RPC operation "delete-route" was removed.

   o  Illegal XPath references from "get-route" to the datastore were
      fixed.

   o  Section "Security Considerations" was written.







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Author's Address

   Ladislav Lhotka
   CZ.NIC

   Email: lhotka@nic.cz













































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