NETMOD L. Lhotka
Internet-Draft CESNET
Intended status: Standards Track April 27, 2011
Expires: October 29, 2011
A YANG Data Model for Routing Configuration
draft-ietf-netmod-routing-cfg-00
Abstract
This document contains a specification of two YANG modules that
together provide a data model for essential configuration of a
routing subsystem. It is expected that this module will serve as a
basis for further development of data models for individual routing
protocols and other related functions. The present data model
defines the building blocks for such configurations - routing
processes, routes and routing tables, routing protocol instances 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 October 29, 2011.
Copyright Notice
Copyright (c) 2011 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. Route . . . . . . . . . . . . . . . . . . . . . . . . . . 9
4.2. Routing Tables . . . . . . . . . . . . . . . . . . . . . . 9
4.3. Routing Protocol Instances . . . . . . . . . . . . . . . . 10
4.3.1. Defining New Routing Protocols . . . . . . . . . . . . 11
4.4. Route Filters . . . . . . . . . . . . . . . . . . . . . . 13
4.5. RPC Operations . . . . . . . . . . . . . . . . . . . . . . 13
5. Routing YANG Module . . . . . . . . . . . . . . . . . . . . . 15
6. IPv4 Unicast Routing YANG Module . . . . . . . . . . . . . . . 24
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 33
8. Security Considerations . . . . . . . . . . . . . . . . . . . 34
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 35
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 36
10.1. Normative References . . . . . . . . . . . . . . . . . . . 36
10.2. Informative References . . . . . . . . . . . . . . . . . . 36
Appendix A. Example - Adding a New Routing Protocol . . . . . . . 37
A.1. Example YANG Module for Routing Information Protocol . . . 37
A.2. Sample Reply to the NETCONF <get> Message . . . . . . . . 38
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 44
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1. Introduction
This document contains an initial specification of two YANG modules,
"ietf-routing" and "ietf-ipv4-unicast-routing", that together define
the so-called core routing data model. This data model will serve as
a basis for the development of data models for more sophisticated
routing configurations. While these two modules can be directly used
for simple IPv4-only devices with static routing, their main purpose
is to provide basic building blocks for more complicated setups
involving other address families such as IPv6, multiple routing
protocols, and advanced functions, for example route filtering and
policy routing. To this end, it is expected that this module 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 [RFC4741]:
o client
o message
o 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
o active route: a route which is actually used for packet
forwarding. If there are multiple candidate routes with the same
destination prefix, then it is up to the routing algorithm to
select the active route.
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2.2. Prefixes in Data Node Names
In this document, names of data nodes 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 with the
standard prefixes associated with YANG modules, as shown in Table 1.
+--------+---------------------------+------------+
| Prefix | YANG module | Reference |
+--------+---------------------------+------------+
| eth | ex-ethernet | [YANG-IF] |
| | | |
| if | ietf-interfaces | [YANG-IF] |
| | | |
| inet | ietf-inet-types | [RFC6021] |
| | | |
| ip | ex-ip | [YANG-IF] |
| | | |
| rip | example-rip | Appendix A |
| | | |
| rt | ietf-routing | Section 5 |
| | | |
| v4ur | ietf-ipv4-unicast-routing | Section 6 |
| | | |
| yang | ietf-yang-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 main 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 two YANG modules. The first
module, "ietf-routing", is rather minimal and provides only a top-
level container ("routing") and a list of routing processes. Each
routing process represents an instance of a (virtual) router with a
separate forwarding table (FIB, forwarding information base). For a
given address family, specified by an Address Family Identifier (AFI)
[IANA-AFI] and Subsequent Address Family Identifier (SAFI)
[IANA-SAFI], several independent routing processes may be configured.
The second YANG module, "ietf-ipv4-unicast-routing", provides a data
modeling framework for IPv4 unicast routing with several essential
components: routes, routing tables, routing protocol instances, route
filters and RPC operations. The following subsections provide
further details about these components.
By combining the components in various ways, and possibly filling
them with appropriate contents defined in other modules, a broad
range of routing setups can be covered.
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+------------+
| FIB |
+------------+
^
|
+---+
| F |
+---+
^
+--------+ |
| 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 1: Example setup of the routing subsystem
Figure 1 shows an example of a more complicated setup:
o Along with the main routing table, which must always be present,
an additional routing table is defined.
o Each routing protocol instance, including the "static" and
"direct" pseudo-protocol instances, is connected to exactly 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 one or both directions.
o The forwarding information base (FIB) is a special routing table
which must always be present. Typically, the FIB receives the
active routes from the main routing table and the operating system
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kernel uses this information for packet forwarding.
o Route exchanges along all connections may be controlled by means
of route filters, denoted by "F" in the figure.
4.1. Route
Routes are basic units of information in a routing system. The
"ietf-ipv4-unicast-routing" module 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 the adjacent router or host to which
packets with destination addresses belonging to destination-prefix
should be sent.
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 is sufficient 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 in both configuration data, for
example as manually configured static routes, as well as in
operational state data, for example as entries in routing tables.
4.2. 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 last-modified - date and time of last modification, or
installation, of the route.
In the core routing data model, the list of routes in routing tables
is represented as operational state data. Routing protocol
operations result in route additions, removals and modifications.
This also includes manipulations via the "static" pseudo-protocol.
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The "ietf-ipv4-unicast-routing" module requires that at least the
following two routing tables MUST be configured for each routing
process:
o The "ipv4-unicast-fib" table is the forwarding information base
used by the operating system kernel for forwarding IPv4 unicast
datagrams.
o The "ipv4-unicast-main" table is the main routing table. By
default, all IPv4 unicast routing protocols exchange routes with
this table, and active routes from the "ipv4-unicast-main" routing
table are installed in the "ipv4-unicast-fib" table and used for
packet forwarding.
Additional routing tables MAY be configured.
Every routing table MAY 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.
4.3. Routing Protocol Instances
The "ietf-ipv4-unicast-routing" module provides an open-ended
framework for defining multiple routing protocol instances. Each of
them is identified by a name, which is unique within a routing
process, and MUST be assigned a type from a selection which includes
all routing protocol types supported by the server, such as RIP, OSPF
or BGP.
Each routing protocol instance is connected to exactly one routing
table. By default, every routing protocol instance is connected to
the main routing table, but any routing protocol instance can be
configured to use a different routing table, provided such an extra
table is configured.
Routes learned from the network by a routing protocol instance are
passed to the connected routing table and vice versa - routes
appearing in a routing table are passed to all routing protocol
connected to the table and advertised by that protocol to the
network.
Two independent route filters (see Section 4.4) 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
routing table:
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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.
The "ietf-ipv4-unicast-routing" module defines two special routing
protocols - "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 routing process MUST contain exactly one instance of the
"direct" pseudo-protocol. It is the source of routes to directly
connected networks (so-called direct routes). Such routes are
supplied by the operating system kernel based on the detected and
configured network interfaces, and they usually appear in the main
routing table. However, using the framework defined in this
document, the target routing table for direct routes can be changed
by connecting the "direct" protocol instance to a non-default routing
table, and the direct routes can also be filtered before they appear
in the routing table.
The "static" routing pseudo-protocol allows for specifying routes
manually. It can be configured in zero or more instances, although
typically one instance suffices.
4.3.1. Defining New Routing Protocols
It is expected that future YANG modules will create data models for
additional routing protocol types. In order to do so, the new module
has to define the protocol-specific information and fit it to the
core routing framework in the following way:
o A new identity MUST be defined for the routing protocol and its
base identity set to "rt:routing-protocol", or to an identity
derived from "rt:routing-protocol".
o Additional route attributes MAY be defined. Their definitions
have to be inserted as operational state data by augmenting the
definition of "v4ur:route" inside "v4ur:routing-table".
Naturally, route attributes (including the extra attributes) may
be used in configuration data, too, as demonstrated by the
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"static" pseudo-protocol.
o The recommended way of defining configuration data specific to the
new protocol is to augment the "routing-protocol-instance" list
entry with a container that encapsulates the configuration
hierarchy of the new protocol. The "augment" statement SHOULD be
made conditional by using a "when" substatement requiring that the
new nodes be used only if the "type" leaf node is equal to the new
protocol's identity.
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.";
}
Second, new route attributes specific for the RIP protocol ("metric"
and "tag") are added:
augment "/rt:routing/rt:routing-process/v4ur:ipv4-unicast-routing/"
+ "v4ur:routing-tables/v4ur:routing-table/"
+ "v4ur:routes/v4ur:route" {
when "../../../../v4ur:routing-protocol-instances/"
+ "v4ur:routing-protocol-instance[rt:name="
+ "current()/v4ur:source-protocol]/v4ur:type='rip:rip'";
description
"RIP-specific route components.";
leaf metric { ... }
leaf tag { ... }
}
The "when" statement is used to make sure that the new route
attributes are only valid when the source protocol is RIP.
Finally, RIP-specific configuration data are integrated into the
"v4ur:routing-protocol-instance" node by using the following
"augment" statement, which applies only to routing protocol instances
whose type is "rip:rip", and which is a part of a routing process
whose address family is "ipV4" and subsequent address family
identifier is "nlri-unicast":
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augment "/rt:routing/rt:routing-process/v4ur:ipv4-unicast-routing/"
+ "v4ur:routing-protocol-instances/"
+ "v4ur:routing-protocol-instance" {
when "v4ur:type = 'rip:rip' and ../../../rt:address-family = 'ipV4'"
+ " and ../../../safi = 'nlri-unicast'";
container rip-configuration {
...
}
}
4.4. Route Filters
The "ietf-ipv4-unicast-routing" module 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 routing
table, or between a source and a recipient routing table. Route
filters may also manipulate routes, i.e., add, delete, or modify
their properties.
By itself, the route filtering framework defined in the "ietf-ipv4-
unicast-routing" module allows to establish only the two extreme
routing policies in which either all routes are allowed or all routes
are denied. It is expected that a real route filtering framework (or
several alternative frameworks) will be developed separately.
Each route filter is identified by a name which is unique within a
routing process. Its type MUST be specified by the "type" identity
reference - this opens the space for multiple route filtering
framework implementations. The default value for route filter type
is the identity "deny-all-route-filter" defined in the "ietf-routing"
module, which represents the "deny all" route filtering policy.
4.5. RPC Operations
The "ietf-ipv4-unicast-routing-module" defines two RPC operations:
o "delete-route" operations allows the client to immediately delete
specific route(s) from a routing table within a routing process.
The first input parameter of this operation is the name of the
routing process, the second parameter is the routing table to act
upon, and the third (optional) parameter is the "route" container
with zero or more of the following route attributes: "destination-
prefix", "next-hop" and "outgoing-interface". All routes that
match these attributes MUST be deleted from the selected routing
table. If the "route" container is missing or empty, all routes
from the selected routing table MUST be deleted.
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o "get-route" is used for querying the forwarding information base
of a routing process. The first input parameter is the name of a
routing process whose FIB is to be queried, and the second
parameter is an IPv4 destination address. The server replies with
an active route which is used for forwarding datagrams to the
destination address within the selected routing process.
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5. Routing YANG Module
<CODE BEGINS> file "ietf-routing@2011-04-27.yang"
module ietf-routing {
namespace "urn:ietf:params:xml:ns:yang:ietf-routing";
prefix rt;
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@cesnet.cz>";
description
"This module contains YANG definitions for top-level containers
for the configuration of routing together with several type
definitions and identities.";
revision 2011-04-27 {
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
"Identity for the pseudo-protocol providing routes to directly
connected networks. An implementation MUST preconfigure
exactly one instance of this pseudo-protocol for each routing
process."; }
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identity static {
base routing-protocol;
description
"Identity for 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;
description
"This identity represents a route filter that blocks all
routes.";
}
/* Type definitions */
typedef address-family {
type enumeration {
enum "other" {
value 0;
description
"none of the following";
}
enum "ipV4" {
value 1;
description
"IP Version 4";
}
enum "ipV6" {
value 2;
description
"IP Version 6";
}
enum "nsap" {
value 3;
description
"NSAP";
}
enum "hdlc" {
value 4;
description
"(8-bit multidrop)";
}
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enum "bbn1822" {
value 5;
description
"BBN Report 1822";
}
enum "all802" {
value 6;
description
"(includes all 802 media plus Ethernet 'canonical
format')";
}
enum "e163" {
value 7;
}
enum "e164" {
value 8;
description
"(SMDS, FrameRelay, ATM)";
}
enum "f69" {
value 9;
description
"(Telex)";
}
enum "x121" {
value 10;
description
"(X.25, Frame Relay)";
}
enum "ipx" {
value 11;
description
"IPX (Internet Protocol Exchange)";
}
enum "appleTalk" {
value 12;
description
"Apple Talk";
}
enum "decnetIV" {
value 13;
description
"DEC Net Phase IV";
}
enum "banyanVines" {
value 14;
description
"Banyan Vines";
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}
enum "e164withNsap" {
value 15;
description
"(E.164 with NSAP format subaddress)";
}
enum "dns" {
value 16;
description
"(Domain Name System)";
}
enum "distinguishedName" {
value 17;
description
"(Distinguished Name, per X.500)";
}
enum "asNumber" {
value 18;
description
"(16-bit quantity, per the AS number space)";
}
enum "xtpOverIPv4" {
value 19;
description
"XTP over IP version 4";
}
enum "xtpOverIpv6" {
value 20;
description
"XTP over IP version 6";
}
enum "xtpNativeModeXTP" {
value 21;
description
"XTP native mode XTP";
}
enum "fibreChannelWWPN" {
value 22;
description
"Fibre Channel World-Wide Port Name";
}
enum "fibreChannelWWNN" {
value 23;
description
"Fibre Channel World-Wide Node Name";
}
enum "gwid" {
value 24;
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description
"Gateway Identifier";
}
enum "afi" {
value 25;
description
"AFI for L2VPN";
}
}
description
"This typedef is a YANG enumeration of IANA-registered
address families.";
reference
"http://www.iana.org/assignments/ianaaddressfamilynumbers-mib";
}
typedef subsequent-address-family {
type enumeration {
enum "nlri-unicast" {
value 1;
description
"Network Layer Reachability Information used for
unicast forwarding";
reference "RFC4760";
}
enum "nlri-multicast" {
value 2;
description
"Network Layer Reachability Information used for
multicast forwarding";
reference "RFC4760";
}
enum "nlri-mpls" {
value 4;
description
"Network Layer Reachability Information (NLRI) with
MPLS Labels";
reference "RFC3107";
}
enum "mcast-vpn" {
value 5;
description
"MCAST-VPN";
reference "draft-ietf-l3vpn-2547bis-mcast-bgp-08";
}
enum "nlri-dynamic-ms-pw" {
value 6;
status obsolete;
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description
"Network Layer Reachability Information used for Dynamic
Placement of Multi-Segment Pseudowires (TEMPORARY -
Expires 2008-08-23)";
reference "draft-ietf-pwe3-dynamic-ms-pw-13";
}
enum "tunnel-safi" {
value 64;
description
"Tunnel SAFI";
reference "draft-nalawade-kapoor-tunnel-safi-05";
}
enum "vpls" {
value 65;
description
"Virtual Private LAN Service (VPLS)";
reference "RFC4761, RFC6074";
}
enum "bgp-mdt" {
value 66;
description
"BGP MDT SAFI";
reference "RFC6037";
}
enum "bgp-4over6" {
value 67;
description
"BGP 4over6 SAFI";
reference "RFC5747";
}
enum "bgp-6over4" {
value 68;
description
"BGP 6over4 SAFI";
reference "mailto:cuiyong&tsinghua.edu.cn";
}
enum "l1vpn-auto-discovery" {
value 69;
description
"Layer-1 VPN auto-discovery information";
reference "draft-ietf-l1vpn-bgp-auto-discovery-05";
}
enum "mpls-vpn" {
value 128;
description
"MPLS-labeled VPN address";
reference "RFC4364";
}
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enum "multicast-bgp-mpls-vpn" {
value 129;
description
"Multicast for BGP/MPLS IP Virtual Private Networks
(VPNs)";
reference
"draft-ietf-l3vpn-2547bis-mcast-10,
draft-ietf-l3vpn-2547bis-mcast-10";
}
enum "route-target-constraints" {
value 132;
description
"Route Target constraints";
reference "RFC4684";
}
enum "ipv4-diss-flow" {
value 133;
description
"IPv4 dissemination of flow specification rules";
reference "RFC5575";
}
enum "vpnv4-diss-flow" {
value 134;
description
"IPv4 dissemination of flow specification rules";
reference "RFC5575";
}
enum "vpn-auto-discovery" {
value 140;
description
"VPN auto-discovery";
reference "draft-ietf-l3vpn-bgpvpn-auto-09";
}
}
description
"This typedef is a YANG enumeration of IANA-registered
subsequent address families.";
reference "http://www.iana.org/assignments/safi-namespace/"
+ "safi-namespace.xml";
}
typedef routing-process-ref {
type leafref {
path "/rt:routing/rt:routing-process/rt:name";
}
description
"This type is used for leafs that reference a routing
process.";
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}
/* Data nodes */
container routing {
description
"Routing parameters.";
list routing-process {
key "name";
description
"Each entry is a container for configuration and operational
state data of a single (virtual) router for a given address
family and subsequent address family identifier (SAFI). Each
entry has a unique name.
The definitions of data for a particular address family and
subsequent address family shall be provided via augmentation
by other modules.";
leaf name {
type string;
description
"The unique name of the routing process.";
}
leaf address-family {
type address-family;
default "ipV4";
description
"Address family of the routing process.";
}
leaf safi {
type subsequent-address-family;
default "nlri-unicast";
description
"Subsequent address family identifier of the routing
process.";
}
leaf description {
type string;
description
"Textual description of the routing process.";
}
leaf enabled {
type boolean;
default "true";
description
"Enable or disable the routing process. The default value
is 'true', which means that the process is enabled.";
}
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}
}
}
<CODE ENDS>
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6. IPv4 Unicast Routing YANG Module
<CODE BEGINS> file "ietf-ipv4-unicast-routing@2011-04-27.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-yang-types {
prefix yang;
}
import ietf-inet-types {
prefix inet;
}
import ietf-interfaces {
prefix if;
}
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@cesnet.cz>";
description
"This module augments the 'ietf-routing' module with YANG
definitions for basic configuration of IPv4 unicast routing.
It is immediately usable for a device that needs just a single
routing table populated with static routes.
On the other hand, the framework is designed to handle
arbitrarily complex configurations with any number of routing
tables and various routing protocols (in multiple instances).";
revision 2011-04-27 {
description
"Initial revision.";
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reference
"RFC XXXX: A YANG Data Model for Routing Configuration";
}
/* Groupings */
grouping routing-process-name {
leaf routing-process-name {
type rt:routing-process-ref;
must "/rt:routing/rt:routing-process[rt:name = current()]"
+ "/rt:address-family = 'ipV4' and "
+ "/rt:routing/rt:routing-process[rt:name = current()]"
+ "/rt:safi = 'nlri-unicast'" {
description
"The referred routing process must be IPv4 unicast.";
}
description "The name of a routing process.";
}
description
"This grouping defines the first common parameter of both
RPC operations below.";
}
/* RPC operations */
rpc get-route {
description
"Query the forwarding information base of an IPv4 unicast
routing process whose name is given as the first
parameter. The second parameter is an IPv4 destination
address. The server returns the route which is currently used
for forwarding datagrams to that destination address, or an
error message, if no such route exists.";
input {
uses routing-process-name;
leaf destination-address {
type inet:ipv4-address;
description
"Second parameter - IPv4 destination address.";
}
}
output {
container route {
description
"Contents of the reply.";
leaf destination-prefix {
type inet:ipv4-prefix;
mandatory true;
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description
"Destination prefix of the returned route.";
}
leaf next-hop {
type inet:ipv4-address;
description
"Next hop address of the returned route.";
}
leaf outgoing-interface {
type if:interface-ref;
description
"Outgoing interface of the returned route.";
}
}
}
}
rpc delete-route {
description
"Delete all routes that match the given attributes from a
routing table within a routing process.
Parameters:
1. routing process name,
2. routing table name,
3. Container 'route' with route attributes.
<ok> is returned by the server upon successful completion.";
input {
uses routing-process-name;
leaf routing-table {
type leafref {
path "/rt:routing/rt:routing-process[rt:name=current()/../"
+ "routing-process-name]/ipv4-unicast-routing/"
+ "routing-tables/routing-table/name";
}
mandatory true;
description
"First parameter.";
}
container route {
description
"Second parameter. All routes matching the route
attributes must be deleted from the routing table.
If this container is empty or missing, all routes
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from the selected routing table are deleted.";
leaf destination-prefix {
type inet:ipv4-prefix;
description
"Match destination prefix.";
}
leaf next-hop {
type inet:ipv4-address;
description
"Match next hop.";
}
leaf outgoing-interface {
type if:interface-ref;
description
"Match outgoing interface.";
}
}
}
}
/* Data nodes */
augment "/rt:routing/rt:routing-process" {
when "afi='ipV4' and safi='nlri-unicast'" {
description
"IPv4 unicast.";
}
description
"Definitions of data nodes that augment a routing process
for IPv4 unicast.";
container ipv4-unicast-routing {
description
"Container for IPv4 unicast routing configuration and
operational state data.";
container routing-protocol-instances {
description
"Container for the list of configured routing protocol
instances.";
list routing-protocol-instance {
key "name";
description
"An instance of a routing protocol.";
container static-routes {
when "../type='rt:static'" {
description
"These data nodes are only valid for the static
pseudo-protocol.";
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}
description
"Configuration of a 'static' pseudo-protocol
instance consists of a list of routes.";
list static-route {
key "id";
ordered-by user;
description
"An user-ordered list of static routes.";
leaf id {
type string;
description
"An identification string for the route.";
}
leaf description {
type string;
description
"Textual description of the route.";
}
leaf destination-prefix {
type inet:ipv4-prefix;
mandatory true;
description
"The destination prefix for which the route may
be used.";
}
leaf next-hop {
type inet:ipv4-address;
description
"IPv4 address of the host or router to which
packets whose address matches 'destination-prefix'
are to be forwarded.";
}
leaf outgoing-interface {
type if:interface-ref;
description
"Name of the outgoing interface. This attribute
is mainly used in direct routes.";
}
}
}
leaf name {
type string;
description
"The name of the routing protocol instance.";
}
leaf description {
type string;
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description
"Textual description of the routing protocol
instance.";
}
leaf type {
type identityref {
base rt:routing-protocol;
}
mandatory true;
description
"Type of the routing protocol - an identity derived
from the 'rt:routing-protocol' base identity.";
}
leaf routing-table {
type leafref {
path "../../../routing-tables/routing-table/name";
}
default "ipv4-unicast-main";
description
"The routing table to which the routing protocol
instance is connected. By default it is the
'ipv4-unicast-main' table.";
}
leaf import-filter {
type leafref {
path "../../../route-filters/route-filter/name";
}
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
'routing-table' 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 "../../../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
'routing-table' sibling 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.";
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}
}
}
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 {
base rt:route-filter;
}
default "rt:deny-all-route-filter";
description
"Type of the route-filter - an identity derived
from the 'rt:route-filter' base identity. The default
value represents an all-blocking filter.";
}
}
}
container routing-tables {
must "routing-table/name='ipv4-unicast-fib'" {
description
"IPv4 unicast forwarding information base.";
}
must "routing-table/name='ipv4-unicast-main'" {
description
"The main IPv4 unicast routing table.";
}
description
"Container for configured routing tables.";
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list routing-table {
key "name";
description
"Each entry represents a configured routing table. At
least two entries with names 'ipv4-unicast-fib' and
'ipv4-unicast-main' must exist.";
container routes {
config false;
description
"Current contents of the routing table. Note that
it is operational state data.";
list route {
description
"A routing table entry.";
leaf destination-prefix {
type inet:ipv4-prefix;
description
"Destination prefix.";
}
leaf next-hop {
type inet:ipv4-address;
description
"IPv4 address of the next hop.";
}
leaf outgoing-interface {
type if:interface-ref;
description
"Name of the outgoing interface.";
}
leaf source-protocol {
type leafref {
path "../../../../../routing-protocol-instances/"
+ "routing-protocol-instance/name";
}
description
"Protocol instance from which the route comes.";
}
leaf last-modified {
type yang:date-and-time;
description
"Time stamp of the last modification of the
route. If the route was never modified, it is the
time when the route was inserted to the routing
table.";
}
}
}
leaf name {
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type string;
description
"The name of the routing table.";
}
leaf description {
type string;
description
"Textual description of the routing table.";
}
list recipient-routing-tables {
key "recipient-name";
description
"A list of routing tables that receive routes from
the parent routing table.";
leaf recipient-name {
type leafref {
path "../../../routing-table/name";
}
description
"The name of the recipient routing table.";
}
leaf filter {
type leafref {
path "../../../../route-filters/route-filter/name";
}
description
"A route filter which is applied to the routes
passed on to the recipient routing table.";
}
}
}
}
}
}
}
<CODE ENDS>
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7. IANA Considerations
This document registers the following two 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.
----------------------------------------------------------
This document registers two YANG modules in the YANG Module Names
registry [RFC6020]:
-------------------------------------------------------------------
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
-------------------------------------------------------------------
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8. Security Considerations
TBD.
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9. Acknowledgments
The author wishes to thank Juergen Schoenwaelder and Martin Bjorklund
for their helpful comments and suggestions.
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10. References
10.1. Normative References
[IANA-AFI]
IANA, "Address Family Numbers.", January 2011.
[IANA-SAFI]
IANA, "Subsequent Address Family Identifiers (SAFI)
Parameters.", March 2011.
[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.
[RFC4741] Enns, R., "NETCONF Configuration Protocol", RFC 4741,
December 2006.
[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.
[YANG-IF] Bjorklund, M., "A YANG Data Model for Interface
Configuration", draft-bjorklund-netmod-interfaces-cfg-00
(work in progress), December 2010.
10.2. Informative References
[RFC6087] Bierman, A., "Guidelines for Authors and Reviewers of YANG
Data Model Documents", RFC 6087, January 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. Appendix A.1 contains a
YANG module which is used for this purpose. It is intended only as
an illustration and not as a real definition of a data model for the
RIP routing protocol. Also, for the sake of brevity, we do not
follow all the guidelines specified in [RFC6087].
Appendix A.2 then contains a complete instance XML document - a reply
to the NETCONF <get> message from a server that uses the RIP protocol
as well as static routing.
A.1. Example YANG Module for Routing Information Protocol
module example-rip {
namespace "http://example.com/rip";
prefix rip;
import ietf-interfaces {
prefix if;
}
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";
}
}
augment "/rt:routing/rt:routing-protocol-instances/" +
"rt:routing-protocol-instance" {
when "rt:type='rip:rip'";
container rip-configuration {
container rip-interfaces {
list rip-interface {
key "name";
leaf name {
type if:interface-ref;
}
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leaf enabled {
type boolean;
default "true";
}
leaf metric {
type rip-metric;
default "1";
}
/* Additional per-interface RIP configuration */
}
}
leaf update-interval {
type uint8 {
range "10..60";
}
units "seconds";
default "30";
description
"Time interval between periodic updates.";
}
/* Additional RIP configuration */
}
}
augment "/rt:routing/rt:routing-tables/rt:routing-table/rt:route" {
when "../../../rt:routing-protocol-instances/" +
"rt:routing-protocol-instance[rt:name=" +
"current()/rt:source-protocol]/rt:type='rip:rip'";
description
"RIP-specific route components.";
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.";
}
}
}
A.2. Sample 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 (and advertizing in
<hello>) the following YANG modules:
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o ietf-interfaces [YANG-IF],
o ex-ethernet [YANG-IF],
o ex-ip [YANG-IF],
o ietf-routing (Section 5),
o ietf-ipv4-unicast-routing (Section 6),
o example-rip (Appendix A.1).
We assume a simple network setup as shown in Figure 2: routers "ISP"
and "A" use RIP for exchanging routing information whereas static
routing is used in the private network. In order to avoid the
redistribution of the routes to the private subnetworks
192.168.1.0/24 and 192.168.2.0/24 in RIP, an export filter is used in
the RIP protocol configuration preventing the routes from the main
routing table from appearing in RIP updates.
+-----------------+
| |
| Router ISP |
| |
+--------+--------+
|192.0.2.2
|
|
eth0|192.0.2.1
+--------+--------+
| |
| Router A |
| |
+--------+--------+
eth1|192.168.1.1
|
|
|192.168.1.254
+--------+--------+
| |
| Router B |
| |
+--------+--------+
|192.168.2.1
|
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Figure 2: Example network configuration
Router "A" then could send the following XML document as its reply to
the NETCONF <get> message:
<?xml version="1.0"?>
<nc:rpc-reply
message-id="101"
xmlns="urn:ietf:params:xml:ns:yang:ietf-ipv4-unicast-routing"
xmlns:nc="urn:ietf:params:xml:ns:netconf:base:1.0"
xmlns:if="urn:ietf:params:xml:ns:yang:ietf-interfaces"
xmlns:eth="http://example.com/ethernet"
xmlns:ip="http://example.com/ip"
xmlns:rt="urn:ietf:params:xml:ns:yang:ietf-routing"
xmlns:rip="http://example.com/rip">
<nc:data>
<if:interfaces>
<if:interface>
<if:name>eth0</if:name>
<if:type>ethernetCsmacd</if:type>
<if:location>05:00.0</if:location>
<ip:ip>
<ip:address>
<ip:ip>192.0.2.1</ip:ip>
<ip:prefix-length>24</ip:prefix-length>
</ip:address>
</ip:ip>
</if:interface>
<if:interface>
<if:name>eth1</if:name>
<if:type>ethernetCsmacd</if:type>
<if:location>05:00.1</if:location>
<ip:ip>
<ip:address>
<ip:ip>192.168.1.1</ip:ip>
<ip:prefix-length>24</ip:prefix-length>
</ip:address>
</ip:ip>
</if:interface>
</if:interfaces>
<rt:routing>
<rt:routing-process>
<rt:name>inet-0</rt:name>
<rt:address-family>ipV4</rt:address-family>
<rt:safi>nlri-unicast</rt:safi>
<ipv4-unicast-routing>
<routing-protocol-instances>
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<routing-protocol-instance>
<name>direct</name>
<type>rt:direct</type>
</routing-protocol-instance>
<routing-protocol-instance>
<name>st0</name>
<description>
Static routing is used for the internal network.
</description>
<type>rt:static</type>
<static-routes>
<static-route>
<id>id-6378</id>
<destination-prefix>192.168.2.0/24</destination-prefix>
<next-hop>192.168.1.254</next-hop>
</static-route>
</static-routes>
</routing-protocol-instance>
<routing-protocol-instance>
<name>rip0</name>
<description>
RIP is used on the uplink.
Static routes to the internal networks are not
advertized in RIP.
</description>
<type>rip:rip</type>
<export-filter>deny-all</export-filter>
<rip:rip-configuration>
<rip:rip-interfaces>
<rip:rip-interface>
<rip:name>eth0</rip:name>
</rip:rip-interface>
</rip:rip-interfaces>
</rip:rip-configuration>
</routing-protocol-instance>
</routing-protocol-instances>
<route-filters>
<route-filter>
<name>deny-all</name>
</route-filter>
</route-filters>
<routing-tables>
<routing-table>
<name>ipv4-unicast-fib</name>
<routes>
<route>
<destination-prefix>192.0.2.1/24</destination-prefix>
<source-protocol>direct</source-protocol>
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<outgoing-interface>eth0</outgoing-interface>
<last-modified>2010-04-01T17:11:27+01:00</last-modified>
</route>
<route>
<destination-prefix>192.168.1.0/24</destination-prefix>
<source-protocol>direct</source-protocol>
<outgoing-interface>eth1</outgoing-interface>
<last-modified>2010-04-01T17:11:27+01:00</last-modified>
</route>
<route>
<destination-prefix>192.168.2.0/24</destination-prefix>
<source-protocol>st0</source-protocol>
<next-hop>192.168.1.254</next-hop>
<last-modified>2010-04-01T17:11:32+01:00</last-modified>
</route>
<route>
<destination-prefix>0.0.0.0/0</destination-prefix>
<source-protocol>rip0</source-protocol>
<next-hop>192.168.1.254</next-hop>
<rip:metric>2</rip:metric>
<rip:tag>64500</rip:tag>
<last-modified>2010-04-01T18:02:45+01:00</last-modified>
</route>
</routes>
</routing-table>
<routing-table>
<name>ipv4-unicast-main</name>
<recipient-routing-tables>
<recipient-name>ipv4-unicast-fib</recipient-name>
</recipient-routing-tables>
<routes>
<route>
<destination-prefix>192.0.2.1/24</destination-prefix>
<source-protocol>direct</source-protocol>
<outgoing-interface>eth0</outgoing-interface>
<last-modified>2010-04-01T17:11:27+01:00</last-modified>
</route>
<route>
<destination-prefix>192.168.1.0/24</destination-prefix>
<source-protocol>direct</source-protocol>
<outgoing-interface>eth1</outgoing-interface>
<last-modified>2010-04-01T17:11:27+01:00</last-modified>
</route>
<route>
<destination-prefix>192.168.2.0/24</destination-prefix>
<source-protocol>st0</source-protocol>
<next-hop>192.168.1.254</next-hop>
<last-modified>2010-04-01T17:11:32+01:00</last-modified>
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</route>
<route>
<destination-prefix>0.0.0.0/0</destination-prefix>
<source-protocol>rip0</source-protocol>
<next-hop>192.168.1.254</next-hop>
<rip:metric>2</rip:metric>
<rip:tag>64500</rip:tag>
<last-modified>2010-04-01T18:02:45+01:00</last-modified>
</route>
</routes>
</routing-table>
</routing-tables>
</ipv4-unicast-routing>
</rt:routing-process>
</rt:routing>
</nc:data>
</nc:rpc-reply>
Lhotka Expires October 29, 2011 [Page 43]
Internet-Draft YANG Routing Configuration April 2011
Author's Address
Ladislav Lhotka
CESNET
Email: lhotka@cesnet.cz
Lhotka Expires October 29, 2011 [Page 44]
