💾 Archived View for gemini.bortzmeyer.org › rfc-mirror › rfc9067.txt captured on 2024-03-21 at 16:14:59.
⬅️ Previous capture (2021-11-30)
-=-=-=-=-=-=-
Internet Engineering Task Force (IETF) Y. Qu
Request for Comments: 9067 Futurewei
Category: Standards Track J. Tantsura
ISSN: 2070-1721 Microsoft
A. Lindem
Cisco
X. Liu
Volta Networks
October 2021
A YANG Data Model for Routing Policy
Abstract
This document defines a YANG data model for configuring and managing
routing policies in a vendor-neutral way. The model provides a
generic routing policy framework that can be extended for specific
routing protocols using the YANG 'augment' mechanism.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc9067.
Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction
1.1. Goals and Approach
2. Terminology and Notation
2.1. Tree Diagrams
2.2. Prefixes in Data Node Names
3. Model Overview
4. Route Policy Expression
4.1. Defined Sets for Policy Matching
4.2. Policy Conditions
4.3. Policy Actions
4.4. Policy Subroutines
5. Policy Evaluation
6. Applying Routing Policy
7. YANG Module and Tree
7.1. Routing Policy Model Tree
7.2. Routing Policy Model
8. Security Considerations
9. IANA Considerations
10. References
10.1. Normative References
10.2. Informative References
Appendix A. Routing Protocol-Specific Policies
Appendix B. Policy Examples
Acknowledgements
Authors' Addresses
1. Introduction
This document describes a YANG data model [RFC7950] for routing
policy configuration based on operational usage and best practices in
a variety of service provider networks. The model is intended to be
vendor neutral to allow operators to manage policy configuration
consistently in environments with routers supplied by multiple
vendors.
The YANG modules in this document conform to the Network Management
Datastore Architecture (NMDA) [RFC8342].
1.1. Goals and Approach
This model does not aim to be feature complete; it is a subset of the
policy configuration parameters available in a variety of vendor
implementations but supports widely used constructs for managing how
routes are imported, exported, and modified across different routing
protocols. The model development approach has been to examine actual
policy configurations in use across several operator networks.
Hence, the focus is on enabling policy configuration capabilities and
structure that are in wide use.
Despite the differences in details of policy expressions and
conventions in various vendor implementations, the model reflects the
observation that a relatively simple condition-action approach can be
readily mapped to several existing vendor implementations and also
gives operators a familiar and straightforward way to express policy.
A side effect of this design decision is that other methods for
expressing policies are not considered.
Consistent with the goal to produce a data model that is vendor
neutral, only policy expressions that are deemed to be widely
available in prevalent implementations are included in the model.
Those configuration items that are only available from a single
implementation are omitted from the model with the expectation they
will be available in separate vendor-provided modules that augment
the current model.
2. Terminology and Notation
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
Routing policy: A routing policy defines how routes are imported,
exported, modified, and advertised between routing protocol
instances or within a single routing protocol instance.
Policy chain: A policy chain is a sequence of policy definitions.
They can be referenced from different contexts.
Policy statement: Policy statements consist of a set of conditions
and actions (either of which may be empty).
The following terms are defined in [RFC8342]:
* client
* server
* configuration
* system state
* operational state
* intended configuration
The following terms are defined in [RFC7950]:
* action
* augment
* container
* container with presence
* data model
* data node
* feature
* leaf
* list
* mandatory node
* module
* schema tree
* RPC (Remote Procedure Call) operation
2.1. Tree Diagrams
Tree diagrams used in this document follow the notation defined in
[RFC8340].
2.2. Prefixes in Data Node Names
In this document, names of data nodes, actions, and other data model
objects are often used without a prefix if it is clear in which YANG
module each name is defined given the context. Otherwise, names are
prefixed using the standard prefix associated with the corresponding
YANG module, as shown in Table 1.
+========+=================+===========+
| Prefix | YANG module | Reference |
+========+=================+===========+
| if | ietf-interfaces | [RFC8343] |
+--------+-----------------+-----------+
| rt | ietf-routing | [RFC8349] |
+--------+-----------------+-----------+
| yang | ietf-yang-types | [RFC6991] |
+--------+-----------------+-----------+
| inet | ietf-inet-types | [RFC6991] |
+--------+-----------------+-----------+
Table 1: Prefixes and Corresponding
YANG Modules
3. Model Overview
The routing policy module has three main parts:
* A generic framework is provided to express policies as sets of
related conditions and actions. This includes match sets and
actions that are useful across many routing protocols.
* A structure that allows routing protocol models to add protocol-
specific policy conditions and actions through YANG augmentations
is also provided. There is a complete example of this for BGP
[RFC4271] policies in the proposed vendor-neutral BGP data model
[IDR-BGP-MODEL]. Appendix A provides an example of how an
augmentation for BGP policies might be accomplished. Note that
this section is not normative, as the BGP model is still evolving.
* Finally, a reusable grouping is defined for attaching import and
export rules in the context of routing configuration for different
protocols, Virtual Routing and Forwarding (VRF) instances, etc.
This also enables the creation of policy chains and the expression
of default policy behavior. In this document, policy chains are
sequences of policy definitions that are applied in order
(described in Section 4).
The module makes use of the standard Internet types, such as IP
addresses, autonomous system numbers, etc., defined in RFC 6991
[RFC6991].
4. Route Policy Expression
Policies are expressed as a sequence of top-level policy definitions,
each of which consists of a sequence of policy statements. Policy
statements in turn consist of simple condition-action tuples.
Conditions may include multiple match or comparison operations, and
similarly, actions may include multiple changes to route attributes
or indicate a final disposition of accepting or rejecting the route.
This structure is shown below.
+--rw routing-policy
+--rw policy-definitions
+--ro match-modified-attributes? boolean
+--rw policy-definition* [name]
+--rw name string
+--rw statements
+--rw statement* [name]
+--rw name string
+--rw conditions
| ...
+--rw actions
...
4.1. Defined Sets for Policy Matching
The model provides a collection of generic sets that can be used for
matching in policy conditions. These sets are applicable for route
selection across multiple routing protocols. They may be further
augmented by protocol-specific models that have their own defined
sets. The defined sets include:
prefix sets: Each prefix set defines a set of IP prefixes, each with
an associated IP prefix and netmask range (or exact length).
neighbor sets: Each neighbor set defines a set of neighboring nodes
by their IP addresses. A neighbor set is used for selecting
routes based on the neighbors advertising the routes.
tag sets: Each tag set defines a set of generic tag values that can
be used in matches for selecting routes.
The model structure for defined sets is shown below.
+--rw routing-policy
+--rw defined-sets
| +--rw prefix-sets
| | +--rw prefix-set* [name]
| | +--rw name string
| | +--rw mode? enumeration
| | +--rw prefixes
| | +--rw prefix-list* [ip-prefix mask-length-lower
| | mask-length-upper]
| | +--rw ip-prefix inet:ip-prefix
| | +--rw mask-length-lower uint8
| | +--rw mask-length-upper uint8
| +--rw neighbor-sets
| | +--rw neighbor-set* [name]
| | +--rw name string
| | +--rw address* inet:ip-address
| +--rw tag-sets
| +--rw tag-set* [name]
| +--rw name string
| +--rw tag-value* tag-type
4.2. Policy Conditions
Policy statements consist of a set of conditions and actions (either
of which may be empty). Conditions are used to match route
attributes against a defined set (e.g., a prefix set) or to compare
attributes against a specific value.
Match conditions may be further modified using the match-set-options
configuration, which allows network operators to change the behavior
of a match. Three options are supported:
'all': Match is true only if the given value matches all members of
the set.
'any': Match is true if the given value matches any member of the
set.
'invert': Match is true if the given value does not match any member
of the given set.
Not all options are appropriate for matching against all defined sets
(e.g., match 'all' in a prefix set does not make sense). In the
model, a restricted set of match options is used where applicable.
Comparison conditions may similarly use options to change how route
attributes should be tested, e.g., for equality or inequality,
against a given value.
While most policy conditions will be added by individual routing
protocol models via augmentation, this routing policy model includes
several generic match conditions and the ability to test which
protocol or mechanism installed a route (e.g., BGP, IGP, static,
etc.). The conditions included in the model are shown below.
+--rw routing-policy
+--rw policy-definitions
+--rw policy-definition* [name]
+--rw name string
+--rw statements
+--rw statement* [name]
+--rw conditions
| +--rw call-policy?
| +--rw source-protocol?
| +--rw match-interface
| | +--rw interface?
| +--rw match-prefix-set
| | +--rw prefix-set?
| | +--rw match-set-options?
| +--rw match-neighbor-set
| | +--rw neighbor-set?
| +--rw match-tag-set
| | +--rw tag-set?
| | +--rw match-set-options?
| +--rw match-route-type
| +--rw route-type*
4.3. Policy Actions
When policy conditions are satisfied, policy actions are used to set
various attributes of the route being processed or to indicate the
final disposition of the route, i.e., accept or reject.
Similar to policy conditions, the routing policy model includes
generic actions in addition to the basic route disposition actions.
These are shown below.
+--rw routing-policy
+--rw policy-definitions
+--rw policy-definition* [name]
+--rw statements
+--rw statement* [name]
+--rw actions
+--rw policy-result? policy-result-type
+--rw set-metric
| +--rw metric-modification?
| | metric-modification-type
| +--rw metric? uint32
+--rw set-metric-type
| +--rw metric-type? identityref
+--rw set-route-level
| +--rw route-level? identityref
+--rw set-route-preference? uint16
+--rw set-tag? tag-type
+--rw set-application-tag? tag-type
4.4. Policy Subroutines
Policy 'subroutines' (or nested policies) are supported by allowing
policy statement conditions to reference other policy definitions
using the call-policy configuration. Called policies apply their
conditions and actions before returning to the calling policy
statement and resuming evaluation. The outcome of the called policy
affects the evaluation of the calling policy. If the called policy
results in an accept-route, then the subroutine returns an effective
Boolean true value to the calling policy. For the calling policy,
this is equivalent to a condition statement evaluating to a true
value, thus the calling party continues in its evaluation of the
policy (see Section 5). Note that the called policy may also modify
attributes of the route in its action statements. Similarly, a
reject-route action returns false, and the calling policy evaluation
will be affected accordingly. When the end of the subroutine policy
statements is reached, the default route disposition action is
returned (i.e., Boolean false for reject-route). Consequently, a
subroutine cannot explicitly accept or reject a route. Rather, the
called policy returns Boolean true if its outcome is accept-route or
Boolean false if its outcome is reject-route. Route acceptance or
rejection is solely determined by the top-level policy.
Note that the called policy may itself call other policies (subject
to implementation limitations). The model does not prescribe a
nesting depth because this varies among implementations. For
example, an implementation may only support a single level of
subroutine recursion. As with any routing policy construction, care
must be taken with nested policies to ensure that the effective
return value results in the intended behavior. Nested policies are a
convenience in many routing policy constructions, but creating
policies nested beyond a small number of levels (e.g., two to three)
is discouraged. Also, implementations MUST perform validation to
ensure that there is no recursion among nested routing policies.
5. Policy Evaluation
Evaluation of each policy definition proceeds by evaluating its
individual policy statements in the order that they are defined.
When all the condition statements in a policy statement are
satisfied, the corresponding action statements are executed. If the
actions include either accept-route or reject-route actions,
evaluation of the current policy definition stops, and no further
policy statement is evaluated. If there are multiple policies in the
policy chain, subsequent policies are not evaluated. Policy chains
are sequences of policy definitions (as described in Section 4).
If the conditions are not satisfied, then evaluation proceeds to the
next policy statement. If none of the policy statement conditions
are satisfied, then evaluation of the current policy definition
stops, and the next policy definition in the chain is evaluated.
When the end of the policy chain is reached, the default route
disposition action is performed (i.e., reject-route unless an
alternate default action is specified for the chain).
Whether the route's pre-policy attributes are used for testing policy
statement conditions is dependent on the implementation-specific
value of the match-modified-attributes leaf. If match-modified-
attributes is false and actions modify route attributes, these
modifications are not used for policy statement conditions.
Conversely, if match-modified-attributes is true and actions modify
the policy application-specific attributes, the attributes as
modified by the policy are used for policy condition statements.
6. Applying Routing Policy
Routing policy is applied by defining and attaching policy chains in
various routing contexts. Policy chains are sequences of policy
definitions (described in Section 4). They can be referenced from
different contexts. For example, a policy chain could be associated
with a routing protocol and used to control its interaction with its
protocol peers, or it could be used to control the interaction
between a routing protocol and the local routing information base. A
policy chain has an associated direction (import or export) with
respect to the context in which it is referenced.
The routing policy model defines an apply-policy grouping that can be
imported and used by other models. As shown below, it allows
definition of import and export policy chains, as well as specifies
the default route disposition to be used when no policy definition in
the chain results in a final decision.
+--rw apply-policy
| +--rw import-policy*
| +--rw default-import-policy? default-policy-type
| +--rw export-policy*
| +--rw default-export-policy? default-policy-type
The default policy defined by the model is to reject the route for
both import and export policies.
7. YANG Module and Tree
7.1. Routing Policy Model Tree
The tree of the routing policy model is shown below.
module: ietf-routing-policy
+--rw routing-policy
+--rw defined-sets
| +--rw prefix-sets
| | +--rw prefix-set* [name mode]
| | +--rw name string
| | +--rw mode enumeration
| | +--rw prefixes
| | +--rw prefix-list* [ip-prefix mask-length-lower
| | mask-length-upper]
| | +--rw ip-prefix inet:ip-prefix
| | +--rw mask-length-lower uint8
| | +--rw mask-length-upper uint8
| +--rw neighbor-sets
| | +--rw neighbor-set* [name]
| | +--rw name string
| | +--rw address* inet:ip-address
| +--rw tag-sets
| +--rw tag-set* [name]
| +--rw name string
| +--rw tag-value* tag-type
+--rw policy-definitions
+--ro match-modified-attributes? boolean
+--rw policy-definition* [name]
+--rw name string
+--rw statements
+--rw statement* [name]
+--rw name string
+--rw conditions
| +--rw call-policy? -> ../../../../../..
| /policy-definitions
| /policy-definition/name
| +--rw source-protocol? identityref
| +--rw match-interface
| | +--rw interface? if:interface-ref
| +--rw match-prefix-set
| | +--rw prefix-set? -> ../../../../../../..
| | /defined-sets
| | /prefix-sets
| | /prefix-set/name
| | +--rw match-set-options?
| | match-set-options-type
| +--rw match-neighbor-set
| | +--rw neighbor-set? -> ../../../../../../..
| | /defined-sets
| | /neighbor-sets
| | /neighbor-set/name
| +--rw match-tag-set
| | +--rw tag-set? -> ../../../../../../..
| | /defined-sets/tag-sets
| | /tag-set/name
| | +--rw match-set-options?
| | match-set-options-type
| +--rw match-route-type
| +--rw route-type* identityref
+--rw actions
+--rw policy-result? policy-result-type
+--rw set-metric
| +--rw metric-modification?
| metric-modification-type
| +--rw metric? uint32
+--rw set-metric-type
| +--rw metric-type? identityref
+--rw set-route-level
| +--rw route-level? identityref
+--rw set-route-preference? uint16
+--rw set-tag? tag-type
+--rw set-application-tag? tag-type
7.2. Routing Policy Model
The following RFCs are not referenced in the document text but are
referenced in the ietf-routing-policy.yang module: [RFC2328],
[RFC3101], [RFC5130], [RFC5302], [RFC6991], and [RFC8343].
<CODE BEGINS> file "ietf-routing-policy@2021-10-11.yang"
module ietf-routing-policy {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-routing-policy";
prefix rt-pol;
import ietf-inet-types {
prefix inet;
reference
"RFC 6991: Common YANG Data Types";
}
import ietf-yang-types {
prefix yang;
reference
"RFC 6991: Common YANG Data Types";
}
import ietf-interfaces {
prefix if;
reference
"RFC 8343: A YANG Data Model for Interface
Management";
}
import ietf-routing {
prefix rt;
reference
"RFC 8349: A YANG Data Model for Routing
Management (NMDA Version)";
}
organization
"IETF RTGWG - Routing Area Working Group";
contact
"WG Web: <https://datatracker.ietf.org/wg/rtgwg/>
WG List: <mailto: rtgwg@ietf.org>
Editors: Yingzhen Qu
<mailto: yingzhen.qu@futurewei.com>
Jeff Tantsura
<mailto: jefftant.ietf@gmail.com>
Acee Lindem
<mailto: acee@cisco.com>
Xufeng Liu
<mailto: xufeng.liu.ietf@gmail.com>";
description
"This module describes a YANG data model for routing policy
configuration. It is a limited subset of all of the policy
configuration parameters available in the variety of vendor
implementations, but supports widely used constructs for
managing how routes are imported, exported, modified, and
advertised across different routing protocol instances or
within a single routing protocol instance. This module is
intended to be used in conjunction with routing protocol
configuration modules (e.g., BGP) defined in other models.
This YANG module conforms to the Network Management
Datastore Architecture (NMDA), as described in RFC 8342.
The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL
NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 'NOT RECOMMENDED',
'MAY', and 'OPTIONAL' in this document are to be interpreted as
described in BCP 14 (RFC 2119) (RFC 8174) when, and only when,
they appear in all capitals, as shown here.
Copyright (c) 2021 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
(https://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC 9067;
see the RFC itself for full legal notices.";
reference
"RFC 9067: A YANG Data Model for Routing Policy.";
revision 2021-10-11 {
description
"Initial revision.";
reference
"RFC 9067: A YANG Data Model for Routing Policy.";
}
/* Identities */
identity metric-type {
description
"Base identity for route metric types.";
}
identity ospf-type-1-metric {
base metric-type;
description
"Identity for the OSPF type 1 external metric types. It
is only applicable to OSPF routes.";
reference
"RFC 2328: OSPF Version 2";
}
identity ospf-type-2-metric {
base metric-type;
description
"Identity for the OSPF type 2 external metric types. It
is only applicable to OSPF routes.";
reference
"RFC 2328: OSPF Version 2";
}
identity isis-internal-metric {
base metric-type;
description
"Identity for the IS-IS internal metric types. It is only
applicable to IS-IS routes.";
reference
"RFC 5302: Domain-Wide Prefix Distribution with
Two-Level IS-IS";
}
identity isis-external-metric {
base metric-type;
description
"Identity for the IS-IS external metric types. It is only
applicable to IS-IS routes.";
reference
"RFC 5302: Domain-Wide Prefix Distribution with
Two-Level IS-IS";
}
identity route-level {
description
"Base identity for route import level.";
}
identity ospf-normal {
base route-level;
description
"Identity for OSPF importation into normal areas.
It is only applicable to routes imported
into the OSPF protocol.";
reference
"RFC 2328: OSPF Version 2";
}
identity ospf-nssa-only {
base route-level;
description
"Identity for the OSPF Not-So-Stubby Area (NSSA) area
importation. It is only applicable to routes imported
into the OSPF protocol.";
reference
"RFC 3101: The OSPF Not-So-Stubby Area (NSSA) Option";
}
identity ospf-normal-nssa {
base route-level;
description
"Identity for OSPF importation into both normal and NSSA
areas. It is only applicable to routes imported into
the OSPF protocol.";
reference
"RFC 3101: The OSPF Not-So-Stubby Area (NSSA) Option";
}
identity isis-level-1 {
base route-level;
description
"Identity for IS-IS Level 1 area importation. It is only
applicable to routes imported into the IS-IS protocol.";
reference
"RFC 5302: Domain-Wide Prefix Distribution with
Two-Level IS-IS";
}
identity isis-level-2 {
base route-level;
description
"Identity for IS-IS Level 2 area importation. It is only
applicable to routes imported into the IS-IS protocol.";
reference
"RFC 5302: Domain-Wide Prefix Distribution with
Two-Level IS-IS";
}
identity isis-level-1-2 {
base route-level;
description
"Identity for IS-IS importation into both Level 1 and Level 2
areas. It is only applicable to routes imported into the
IS-IS protocol.";
reference
"RFC 5302: Domain-Wide Prefix Distribution with
Two-Level IS-IS";
}
identity proto-route-type {
description
"Base identity for route type within a protocol.";
}
identity isis-level-1-type {
base proto-route-type;
description
"Identity for IS-IS Level 1 route type. It is only
applicable to IS-IS routes.";
reference
"RFC 5302: Domain-Wide Prefix Distribution with
Two-Level IS-IS";
}
identity isis-level-2-type {
base proto-route-type;
description
"Identity for IS-IS Level 2 route type. It is only
applicable to IS-IS routes.";
reference
"RFC 5302: Domain-Wide Prefix Distribution with
Two-Level IS-IS";
}
identity ospf-internal-type {
base proto-route-type;
description
"Identity for OSPF intra-area or inter-area route type.
It is only applicable to OSPF routes.";
reference
"RFC 2328: OSPF Version 2";
}
identity ospf-external-type {
base proto-route-type;
description
"Identity for OSPF external type 1/2 route type.
It is only applicable to OSPF routes.";
reference
"RFC 2328: OSPF Version 2";
}
identity ospf-external-t1-type {
base ospf-external-type;
description
"Identity for OSPF external type 1 route type.
It is only applicable to OSPF routes.";
reference
"RFC 2328: OSPF Version 2";
}
identity ospf-external-t2-type {
base ospf-external-type;
description
"Identity for OSPF external type 2 route type.
It is only applicable to OSPF routes.";
reference
"RFC 2328: OSPF Version 2";
}
identity ospf-nssa-type {
base proto-route-type;
description
"Identity for OSPF NSSA type 1/2 route type.
It is only applicable to OSPF routes.";
reference
"RFC 3101: The OSPF Not-So-Stubby Area (NSSA) Option";
}
identity ospf-nssa-t1-type {
base ospf-nssa-type;
description
"Identity for OSPF NSSA type 1 route type.
It is only applicable to OSPF routes.";
reference
"RFC 3101: The OSPF Not-So-Stubby Area (NSSA) Option";
}
identity ospf-nssa-t2-type {
base ospf-nssa-type;
description
"Identity for OSPF NSSA type 2 route type.
It is only applicable to OSPF routes.";
reference
"RFC 3101: The OSPF Not-So-Stubby Area (NSSA) Option";
}
identity bgp-internal {
base proto-route-type;
description
"Identity for routes learned from internal BGP (IBGP).
It is only applicable to BGP routes.";
reference
"RFC 4271: A Border Gateway Protocol 4 (BGP-4)";
}
identity bgp-external {
base proto-route-type;
description
"Identity for routes learned from external BGP (EBGP).
It is only applicable to BGP routes.";
reference
"RFC 4271: A Border Gateway Protocol 4 (BGP-4)";
}
/* Type Definitions */
typedef default-policy-type {
type enumeration {
enum accept-route {
description
"Default policy to accept the route.";
}
enum reject-route {
description
"Default policy to reject the route.";
}
}
description
"Type used to specify route disposition in
a policy chain. This typedef is used in
the default import and export policy.";
}
typedef policy-result-type {
type enumeration {
enum accept-route {
description
"Policy accepts the route.";
}
enum reject-route {
description
"Policy rejects the route.";
}
}
description
"Type used to specify route disposition in
a policy chain.";
}
typedef tag-type {
type union {
type uint32;
type yang:hex-string;
}
description
"Type for expressing route tags on a local system,
including IS-IS and OSPF; may be expressed as either decimal
or hexadecimal integer.";
reference
"RFC 2328: OSPF Version 2
RFC 5130: A Policy Control Mechanism in IS-IS Using
Administrative Tags";
}
typedef match-set-options-type {
type enumeration {
enum any {
description
"Match is true if given value matches any member
of the defined set.";
}
enum all {
description
"Match is true if given value matches all
members of the defined set.";
}
enum invert {
description
"Match is true if given value does not match any
member of the defined set.";
}
}
default "any";
description
"Options that govern the behavior of a match statement. The
default behavior is any, i.e., the given value matches any
of the members of the defined set.";
}
typedef metric-modification-type {
type enumeration {
enum set-metric {
description
"Set the metric to the specified value.";
}
enum add-metric {
description
"Add the specified value to the existing metric.
If the result overflows the maximum metric
(0xffffffff), set the metric to the maximum.";
}
enum subtract-metric {
description
"Subtract the specified value from the existing metric. If
the result is less than 0, set the metric to 0.";
}
}
description
"Type used to specify how to set the metric given the
specified value.";
}
/* Groupings */
grouping prefix {
description
"Configuration data for a prefix definition.
The combination of mask-length-lower and mask-length-upper
define a range for the mask length or single 'exact'
length if mask-length-lower and mask-length-upper are
equal.
Example: 192.0.2.0/24 through 192.0.2.0/26 would be
expressed as prefix: 192.0.2.0/24,
mask-length-lower=24,
mask-length-upper=26
Example: 192.0.2.0/24 (an exact match) would be
expressed as prefix: 192.0.2.0/24,
mask-length-lower=24,
mask-length-upper=24
Example: 2001:DB8::/32 through 2001:DB8::/64 would be
expressed as prefix: 2001:DB8::/32,
mask-length-lower=32,
mask-length-upper=64";
leaf ip-prefix {
type inet:ip-prefix;
mandatory true;
description
"The IP prefix represented as an IPv6 or IPv4 network
number followed by a prefix length with an intervening
slash character as a delimiter. All members of the
prefix-set MUST be of the same address family as the
prefix-set mode.";
}
leaf mask-length-lower {
type uint8 {
range "0..128";
}
description
"Mask length range lower bound. It MUST NOT be less than
the prefix length defined in ip-prefix.";
}
leaf mask-length-upper {
type uint8 {
range "1..128";
}
must '../mask-length-upper >= ../mask-length-lower' {
error-message "The upper bound MUST NOT be less "
+ "than lower bound.";
}
description
"Mask length range upper bound. It MUST NOT be less than
lower bound.";
}
}
grouping match-set-options-group {
description
"Grouping containing options relating to how a particular set
will be matched.";
leaf match-set-options {
type match-set-options-type;
description
"Optional parameter that governs the behavior of the
match operation.";
}
}
grouping match-set-options-restricted-group {
description
"Grouping for a restricted set of match operation
modifiers.";
leaf match-set-options {
type match-set-options-type {
enum any {
description
"Match is true if given value matches any
member of the defined set.";
}
enum invert {
description
"Match is true if given value does not match
any member of the defined set.";
}
}
description
"Optional parameter that governs the behavior of the
match operation. This leaf only supports
the 'any' and 'invert' match options.
Matching on 'all' is not supported.";
}
}
grouping apply-policy-group {
description
"Top-level container for routing policy applications. This
grouping is intended to be used in routing models where
needed.";
container apply-policy {
description
"Anchor point for routing policies in the model.
Import and export policies are with respect to the local
routing table, i.e., export (send) and import (receive),
depending on the context.";
leaf-list import-policy {
type leafref {
path "/rt-pol:routing-policy/rt-pol:policy-definitions/"
+ "rt-pol:policy-definition/rt-pol:name";
require-instance true;
}
ordered-by user;
description
"List of policy names in sequence to be applied on
receiving redistributed routes from another routing
protocol or receiving a routing update in the current
context, e.g., for the current peer group, neighbor,
address family, etc.";
}
leaf default-import-policy {
type default-policy-type;
default "reject-route";
description
"Explicitly set a default policy if no policy definition
in the import policy chain is satisfied.";
}
leaf-list export-policy {
type leafref {
path "/rt-pol:routing-policy/rt-pol:policy-definitions/"
+ "rt-pol:policy-definition/rt-pol:name";
require-instance true;
}
ordered-by user;
description
"List of policy names in sequence to be applied on
redistributing routes from one routing protocol to another
or sending a routing update in the current context, e.g.,
for the current peer group, neighbor, address family,
etc.";
}
leaf default-export-policy {
type default-policy-type;
default "reject-route";
description
"Explicitly set a default policy if no policy definition
in the export policy chain is satisfied.";
}
}
}
container routing-policy {
description
"Top-level container for all routing policy.";
container defined-sets {
description
"Predefined sets of attributes used in policy match
statements.";
container prefix-sets {
description
"Data definitions for a list of IPv4 or IPv6
prefixes that are matched as part of a policy.";
list prefix-set {
key "name mode";
description
"List of the defined prefix sets";
leaf name {
type string;
description
"Name of the prefix set; this is used as a label to
reference the set in match conditions.";
}
leaf mode {
type enumeration {
enum ipv4 {
description
"Prefix set contains IPv4 prefixes only.";
}
enum ipv6 {
description
"Prefix set contains IPv6 prefixes only.";
}
}
description
"Indicates the mode of the prefix set in terms of
which address families (IPv4 or IPv6) are present.
The mode provides a hint; all prefixes MUST be of
the indicated type. The device MUST validate
all prefixes and reject the configuration if there
is a discrepancy.";
}
container prefixes {
description
"Container for the list of prefixes in a policy
prefix list. Since individual prefixes do not have
unique actions, the order in which the prefix in
prefix-list are matched has no impact on the outcome
and is left to the implementation. A given prefix-set
condition is satisfied if the input prefix matches
any of the prefixes in the prefix-set.";
list prefix-list {
key "ip-prefix mask-length-lower mask-length-upper";
description
"List of prefixes in the prefix set.";
uses prefix;
}
}
}
}
container neighbor-sets {
description
"Data definition for a list of IPv4 or IPv6
neighbors that can be matched in a routing policy.";
list neighbor-set {
key "name";
description
"List of defined neighbor sets for use in policies.";
leaf name {
type string;
description
"Name of the neighbor set; this is used as a label
to reference the set in match conditions.";
}
leaf-list address {
type inet:ip-address;
description
"List of IP addresses in the neighbor set.";
}
}
}
container tag-sets {
description
"Data definitions for a list of tags that can
be matched in policies.";
list tag-set {
key "name";
description
"List of tag set definitions.";
leaf name {
type string;
description
"Name of the tag set; this is used as a label to
reference the set in match conditions.";
}
leaf-list tag-value {
type tag-type;
description
"Value of the tag set member.";
}
}
}
}
container policy-definitions {
description
"Enclosing container for the list of top-level policy
definitions.";
leaf match-modified-attributes {
type boolean;
config false;
description
"This boolean value dictates whether matches are performed
on the actual route attributes or route attributes
modified by policy statements preceding the match.";
}
list policy-definition {
key "name";
description
"List of top-level policy definitions, keyed by unique
name. These policy definitions are expected to be
referenced (by name) in policy chains specified in
import or export configuration statements.";
leaf name {
type string;
description
"Name of the top-level policy definition; this name
is used in references to the current policy.";
}
container statements {
description
"Enclosing container for policy statements.";
list statement {
key "name";
ordered-by user;
description
"Policy statements group conditions and actions
within a policy definition. They are evaluated in
the order specified.";
leaf name {
type string;
description
"Name of the policy statement.";
}
container conditions {
description
"Condition statements for the current policy
statement.";
leaf call-policy {
type leafref {
path "../../../../../../"
+ "rt-pol:policy-definitions/"
+ "rt-pol:policy-definition/rt-pol:name";
require-instance true;
}
description
"Applies the statements from the specified policy
definition and then returns control to the current
policy statement. Note that the called policy
may itself call other policies (subject to
implementation limitations). This is intended to
provide a policy 'subroutine' capability. The
called policy SHOULD contain an explicit or a
default route disposition that returns an
effective true (accept-route) or false
(reject-route); otherwise, the behavior may be
ambiguous. The call-policy MUST NOT have been
previously called without returning (i.e.,
recursion is not allowed).";
}
leaf source-protocol {
type identityref {
base rt:control-plane-protocol;
}
description
"Condition to check the protocol / method used to
install the route into the local routing table.";
}
container match-interface {
leaf interface {
type if:interface-ref;
description
"Reference to a base interface.";
}
description
"Container for interface match conditions";
}
container match-prefix-set {
leaf prefix-set {
type leafref {
path "../../../../../../../defined-sets/"
+ "prefix-sets/prefix-set/name";
}
description
"References a defined prefix set.";
}
uses match-set-options-restricted-group;
description
"Match a referenced prefix-set according to the
logic defined in the match-set-options leaf.";
}
container match-neighbor-set {
leaf neighbor-set {
type leafref {
path "../../../../../../../defined-sets/"
+ "neighbor-sets/neighbor-set/name";
require-instance true;
}
description
"References a defined neighbor set.";
}
description
"Match a referenced neighbor set.";
}
container match-tag-set {
leaf tag-set {
type leafref {
path "../../../../../../../defined-sets/"
+ "tag-sets/tag-set/name";
require-instance true;
}
description
"References a defined tag set.";
}
uses match-set-options-group;
description
"Match a referenced tag set according to the logic
defined in the match-set-options leaf.";
}
container match-route-type {
description
"This container provides route-type match
condition";
leaf-list route-type {
type identityref {
base proto-route-type;
}
description
"Condition to check the protocol-specific type
of route. This is normally used during route
importation to select routes or to set
protocol-specific attributes based on the route
type.";
}
}
}
container actions {
description
"Top-level container for policy action
statements.";
leaf policy-result {
type policy-result-type;
description
"Select the final disposition for the route,
either accept or reject.";
}
container set-metric {
leaf metric-modification {
type metric-modification-type;
description
"Indicates how to modify the metric.";
}
leaf metric {
type uint32;
description
"Metric value to set, add, or subtract.";
}
description
"Set the metric for the route.";
}
container set-metric-type {
leaf metric-type {
type identityref {
base metric-type;
}
description
"Route metric type.";
}
description
"Set the metric type for the route.";
}
container set-route-level {
leaf route-level {
type identityref {
base route-level;
}
description
"Route import level.";
}
description
"Set the level for importation or
exportation of routes.";
}
leaf set-route-preference {
type uint16;
description
"Set the preference for the route. It is also
known as 'administrative distance' and allows for
selecting the preferred route among routes with
the same destination prefix. A smaller value is
more preferred.";
}
leaf set-tag {
type tag-type;
description
"Set the tag for the route.";
}
leaf set-application-tag {
type tag-type;
description
"Set the application tag for the route.
The application-specific tag is an additional tag
that can be used by applications that require
semantics and/or policy different from that of the
tag. For example, the tag is usually
automatically advertised in OSPF AS-External Link
State Advertisements (LSAs) while this
application-specific tag is not advertised
implicitly.";
}
}
}
}
}
}
}
}
<CODE ENDS>
8. Security Considerations
The YANG module specified in this document defines a schema for data
that is designed to be accessed via network management protocols such
as NETCONF [RFC6241] or RESTCONF [RFC8040]. The lowest NETCONF layer
is the secure transport layer, and the mandatory-to-implement secure
transport is Secure Shell (SSH) [RFC6242]. The lowest RESTCONF layer
is HTTPS, and the mandatory-to-implement secure transport is TLS
[RFC8446].
The Network Configuration Access Control Model (NACM) [RFC8341]
provides the means to restrict access for particular NETCONF or
RESTCONF users to a preconfigured subset of all available NETCONF or
RESTCONF protocol operations and content.
There are a number of data nodes defined in this YANG module that are
writable/creatable/deletable (i.e., config true, which is the
default). These data nodes may be considered sensitive or vulnerable
in some network environments. Write operations (e.g., edit-config)
to these data nodes without proper protection can have a negative
effect on network operations. These are the subtrees and data nodes
and their sensitivity/vulnerability:
/routing-policy/defined-sets/prefix-sets
Modification to prefix sets could result in a Denial-of-Service
(DoS) attack. An attacker may try to modify prefix sets and
redirect or drop traffic. Redirection of traffic could be used as
part of a more elaborate attack to either collect sensitive
information or masquerade a service. Additionally, a control
plane DoS attack could be accomplished by allowing a large number
of routes to be leaked into a routing protocol domain (e.g., BGP).
/routing-policy/defined-sets/neighbor-sets
Modification to the neighbor sets could be used to mount a DoS
attack or more elaborate attack as with prefix sets. For example,
a DoS attack could be mounted by changing the neighbor set from
which routes are accepted.
/routing-policy/defined-sets/tag-sets
Modification to the tag sets could be used to mount a DoS attack.
Routes with certain tags might be redirected or dropped. The
implications are similar to prefix sets and neighbor sets.
However, the attack may be more difficult to detect as the routing
policy usage of route tags and intent must be understood to
recognize the breach. Conversely, the implications of prefix set
or neighbor set modification are easier to recognize.
/routing-policy/policy-definitions/policy-
definition/statements/statement/conditions
Modification to the conditions could be used to mount a DoS attack
or other attack. An attacker may change a policy condition and
redirect or drop traffic. As with prefix sets, neighbor sets, or
tag sets, traffic redirection could be used as part of a more
elaborate attack.
/routing-policy/policy-definitions/policy-
definition/statements/statement/actions
Modification to actions could be used to mount a DoS attack or
other attack. Traffic may be redirected or dropped. As with
prefix sets, neighbor sets, or tag sets, traffic redirection could
be used as part of a more elaborate attack. Additionally, route
attributes may be changed to mount a second-level attack that is
more difficult to detect.
Some of the readable data nodes in the YANG module may be considered
sensitive or vulnerable in some network environments. It is thus
important to control read access (e.g., via get, get-config, or
notification) to these data nodes. These are the subtrees and data
nodes and their sensitivity/vulnerability:
/routing-policy/defined-sets/prefix-sets
Knowledge of these data nodes can be used to ascertain which local
prefixes are susceptible to a DoS attack.
/routing-policy/defined-sets/neighbor-sets
Knowledge of these data nodes can be used to ascertain local
neighbors against whom to mount a DoS attack.
/routing-policy/policy-definitions/policy-definition/statements/
Knowledge of these data nodes can be used to attack the local
router with a DoS attack. Additionally, policies and their
attendant conditions and actions should be considered proprietary
and disclosure could be used to ascertain partners, customers, and
suppliers. Furthermore, the policies themselves could represent
intellectual property and disclosure could diminish their
corresponding business advantage.
Routing policy configuration has a significant impact on network
operations, and as such, other YANG data models that reference
routing policies are also susceptible to vulnerabilities relating to
the YANG data nodes specified above.
9. IANA Considerations
IANA has registered the following URI in the "ns" subregistry of the
"IETF XML Registry" [RFC3688]:
URI: urn:ietf:params:xml:ns:yang:ietf-routing-policy
Registrant Contact: The IESG
XML: N/A; the requested URI is an XML namespace.
IANA has registered the following YANG module in the "YANG Module
Names" subregistry [RFC6020] within the "YANG Parameters" registry:
Name: ietf-routing-policy
Maintained by IANA? N
Namespace: urn:ietf:params:xml:ns:yang:ietf-routing-policy
Prefix: rt-pol
Reference: RFC 9067
10. References
10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328,
DOI 10.17487/RFC2328, April 1998,
<https://www.rfc-editor.org/info/rfc2328>.
[RFC3101] Murphy, P., "The OSPF Not-So-Stubby Area (NSSA) Option",
RFC 3101, DOI 10.17487/RFC3101, January 2003,
<https://www.rfc-editor.org/info/rfc3101>.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
DOI 10.17487/RFC3688, January 2004,
<https://www.rfc-editor.org/info/rfc3688>.
[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
Border Gateway Protocol 4 (BGP-4)", RFC 4271,
DOI 10.17487/RFC4271, January 2006,
<https://www.rfc-editor.org/info/rfc4271>.
[RFC5130] Previdi, S., Shand, M., Ed., and C. Martin, "A Policy
Control Mechanism in IS-IS Using Administrative Tags",
RFC 5130, DOI 10.17487/RFC5130, February 2008,
<https://www.rfc-editor.org/info/rfc5130>.
[RFC5302] Li, T., Smit, H., and T. Przygienda, "Domain-Wide Prefix
Distribution with Two-Level IS-IS", RFC 5302,
DOI 10.17487/RFC5302, October 2008,
<https://www.rfc-editor.org/info/rfc5302>.
[RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for
the Network Configuration Protocol (NETCONF)", RFC 6020,
DOI 10.17487/RFC6020, October 2010,
<https://www.rfc-editor.org/info/rfc6020>.
[RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
and A. Bierman, Ed., "Network Configuration Protocol
(NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
<https://www.rfc-editor.org/info/rfc6241>.
[RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure
Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011,
<https://www.rfc-editor.org/info/rfc6242>.
[RFC6991] Schoenwaelder, J., Ed., "Common YANG Data Types",
RFC 6991, DOI 10.17487/RFC6991, July 2013,
<https://www.rfc-editor.org/info/rfc6991>.
[RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
RFC 7950, DOI 10.17487/RFC7950, August 2016,
<https://www.rfc-editor.org/info/rfc7950>.
[RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
<https://www.rfc-editor.org/info/rfc8040>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams",
BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018,
<https://www.rfc-editor.org/info/rfc8340>.
[RFC8341] Bierman, A. and M. Bjorklund, "Network Configuration
Access Control Model", STD 91, RFC 8341,
DOI 10.17487/RFC8341, March 2018,
<https://www.rfc-editor.org/info/rfc8341>.
[RFC8342] Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K.,
and R. Wilton, "Network Management Datastore Architecture
(NMDA)", RFC 8342, DOI 10.17487/RFC8342, March 2018,
<https://www.rfc-editor.org/info/rfc8342>.
[RFC8343] Bjorklund, M., "A YANG Data Model for Interface
Management", RFC 8343, DOI 10.17487/RFC8343, March 2018,
<https://www.rfc-editor.org/info/rfc8343>.
[RFC8349] Lhotka, L., Lindem, A., and Y. Qu, "A YANG Data Model for
Routing Management (NMDA Version)", RFC 8349,
DOI 10.17487/RFC8349, March 2018,
<https://www.rfc-editor.org/info/rfc8349>.
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/info/rfc8446>.
10.2. Informative References
[IDR-BGP-MODEL]
Jethanandani, M., Patel, K., Hares, S., and J. Haas, "BGP
YANG Model for Service Provider Networks", Work in
Progress, Internet-Draft, draft-ietf-idr-bgp-model-09, 28
June 2020, <https://datatracker.ietf.org/doc/html/draft-
ietf-idr-bgp-model-09>.
[W3C.REC-xml11]
Bray, T., Paoli, J., Sperberg-McQueen, M., Maler, E.,
Yergeau, F., and J. Cowan, "Extensible Markup Language
(XML) 1.1 (Second Edition)", W3C Consortium
Recommendation REC-xml11-20060816, 16 August 2006,
<https://www.w3.org/TR/2006/REC-xml11-20060816>.
Appendix A. Routing Protocol-Specific Policies
Routing models that require the ability to apply routing policy may
augment the routing policy model with protocol or other specific
policy configuration. The routing policy model assumes that
additional defined sets, conditions, and actions may all be added by
other models.
The example below illustrates how another data model can augment
parts of this routing policy data model. It uses specific examples
from draft-ietf-idr-bgp-model-09 to show in a concrete manner how the
different pieces fit together. This example is not normative with
respect to [IDR-BGP-MODEL]. The model similarly augments BGP-
specific conditions and actions in the corresponding sections of the
routing policy model. In the example below, the XPath prefix "bp:"
specifies import from the ietf-bgp-policy sub-module and the XPath
prefix "bt:" specifies import from the ietf-bgp-types sub-module
[IDR-BGP-MODEL].
module: ietf-routing-policy
+--rw routing-policy
+--rw defined-sets
| +--rw prefix-sets
| | +--rw prefix-set* [name]
| | +--rw name string
| | +--rw mode? enumeration
| | +--rw prefixes
| | +--rw prefix-list* [ip-prefix mask-length-lower
| | mask-length-upper]
| | +--rw ip-prefix inet:ip-prefix
| | +--rw mask-length-lower uint8
| | +--rw mask-length-upper uint8
| +--rw neighbor-sets
| | +--rw neighbor-set* [name]
| | +--rw name string
| | +--rw address* inet:ip-address
| +--rw tag-sets
| | +--rw tag-set* [name]
| | +--rw name string
| | +--rw tag-value* tag-type
| +--rw bp:bgp-defined-sets
| +--rw bp:community-sets
| | +--rw bp:community-set* [name]
| | +--rw bp:name string
| | +--rw bp:member* union
| +--rw bp:ext-community-sets
| | +--rw bp:ext-community-set* [name]
| | +--rw bp:name string
| | +--rw bp:member* union
| +--rw bp:as-path-sets
| +--rw bp:as-path-set* [name]
| +--rw bp:name string
| +--rw bp:member* string
+--rw policy-definitions
+--ro match-modified-attributes? boolean
+--rw policy-definition* [name]
+--rw name string
+--rw statements
+--rw statement* [name]
+--rw name string
+--rw conditions
| +--rw call-policy?
| +--rw source-protocol? identityref
| +--rw match-interface
| | +--rw interface? if:interface-ref
| +--rw match-prefix-set
| | +--rw prefix-set? prefix-set/name
| | +--rw match-set-options?
| | match-set-options-type
| +--rw match-neighbor-set
| | +--rw neighbor-set?
| +--rw match-tag-set
| | +--rw tag-set?
| | +--rw match-set-options?
| | match-set-options-type
| +--rw match-route-type
| +--rw route-type* identityref
| +--rw bp:bgp-conditions
| +--rw bp:med-eq? uint32
| +--rw bp:origin-eq? bt:bgp-origin-attr-type
| +--rw bp:next-hop-in* inet:ip-address-no-zone
| +--rw bp:afi-safi-in* identityref
| +--rw bp:local-pref-eq? uint32
| +--rw bp:route-type? enumeration
| +--rw bp:community-count
| +--rw bp:as-path-length
| +--rw bp:match-community-set
| | +--rw bp:community-set?
| | +--rw bp:match-set-options?
| +--rw bp:match-ext-community-set
| | +--rw bp:ext-community-set?
| | +--rw bp:match-set-options?
| +--rw bp:match-as-path-set
| +--rw bp:as-path-set?
| +--rw bp:match-set-options?
+--rw actions
+--rw policy-result? policy-result-type
+--rw set-metric
| +--rw metric-modification?
| +--rw metric? uint32
+--rw set-metric-type
| +--rw metric-type? identityref
+--rw set-route-level
| +--rw route-level? identityref
+--rw set-route-preference? uint16
+--rw set-tag? tag-type
+--rw set-application-tag? tag-type
+--rw bp:bgp-actions
+--rw bp:set-route-origin?
| bt:bgp-origin-attr-type
+--rw bp:set-local-pref? uint32
+--rw bp:set-next-hop? bgp-next-hop-type
+--rw bp:set-med? bgp-set-med-type
+--rw bp:set-as-path-prepend
| +--rw bp:repeat-n? uint8
+--rw bp:set-community
| +--rw bp:method? enumeration
| +--rw bp:options?
| +--rw bp:inline
| | +--rw bp:communities* union
| +--rw bp:reference
| +--rw bp:community-set-ref?
+--rw bp:set-ext-community
+--rw bp:method? enumeration
+--rw bp:options?
+--rw bp:inline
| +--rw bp:communities* union
+--rw bp:reference
+--rw bp:ext-community-set-ref?
Appendix B. Policy Examples
Below, we show examples of XML-encoded configuration data using the
routing policy and BGP models to illustrate both how policies are
defined and how they can be applied. Note that the XML
[W3C.REC-xml11] has been simplified for readability.
The following example shows how prefix set and tag set can be
defined. The policy condition is to match a prefix set and a tag
set, and the action is to accept routes that match the condition.
<config xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<routing-policy
xmlns="urn:ietf:params:xml:ns:yang:ietf-routing-policy">
<defined-sets>
<prefix-sets>
<prefix-set>
<name>prefix-set-A</name>
<mode>ipv4</mode>
<prefixes>
<prefix-list>
<ip-prefix>192.0.2.0/24</ip-prefix>
<mask-length-lower>24</mask-length-lower>
<mask-length-upper>32</mask-length-upper>
</prefix-list>
<prefix-list>
<ip-prefix>198.51.100.0/24</ip-prefix>
<mask-length-lower>24</mask-length-lower>
<mask-length-upper>32</mask-length-upper>
</prefix-list>
</prefixes>
</prefix-set>
<prefix-set>
<name>prefix-set-B</name>
<mode>ipv6</mode>
<prefixes>
<prefix-list>
<ip-prefix>2001:DB8::/32</ip-prefix>
<mask-length-lower>32</mask-length-lower>
<mask-length-upper>64</mask-length-upper>
</prefix-list>
</prefixes>
</prefix-set>
</prefix-sets>
<tag-sets>
<tag-set>
<name>cust-tag1</name>
<tag-value>10</tag-value>
</tag-set>
</tag-sets>
</defined-sets>
<policy-definitions>
<policy-definition>
<name>export-tagged-BGP</name>
<statements>
<statement>
<name>term-0</name>
<conditions>
<match-prefix-set>
<prefix-set>prefix-set-A</prefix-set>
</match-prefix-set>
<match-tag-set>
<tag-set>cust-tag1</tag-set>
</match-tag-set>
</conditions>
<actions>
<policy-result>accept-route</policy-result>
</actions>
</statement>
</statements>
</policy-definition>
</policy-definitions>
</routing-policy>
</config>
In the following example, all routes in the RIB that have been
learned from OSPF advertisements corresponding to OSPF intra-area and
inter-area route types should get advertised into IS-IS level 2
advertisements.
<config xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<routing-policy
xmlns="urn:ietf:params:xml:ns:yang:ietf-routing-policy">
<policy-definitions>
<policy-definition>
<name>export-all-OSPF-prefixes-into-IS-IS-level-2</name>
<statements>
<statement>
<name>term-0</name>
<conditions>
<match-route-type>
<route-type>ospf-internal-type</route-type>
</match-route-type>
</conditions>
<actions>
<set-route-level>
<route-level>isis-level-2</route-level>
</set-route-level>
<policy-result>accept-route</policy-result>
</actions>
</statement>
</statements>
</policy-definition>
</policy-definitions>
</routing-policy>
</config>
Acknowledgements
The routing policy module defined in this document is based on the
OpenConfig route policy model. The authors would like to thank
OpenConfig for their contributions, especially those of Anees Shaikh,
Rob Shakir, Kevin D'Souza, and Chris Chase.
The authors are grateful for valuable contributions to this document
and the associated models from Ebben Aires, Luyuan Fang, Josh George,
Stephane Litkowski, Ina Minei, Carl Moberg, Eric Osborne, Steve
Padgett, Juergen Schoenwaelder, Jim Uttaro, Russ White, and John
Heasley.
Thanks to Mahesh Jethanandani, John Scudder, Alvaro Retana, Chris
Bowers, Tom Petch, and Kris Lambrechts for their reviews and
comments.
Authors' Addresses
Yingzhen Qu
Futurewei
2330 Central Expressway
Santa Clara, CA 95050
United States of America
Email: yingzhen.qu@futurewei.com
Jeff Tantsura
Microsoft
Email: jefftant.ietf@gmail.com
Acee Lindem
Cisco
301 Midenhall Way
Cary, NC 27513
United States of America
Email: acee@cisco.com
Xufeng Liu
Volta Networks
Email: xufeng.liu.ietf@gmail.com