Network Working Group B. Linowski
Internet-Draft TCS/Nokia Siemens Networks
Intended status: Standards Track M. Ersue
Expires: April 29, 2010 Nokia Siemens Networks
October 26, 2009
Extending YANG with Language Abstractions
draft-linowski-netmod-yang-abstract-01
Status of This Memo
This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet-
Drafts.
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."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
This Internet-Draft will expire on April 29, 2010.
Copyright Notice
Copyright (c) 2009 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 in effect on the date of
publication of this document (http://trustee.ietf.org/license-info).
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document.
Abstract
YANG - the NETCONF Data Modeling Language - supports modeling of a
tree of data elements that represent the configuration and runtime
Linowski & Ersue Expires April 29, 2010 [Page 1]
Internet-Draft YANG Language Abstractions October 2009
status of a particular network element managed via NETCONF. This
memo suggests to enhance YANG with supplementary modeling features
and language abstractions with the aim to improve the model
extensibility and reuse.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Key Words . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2. Motivation . . . . . . . . . . . . . . . . . . . . . . . . 3
1.3. Modeling Improvements with Language Abstractions . . . . . 4
1.4. Design Approach . . . . . . . . . . . . . . . . . . . . . 5
2. Complex Types . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1. Definition . . . . . . . . . . . . . . . . . . . . . . . . 5
2.2. complex-type extension statement . . . . . . . . . . . . . 6
2.3. instance extension statement . . . . . . . . . . . . . . . 7
2.4. instance-list extension statement . . . . . . . . . . . . 8
2.5. extends extension statement . . . . . . . . . . . . . . . 9
2.6. abstract extension statement . . . . . . . . . . . . . . . 10
2.7. XML Encoding Rules . . . . . . . . . . . . . . . . . . . . 10
2.8. Type Encoding Rules . . . . . . . . . . . . . . . . . . . 10
2.9. Extension and Feature Definition Module . . . . . . . . . 11
2.10. Model Example . . . . . . . . . . . . . . . . . . . . . . 13
2.11. NETCONF Payload Example . . . . . . . . . . . . . . . . . 14
2.12. Update Rules for Modules Using Complex Types . . . . . . . 15
2.13. Using Complex Types . . . . . . . . . . . . . . . . . . . 16
2.13.1. Overriding Complex Types Data Nodes . . . . . . . . . 16
2.13.2. Augmenting Complex Types . . . . . . . . . . . . . . 16
2.13.3. Controlling the Use of Complex Types . . . . . . . . 17
3. Typed Instance Identifier . . . . . . . . . . . . . . . . . . 17
3.1. Definition . . . . . . . . . . . . . . . . . . . . . . . . 17
3.2. instance-type extension statement . . . . . . . . . . . . 17
3.3. Typed Instance Identifier Example . . . . . . . . . . . . 18
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19
5. Security Considerations . . . . . . . . . . . . . . . . . . . 19
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 19
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 19
7.1. Normative References . . . . . . . . . . . . . . . . . . . 19
7.2. Informative References . . . . . . . . . . . . . . . . . . 20
Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 20
A.1. 00-01 . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Appendix B. Example Model . . . . . . . . . . . . . . . . . . . . 20
B.1. Modeling Improvements for the IPFIX/PSAMP Model with
Complex types and Typed instance identifiers . . . . . . . 20
B.2. IPFIX/PSAMP Model with Complex Types and Typed
Instance Identifiers . . . . . . . . . . . . . . . . . . . 22
Linowski & Ersue Expires April 29, 2010 [Page 2]
Internet-Draft YANG Language Abstractions October 2009
1. Introduction
YANG - the NETCONF Data Modeling Language - supports modeling of a
tree of data elements that represent the configuration and runtime
status of a particular network element managed via NETCONF. This
document suggests to extend YANG with supplementary modeling features
and language abstractions with the aim to improve the model
extensibility and reuse.
1.1. Key Words
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].
1.2. Motivation
o Many systems today have a management information base that in
effect is organized as a tree build of recursively nested
container nodes. For example, the physical resources in the
ENTITY-MIB conceptually form a containment tree. The index
entPhysicalContainedIn points to the containing entity in a flat
list. The ability to represent nested, recursive data structures
of arbitrary depth would enable the representation of the primary
containment hierarchy of physical entities as a real tree in the
agent MIB and in the NETCONF payload.
o An agent scanning the network in order to update the state of an
inventory management system might be only interested in data
structures that represent a specific type of network elements.
Such an agent would then look for entities that are of this
specific type. It becomes beneficial that reusable named types
indicate the type of the concept the particular data structure
represents.
o A system that is managing network elements is concerned e.g. with
managed objects of type "plug-in modules" that have a name, a
version and an activation state. In this context, it is useful to
define the "plug-in module" as a concept that is supposed to be
further detailed and extended by additional concrete module
artifacts. In order to realize such a system, it is worth to
model abstract entities to be able to define concrete refinements
of that abstract entity.
o As particular network elements have specific type of components
that need to be managed (OS images, plug-in modules, equipment,
etc.), it should be possible to define concrete types, which
Linowski & Ersue Expires April 29, 2010 [Page 3]
Internet-Draft YANG Language Abstractions October 2009
describe the managed object precisely. By using type-safe
extensions of basic concepts a system in the manager role can
safely and explicitely determine that e.g. the "equipment" is
actually of type "network card".
o Currently different SDOs are working on the harmonization of their
management information models. Often a model mapping or
transformation between systems becomes necessary. The
harmonization of the models is done e.g. by mapping of the two
models on object level or integrating an object hierarchy into an
existing information model. Extending YANG with modeling language
abstractions can simplify the adoption of IETF resource models by
other SDOs and facilitate the alignment with other SDO's resource
models (e.g. TM Forum SID).
The challenges listed above mainly address issues, where it is
beneficial to use language abstractions for modeling. This memo
proposes additional modeling features for the YANG language in the
area of resource typing, referring to typed entities as well as
typed, structured model extensions and discusses how these new
features can improve the modeling capabilities of YANG.
1.3. Modeling Improvements with Language Abstractions
Complex Types and Typed Instance Identifiers provide various
technical improvements on modelling level:
o In case the model of a system that should be managed with NETCONF
is using inheritance (e.g. TM Forum SID), complex types enable an
almost one-to-one mapping between the classes in the original
model and the YANG module.
o Typed instance identifiers allow representing associations between
the concepts in a type-safe way. This avoids to refer to a
particular location in the MIB, which is not mandated by the
domain model.
o Complex types allow to define fully complete, self contained type
definitions. It is not necessary to explicitly add a key
statement to containers that otherwise only use a grouping, which
provides the data nodes.
o Complex types simplify concept refinement by extending a base
complex type and make it superfluous to represent concept
refinements with workarounds such as huge choice-statements with
complex branches.
Linowski & Ersue Expires April 29, 2010 [Page 4]
Internet-Draft YANG Language Abstractions October 2009
o Abstract complex types ensure correct usage of abstract concepts
by enforcing the refinement of common set of properties before
instantiation.
o Complex types allow to define recursive structures. This enables
to represent complex structures of arbitrary depth by nesting
instances of basic complex types that may contain themselves.
o Complex types avoid introducing meta-data types (e.g. type code
enumerations) and meta-data leafs (e.g. leafs containing a type
code) to indicate, which concrete type of object is actually
represented by a generic container in the MIB. This also avoids
to explicitly rule out illegal use of sub-type specific properties
in generic containers.
o Complex type instances include the type information in the NETCONF
payload, which allows to determine the actual type of an instance
during the NETCONF payload parsing and avoids the use of
additional leafs in the model providing the type information as
content.
o Complex types may be declared explicitly as optional features,
which is not possible when the actual type of an entity
represented by a generic container is indicated with a type code
enumeration.
[Appendix B: Example Model] lists technical improvements for modeling
with Complex Types and Typed Instance Identifiers and exemplifies the
usage of the proposed YANG extensions based on the IPFIX/PSAMP
configuration model in [IPFIXCONF].
1.4. Design Approach
The proposed additional features for YANG in this memo are designed
to reuse existing YANG statements whenever possible. Additional
semantics is then expressed by an extension that is supposed to be
used as a substatement of an existing statement.
The proposed features don't change the semantics of models that are
valid with respect to the YANG specification [YANG].
2. Complex Types
2.1. Definition
YANG type concept is currently restricted to define simple types,
e.g. restrictions of primitive types, enumerations or union of simple
types.
Linowski & Ersue Expires April 29, 2010 [Page 5]
Internet-Draft YANG Language Abstractions October 2009
Complex types are types with a rich internal structure, which may be
composed of lists, leafs, containers, choices, etc.. A new complex
type may extend an existing complex type. This allows to provide
type-safe extensions to existing YANG models as instances of the new
type, to be used wherever an instance of the base type may appear.
Complex types have the following characteristics:
o Introduction of new types, as a named, formal description of a
concrete manageable resource as well as abstract concepts.
o Types can be extended, i.e. new types can be defined by
specializing existing types adding new features. Instances of
such an extended type can be used wherever instances of the base
type can appear.
o The type information is made part of the NETCONF payload in case a
derived type substitutes a base type. This enables easy and
efficient consumption of payload elements representing complex
type instances.
2.2. complex-type extension statement
The extension statement "complex-type" is introduced that accepts an
arbitrary number of node tree defining statements among other common
YANG statements ("YANG Statements", [YANG] section 7.).
Linowski & Ersue Expires April 29, 2010 [Page 6]
Internet-Draft YANG Language Abstractions October 2009
+------------------+-------------+
| substatement | cardinality |
+------------------+-------------+
| abstract | 0..1 |
| anyxml | 0..n |
| choice | 0..n |
| config | 0..1 |
| container | 0..n |
| description | 0..1 |
| instance | 0..n |
| instance-list | 0..n |
| extends | 0..1 |
| grouping | 0..n |
| if-feature | 0..n |
| key | 0..1 |
| leaf | 0..n |
| leaf-list | 0..n |
| list | 0..n |
| must | 0..n |
| optional-feature | 0..n |
| ordered-by | 0..n |
| reference | 0..1 |
| refine | 0..n |
| status | 0..1 |
| typedef | 0..n |
| uses | 0..n |
+------------------+-------------+
Table 1: complex-type's substatements
All complex type names defined within a parent node or at the top-
level of the module or its submodules share the same type identifier
namespace. This namespace is scoped to the parent node or module.
A complex type MAY have an instance key. An instance key is either
defined with the "key" statement as part of the complex type or is
inherited from the base complex type.
Complex-type definitions do not create nodes in the management
information tree.
2.3. instance extension statement
The "instance" extension statement is used to instantiate a complex
type by creating a subtree in the management information node tree.
The instance statement takes one argument that is the identifier of
the complex type instance. It is followed by a block of
substatements.
Linowski & Ersue Expires April 29, 2010 [Page 7]
Internet-Draft YANG Language Abstractions October 2009
The type of the instance is specified with the mandatory "type" sub-
statement. The type of an instance MUST be a complex type. Common
YANG statements may be used as substatements of the "instance"
statement. An instance is by default optional. To make an instance
mandatory, "mandatory true" has to be applied as substatement.
+--------------+-------------+
| substatement | cardinality |
+--------------+-------------+
| description | 0..1 |
| config | 0..1 |
| if-feature | 0..1 |
| mandatory | 0..1 |
| must | 0..n |
| reference | 0..1 |
| status | 0..1 |
| type | 1 |
| when | 0..1 |
+--------------+-------------+
Table 2: instance's substatements
The "instance" and "instance-list" extension statements (see chapter
below) are similar to the existing "leaf" and "leaf-list" statements,
with the exception that the content is composed of subordinate
elements according to the instantiated complex type.
2.4. instance-list extension statement
The "instance-list" extension statement is used to instantiate a
complex type by defining a sequence of subtrees in the management
information node tree. Also the "instance-list" statement takes one
argument that is the identifier of the complex type instances. It is
followed by a block of substatements.
The type of the instance is specified with the mandatory "type" sub-
statement. In addition it can be stated how often an instance may
appear in the management information tree by using the min-elements
and max-elements substatements. Common YANG statements may be used
as substatements of the "element" statement.
Linowski & Ersue Expires April 29, 2010 [Page 8]
Internet-Draft YANG Language Abstractions October 2009
+---------------+-------------+
| substatementc | cardinality |
+---------------+-------------+
| description | 0..1 |
| config | 0..1 |
| if-feature | 0..1 |
| max-elements | 0..1 |
| min-elements | 0..1 |
| must | 0..n |
| ordered-by | 0..1 |
| reference | 0..1 |
| status | 0..1 |
| type | 1 |
| when | 0..1 |
+---------------+-------------+
Table 3: instance-list's substatements
In case the instance list represents configuration, the used complex
type of an element MUST have an element key.
In case the configuration data status is specified in the complex
type, it MUST NOT differ from the effective configuration status of
the instance or instance-list. Instances as well as instance lists
may appear as arguments of the "deviate" statement.
2.5. extends extension statement
A complex type MAY extend exactly one existing base complex type by
using the "extends" extension statement. The keyword "extends"
statement MAY occur as substatement of the "complex-type" extension
statement. The base complex type is referred to in the single
argument via its scoped name. In case a complex type represents
configuration data (the default), it MUST have a key, otherwise it
MAY have a key. A key is either defined with the key statement as
part of the complex type or is inherited from the base complex type.
+--------------+-------------+
| substatement | cardinality |
+--------------+-------------+
| description | 0..1 |
| reference | 0..1 |
| status | 0..1 |
+--------------+-------------+
Table 4: extends' substatements
Linowski & Ersue Expires April 29, 2010 [Page 9]
Internet-Draft YANG Language Abstractions October 2009
2.6. abstract extension statement
Complex types may be declared to be abstract by using the "abstract"
extension statement. An abstract complex type cannot be
instantiated, meaning it cannot appear as most specific type of an
instance in NETCONF payload. In case an abstract type extends a base
type, the base complex type MUST also be abstract. By default,
complex types are not abstract.
The complex type serve only as base types for derived concrete
complex types and cannot be used as type for an instance in NETCONF
payload.
The "abstract" extension statement takes a single string argument
which is either "true" or "false". In case a "complex-type"
statement does not contain an "abstract" statement as substatement,
the default is "false". The "abstract" statement does not support
any substatements.
2.7. XML Encoding Rules
An "instance" node is encoded as an XML element where an "instance-
list" node is encoded as a series of XML elements. The XML element
name is the "instance" respectively "instance-list" identifier, and
its XML namespace is the module's XML namespace. The instance key
nodes are encoded as subelements to the instance identifier XML
element, in the same order as they are defined within the "key"
statement of the instances complex type. The rest of the instance
child nodes are encoded as subelements to the instance XML element,
after the keys, in the same order as they are defined within the
complex type statement. Child nodes of an extending complex type
precede the child nodes of the extended complex type. As such, the
XML encoding of lists is very similar to the encoding of containers
and lists. The only exception is the encoding of the type of actual
complex type instance, described in the following section.
2.8. Type Encoding Rules
In order to encode the type of an instance in NETCONF payload, XML
elements named "type" belonging to the XML namespace
"urn:ietf:params:xml:ns:yang:complex-type-instance" are added to the
serialized form of instance and instance-list instances. The
suggested namespace prefix is "ct". This "ct:type" XML elements are
inserted before the serialized form of all (non-key) members that
have been declared in the according complex type definition. The
"ct:type" element is inserted for each type in the extension chain
from the type specified in the "instance" or "instance-list"
statement to the actual type of the instance in reverse order (most
Linowski & Ersue Expires April 29, 2010 [Page 10]
Internet-Draft YANG Language Abstractions October 2009
specific first). Each type name includes the namespace.
The type of a complex type instance MUST be encoded in the reply to
NETCONF <get> and <get-config> operations, and also in the payload of
NETCONF <edit-config> operation if the operation is "create" or
"replace". The type MUST also be specified in case <copy-config> is
used to export a configuration to a resource addressed with an URI.
Also the type has to be specified in user defined RPC's.
The type MAY be specified in case the operation is "merge" (either
because this is explicitly specified or no operation attribute is
provided).
In case the node already exists in the target configuration and the
type is specified but differs from the data in the target, an <rpc-
error> element is returned with an <error-tag> value of "wrong-type".
In case no such element is present in the target configuration but
the type attribute is missing in the configuration data, an <rpc-
error> element is returned with an <error-tag> value of "missing-
type".
The type MUST NOT be specified in case the operation is "delete".
2.9. Extension and Feature Definition Module
The module below contains all YANG extension definitions for complex
types and typed instance identifiers. In addition a "complex-type"
feature is defined, which may be used to provide conditional or
alternative modelling for depending on the support status of complex
types in a NETCONF agent. An agent that supports the complex types
modelling features and the XML encoding for complex types as defined
in this document MUST advertise this as a feature. This is done by
including the feature name "complex-types" into the feature parameter
list as part of the NETCONF <hello> message as described in section
5.6.4 in [YANG].
<CODE BEGINS>
module complex-types {
namespace "urn:ietf:params:xml:ns:yang:complex-types";
prefix "ct";
organization
"Nokia Siemens Networks";
contact
Linowski & Ersue Expires April 29, 2010 [Page 11]
Internet-Draft YANG Language Abstractions October 2009
"Bernd Linowski";
description
"This module defines extensions to model complex types
and typed instance identifiers.";
revision 2009-09-29 {
description "Initial revision.";
}
extension complex-type {
description "Defines a complex-type.";
reference "chapter 2.2., complex-type extension statement";
argument type-identifier {
yin-element true;
}
}
extension extends {
description "Defines the base type of a complex-type.";
reference "chapter 2.5., extends extension statement";
argument base-type-identifier {
yin-element true;
}
}
extension abstract {
description "Makes the complex-type abstract.";
reference "chapter 2.6., complex-type extension statement";
argument status;
}
extension instance {
description "Declares an instance of the given
complex type.";
reference "chapter 2.3., instance extension statement";
argument ct-instance-identifier {
yin-element true;
}
}
extension instance-list {
description "Declares a list of instances of the given
complex type";
Linowski & Ersue Expires April 29, 2010 [Page 12]
Internet-Draft YANG Language Abstractions October 2009
reference "chapter 2.4., instance-list extension statement";
argument ct-instance-identifier {
yin-element true;
}
}
extension instance-type {
description "Tells to which type instance the instance
identifier refers to.";
reference "chapter 3.2., instance-type extension statement";
argument target-type-identifier {
yin-element true;
}
}
feature complex-types {
description "This feature indicates that the agent supports
complex types and instance identifiers.";
}
}
<CODE ENDS>
2.10. Model Example
The example below shows how complex types can be used to represent
physical equipment in a vendor independent, abstract way.
module hw {
namespace "urn:org:example:xml:ct:hw";
prefix "hw";
import complex-types {prefix "ct"; }
ct:complex-type ManagedHardware {
ct:abstract true;
key object-id;
leaf objectId { type string { length "1..32"; } }
leaf serialNumber { type string; config false; }
leaf commonName { type string; }
}
ct:complex-type Equipment {
Linowski & Ersue Expires April 29, 2010 [Page 13]
Internet-Draft YANG Language Abstractions October 2009
ct:extends ManagedHardware;
ct:abstract true;
leaf installed {type boolean; config false; }
leaf version { type string; }
leaf redundancy {type uint16; }
}
ct:complex-type EquipmentHolder {
ct:extends ManagedHardware;
ct:abstract true;
ct:instance-list equipment { type Equipment; }
ct:instance-list holder { type EquipmentHolder; }
}
// Holder types
ct:complex-type Slot {
ct:extends EquipmentHolder;
leaf slotNumber { type uint16; config false; }
}
ct:complex-type Chassis {
ct:extends EquipmentHolder;
leaf numberOfSlots { type uint16; config false; }
}
// Equipment types
ct:complex-type Card {
ct:extends Equipment;
leaf usedSlots { type uint16; mandatory true; }
}
// Root Element
ct:instance hardware { type ManagedHardware; }
} // hw module
2.11. NETCONF Payload Example
Following example shows the payload of a reply to a NETCONF <get>
command. The actual type of managed hardware instances is indicated
with the "ct:type" elements as required by the type encoding rules.
The containment hierarchy in the NETCONF XML payload reflects the
Linowski & Ersue Expires April 29, 2010 [Page 14]
Internet-Draft YANG Language Abstractions October 2009
containment hierarchy of hardware instances. This makes filtering
based on the containment hierarchy possible without having to deal
with values of key-ref leafs that represent the tree structure in a
flattened hierarchy.
<hardware>
<objectId>R31r1</objectId>
<ct:type>hw:Chassis</ct:type>
<numberOfSlots>6</numberOfSlots>
<ct:type>hw:EquipmentHolder</ct:type>
<holder>
<objectId>R31s2</objectId>
<ct:type>hw:Slot</ct:type>
<slotNumber>1</slotNumber>
<ct:type>hw:EquipmentHolder</ct:type>
<equipment>
<objectId>ATM-45252</objectId>
<ct:type>hw:Card</ct:type>
<usedSlots>1</usedSlots>
<ct:type>hw:Equipment</ct:type>
<installed>true</installed>
<version>A2</version>
<redundancy>1</redundancy>
<serialNumber>A-778911-b</serialNumber>
<commonName>ATM-ADM 2</commonName>
</equipment>
<serialNumber>T-K4733890x45</serialNumber>
<commonName>CU-Slot</commonName>
</holder>
<ct:type>hw:ManagedHardware</ct:type>
<serialNumber>R-US-3276279a</serialNumber>
<commonName>Rack R322-1</commonName>
// ...
</hardware>
2.12. Update Rules for Modules Using Complex Types
In addition to the module update rules specified in chapter 10 of
[YANG], modules that define complex-types, instances of complex types
and typed instance identifiers must obey following rules:
o New complex types MAY be added.
o A new complex type MAY extend an existing complex type.
Linowski & Ersue Expires April 29, 2010 [Page 15]
Internet-Draft YANG Language Abstractions October 2009
o New data definition statements MAY be added to a complex type only
if:
* they are not mandatory
* if they are not conditionally dependent on a new feature (i.e.,
have a "if-feature" statement which refers to a new feature).
o The type referred to by the instance-type statement may be changed
to a type that derives from the original type only if the original
type does not represent configuration data.
2.13. Using Complex Types
All data nodes defined inside a complex type reside in the namespace,
in which the complex type is defined.
2.13.1. Overriding Complex Types Data Nodes
It is not possible to override a data node inherited from a base
type. I.e. in case complex types "base" and "derived" are defined in
the same module and the complex type "base" has a leaf node named
"foo", which is extended by the complex type "derived", which defines
a node "foo", this is an error. In case they are derived in
different modules, there are two distinct "foo" nodes residing in
different namespaces.
On the other hand a complex type that extends a basic complex type
may use the "refine" statement in order to improve an inherited data
node. The target node identifier must be qualified by the module
prefix to indicate clearly, which inherited node is refined. All
kind of refinements as defined in section 7.12.2 in [YANG] are
allowed (changing the default value, changing min- or max-element
values etc.).
2.13.2. Augmenting Complex Types
If the target node of an "augment" statement is a complex type, only
the "container", "leaf", "list", "leaf-list", "choice" and "if-
feature" statements can be used within the "augment" statement. If
the target node is in another module, then nodes added by the
augmentation MUST NOT be mandatory nodes. The augment statement MUST
NOT add multiple nodes with the same name from the same module to the
target node.
Although augmenting a complex type definition is possible, it is NOT
recommended to do so, as mixing complex types with augmentations
might have side effects.
Linowski & Ersue Expires April 29, 2010 [Page 16]
Internet-Draft YANG Language Abstractions October 2009
2.13.3. Controlling the Use of Complex Types
A module might not want to support all complex types derived from a
base class defined in an other module. This issue can be addressed
with YANG features as follows:
o Features are defined that are used inside complex type definitions
(by using "if-feature" as substatement) to make them optional. In
this case such complex types may only be instantiated if the
feature is supported (advertized as capability in the NETCONF
<hello> message)
o A complex type can be disabled by marking it as not supported in
the related "deviation" statement (e.g. "deviate not-supported;").
3. Typed Instance Identifier
3.1. Definition
Typed instance identifier relationships are an addition to the
relationship types already defined in YANG, where the leaf-ref
relationship is location dependent, and the instance-identifier is
not type-safe.
Typed instance identifiers represent references to instances of a
complex type without being restricted to a particular location in the
containment tree. This is done by using the extension statement
"instance-type" as a sub-statement of the existing "type instance
identifier" statement. .
Typed instance identifiers allow referring to instances of complex
types that may be located anywhere in the management information
tree. The "type" statement plays the role of a restriction that must
be fulfilled by the node that is referred to with the instance
identifier. The restriction is that it must be of a particular
complex type, either the type itself or any type that extends this
complex type.
3.2. instance-type extension statement
The "instance-type" extension statement defines, which complex type
must be instantiated by the instance the identifier points to, or any
complex type that extends the referred complex type. The instance
complex type is identified by the single argument via its scoped
name. The referred complex type MUST have a key. This extension
statement MUST be used as a sub-statement of the instance-identifier
statement. The "instance-type" extension statement does not support
any substatements.
Linowski & Ersue Expires April 29, 2010 [Page 17]
Internet-Draft YANG Language Abstractions October 2009
3.3. Typed Instance Identifier Example
In the example below, a physical link connects an arbitrary number of
physical ports. Here typed instance identifiers are used to denote
which "PhysicalPort" instances (anywhere in the data tree) are
connected by a "PhysicalLink".
// Extended version of type Card
ct:complex-type Card {
ct:extends Equipment;
leaf usedSlot { type uint16; mandatory true; }
ct:instance-list port {
type PhysicalPort;
}
}
ct:complex-type PhysicalPort {
ct:extends ManagedHardware;
leaf portNumber { type int32; mandatory true; }
}
ct:complex-type PhysicalLink {
ct:extends ManagedHardware;
leaf media { type string; }
leaf-list connectedPort {
type instance-identifier {
ct:instance-type PhysicalPort;
}
min-elements 2;
}
}
The XML encoding of an element named "link" of type "PhysicalLink"
appears as below:
<link>
<objectId>FTCL-771</objectId>
<media>Fiber</media>
<connectedPort>/hw:hardware[objectId='R-11']
/hw:equipment[objectId='AT22']/hw:port[objectId='P12']
</connectedPort>
<connectedPort>/hw:hardware[objectId='R-42]
/hw:equipment[objectId='AT30']/hw:port[objectId='P3']
</connectedPort>
<serialNumeber>F-7786828</serialNumber>
<commonName>FibCon 7</commonName>
Linowski & Ersue Expires April 29, 2010 [Page 18]
Internet-Draft YANG Language Abstractions October 2009
</link>
4. IANA Considerations
This document registers two URIs in the IETF XML registry [RFC3688].
Following the format in RFC 3688, the following registrations are
requested:
URI: urn:ietf:params:xml:ns:yang:complex-types
URI: urn:ietf:params:xml:ns:yang:complex-type-instance
Registrant Contact: The NETCONF WG of the IETF.
XML: N/A, the requested URIs are XML namespaces.
In the registry "IETF YANG Modules", the following YANG module shall
be recorded (after IETF review as defined in [RFC5226]):
YANG Module XML namespace Reference
------------- ----------------------------------------- ---------
complex-types urn:ietf:params:xml:ns:yang:complex-types RFC XXXX
RFC Ed.: Please replace XXXX with actual RFC number and remove this
note.
5. Security Considerations
Complex-types and Typed Instance Identifiers themselves do not have
any security impact on the Internet.
The security considerations described throughout [YANG] apply here as
well.
6. Acknowledgements
The authors would like to thank to Martin Bjorklund, Balazs Lengyel,
Gerhard Muenz and Martin Storch for their valuable comments and
hints.
7. References
7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", March 1997.
[RFC3688] Mealling, M., "The IETF XML Registry", January 2004.
Linowski & Ersue Expires April 29, 2010 [Page 19]
Internet-Draft YANG Language Abstractions October 2009
[RFC5226] Narten, T., "Guidelines for Writing an IANA
Considerations Section in RFCs", May 2008.
7.2. Informative References
[IPFIXCONF] Muenz, G., "Configuration Data Model for IPFIX and
PSAMP", draft-ietf-ipfix-configuration-model-04 (work in
progress), July 2009.
[YANG] Bjorklund, M., "YANG - A data modeling language for
NETCONF", draft-ietf-netmod-yang-08 (work in progress),
July 2009.
Appendix A. Change Log
A.1. 00-01
o Transformed proposed new YANG statements to YANG extension
statements (complex-type, element, extends, abstract).
o Renamed statement "element" to the extension statement "instance"
in order to avoid confusion with XML payload elements.
o Introduced extension statement "instance-type" as allowing the use
of the existing "type" statement as substatement in the existing
"instance-identifier" statement cannot be done with extensions.
o Added the complex type extension statement module.
o Updated examples to reflect the changes mentioned above.
o Added update rules for complex types.
o Updated IANA Considerations section.
o Added this change log.
Appendix B. Example Model
B.1. Modeling Improvements for the IPFIX/PSAMP Model with Complex types
and Typed instance identifiers
The module below is a variation of the IPFIX/PSAMP configuration
model, which uses complex types and typed instance identifiers to
model the concept outlined in [IPFIXCONF].
When looking at the YANG module with complex types and typed instance
identifiers, various technical improvements on modeling level become
Linowski & Ersue Expires April 29, 2010 [Page 20]
Internet-Draft YANG Language Abstractions October 2009
apparent.
o There is almost a one-to-one mapping between the domain concepts
introduced in IPFIX and the complex types in the YANG module
o All associations between the concepts (which are not containment)
are represented with typed identifiers. That avoids having to
refer to a particular location in the tree which is not mandated
by the original model.
o It is superfluous to represent concept refinement (class
inheritance in the original model) with containment in form of
quite big choice-statements with complex branches. Instead,
concept refinement is realized by complex types extending a base
complex type.
o It is not required to make an artificial distinction between IP-
and file destinations (see list "exportingProcess" in
[IPFIXCONF]). Instead an abstract base class is used to capture
the commonalities of all destinations.
o It is unnecessary to introduce metadata types and leafs (e.g.
"typedef ipfixTransportProtocol" and "leaf transportProtocol" in
"grouping destinationParamters") that just serve the purpose of
indicating which concrete sub-type type of a generic type (modeled
as grouping which contains the union of all features of all
subtypes) is actually represented in the MIB.
o Ruling out illegal use of sub-type specific properties (e.g. "leaf
templateRefreshTimeout") by using "must" statements that refer to
a sub-type discriminator is not necessary (e.g. must
"../transportProtocol=udp").
o It is not needed to define properties like the configuration
status wherever a so called "parameter grouping" is used. Instead
those definitions can be put inside the complex-type definition
itself (e.g. "config false" statements).
o Declaring the key of a type repeatedly at every place, where a
grouping is used becomes superfluous (see use of "grouping
optionTemplate").
o Complex types may be declared as optional features. If the type
is indicated with an enumeration which has a literal per type
(e.g. "typedef ipfixTransportProtocol"), this is not possible,
because "if-feature" is not allowed as a substatement of "enum".
Linowski & Ersue Expires April 29, 2010 [Page 21]
Internet-Draft YANG Language Abstractions October 2009
B.2. IPFIX/PSAMP Model with Complex Types and Typed Instance
Identifiers
<CODE BEGINS>
module ipfix-psamp {
namespace "urn:ietf:params:xml:ns:ipfix-psamp-config";
prefix ipfix;
import yang-types { prefix yang; }
import inet-types { prefix inet; }
import complex-types {prefix "ct"y; }
description "Example IPFIX/PSAMP Configuration Data Model
with complex types and typed instance identifiers";
revision 2009-03-02 {
description "Version of draft-ietf-ipfix-configuration-model-02
modeled with complex types and typed instance
identifiers.";
}
feature exporter {
description "If supported, the device can be used as an Exporter.
Exporting Processes can be configured.";
}
feature collector {
description "If supported, the device can be used as a Collector.
Collecting Processes can be configured.";
}
feature meter {
description "If supported, Observation Points, Selection
Processes, and Caches can be configured.";
}
feature psampSampCountBased {
description "If supported, the device supports count-based Sampling.
The Selector method sampCountBased can be configured.";
}
feature psampSampTimeBased {
description "If supported, the device supports time-based Sampling.
The Selector method sampTimeBased can be configured.";
Linowski & Ersue Expires April 29, 2010 [Page 22]
Internet-Draft YANG Language Abstractions October 2009
}
feature psampSampRandOutOfN {
description "If supported, the device supports random n-out-of-N
Sampling. The Selector method sampRandOutOfN can be configured.";
}
feature psampSampUniProb {
description "If supported, the device supports uniform probabilistic
Sampling. The Selector method sampUniProb can be configured.";
}
feature psampSampNonUniProb {
description "If supported, the device supports non-uniform
probabilistic Sampling. The Selector method sampNonUniProb can be
configured.";
}
feature psampSampFlowState {
description "If supported, the device supports flow state dependent
Sampling. The Selector method sampFlowState can be configured.";
}
feature psampFilterMatch {
description "If supported, the device supports property match
Filtering. The Selector method filterMatch can be configured.";
}
feature psampFilterHash {
description "If supported, the device supports hash-based Filtering.
The Selector method filterHash can be configured.";
}
feature psampFilterRState {
description "If supported, the device supports router state
Filtering. The Selector method filterRState can be configured.";
}
feature udpTransport {
description "If supported, the device supports UDP as transport
protocol.";
}
feature tcpTransport {
description "If supported, the device supports TCP as transport
protocol.";
}
Linowski & Ersue Expires April 29, 2010 [Page 23]
Internet-Draft YANG Language Abstractions October 2009
feature fileReader {
description "If supported, the device supports the configuration
of Collecting Processes as File Readers.";
}
feature fileWriter {
description "If supported, the device supports the configuration
of Exporting Processes as File Writers.";
}
typedef direction {
type enumeration {
enum ingress;
enum egress;
enum both;
}
description "Direction of packets going through an interface or
linecard.";
}
typedef optionType {
type enumeration {
enum meteringStatistics {
description "Metering Process Statistics.";
reference "RFC 5101, section 4.1.";
}
enum meteringReliability {
description "Metering Process Reliability Statistics.";
reference "RFC 5101, section 4.2.";
}
enum exportingReliability {
description "Exporting Process Reliability
Statistics.";
reference "RFC 5101, section 4.3.";
}
enum flowKeys {
description "Flow Keys.";
reference "RFC 5101, section 4.4.";
}
enum selectionSequence {
description "Selection Sequence and Selector Reports.";
reference "draft-ietf-psamp-protocol-09, section 6.5.1
and 6.5.2.";
}
enum selectionStatistics {
description "Selection Sequence Statistics Report.";
reference "draft-ietf-psamp-protocol-09, section
Linowski & Ersue Expires April 29, 2010 [Page 24]
Internet-Draft YANG Language Abstractions October 2009
6.5.3.";
}
enum accuracy {
description "Accuracy Report.";
reference "draft-ietf-psamp-protocol-09, section
6.5.4.";
}
enum reducingRedundancy {
description "Application of ipfix-reducing-redundancy.";
reference "draft-ietf-ipfix-reducing-redundancy-04";
}
}
description "Options Templates specified by IPFIX and PSAMP.";
}
typedef templateFieldFlags {
type bits {
bit scope {
position 0;
}
bit flowKey {
position 1;
}
}
description "Attributes of a field in a Template.";
reference "draft-ietf-ipfix-mib-05, section 7
(ipfixTemplateDefinitionFlags)";
}
typedef transportSessionStatus {
type enumeration {
enum inactive;
enum active;
enum unknown;
}
description "Status of a Transport Session.";
reference "draft-ietf-ipfix-mib-05, section 7
(ipfixTransportSessionStatus).";
}
typedef filterRStateFunction {
type enumeration {
enum other;
enum ingressIf;
enum egressIf;
enum aclViolation;
enum rpfFailure;
enum noResources;
Linowski & Ersue Expires April 29, 2010 [Page 25]
Internet-Draft YANG Language Abstractions October 2009
enum noRoute;
enum originAS;
enum destAS;
}
description "Filter function applied to router state.";
reference "draft-ietf-psamp-mib-06, section 5.2.3.";
}
typedef exportMemberType {
type enumeration {
enum primary;
enum secondary;
enum duplicate;
enum loadBalancing;
enum unused;
}
description "This type defines different usages of an export
destination among all destinations of an Exporting Process.
It corresponds to ipfixExportMemberType in IPFIX-MIB.";
reference "draft-ietf-ipfix-mib-05.";
}
grouping informationElement {
description "Parameters of an Information Element.";
choice nameOrId {
mandatory true;
description "Name or ID of the Information Element.";
reference "RFC5102";
leaf ieName { type string; }
leaf ieId { type uint16; }
}
leaf ieLength {
type uint16;
description "Length can be omitted if a default length exists
for the specified Information Element. A value of 65535
specifies a variable-length Information Element.";
reference "RFC5102";
}
leaf ieEnterpriseNumber {
type uint32;
description "If present, this is an enterprise-specific
Information Element.";
reference "RFC5101, RFC5102";
}
}
grouping cacheLayoutParameters {
description "Fields of a Cache Layout.";
Linowski & Ersue Expires April 29, 2010 [Page 26]
Internet-Draft YANG Language Abstractions October 2009
list cacheField {
key name;
min-elements 1;
leaf name { type string; }
uses informationElement;
leaf isFlowKey {
type empty;
description "If present, this is a flow key.";
}
}
}
ct:complex-type Receiver {
description "Receiver of a Collecting Process";
ct:abstract true;
key name;
leaf name { type string; }
}
ct:complex-type IpReceiver {
ct:extends Receiver;
ct:abstract true;
leaf destinationIpAddress {
type inet:ip-address;
mandatory true;
}
leaf destinationPort {
type inet:port-number;
default 4739;
}
leaf sendBufferSize {
type uint32;
units bytes;
description "Size of the socket send buffer.
If not configured, this parameter is set by the monitoring
device";
}
leaf rateLimit {
type uint32;
units "bytes per second";
description "Maximum number of bytes per second the Exporting
Process may export to the given destination. The number of
bytes is calculated from the lengths of the IPFIX Messages
exported. If not configured, no rate limiting is
performed.";
reference "draft-ietf-psamp-protocol-09, section 6.3.";
}
Linowski & Ersue Expires April 29, 2010 [Page 27]
Internet-Draft YANG Language Abstractions October 2009
}
ct:complex-type SctpReceiver {
ct:extends IpReceiver;
description "SCTP receiver";
reference "RFC 4960.";
leaf-list localIpAddress {
type inet:ip-address;
description "List of eligible local IP addresses to be
used by the SCTP endpoint. If not configured, all locally
assigned IP addresses are used by the local endpoint.";
reference "RFC 3758, RFC 4960.";
}
leaf timedReliability {
type yang:timeticks;
default 0;
description "PR-SCTP lifetime for IPFIX Messages
containing Data Sets only. Zero means reliable transport.";
reference "RFC 3758, RFC 4960.";
}
leaf numberOfStreams {
type uint16;
description "Number of outbound streams requested for the
SCTP association.
If not configured, this parameter is set by the monitoring
device.";
reference "RFC 3758, RFC 4960.";
}
leaf orderedDelivery {
type boolean;
default true;
description "Ordered delivery of IPFIX Messages
containing Data Sets.";
reference "RFC 3758, RFC 4960.";
}
}
ct:complex-type UdpReceiver {
if-feature udpTransport;
ct:extends IpReceiver;
description "UDP receiver.";
leaf sourceIpAddress {
type inet:ip-address;
description "Sets source IP address if UDP is transport
protocol. If not configured, the IP address assigned to the
outgoing interface is used.";
}
leaf templateRefreshTimeout {
Linowski & Ersue Expires April 29, 2010 [Page 28]
Internet-Draft YANG Language Abstractions October 2009
type uint32;
units seconds;
default 600;
description "Sets time after which Templates are resent if
UDP is transport protocol.";
reference "RFC5101.";
}
leaf optionTemplateRefreshTimeout {
type uint32;
units seconds;
default 600;
description "Sets time after which Options Templates are
resent if UDP is transport protocol.";
reference "RFC5101.";
}
leaf templateRefreshPacket {
type uint32;
units "IPFIX Messages";
description "Sets number of IPFIX Messages after which
Templates are resent if UDP is transport protocol.
If omitted, Templates are only resent after timeout.";
reference "RFC5101.";
}
leaf optionTemplateRefreshPacket {
type uint32;
units "IPFIX Messages";
description "Sets number of IPFIX Messages after which
Options Templates are resent if UDP is transport protocol.
If omitted, Templates are only resent after timeout.";
reference "RFC5101.";
}
}
ct:complex-type TcpReceiver {
if-feature tcpTransport;
ct:extends IpReceiver;
description "TCP receiver.";
}
ct:complex-type FileReader {
if-feature fileReader;
ct:extends Receiver;
description "File Reader parameters.";
leaf uri {
mandatory true;
type yang:uri;
}
}
Linowski & Ersue Expires April 29, 2010 [Page 29]
Internet-Draft YANG Language Abstractions October 2009
ct:complex-type CollectingProcess {
description "A Collecting Process.";
key name;
leaf name {
description "Arbitrary but unique name of the Collecting
Process.";
type string;
}
ct:instance-list receiver {
description "Receivers of the collection process.";
type Receiver;
min-elements 1;
}
leaf-list exportingProcess {
description "Export of received records without any
modifications. Records are processed by all Exporting
Processes in the list.";
type instance-identifier { ct:instance-type ExportingProcess; }
}
ct:instance-list Template {
type Template;
}
ct:instance-list transportSession {
type TransportSession;
}
}
ct:complex-type ObservationPoint {
description "Base Observation Point.";
ct:abstract true;
key name;
leaf name {
description "Arbitrary but unique name of the Observation
Point.";
type string;
}
leaf observationPointId {
description "If omitted, the Observation Point ID is assigned
by the monitoring device.";
type uint32;
}
leaf observationDomainId {
description "The Observation Domain ID associates the
Observation Point to an Observation Domain. Observation
Points with identical Observation Domain ID belong to the
same Observation Domain.";
mandatory true;
Linowski & Ersue Expires April 29, 2010 [Page 30]
Internet-Draft YANG Language Abstractions October 2009
type uint32;
}
leaf-list selectionProcess {
description "Selection Processes in this list process packets
in parallel.";
type instance-identifier { ct:instance-type SelectionProcess; }
}
}
ct:complex-type LinecardObservationPoint {
ct:extends ObservationPoint;
description "Linecard Observation Point.";
leaf physicalEntity {
description "Instance identifier of the observed linecard";
type instance-identifer {type PhysicalEntity; }
}
// Note: This modeling assumes that also physical entities are
// modeled with complex types. Otherwise a choice
// with an index or name needs to be used.
leaf direction {
description "Direction of packets. If not applicable (e.g.,
in the case of a sniffing interface in promiscuous mode),
this parameter is omitted";
type Direction;
default both;
}
}
ct:complex-type InterfaceObservationPoint {
ct:extends ObservationPoint;
description "Interface Observation Point.";
leaf interface {
description "Instance identifier of the observed interface";
type instance-identifer {type Interface;}
}
// Note: this modeling assumes that also interfaces
// are modeled with complex types. Otherwise a choice
// with an index or name as to be used.
leaf direction {
description "Direction of packets. If not applicable (e.g.,
in the case of a sniffing interface in promiscuous mode),
this parameter is omitted";
type Direction;
default both;
}
}
Linowski & Ersue Expires April 29, 2010 [Page 31]
Internet-Draft YANG Language Abstractions October 2009
ct:complex-type Selector {
ct:abstract true;
description "Abstract Selector.";
key name;
leaf name {
description "Arbitrary but unique name of the Selector.";
type string;
}
leaf selectorId {
type uint16;
description "The Selector ID must be unique within the
Observation Domain.
If not configured, this parameter is set by the monitoring
device.";
reference "draft-ietf-psamp-info-11";
}
leaf packetsObserved {
type yang:counter64;
config false;
description "Corresponds to ipfixSelectorStatsPacketsObserved
in IPFIX-MIB.";
reference "draft-ietf-ipfix-mib-05, section 7
(ipfixSelectorStatsPacketsObserved).";
}
leaf packetsDropped {
type yang:counter64;
config false;
description "Corresponds to ipfixSelectorStatsPacketsDropped
in IPFIX-MIB.";
reference "draft-ietf-ipfix-mib-05, section 7
(ipfixSelectorStatsPacketsDropped).";
}
}
ct:complex-type SelectAll {
ct:extends Selector;
}
ct:complex-type SampCountBased {
if-feature psampSampCountBased;
ct:extends Selector;
leaf interval {
type uint32;
mandatory true;
}
leaf spacing {
type uint32;
mandatory true;
Linowski & Ersue Expires April 29, 2010 [Page 32]
Internet-Draft YANG Language Abstractions October 2009
}
}
ct:complex-type SampTimeBased {
if-feature psampSampTimeBased;
ct:extends Selector;
leaf interval {
type uint32;
mandatory true;
}
leaf spacing {
type uint32;
mandatory true;
}
}
ct:complex-type SampRandOutOfN {
if-feature psampSampRandOutOfN;
ct:extends Selector;
leaf population {
type uint32;
mandatory true;
}
leaf sample {
type uint32;
mandatory true;
}
}
ct:complex-type SampUniProb {
if-feature psampSampUniProb;
ct:extends Selector;
leaf probability {
type uint32;
mandatory true;
description "The given value must be divided by
4294967295.";
}
}
ct:complex-type SampNonUniProb {
if-feature psampSampNonUniProb;
ct:extends Selector;
leaf function {
type yang:object-identifier;
mandatory true;
}
leaf funcParam {
Linowski & Ersue Expires April 29, 2010 [Page 33]
Internet-Draft YANG Language Abstractions October 2009
type yang:object-identifier;
mandatory true;
}
}
ct:complex-type SampFlowState {
if-feature psampSampFlowState;
ct:extends Selector;
leaf function {
type yang:object-identifier;
mandatory true;
}
leaf funcParam {
type yang:object-identifier;
mandatory true;
}
}
ct:complex-type FilterMatch {
if-feature psampFilterMatch;
ct:extends Selector;
choice nameOrId {
mandatory true;
description "Deviating from the PSAMP MIB, the field is
specified by either the name or the ID of the
Information Element.";
leaf ieName {
type string;
}
leaf ieId {
type uint16;
}
}
leaf ieEnterpriseNumber {
type uint32;
description "Deviating from the PSAMP MIB, an enterprise
number may be specified to refer to an
enterprise-specific Information Element.";
}
leaf startValue {
type string;
mandatory true;
}
leaf stopValue {
type string;
mandatory true;
}
leaf mask {
Linowski & Ersue Expires April 29, 2010 [Page 34]
Internet-Draft YANG Language Abstractions October 2009
type string;
description "If not configured, no mask is applied.";
}
}
ct:complex-type FilterHash {
if-feature psampFilterHash;
ct:extends Selector;
leaf addrType {
type inet:ip-version;
mandatory true;
}
leaf headerBits {
type string {
length 40;
}
mandatory true;
description "If addrType is 'ipv4', only the first 20 bytes
are used.";
}
leaf payloadBytes {
type uint32;
default 0;
}
leaf payloadBits {
type string;
description "If not configured, all bits included in the
payload section defined by payloadBytes are used.";
}
leaf function {
type yang:object-identifier;
mandatory true;
}
leaf funcParam {
type yang:object-identifier;
mandatory true;
}
leaf inputBits {
type uint32;
mandatory true;
}
leaf outputBits {
type uint32;
mandatory true;
}
leaf outputMask {
type string;
mandatory true;
Linowski & Ersue Expires April 29, 2010 [Page 35]
Internet-Draft YANG Language Abstractions October 2009
}
leaf selection {
type string;
mandatory true;
}
}
ct:complex-type FilterRState {
if-feature psampFilterRState;
ct:extends Selector;
leaf function {
type filterRStateFunction;
mandatory true;
}
leaf negate {
type boolean;
default false;
}
leaf ifIndex {
type uint32;
mandatory true;
description "Index of the interface as stored in the
ifTable of IF-MIB.";
reference "RFC 2863.";
}
leaf startAS {
type inet:autonomous-system-number;
must "../function=originAS or ../function=destAS";
}
leaf stopAS {
type inet:autonomous-system-number;
must "../function=originAS or ../function=destAS";
}
leaf vendorFunc {
type yang:object-identifier;
must "../function=other";
}
}
ct:complex-type SelectionProcess {
description "A Selection Process.";
key name;
leaf name {
description "Arbitrary but unique name of the Selection
Process.";
type string;
}
Linowski & Ersue Expires April 29, 2010 [Page 36]
Internet-Draft YANG Language Abstractions October 2009
leaf selectionSequenceId {
description "The Selection Sequence ID must be unique within
the Observation Domain. If not configured, this parameter
is set by the monitoring device.";
reference "draft-ietf-psamp-info-11";
type uint64;
}
ct:instance-list selector {
description "List of Selectors that define the action of the
Selection Process on a single packet. The Selectors are
serially invoked in the same order as they appear in this
list.";
min-elements 1;
ordered-by user;
type Selector;
}
leaf-list selectionProcess {
description "A Selection Process may pass selected packets
to further Selection Processes.";
type instance-identifier { ct:instance-type SelectionProcess; }
}
leaf-list cache {
description "Caches in this list receive the selected packets
in parallel.";
type instance-identifier { ct:instance-type Cache; }
}
}
typedef cacheType {
type enumeration {
enum immediate {
description "Flow expiration after the first packet,
generation of Packet Records.";
}
enum timeout {
description "Flow expiration after active and inactive
timeout, generation of Flow Records.";
}
enum permanent {
description "No flow expiration, periodical export after
active timeout, generation of Flow Records.";
}
}
description "Cache Type specifies the Flow expiration policy of
a Cache.";
}
Linowski & Ersue Expires April 29, 2010 [Page 37]
Internet-Draft YANG Language Abstractions October 2009
ct:complex-type cache {
if-feature meter;
description "A Cache";
key name;
leaf name { type string; }
leaf cacheType {
description "Actual cache type. May be changed at run time.";
type cacheType;
mandatory true;
}
leaf maxRecords {
type uint32;
description "If not configured, this parameter is set by the
Monitoring Device.";
}
leaf activeTimeout {
type uint32;
units seconds;
must "../cacheType!=immediate";
description "If not configured, this parameter is set by the
Monitoring Device.";
}
leaf inactiveTimeout {
type uint32;
units seconds;
must "../cacheType!=permanent";
description "If not configured, this parameter is set by the
Monitoring Device.";
}
container cacheLayout { uses cacheLayoutParameters; }
leaf-list exportingProcess {
type keyref { path "/ipfix/exportingProcess/name"; }
description "Records are exported by all Exporting Processes in
the list.";
}
leaf activeFlows {
type uint32;
units flows;
config false;
description "Corresponds to
ipfixMeteringProcessCacheActiveFlows in IPFIX-MIB.";
reference "ietf-draft-ipfix-mib-05, section 7
(ipfixMeteringProcessCacheActiveFlows)";
}
leaf inactiveFlows {
type uint32;
units flows;
config false;
Linowski & Ersue Expires April 29, 2010 [Page 38]
Internet-Draft YANG Language Abstractions October 2009
description "Corresponds to
ipfixMeteringProcessCacheInactiveFlows in IPFIX-MIB.";
reference "ietf-draft-ipfix-mib-0, section 7
(ipfixMeteringProcessCacheInactiveFlows)";
}
leaf dataRecords {
type yang:counter64;
units "Data Records";
config false;
description "Corresponds to
ipfixMeteringProcessDataRecords in IPFIX-MIB.";
reference "ietf-draft-ipfix-mib-0, section 7
(ipfixMeteringProcessDataRecords)";
}
}
ct:complex-type Destination {
ct:abstract true;
key name;
leaf name { type string; }
leaf type {
type exportMemberType;
}
ct:instance-list option {
type Option;
}
}
ct:complex-type IpDestination {
ct:extends Destination;
ct:abstract true;
leaf destinationIpAddress {
type inet:ip-address;
mandatory true;
}
leaf destinationPort {
type inet:port-number;
default 4739;
}
leaf sendBufferSize { type uint32; }
leaf rateLimit {
description "Maximum number of bytes per second the Exporting
Process may export to the given destination. The number of
bytes is calculated from the lengths of the IPFIX Messages
exported.";
reference "draft-ietf-psamp-protocol-09, section 6.3.";
type uint32;
Linowski & Ersue Expires April 29, 2010 [Page 39]
Internet-Draft YANG Language Abstractions October 2009
}
}
ct:complex-type SctpExport {
ct:extends IpDestination;
description "SCTP export parameters.";
reference "RFC 3758, RFC 4960.";
leaf-list sourceIpAddress {
description "List of eligible local IP addresses to be
used by the SCTP endpoint. If omitted, all locally
assigned IP addresses are used by the local endpoint.";
type inet:ip-address;
}
leaf timedReliability {
description "PR-SCTP lifetime for IPFIX Messages
containing Data Sets only.";
type yang:timeticks;
default 0;
}
leaf numberOfStreams {
description "Number of outbound streams requested for the
SCTP association.";
type uint16;
}
leaf orderedDelivery {
description "Ordered delivery of IPFIX Messages
containing Data Sets.";
type boolean;
default "true";
}
}
ct:complex-type UdpExport {
if-feature udpTransport;
ct:extends IpDestination;
description "UDP export parameters.";
leaf sourceIpAddress {
description "Source IP address. If omitted, the address
assigned to the outgoing interface is used.";
type inet:ip-address;
}
leaf templateRefreshTimeout {
type uint32;
units seconds;
default 600;
description "Sets time after which Templates are resent if
Linowski & Ersue Expires April 29, 2010 [Page 40]
Internet-Draft YANG Language Abstractions October 2009
UDP is transport protocol.";
reference "RFC5101.";
}
leaf optionTemplateRefreshTimeout {
type uint32;
units seconds;
default 600;
description "Sets time after which Options Templates are
resent if UDP is transport protocol.";
reference "RFC5101.";
}
leaf templateRefreshPacket {
type uint32;
units "IPFIX Messages";
description "Sets number of IPFIX Messages after which
Templates are resent if UDP is transport protocol.
If omitted, Templates are only resent after timeout.";
reference "RFC5101.";
}
leaf optionTemplateRefreshPacket {
type uint32;
units "IPFIX Messages";
description "Sets number of IPFIX Messages after which
Options Templates are resent if UDP is transport protocol.
If omitted, Templates are only resent after timeout.";
reference "RFC5101.";
}
}
ct:complex-type TcpExport {
if-feature tcpTransport;
description "TCP export parameters.";
ct:extends IpDestination;
}
ct:complex-type FileWriter {
if-feature fileWriter;
ct:extends Destination;
description "File Writer.";
leaf uri {
type inet:uri;
mandatory true;
description "URI specifying the location of the file.";
}
must "current().type!=loadBalancing";
}
Linowski & Ersue Expires April 29, 2010 [Page 41]
Internet-Draft YANG Language Abstractions October 2009
ct:complex-type Option {
description "Specification of the data to export using an
Options Template.";
key name;
leaf name { type string; }
leaf type {
type optionType;
mandatory true;
}
leaf timeout {
type yang:timeticks;
default 0;
description "Time interval for exporting options data.
If set to zero, the options data is sent once.";
}
container optionTemplate {
description "If no Options Template is specified, the
Exporter defines a template according to options type and
available options data.";
list optionField {
key name;
ordered-by user;
leaf name { type string; }
uses informationElement;
leaf isScope {
type empty;
description "If present, this is a scope field.";
}
}
}
}
ct:complex-type Template {
description "A Template used by an Exporting
Process or received by a Collecting Process. Parameter names
and semantics correspond to the managed objects in IPFIX-
MIB";
reference "draft-ietf-ipfix-mib-05, section 7
(ipfixTemplateEntry, ipfixTemplateDefinitionEntry,
ipfixTemplateStatsEntry)";
config false;
leaf observationDomainId { type uint32; }
leaf templateId { type uint16; }
leaf setId { type uint16; }
leaf accessTime { type yang:date-and-time; }
leaf dataRecords { type yang:counter64; }
list field {
Linowski & Ersue Expires April 29, 2010 [Page 42]
Internet-Draft YANG Language Abstractions October 2009
leaf ieId { type uint16; }
leaf ieLength { type uint16; }
leaf enterprise { type uint32; }
leaf flags { type templateFieldFlags; }
}
}
ct:complex-type TransportSession {
description "State of a Transport Session originating
from an Exporting or terminating at a Collecting Process.
Parameter names and semantics correspond to the managed
objects in IPFIX-MIB";
reference "draft-ietf-ipfix-mib-05, section 7
(ipfixTransportSessionEntry, ipfixTransportSessionStatsEntry)";
config false;
leaf index { type int32; }
leaf sourceAddress { type inet:ip-address; }
leaf destinationAddress { type inet:ip-address; }
leaf sourcePort { type inet:port-number; }
leaf destinationPort { type inet:port-number; }
leaf sctpAssocId { type uint32; }
leaf templateRefreshTimeout {
type uint32;
units seconds;
}
leaf optionTemplateRefreshTimeout {
type uint32;
units seconds;
}
leaf templateRefreshPacket {
type uint32;
units "IPFIX Messages";
}
leaf optionTemplateRefreshPacket {
type uint32;
units "IPFIX Messages";
}
leaf status { type transportSessionStatus; }
leaf rate {
type int32;
units "bytes per second";
}
leaf packets {
type yang:counter64;
units packets;
}
leaf bytes {
Linowski & Ersue Expires April 29, 2010 [Page 43]
Internet-Draft YANG Language Abstractions October 2009
type yang:counter64;
units bytes;
}
leaf messages {
type yang:counter64;
units "IPFIX Messages";
}
leaf discardedMessages {
type yang:counter64;
units "IPFIX Messages";
}
leaf records {
type yang:counter64;
units "Data Records";
}
leaf templates {
type yang:counter32;
units "Templates";
}
leaf optionTemplates {
type yang:counter32;
units "Options Templates";
}
}
ct:complex-type ExportingProcess {
description "An Exporting Process.";
key name;
leaf name {
description "Arbitrary but unique name of the Exporting
Process.";
type string;
}
leaf exportingProcessId {
description "If omitted, the Exporting Process ID
is assigned by the monitoring device.";
type uint32;
}
ct:instance-list destination {
type Destination;
}
ct:instance-list options {
type Option;
}
ct:instance-list Template {
type Template;
}
Linowski & Ersue Expires April 29, 2010 [Page 44]
Internet-Draft YANG Language Abstractions October 2009
ct:instance-list transportSession {
type TransportSession;
}
}
container ipfix {
ct:instance-list collectingProcess {
if-feature collector;
type CollectingProcess;
}
ct:instance-list observationPoint {
if-feature meter;
type ObservationPoint;
}
ct:instance-list selectionProcess {
if-feature meter;
type SelectionProcess;
}
ct:instance-list cache {
if-feature meter;
type Cache;
}
ct:instance-list exportingProcess {
if-feature exporter;
type ExportingProcess;
}
}
}
<CODE ENDS>
Linowski & Ersue Expires April 29, 2010 [Page 45]
Internet-Draft YANG Language Abstractions October 2009
Authors' Addresses
Bernd Linowski
TCS/Nokia Siemens Networks
Heltorfer Strasse 1
Duesseldorf 40472
Germany
EMail: bernd.linowski@ext.nsn.com
Mehmet Ersue
Nokia Siemens Networks
St.-Martin-Strasse 53
Munich 81541
Germany
EMail: mehmet.ersue@nsn.com
Linowski & Ersue Expires April 29, 2010 [Page 46]
