draft-ietf-forces-model-extension-02.txt   draft-ietf-forces-model-extension-03.txt 
Internet Engineering Task Force E. Haleplidis Internet Engineering Task Force E. Haleplidis
Internet-Draft University of Patras Internet-Draft University of Patras
Intended status: Standards Track May 20, 2014 Updates: 5812 (if approved) July 4, 2014
Expires: November 21, 2014 Intended status: Standards Track
Expires: January 5, 2015
ForCES Model Extension ForCES Model Extension
draft-ietf-forces-model-extension-02 draft-ietf-forces-model-extension-03
Abstract Abstract
Forwarding and Control Element Separation (ForCES) defines an Forwarding and Control Element Separation (ForCES) defines an
architectural framework and associated protocols to standardize architectural framework and associated protocols to standardize
information exchange between the control plane and the forwarding information exchange between the control plane and the forwarding
plane in a ForCES Network Element (ForCES NE). RFC5812 has defined plane in a ForCES Network Element (ForCES NE). RFC5812 has defined
the ForCES Model provides a formal way to represent the capabilities, the ForCES Model that provides a formal way to represent the
state, and configuration of forwarding elements within the context of capabilities, state, and configuration of forwarding elements within
the ForCES protocol, so that control elements (CEs) can control the the context of the ForCES protocol, so that control elements (CEs)
FEs accordingly. More specifically, the model describes the logical can control the FEs accordingly. More specifically, the model
functions that are present in an FE, what capabilities these describes the logical functions that are present in a forwarding
functions support, and how these functions are or can be element (FE), what capabilities these functions support, and how
interconnected. these functions are or can be interconnected.
RFC5812 has been around for two years and experience in its use has RFC5812 has been around for two years and experience in its use has
shown room for small extensions without a need to alter the protocol shown room for small extensions without a need to alter the protocol
while retaining backward compatibility with older xml libraries. while retaining backward compatibility with older xml libraries.
This document extends the model to allow complex datatypes for This document update RFC5812 and extends the model to allow complex
metadata, optional default values for datatypes, optional access datatypes for metadata, optional default values for datatypes,
types for structures and fixes an issue with LFB inheritance. The optional access types for structures and fixes an issue with LFB
document also introduces two new features a new event condition inheritance. The document also introduces two new features a new
BecomesEqualTo and LFB properties. event condition BecomesEqualTo and LFB properties.
Status of This Memo Status of This Memo
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provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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This Internet-Draft will expire on January 5, 2015.
This Internet-Draft will expire on November 21, 2014.
Copyright Notice Copyright Notice
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Table of Contents Table of Contents
1. Terminology and Conventions . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 2 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
1.2. Definitions . . . . . . . . . . . . . . . . . . . . . . . 3 1.2. Definitions . . . . . . . . . . . . . . . . . . . . . . . 3
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4 2. ForCES Model Extensions . . . . . . . . . . . . . . . . . . . 4
3. ForCES Model Extension proposal . . . . . . . . . . . . . . . 4 2.1. Complex datatypes for Metadata . . . . . . . . . . . . . 4
3.1. Complex datatypes for Metadata . . . . . . . . . . . . . 4 2.2. Optional Default Value for Datatypes . . . . . . . . . . 5
3.2. Optional Default Value for Datatypes . . . . . . . . . . 6 2.3. Optional Access Type for Structs . . . . . . . . . . . . 8
3.3. Optional Access Type for Structs . . . . . . . . . . . . 8 2.4. New Event Condition: BecomesEqualTo . . . . . . . . . . . 10
3.4. New Event Condition: BecomesEqualTo . . . . . . . . . . . 10 2.5. LFB Properties . . . . . . . . . . . . . . . . . . . . . 11
3.5. LFB Properties . . . . . . . . . . . . . . . . . . . . . 11 2.6. LFB class inheritance . . . . . . . . . . . . . . . . . . 13
3.6. LFB class inheritance . . . . . . . . . . . . . . . . . . 12 2.7. Enhancing XML Validation . . . . . . . . . . . . . . . . 14
3.7. Enhancing XML Validation . . . . . . . . . . . . . . . . 13 3. XML Extension Schema for LFB Class Library Documents . . . . 14
4. XML Extension Schema for LFB Class Library Documents . . . . 14 4. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 28
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 27 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 28
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 27 6. Security Considerations . . . . . . . . . . . . . . . . . . . 28
7. Security Considerations . . . . . . . . . . . . . . . . . . . 27 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 28
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 27 7.1. Normative References . . . . . . . . . . . . . . . . . . 28
8.1. Normative References . . . . . . . . . . . . . . . . . . 27 7.2. Informative References . . . . . . . . . . . . . . . . . 29
8.2. Informative References . . . . . . . . . . . . . . . . . 27 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 29
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 27
1. Terminology and Conventions 1. Introduction
The ForCES Model [RFC5812] presents a formal way to define FEs
Logical Function Blocks (LFBs) using the eXtensible Markup Language
(XML). [RFC5812] has been published a more than two years and
current experience in its use has demonstrated need for adding new
and changing existing modeling concepts.
Specifically this document updates the ForCES Model [RFC5812] to
allow complex datatypes for metadata (Section 2.1), optional default
values for datatypes (Section 2.2), optional access types for
structures (Section 2.3) and fixes an issue with LFB class
inheritance (Section 2.6). Additionally the document introduces two
new features a new event condition BecomesEqualTo (Section 2.4) and
LFB properties (Section 2.5).
These extensions are an update to the ForCES model [RFC5812] and do
not require any changes on the ForCES protocol [RFC5810] as they are
simply changes of the schema definition. Additionally backward
compatibility is ensured as XML libraries produced with the earlier
schema are still valid with the new one. In order for XML libraries
produced by the new schema to be compatible with existing ForCES
implementations, the XML Libraries MUST NOT include any of the
features described in this document, else the old implementation will
be unable to parse the XML library.
1.1. Requirements Language 1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
1.2. Definitions 1.2. Definitions
This document follows the terminology defined by the ForCES Model in This document uses the terminology defined in the ForCES Model in
[RFC5812]. The required definitions are repeated below for clarity. [RFC5812]. In particular, the reader is expected to be familiar with
the following terms:
FE Model - The FE model is designed to model the logical
processing functions of an FE. The FE model proposed in this
document includes three components; the LFB modeling of individual
Logical Functional Block (LFB model), the logical interconnection
between LFBs (LFB topology), and the FE-level attributes,
including FE capabilities. The FE model provides the basis to
define the information elements exchanged between the CE and the
FE in the ForCES protocol [RFC5810].
LFB (Logical Functional Block) Class (or type) - A template that
represents a fine-grained, logically separable aspect of FE
processing. Most LFBs relate to packet processing in the data
path. LFB classes are the basic building blocks of the FE model.
LFB Instance - As a packet flows through an FE along a data path,
it flows through one or multiple LFB instances, where each LFB is
an instance of a specific LFB class. Multiple instances of the
same LFB class can be present in an FE's data path. Note that we
often refer to LFBs without distinguishing between an LFB class
and LFB instance when we believe the implied reference is obvious
for the given context.
LFB Model - The LFB model describes the content and structures in
an LFB, plus the associated data definition. XML is used to
provide a formal definition of the necessary structures for the
modeling. Four types of information are defined in the LFB model.
The core part of the LFB model is the LFB class definitions; the
other three types of information define constructs associated with
and used by the class definition. These are reusable data types,
supported frame (packet) formats, and metadata.
Element - Element is generally used in this document in accordance FE Model
with the XML usage of the term. It refers to an XML tagged part
of an XML document. For a precise definition, please see the full
set of XML specifications from the W3C. This term is included in
this list for completeness because the ForCES formal model uses
XML.
Attribute - Attribute is used in the ForCES formal modeling in LFB (Logical Functional Block) Class (or type)
accordance with standard XML usage of the term, i.e., to provide
attribute information included in an XML tag.
LFB Metadata - Metadata is used to communicate per-packet state LFB Instance
from one LFB to another, but is not sent across the network. The
FE model defines how such metadata is identified, produced, and
consumed by the LFBs, but not how the per-packet state is
implemented within actual hardware. Metadata is sent between the
FE and the CE on redirect packets.
ForCES Component - A ForCES Component is a well-defined, uniquely LFB Model
identifiable and addressable ForCES model building block. A
component has a 32-bit ID, name, type, and an optional synopsis
description. These are often referred to simply as components.
LFB Component - An LFB component is a ForCES component that
defines the Operational parameters of the LFBs that must be
visible to the CEs.
LFB Class Library - The LFB class library is a set of LFB classes Element
that has been identified as the most common functions found in
most FEs and hence should be defined first by the ForCES Working
Group.
2. Introduction Attribute
The ForCES Model [RFC5812] presents a formal way to define FEs LFB Metadata
Logical Function Blocks (LFBs) using XML. [RFC5812] has been
published a more than two years and current experience in its use has
demonstrated need for adding new and changing existing modeling
concepts.
Specifically this document extends the ForCES Model to allow complex ForCES Component
datatypes for metadata, optional default values for datatypes,
optional access types for structures and fixes an issue with the LFB
inheritance. Additionally the document introduces two new features a
new event condition BecomesEqualTo and LFB properties.
These extensions are an addendum to the ForCES model [RFC5812] and do LFB Class Library
not require any changes on the ForCES protocol [RFC5810] as they are
simply changes of the schema definition. Additionally backward
compatibility is ensured as xml libraries produced with the earlier
schema are still valid with the new one.
3. ForCES Model Extension proposal 2. ForCES Model Extensions
3.1. Complex datatypes for Metadata 2.1. Complex datatypes for Metadata
Section 4.6. (Element for Metadata Definitions) in the ForCES Model Section 4.6. (Element for Metadata Definitions) in the ForCES Model
[RFC5812] limits the datatype use in metadata to only atomic types. [RFC5812] limits the datatype use in metadata to only atomic types.
Figure 1 shows the xml schema excerpt where ony typeRef and atomic Figure 1 shows the xml schema excerpt where ony typeRef and atomic
are allowed for a metadata definition. are allowed for a metadata definition.
However there are cases where complex metadata are used in the However there are cases where complex metadata are used in the
datapath, for example two simple use cases can be seen in the datapath, for example two simple use cases can be seen in the
OpenFlow switch 1.1 [OpenFlowSpec1.1] and beyond: OpenFlow switch 1.1 [OpenFlowSpec1.1] and beyond:
1. The Action Set metadata follows a packet inside the Flow Tables. 1. The Action Set metadata is an array of actions descriptors, which
The Action Set metadata is an array of actions to be performed at traverses the processing pipeline along with the packet data.
the end of the pipeline.
2. When a packet is received from a controller it may be accompanied 2. When a packet is received from a controller it may be accompanied
by a list of actions to be performed on it prior to be sent on by a list of actions, as metadata, to be performed on it prior to
the flow table pipeline which is also an array. being sent on the processing pipeline. This list of actions is
also an array.
With this extension (Figure 2), complex data types are also allowed, With this extension (Figure 2), complex data types are also allowed,
specifically structs and arrays as metadata. The key declarations specifically structs and arrays as metadata. The key declarations
are required to check for validity of content keys in arrays and are required to check for validity of content keys in arrays and
componentIDs in structs. componentIDs in structs.
<xsd:complexType name="metadataDefsType"> <xsd:complexType name="metadataDefsType">
<xsd:sequence> <xsd:sequence>
<xsd:element name="metadataDef" maxOccurs="unbounded"> <xsd:element name="metadataDef" maxOccurs="unbounded">
<xsd:complexType> <xsd:complexType>
skipping to change at page 6, line 37 skipping to change at page 5, line 37
</xsd:element> </xsd:element>
</xsd:choice> </xsd:choice>
</xsd:sequence> </xsd:sequence>
</xsd:complexType> </xsd:complexType>
</xsd:element> </xsd:element>
</xsd:sequence> </xsd:sequence>
</xsd:complexType> </xsd:complexType>
Figure 2: New MetadataDefType Definition for the schema Figure 2: New MetadataDefType Definition for the schema
3.2. Optional Default Value for Datatypes 2.2. Optional Default Value for Datatypes
In the original schema, default values can only be defined for In the original schema, default values can only be defined for
datatypes defined inside LFB components and not inside structures or datatypes defined inside LFB components and not inside structures or
arrays. Therefore default values of datatypes that are constantly arrays. Therefore default values of datatypes that are constantly
being reused, e.g. counters with default value of 0, have to be being reused, e.g. counters with default value of 0, have to be
constantly respecified. Additionally, datatypes inside complex constantly respecified. Additionally, datatypes inside complex
datatypes cannot be defined with a default value, e.g. a counter datatypes cannot be defined with a default value, e.g. a counter
inside a struct that has a default value of 0. inside a struct that has a default value of 0.
This extension allows optionally to add default values to atomic and This extension allows optionally to add default values to atomic and
typeref types, whether they are as simple or complex datatypes. A typeref types, whether they are as simple or complex datatypes. A
simple use case would be to have a struct component where one of the simple use case would be to have a struct component where one of the
components is a counter which the default value would be zero. components is a counter which the default value would be zero.
This extension alters the definition of the typeDeclarationGroup in This extension alters the definition of the typeDeclarationGroup in
the xml schema from Figure 3 to Figure 4 to allow default values to the XML schema from Figure 3 to Figure 4 to allow default values to
TypeRef. TypeRef.
<xsd:element name="typeRef" type="typeRefNMTOKEN"/> <xsd:element name="typeRef" type="typeRefNMTOKEN"/>
Figure 3: Initial Excerpt of typeDeclarationGroup Defintion in the Figure 3: Initial Excerpt of typeDeclarationGroup Defintion in the
schema schema
<xsd:sequence> <xsd:sequence>
<xsd:element name="typeRef" type="typeRefNMTOKEN"/> <xsd:element name="typeRef" type="typeRefNMTOKEN"/>
<xsd:element name="DefaultValue" type="xsd:token" <xsd:element name="DefaultValue" type="xsd:token"
minOccurs="0"/> minOccurs="0"/>
</xsd:sequence> </xsd:sequence>
Figure 4: New Excerpt of typeDeclarationGroup Definition in the Figure 4: New Excerpt of typeDeclarationGroup Definition in the
schema schema
Additionally it appends to the declaration of the AtomicType this xml Additionally this document appends to the declaration of the
(Figure 5) to allow default values to Atomic datatypes. AtomicType from Figure 5 to Figure 6 to allow default values to
Atomic datatypes. Note that both declarations include the new
special value validation described in Section 2.7
<xsd:element name="defaultValue" type="xsd:token" minOccurs="0"/> <xsd:complexType name="atomicType">
<xsd:sequence>
<xsd:element name="baseType" type="typeRefNMTOKEN"/>
<xsd:element name="rangeRestriction" type="rangeRestrictionType"
minOccurs="0"/>
<xsd:element name="specialValues" type="specialValuesType"
minOccurs="0">
<!-- Extension -->
<xsd:key name="SpecialValue">
<xsd:selector xpath="specialValue"/>
<xsd:field xpath="@value"/>
</xsd:key>
<!-- /Extension -->
</xsd:element>
</xsd:sequence>
Figure 5: Appending xml in of AtomicType Definition in the schema Figure 5: Initial Excerpt of AtomicType Definition in the schema
<xsd:complexType name="atomicType">
<xsd:sequence>
<xsd:element name="baseType" type="typeRefNMTOKEN"/>
<xsd:element name="rangeRestriction" type="rangeRestrictionType"
minOccurs="0"/>
<xsd:element name="specialValues" type="specialValuesType"
minOccurs="0">
<!-- Extension -->
<xsd:key name="SpecialValue">
<xsd:selector xpath="specialValue"/>
<xsd:field xpath="@value"/>
</xsd:key>
<!-- /Extension -->
</xsd:element>
<!-- Extension -->
<xsd:element name="defaultValue" type="xsd:token"
minOccurs="0"/>
<!-- /Extension -->
</xsd:sequence>
Figure 6: New Excerpt of AtomicType Definition in the schema
Examples of using default values is depicted in Figure 7.
<dataTypeDef> <dataTypeDef>
<name>Counter Values</name> <name>Counter Values</name>
<synopsis>Example default values in struct</synopsis> <synopsis>Example default values in struct</synopsis>
<struct> <struct>
<component componentID="1"> <component componentID="1">
<name>GoodPacketCoutner</name> <name>GoodPacketCoutner</name>
<synopsis>A counter for good packets</synopsis> <synopsis>A counter for good packets</synopsis>
<typeRef>uint32</typeRef> <typeRef>uint32</typeRef>
<DefaultValue>0</DefaultValue> <DefaultValue>0</DefaultValue>
</component> </component>
<component componentID="2"> <component componentID="2">
<name>BadPacketCoutner</name> <name>BadPacketCoutner</name>
<synopsis>A counter for bad packets</synopsis> <synopsis>A counter for bad packets</synopsis>
<typeRef>uint32</typeRef> <typeRef>uint32</typeRef>
<DefaultValue>0</DefaultValue> <DefaultValue>0</DefaultValue>
</component> </component>
</struct> </struct>
</dataTypeDef> </dataTypeDef>
Figure 6: Example of optional default values Figure 7: Example of optional default values
3.3. Optional Access Type for Structs 2.3. Optional Access Type for Structs
In the original schema, the access type can be only be defined on In the original schema, the access type can only be defined on
components of LFB and not on components in structs or arrays. components of an LFB and not on components in structs or arrays.
However when it's a struct datatype it is not possible to fine-tune However when it's a struct datatype it is not possible to fine-tune
access type per component in the struct. A simple use case would be access type per component in the struct. A simple use case would be
to have a read-write struct component where one of the components is to have a read-write struct component where one of the components is
a counter where the access-type could be read-reset or read-only, a counter where the access-type could be read-reset or read-only,
e.g. a read-reset or a read-only counter inside a struct. e.g. a read-reset or a read-only counter inside a struct.
With this extension is it allowed to define the access type for a With this extension is it allowed to define the access type for a
struct component either in the datatype definitions or in the LFB struct component either in the datatype definitions or in the LFB
component definitions. component definitions.
When the optional access type for a struct component is defined it When the optional access type for a struct component is defined it
MUST override the access type of the struct. If by accident an MUST override the access type of the struct. The access type for a
access type for a component in a capability is defined, the access component in a capability is always read-only per [RFC5812]. If an
type MUST NOT be taken into account and MUST always be considered as access type is provided for a component in a capability it MUST be
read-only. ignored. Similarly if an access type is provided for a struct in a
metadata it MUST be ignored.
This extension alters the definition of the struct in the xml schema This extension alters the definition of the struct in the xml schema
from Figure 7 to Figure 8. from Figure 8 to Figure 9.
<xsd:complexType name="structType"> <xsd:complexType name="structType">
<xsd:sequence> <xsd:sequence>
<xsd:element name="derivedFrom" type="typeRefNMTOKEN" <xsd:element name="derivedFrom" type="typeRefNMTOKEN"
minOccurs="0"/> minOccurs="0"/>
<xsd:element name="component" maxOccurs="unbounded"> <xsd:element name="component" maxOccurs="unbounded">
<xsd:complexType> <xsd:complexType>
<xsd:sequence> <xsd:sequence>
<xsd:element name="name" type="xsd:NMTOKEN"/> <xsd:element name="name" type="xsd:NMTOKEN"/>
<xsd:element ref="synopsis"/> <xsd:element ref="synopsis"/>
skipping to change at page 8, line 48 skipping to change at page 8, line 49
<xsd:element name="optional" minOccurs="0"/> <xsd:element name="optional" minOccurs="0"/>
<xsd:group ref="typeDeclarationGroup"/> <xsd:group ref="typeDeclarationGroup"/>
</xsd:sequence> </xsd:sequence>
<xsd:attribute name="componentID" type="xsd:unsignedInt" <xsd:attribute name="componentID" type="xsd:unsignedInt"
use="required"/> use="required"/>
</xsd:complexType> </xsd:complexType>
</xsd:element> </xsd:element>
</xsd:sequence> </xsd:sequence>
</xsd:complexType> </xsd:complexType>
Figure 7: Initial xml for the struct definition in the schema Figure 8: Initial xml for the struct definition in the schema
<xsd:complexType name="structType"> <xsd:complexType name="structType">
<xsd:sequence> <xsd:sequence>
<xsd:element name="derivedFrom" type="typeRefNMTOKEN" <xsd:element name="derivedFrom" type="typeRefNMTOKEN"
minOccurs="0"/> minOccurs="0"/>
<xsd:element name="component" maxOccurs="unbounded"> <xsd:element name="component" maxOccurs="unbounded">
<xsd:complexType> <xsd:complexType>
<xsd:sequence> <xsd:sequence>
<xsd:element name="name" type="xsd:NMTOKEN"/> <xsd:element name="name" type="xsd:NMTOKEN"/>
<xsd:element ref="synopsis"/> <xsd:element ref="synopsis"/>
<xsd:element ref="description" minOccurs="0"/> <xsd:element ref="description" minOccurs="0"/>
skipping to change at page 9, line 30 skipping to change at page 9, line 30
<xsd:list itemType="accessModeType"/> <xsd:list itemType="accessModeType"/>
</xsd:simpleType> </xsd:simpleType>
</xsd:attribute> </xsd:attribute>
<xsd:attribute name="componentID" type="xsd:unsignedInt" <xsd:attribute name="componentID" type="xsd:unsignedInt"
use="required"/> use="required"/>
</xsd:complexType> </xsd:complexType>
</xsd:element> </xsd:element>
</xsd:sequence> </xsd:sequence>
</xsd:complexType> </xsd:complexType>
Figure 8: New xml for the struct definition in the schema Figure 9: New xml for the struct definition in the schema
An example of using optional access types for structs can be depicted
in Figure 10
<component componentID="1" access="read-write"> <component componentID="1" access="read-write">
<name>PacketFlows</name> <name>PacketFlows</name>
<synopsis>Packet Flows, match and counter</synopsis> <synopsis>Packet Flows, match and counter</synopsis>
<struct> <struct>
<component componentID="1"> <component componentID="1">
<name>FlowMatch</name> <name>FlowMatch</name>
<synopsis>Flow Match</synopsis> <synopsis>Flow Match</synopsis>
<typeRef>MatchType</typeRef> <typeRef>MatchType</typeRef>
</component> </component>
<component componentID="2" access="read-only"> <component componentID="2" access="read-only">
<name>MatchCounter</name> <name>MatchCounter</name>
<synopsis>Packets matching the flow match</synopsis> <synopsis>Packets matching the flow match</synopsis>
<typeRef>uint32</typeRef> <typeRef>uint32</typeRef>
<DefaultValue>0</DefaultValue> <DefaultValue>0</DefaultValue>
</component> </component>
</struct> </struct>
</component> </component>
Figure 9: Example of optional access types for struct Figure 10: Example of optional access types for struct
3.4. New Event Condition: BecomesEqualTo 2.4. New Event Condition: BecomesEqualTo
This extensions adds one more event condition in the model schema, This extensions adds one more event condition in the model schema,
that of BecomesEqualTo. The difference between Greater Than and Less that of BecomesEqualTo. The difference between Greater Than and Less
Than, is that when the value is exactly that of the BecomesEqualTo, Than, is that when the value is exactly that of the BecomesEqualTo,
the event is triggered. This event condition is particular useful the event is triggered. This event condition is particularly useful
when there is a need to monitor one or more states of an LFB or the when there is a need to monitor one or more states of an LFB or the
FE. For example in the CEHA [I-D.ietf-forces-ceha] document it may FE. For example in the CE High Availability (CEHA) [RFC7121] RFC it
be useful for the master CE to know which backup CEs have just become may be useful for the master CE to know which backup CEs have just
associated in order to connect to them and begin synchronizing the become associated in order to connect to them and begin synchronizing
state of the FE. The master CE could always poll for such the state of the FE. The master CE could always poll for such
information but getting such an event will speed up the process and information but getting such an event will speed up the process and
the event may be useful in other cases as well for monitoring state. the event may be useful in other cases as well for monitoring state.
The event MUST be triggered only when the value of the targeted The event MUST be triggered only when the value of the targeted
component becomes equal to the event condition value and MUST NOT component becomes equal to the event condition value and MUST NOT
generate events while the targeted component's value remains equal to generate events while the targeted component's value remains equal to
the event condition's value. the event condition's value.
The BecomesEqualTo is appended to the schema as follows: The BecomesEqualTo is appended to the schema as follows:
<xsd:element name="eventBecomesEqualTo" <xsd:element name="eventBecomesEqualTo"
substitutionGroup="eventCondition"/> substitutionGroup="eventCondition"/>
Figure 10: New Excerpt of BecomesEqualTo event condition definition Figure 11: New Excerpt of BecomesEqualTo event condition definition
in the schema in the schema
It can become useful for the CE to be notified when the state has It can become useful for the CE to be notified when the state has
changed once the BecomesEqualTo event has been triggered, e.g. the CE changed once the BecomesEqualTo event has been triggered, e.g. the CE
may need to know when a backup CE has lost association. Such an may need to know when a backup CE has lost association. Such an
event can be generated either by defining a second event on the same event can be generated either by defining a second event on the same
component, namely an Event Changed, or by simply reusing component, namely an Event Changed, or by simply reusing
BecomesEqualTo and use event properties, in particular event BecomesEqualTo and use event properties, in particular event
hysteresis. We append the following definition for the event hysteresis. We append the following definition for the event
hysteresis defined in section 4.8.5.2 in [RFC5812], with V being the hysteresis defined in section 4.8.5.2 in [RFC5812], with V being the
skipping to change at page 11, line 5 skipping to change at page 11, line 27
generated only one time once the value has changed by +/- V. generated only one time once the value has changed by +/- V.
For example using the value of 1 for V, will in effect create a For example using the value of 1 for V, will in effect create a
singular event that will notify the CE that the value has changed by singular event that will notify the CE that the value has changed by
at least 1. at least 1.
A developer of a CE must also take into account to use count or time A developer of a CE must also take into account to use count or time
filtering to avoid being overrun by messages, e.g. in the case of filtering to avoid being overrun by messages, e.g. in the case of
rapid state changes. rapid state changes.
3.5. LFB Properties 2.5. LFB Properties
The current model definition specifies properties for components of The current model definition specifies properties for components of
LFBs. Experience however has proven valuable at least for debug LFBs. Experience has shown that, at least for debug reasons, it
reasons, to have statistics per LFB instance to monitor sent/received would be useful to have statistics per LFB instance to monitor sent/
messages and errors for communication between CE and FE. These received messages and errors in communication between CE and FE.
properties are read-only. These properties are read-only.
In order to avoid ambiguity on protocol path semantics, this document In order to avoid ambiguity on protocol path semantics, this document
reserves LFB component 0 for LFB properties. This reservation is defines that the LFB component with ID 0 specifically MUST target LFB
backwards compatible as no LFB definition uses LFB component 0. Any properties and ID 0 MUST NOT be used for any component definition.
command with a path starting from LFB component 0 refers to LFB This disallowment is backwards compatible as no known LFB definition
properties. The following change in the xml schema disallows usage uses LFB component with ID 0. Any command with a path starting from
of LFB component 0: LFB component 0 refers to LFB properties. The following change in
the xml schema disallows usage of LFB component 0:
<xsd:attribute name="componentID" type="xsd:unsignedInt" <xsd:attribute name="componentID" type="xsd:unsignedInt"
use="required"> use="required">
Figure 11: Initial xml for LFB Component IDs Figure 12: Initial xml for LFB Component IDs
<!-- Extension Added restriction to component ID --> <!-- Extension Added restriction to component ID -->
<xsd:attribute name="componentID" use="required"> <xsd:attribute name="componentID" use="required">
<xsd:simpleType> <xsd:simpleType>
<xsd:restriction base="xsd:unsignedInt"> <xsd:restriction base="xsd:unsignedInt">
<xsd:minExclusive value="0"/> <xsd:minExclusive value="0"/>
</xsd:restriction> </xsd:restriction>
</xsd:simpleType> </xsd:simpleType>
</xsd:attribute> </xsd:attribute>
<!-- End of extension --> <!-- End of extension -->
Figure 12: New xml for the disallowing usage of 0 as LFB Component Figure 13: New xml for the disallowing usage of 0 as LFB Component
The following datatype definitions are to be used as properties for The following datatype definitions are to be used as properties for
LFB instances. LFB instances.
<dataTypeDef> <dataTypeDef>
<name>LFBProperties</name> <name>LFBProperties</name>
<synopsis>LFB Properties definition</synopsis> <synopsis>LFB Properties definition</synopsis>
<struct> <struct>
<component componentID="1"> <component componentID="1">
<name>PacketsSentToCE</name> <name>PacketsSentToCE</name>
skipping to change at page 12, line 41 skipping to change at page 13, line 21
<component componentID="8"> <component componentID="8">
<name>ReceivedErrorBytesFromCE</name> <name>ReceivedErrorBytesFromCE</name>
<synopsis>Error Bytes received from CE</synopsis> <synopsis>Error Bytes received from CE</synopsis>
<typeRef>uint32</typeRef> <typeRef>uint32</typeRef>
</component> </component>
</struct> </struct>
</dataTypeDef> </dataTypeDef>
Properties for LFB instances Properties for LFB instances
3.6. LFB class inheritance 2.6. LFB class inheritance
The ForCES model [RFC5812] allows inheritance for LFB classes. The ForCES model [RFC5812] allows inheritance for LFB classes.
However the xml schema defines only the LFB class from which an LFB However the xml schema defines only the LFB class from which an LFB
class may inherit. Recent implementations have identified an issue class may inherit. Recent implementations have identified an issue
where ambiguity rises when different versions of an LFB class exists. where ambiguity rises when different versions of an LFB class exists.
This document augments the derivedFrom part of the LFB class This document augments the derivedFrom part of the LFB class
definition with a mandatory version attribute when the derivedFrom definition with an optional version attribute when the derivedFrom
field is used. field is used.
Having the version attribute as optional was a decision based on the
need to maintain backwards compatibility with the XML schema defined
in [RFC5812]. However if the version is omitted, then in the
presence of multiple versions of the same LFB class, the derivedFrom
will always select the latest version.
This extension alters the definition of the derivedFrom in the xml This extension alters the definition of the derivedFrom in the xml
schema from Figure 13 to Figure 14. schema from Figure 14 to Figure 15.
<xsd:element name="derivedFrom" minOccurs="0"/> <xsd:element name="derivedFrom" minOccurs="0"/>
Figure 13: Initial xml for the LFB class inheritance Figure 14: Initial xml for the LFB class inheritance
<xsd:element name="derivedFrom" minOccurs="0"> <xsd:element name="derivedFrom" minOccurs="0">
<xsd:complexType> <xsd:complexType>
<xsd:simpleContent> <xsd:simpleContent>
<xsd:extension base="xsd:NMTOKEN"> <xsd:extension base="xsd:NMTOKEN">
<xsd:attribute name="version" <xsd:attribute name="version"
type="versionType" use="required"/> type="versionType" use="optional"/>
</xsd:extension> </xsd:extension>
</xsd:simpleContent> </xsd:simpleContent>
</xsd:complexType> </xsd:complexType>
</xsd:element> </xsd:element>
Figure 14: New xml for the LFB class inheritance Figure 15: New xml for the LFB class inheritance
An example of the use of the version attribute is given in Figure 16
<derivedFrom version="1.0">EtherPHYCop</derivedFrom> <derivedFrom version="1.0">EtherPHYCop</derivedFrom>
Figure 15: Example of use of new xml for LFB class Inheritance Figure 16: Example of use of new xml for LFB class Inheritance
3.7. Enhancing XML Validation 2.7. Enhancing XML Validation
As specified earlier this is not an extension but an enhancement of As specified earlier this is not an extension but an enhancement of
the schema to provide additional validation rules. This includes the schema to provide additional validation rules. This includes
adding new key declarations to provide uniqueness as defined by the adding new key declarations to provide uniqueness as defined by the
ForCES Model [RFC5812]. Such validations work only on within the ForCES Model [RFC5812]. Such validations work only on within the
same xml file. same xml file.
The following validation rules have been appended in the original The following validation rules have been introduced that did not
schema in [RFC5812]: exist in the original schema in [RFC5812]:
1. Each metadata ID must be unique. 1. Each metadata ID must be unique.
2. LFB Class IDs must be unique. 2. LFB Class IDs must be unique.
3. Component ID, Capability ID and Event Base ID must be unique per 3. Component ID, Capability ID and Event Base ID must be unique per
LFB. LFB.
4. Event IDs must be unique per LFB. 4. Event IDs must be unique per LFB.
5. Special Values in Atomic datatypes must be unique per atomic 5. Special Values in Atomic datatypes must be unique per atomic
datatype. datatype.
4. XML Extension Schema for LFB Class Library Documents 3. XML Extension Schema for LFB Class Library Documents
This section includes the new XML Schema. Note that the namespace
number has been updated from 1.0 to 1.1
<?xml version="1.0" encoding="UTF-8"?> <?xml version="1.0" encoding="UTF-8"?>
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" <xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema"
xmlns="urn:ietf:params:xml:ns:forces:lfbmodel:1.0" xmlns="urn:ietf:params:xml:ns:forces:lfbmodel:1.1"
xmlns:lfb="urn:ietf:params:xml:ns:forces:lfbmodel:1.0" xmlns:lfb="urn:ietf:params:xml:ns:forces:lfbmodel:1.1"
targetNamespace="urn:ietf:params:xml:ns:forces:lfbmodel:1.0" targetNamespace="urn:ietf:params:xml:ns:forces:lfbmodel:1.1"
elementFormDefault="qualified" attributeFormDefault="unqualified"> elementFormDefault="qualified" attributeFormDefault="unqualified">
<xsd:annotation> <xsd:annotation>
<xsd:documentation xml:lang="en"> <xsd:documentation xml:lang="en">
Schema for Defining LFB Classes and associated types Schema for Defining LFB Classes and associated types
(frames, data types for LFB attributes, and metadata). (frames, data types for LFB attributes, and metadata).
</xsd:documentation> </xsd:documentation>
</xsd:annotation> </xsd:annotation>
<xsd:element name="description" type="xsd:string"/> <xsd:element name="description" type="xsd:string"/>
<xsd:element name="synopsis" type="xsd:string"/> <xsd:element name="synopsis" type="xsd:string"/>
<!-- Document root element: LFBLibrary --> <!-- Document root element: LFBLibrary -->
skipping to change at page 16, line 32 skipping to change at page 17, line 28
<!-- Extension --> <!-- Extension -->
<!--declare keys to have unique IDs --> <!--declare keys to have unique IDs -->
<xsd:key name="contentKeyID"> <xsd:key name="contentKeyID">
<xsd:selector xpath="lfb:contentKey"/> <xsd:selector xpath="lfb:contentKey"/>
<xsd:field xpath="@contentKeyID"/> <xsd:field xpath="@contentKeyID"/>
</xsd:key> </xsd:key>
<!-- /Extension --> <!-- /Extension -->
</xsd:element> </xsd:element>
<xsd:element name="struct" type="structType"> <xsd:element name="struct" type="structType">
<!-- Extension --> <!-- Extension -->
<!-- key declaration to make componentIDs unique in a struct --> <!-- key declaration to make componentIDs
unique in a struct -->
<xsd:key name="structComponentID"> <xsd:key name="structComponentID">
<xsd:selector xpath="lfb:component"/> <xsd:selector xpath="lfb:component"/>
<xsd:field xpath="@componentID"/> <xsd:field xpath="@componentID"/>
</xsd:key> </xsd:key>
<!-- /Extension --> <!-- /Extension -->
</xsd:element> </xsd:element>
<xsd:element name="union" type="structType"/> <xsd:element name="union" type="structType"/>
<xsd:element name="alias" type="typeRefNMTOKEN"/> <xsd:element name="alias" type="typeRefNMTOKEN"/>
</xsd:choice> </xsd:choice>
</xsd:group> </xsd:group>
skipping to change at page 17, line 5 skipping to change at page 17, line 51
<xsd:restriction base="xsd:token"> <xsd:restriction base="xsd:token">
<xsd:pattern value="\c+"/> <xsd:pattern value="\c+"/>
<xsd:pattern value="string\[\d+\]"/> <xsd:pattern value="string\[\d+\]"/>
<xsd:pattern value="byte\[\d+\]"/> <xsd:pattern value="byte\[\d+\]"/>
<xsd:pattern value="octetstring\[\d+\]"/> <xsd:pattern value="octetstring\[\d+\]"/>
</xsd:restriction> </xsd:restriction>
</xsd:simpleType> </xsd:simpleType>
<xsd:complexType name="atomicType"> <xsd:complexType name="atomicType">
<xsd:sequence> <xsd:sequence>
<xsd:element name="baseType" type="typeRefNMTOKEN"/> <xsd:element name="baseType" type="typeRefNMTOKEN"/>
<xsd:element name="rangeRestriction" type="rangeRestrictionType" <xsd:element name="rangeRestriction"
minOccurs="0"/> type="rangeRestrictionType" minOccurs="0"/>
<xsd:element name="specialValues" type="specialValuesType" <xsd:element name="specialValues" type="specialValuesType"
minOccurs="0"> minOccurs="0">
<!-- Extension --> <!-- Extension -->
<xsd:key name="SpecialValue"> <xsd:key name="SpecialValue">
<xsd:selector xpath="specialValue"/> <xsd:selector xpath="specialValue"/>
<xsd:field xpath="@value"/> <xsd:field xpath="@value"/>
</xsd:key> </xsd:key>
<!-- /Extension --> <!-- /Extension -->
</xsd:element> </xsd:element>
<!-- Extension --> <!-- Extension -->
skipping to change at page 19, line 30 skipping to change at page 20, line 27
<xsd:element name="array" type="arrayType"> <xsd:element name="array" type="arrayType">
<!--declare keys to have unique IDs --> <!--declare keys to have unique IDs -->
<xsd:key name="contentKeyID1"> <xsd:key name="contentKeyID1">
<xsd:selector xpath="lfb:contentKey"/> <xsd:selector xpath="lfb:contentKey"/>
<xsd:field xpath="@contentKeyID"/> <xsd:field xpath="@contentKeyID"/>
</xsd:key> </xsd:key>
<!-- /Extension --> <!-- /Extension -->
</xsd:element> </xsd:element>
<xsd:element name="struct" type="structType"> <xsd:element name="struct" type="structType">
<!-- Extension --> <!-- Extension -->
<!-- key declaration to make componentIDs unique <!-- key declaration to make componentIDs
in a struct --> unique in a struct -->
<xsd:key name="structComponentID1"> <xsd:key name="structComponentID1">
<xsd:selector xpath="lfb:component"/> <xsd:selector xpath="lfb:component"/>
<xsd:field xpath="@componentID"/> <xsd:field xpath="@componentID"/>
</xsd:key> </xsd:key>
<!-- /Extension --> <!-- /Extension -->
</xsd:element> </xsd:element>
</xsd:choice> </xsd:choice>
</xsd:sequence> </xsd:sequence>
</xsd:complexType> </xsd:complexType>
</xsd:element> </xsd:element>
skipping to change at page 20, line 8 skipping to change at page 21, line 6
<xsd:complexType> <xsd:complexType>
<xsd:sequence> <xsd:sequence>
<xsd:element name="name" type="xsd:NMTOKEN"/> <xsd:element name="name" type="xsd:NMTOKEN"/>
<xsd:element ref="synopsis"/> <xsd:element ref="synopsis"/>
<xsd:element name="version" type="versionType"/> <xsd:element name="version" type="versionType"/>
<xsd:element name="derivedFrom" minOccurs="0"> <xsd:element name="derivedFrom" minOccurs="0">
<xsd:complexType> <xsd:complexType>
<xsd:simpleContent> <xsd:simpleContent>
<xsd:extension base="xsd:NMTOKEN"> <xsd:extension base="xsd:NMTOKEN">
<xsd:attribute name="version" <xsd:attribute name="version"
type="versionType" use="required"/> type="versionType" use="optional"/>
</xsd:extension> </xsd:extension>
</xsd:simpleContent> </xsd:simpleContent>
</xsd:complexType> </xsd:complexType>
</xsd:element> </xsd:element>
<xsd:element name="inputPorts" <xsd:element name="inputPorts"
type="inputPortsType" minOccurs="0"/> type="inputPortsType" minOccurs="0"/>
<xsd:element name="outputPorts" <xsd:element name="outputPorts"
type="outputPortsType" minOccurs="0"/> type="outputPortsType" minOccurs="0"/>
<xsd:element name="components" <xsd:element name="components"
type="LFBComponentsType" minOccurs="0"/> type="LFBComponentsType" minOccurs="0"/>
skipping to change at page 26, line 51 skipping to change at page 27, line 48
</xsd:sequence> </xsd:sequence>
</xsd:complexType> </xsd:complexType>
<xsd:simpleType name="booleanType"> <xsd:simpleType name="booleanType">
<xsd:restriction base="xsd:string"> <xsd:restriction base="xsd:string">
<xsd:enumeration value="0"/> <xsd:enumeration value="0"/>
<xsd:enumeration value="1"/> <xsd:enumeration value="1"/>
</xsd:restriction> </xsd:restriction>
</xsd:simpleType> </xsd:simpleType>
</xsd:schema> </xsd:schema>
OpenFlow XML Library ForCES LFB XML Schema
5. Acknowledgements 4. Acknowledgements
The author would like to acknowledge Joel Halpern, Jamal Hadi Salim The author would like to acknowledge Joel Halpern, Jamal Hadi Salim
and Dave Hood for their comments and discussion that helped shape and Dave Hood for their comments and discussion that helped shape
this document in a better way. this document in a better way.
6. IANA Considerations 5. IANA Considerations
This specification requests that LFB Component ID 0 to be reserved. IANA has registered a new XML namespace, as per the guidelines in RFC
3688 [RFC3688].
7. Security Considerations URI: The URI for this namespace is
The security considerations that have been described in the ForCES urn:ietf:params:xml:ns:forces:lfbmodel:1.1
Model RFC [RFC5812] apply to this document as well.
8. References Registrant Contact: IESG
8.1. Normative References XML: none, this is an XML namespace
[I-D.ietf-forces-ceha] 6. Security Considerations
Ogawa, K., Wang, W., Haleplidis, E., and J. Salim, "ForCES
Intra-NE High Availability", draft-ietf-forces-ceha-08
(work in progress), October 2013.
[OpenFlowSpec1.1] The changes described in this document have no effect on security as
http://www.OpenFlow.org/, "The OpenFlow 1.1 they are simply constructs to write XML library definitions. Thus
Specification.", <http://www.OpenFlow.org/documents/ they have no effect on security semantics with the protocol and as
OpenFlow-spec-v1.1.0.pdf>. such the security considerations that have been described in the
ForCES Model RFC [RFC5812] apply to this document as well.
7. References
7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
January 2004.
[RFC5810] Doria, A., Hadi Salim, J., Haas, R., Khosravi, H., Wang, [RFC5810] Doria, A., Hadi Salim, J., Haas, R., Khosravi, H., Wang,
W., Dong, L., Gopal, R., and J. Halpern, "Forwarding and W., Dong, L., Gopal, R., and J. Halpern, "Forwarding and
Control Element Separation (ForCES) Protocol Control Element Separation (ForCES) Protocol
Specification", RFC 5810, March 2010. Specification", RFC 5810, March 2010.
[RFC5812] Halpern, J. and J. Hadi Salim, "Forwarding and Control [RFC5812] Halpern, J. and J. Hadi Salim, "Forwarding and Control
Element Separation (ForCES) Forwarding Element Model", RFC Element Separation (ForCES) Forwarding Element Model", RFC
5812, March 2010. 5812, March 2010.
8.2. Informative References [RFC7121] Ogawa, K., Wang, W., Haleplidis, E., and J. Hadi Salim,
"High Availability within a Forwarding and Control Element
Separation (ForCES) Network Element", RFC 7121, February
2014.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 7.2. Informative References
Requirement Levels", BCP 14, RFC 2119, March 1997.
[OpenFlowSpec1.1]
http://www.OpenFlow.org/, "The OpenFlow 1.1
Specification.", <http://www.OpenFlow.org/documents/
OpenFlow-spec-v1.1.0.pdf>.
Author's Address Author's Address
Evangelos Haleplidis Evangelos Haleplidis
University of Patras University of Patras
Department of Electrical and Computer Engineering Department of Electrical and Computer Engineering
Patras 26500 Patras 26500
Greece Greece
Email: ehalep@ece.upatras.gr Email: ehalep@ece.upatras.gr
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