One document matched: draft-xia-sdnrg-nemo-language-00.xml
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<rfc category="std" docName="draft-xia-sdnrg-nemo-language-00"
ipr="trust200902">
<front>
<title abbrev="NEtwork MOdeling Language">NEMO (NEtwork MOdeling)
Language</title>
<author fullname="Yinben Xia" initials="Y." role="editor" surname="Xia">
<organization>Huawei Technologies Co., Ltd</organization>
<address>
<postal>
<street>Q14, Huawei Campus, No.156 Beiqing Road</street>
<city>Hai-Dian District, Beijing, 100095</city>
<country>P.R. China</country>
</postal>
<email>xiayinben@huawei.com</email>
</address>
</author>
<author fullname="Sheng Jiang" initials="S." role="editor" surname="Jiang">
<organization>Huawei Technologies Co., Ltd</organization>
<address>
<postal>
<street>Q14, Huawei Campus, No.156 Beiqing Road</street>
<city>Hai-Dian District, Beijing, 100095</city>
<country>P.R. China</country>
</postal>
<email>jiangsheng@huawei.com</email>
</address>
</author>
<author fullname="Tianran Zhou" initials="T." role="editor" surname="Zhou">
<organization>Huawei Technologies Co., Ltd</organization>
<address>
<postal>
<street>Q14, Huawei Campus, No.156 Beiqing Road</street>
<city>Hai-Dian District, Beijing, 100095</city>
<country>P.R. China</country>
</postal>
<email>zhoutianran@huawei.com</email>
</address>
</author>
<author fullname="Susan Hares" initials="S." surname="Hares">
<organization>Huawei Technologies Co., Ltd</organization>
<address>
<postal>
<street>7453 Hickory Hill</street>
<!-- Reorder these if your country does things differently -->
<city>Saline</city>
<region>CA</region>
<code>48176</code>
<country>USA</country>
</postal>
<email>shares@ndzh.com</email>
<!-- uri and facsimile elements may also be added -->
</address>
</author>
<!--<Sheng> It is actually network service orchestration interface.-->
<date month="" year="2014" />
<area>IRTF</area>
<workgroup>SDNRG</workgroup>
<keyword>SDN Controller Northbound Interface, NEtwork MOdeling
Language</keyword>
<abstract>
<t>The North-Bound Interface (NBI), located between the network control
plane and the applications, is essential to enable the application
innovations and nourish the eco-system of SDN. </t>
<t>While most of the NBIs are provided in the form of API, this document
proposes the NEtwork MOdeling (NEMO) language which is anther NBI
fashion. Concept, model and syntax are introduced in the document. </t>
</abstract>
</front>
<middle>
<section title="Introduction">
<t>While SDN (Software Defined Network) is becoming one of the most
important directions of network evolution, the essence of SDN is to make
the network more flexible and easy to use. The North-Bound Interface
(NBI), located between the control plane and the applications, is
essential to enable the application innovations and nourish the
eco-system of SDN by abstracting the network capabilities/information
and opening the abstract/logic network to applications.</t>
<t>The NBI is usually provided in the form of API (Application
Programming Interface). Different vendors provide self-defined API sets.
Each API set, such as OnePK from Cisco and OPS from Huawei, often
contains hundreds of specific APIs. Diverse APIs without consistent
style are hard to remember and use, and nearly impossible to be
standardized.</t>
<t>Most of those APIs are designed by network domain experts, who are
used to thinking from the network system perspective. The interface
designer does not know how the users will use the device and exposes
information details as much as possible. It enables better control of
devices, but leaves huge burden of selecting useful information to users
without well training. Since the NBI is used by network users, a more
appropriate design is to think from the user perspective and abstract
the network from the top down. <xref
target="I-D.sdnrg-service-description-language"></xref> describe the
requirements for a service description language and the design
considerations.</t>
<t>A top-down NBI design contains following features:</t>
<t><list style="symbols">
<t>Express user intent<vspace blankLines="1" />To simplify the
operation, applications or users can use the NBI directly to
describe their requirements for the network without taking care of
the implementation. All the parameters without user concern will be
concealed by the NBI.</t>
<t>Platform independent<vspace blankLines="1" />With the NBI, the
application or user can describe network demand in a generic way, so
that any platform or system can get the identical knowledge and
consequently execute to the same result. Any low-level and
device/vendor specific configurations and dependencies should be
avoided.</t>
<t>Intuitive domain specific language (DSL) for network<vspace
blankLines="1" />The expression of the DSL should be human-friendly
and be easily understood by network operators. DSL should be
directly used by the system.</t>
<t>Privilege control<vspace blankLines="1" />Every application or
user is authorized within a specific network domain, which can be
physical or virtual. While different network domains are isolated
without impact, the application or user may have access to all the
resource and capabilities within its domain. The user perception of
the network does not have to be the same as the network operators.
The proposed NEtwork MOdeling (NEMO) language works on the user's
view so the users can create topologies based on the resources the
network-operators allow them to have.</t>
<t>Declarative style<vspace blankLines="1" />As described above,
NEMO language is designed to help defining service requirement to
network, detailed configurations and instructions performed by
network devices are opaque to network operators. So NEMO language
should be declarative rather than imperative. </t>
</list>To implement such an NBI design, we can learn from the
successful case of SQL (Structured Query Language), which simplified the
complicated data operation to a unified and intuitive way in the form of
language. Applications do not care about the way of data storage and
data operation, but to describe the demand for the data storage and
operation and then get the result. As a data domain DSL, SQL is simple
and intuitive, and can be embedded in applications. So what we need for
the network NBI is a set of "network domain SQL". </t>
</section>
<section title="Terminology">
<t>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 <xref
target="RFC2119"></xref> when they appear in ALL CAPS. When these words
are not in ALL CAPS (such as "should" or "Should"), they have their
usual English meanings, and are not to be interpreted as <xref
target="RFC2119"></xref> key words.<list hangIndent="5" style="hanging">
<t hangText="Network service">also "service" for short, is the
service logic that contains network operation requirements;</t>
<t hangText="Network APP">also "APP" for short, is the application
to implement the network service;</t>
<t hangText="Network user">also "user" for short, is the network
administrator or operator.</t>
</list></t>
</section>
<section title="Related work">
<t>YANG is a data modeling language used to model configuration and
state data manipulated by the Network Configuration Protocol (NETCONF),
NETCONF remote procedure calls, and NETCONF notifications <xref
target="RFC6020"></xref>. Although it is extensible for more data
modeling in addition to NETCONF, YANG is not capable of describing high
level network requirements, such as SLA (Service Level Agreement). YANG
is designed for north-bound interfaces of the device, which is also the
south-bound of the controller. It is not proper to model the north-bound
interface of the controller, aka the NBI. Moreover, the YANG is not
capable of describing the service processing logic, which typically
includes transition of conditions and states.</t>
<t>UML (Unified Modeling Language) is a powerful modeling language,
which is domain agnostic. It is hard to describe the network demand, and
cannot be embedded in network applications. UML is appropriate to
describe the model behind the NBI language not the NBI itself.</t>
<t>With the emergence of the SDN concept, it is a consensus to simplify
the network operation, which leads to many cutting-edge explorations in
the academic area.</t>
<t>Nick McKeown from Stanford University proposed the SFNet <xref
target="TSFNet"></xref>, which translated the high level network demand
to the underlying controller interfaces. By concealing the low level
network details, the controller simplified the operation of resource,
flow, and information for applications. The SFNet is used for the SDN
architecture design, and does not go into the NBI design.</t>
<t>Jennifer from Princeton University designed the Frenetic <xref
target="Frenetic"></xref> based on the OpenFlow protocol. It is an
advanced language for flow programming, and systematically defines the
operating model and mode for the flow. However, the network requirement
from the service is not only the flow operations, but also includes
operations of resource, service conditions, and service logic.</t>
<t>In the book <xref target="PBNM"></xref>, John Strassner defined the
policy concept and proposed the formal description for network
operations by using the policy. The method for querying network
information is absent in the book. Virtual tenant network and operations
to the tenant network are not considered.</t>
<t>All these investigations direct to the future SDN that use simple and
intuitive interfaces to describe the network demands without complex
programming.</t>
</section>
<section title="The NEMO Language overview">
<t>NEMO language is a domain specific language (DSL) based on
abstraction of network models and conclusion of operation patterns. It
provides NBI fashion in the form of language. With limited number of key
words and expressions, NEMO language defines the entity and capability
models for users with different view of network abstraction, and enables
network users/applications to describe their demands for network
resources, services and logical operations in an intuitive expression.
And finally the NEMO language description can be explained and executed
by a language engine.</t>
<section title="Network Model of the NEMO Language">
<t>Behind the NEMO language, there is a set of meta-models abstracting
the network demands from the top down according to the service
requirement. Those demands can be divided into two types: the demand
for network resources and the demands for network behaviors.</t>
<t>The network resource is composed of three kinds of entities: node,
link and flow. Each entity contains property and statistic
information. With a globally unique identifier, the network entity is
the basic object for operation.</t>
<t><list style="symbols">
<t>Node model: describes the entity with the capability of packet
processing. According to the functionality, there are three types
of node<list style="symbols">
<t>The forwarding node (FN) only deals with L2/3 forwarding.
It forwards packets according to the forwarding table and
modifies packet heads.</t>
<t>The processing node (PN) provides L4-7 network services,
and will modify the body of packets.</t>
<t>The logical node (LN) describes a set of network elements
and their links, such as subnet, autonomous system, and
internet. It conceals the internal topology and exposes
properties as one entity. It also enables iteration, i.e., a
network entity may include other network entities.</t>
</list></t>
<t>Link model: describes the connectivity between node entities.
According to the forwarding capability, links are usually divided
into layer 2 and layer 3 types</t>
<t>Flow model: describes a sequence of packets with certain common
characters, such as source/destination IP address, port, and
protocol. From the northbound perspective, flow is the special
traffic with user concern, which may be per device or across many
devices. So the flow characters also include ingress/egress node,
and so on.</t>
</list>Network behavior includes the information and control
operations.</t>
<t>The information operation provides two methods to get the network
information for users.</t>
<t><list style="symbols">
<t>Query: a synchronous mode to get the information, i.e., one can
get the response when a request is sent out.</t>
<t>Notification: an asynchronous mode to get the information,
i.e., with one request, one or multiple responses will be sent to
the subscriber automatically whenever trigger conditions meet.</t>
</list>The NEMO language uses policy to describe the control
operation.</t>
<t><list style="symbols">
<t>Policy: control the behavior of specific entities by APP, such
as flow policy, node policy. All the policies follow the same
pattern "with <condition>, to execute <action>", and
can be applied to any entity</t>
</list></t>
</section>
<section title="Primitives">
<t>The primitives of NEMO language are derived from the network model,
and fall into four categories.</t>
<t><list style="letters">
<t>Resource access primitives<figure>
<artwork><![CDATA[Node/UnNode entity_id Type {FN|PN|LN}
Owner node_id
Properties key1 ,value1
Node/UnNode: create/delete a node
Entity id: system allocated URI for the node entity
Type: Node type of FN (forwarding node), PN (processing node)
or LN (logical node)
Owner: since the node can be nested, this primitive figures
out which node the new one belongs to
Properties: other properties to describe the node in the form of
(key, value).
Link/UnLink entity_id Endnodes (node1_id,node2_id)
SLA key,value
Properties key1 ,value1
Link/UnLink: create/delete a link.
Entity id: system allocated URI for the link entity
Endnodes: two end-node IDs of the link
SLA: SLA description for the link
Properties: other properties to describe the link in the form of
(key, value).
Flow/UnFlow entity_id Match/UnMatch key1, value1|
Range(value, value) |
Mask(value, value)
Properties key1 ,value1
Flow/UnFlow: create/delete a flow.
Match/UnMatch: create/delete match items for the flow
Range: describe the range of the value
Mask: use mask to describe a range of the value
Properties: other properties to describe the flow in the form of
(key, value).
]]></artwork>
</figure></t>
<t>Behavior primitives<figure>
<artwork><![CDATA[Query key Value {value}
From entity_id
Query: generate a synchronously query
key: the parameter name to be queried
Value: the return value for the query
From: the entity to be queried (define entity_id).
Policy/UnPolicy policy_id Appliesto entity_id
Condition {expression}
Action {"forwardto"|"drop"|"gothrough"|
"bypass"|"guaranteeSLA"|"Set"|
"Packetout"|Node|UnNode|Link|Unlink}
Policy/UnPolicy: create/delete a policy
Appliesto: apply the policy to an entity
Condition: condition to execute the policy
Action: actions to be executed when conditions are met
Notification/UnNotification entity_id On key
Every period
RegisterListener
callbackfunc
Notification/UnNotification: create/delete a notification for an
entity
On: the notification will monitor the state change of a
parameter identified by the "key"
Every: time period at which to report the state
RegisterListener: the callback function that is used to process the
notification.
]]></artwork>
</figure></t>
<t>Connection management primitives<figure>
<artwork><![CDATA[Connect conn_id Address ip_address
Port port_num
Disconnect conn_id
Connect: set up a connection to the controller
Address: IP address of the controller to connect to
Port: port of the controller to connect to
Disconnect: disconnect to the controller.
]]></artwork>
</figure></t>
<t>Transaction primitives<figure>
<artwork><![CDATA[Transaction
Commit
Transaction: indicate the beginning of a transaction
Commit: commit to execute the transaction
]]></artwork>
</figure></t>
</list></t>
</section>
</section>
<section title="The NEMO Language Examples">
<t>A tenant needs two connections to carry different service flows
between two datacenters.</t>
<t>one connection of the tenant is 40G bandwidth with less than 400ms
delay, another connection is 100M bandwidth with less than 50ms
delay.<figure>
<artwork><![CDATA[{
Link Link1_id
Endnodes (DC1_node_id, DC2_node_id)
Property "NAME","DC1_DC2_link_one","Bandwith",40G,"Delay",400ms
Link Link2_id
Endnodes (DC1_node_id, DC2_node_id)
Property "NAME","DC1_DC2_link_two","Bandwith",100M,"Delay",50ms
}
]]></artwork>
</figure>The tenant has two types of traffic, CDN sync traffic uses
high bandwidth connection and online game traffic uses low latency
connection.</t>
<t><figure>
<artwork><![CDATA[{
Flow flow1_id
Match "srcip","10.0.1.1/24","dstip","20.0.1.1/24","Port","55555"
Property "NAME","CDN sync flow","Bidirection","true"
Flow flow2_id
Match "srcip","10.0.1.1/24","dstip","20.0.1.1/24","Port","56663"
Property "NAME","online Game","Bidirection","true"
Policy policy1_id
Appliesto flow1_id
Action "forwardto",link1_id
Policy policy2_id
Appliesto flow2_id
Action "gothrough",link2_id
}
]]></artwork>
</figure>The tenant wants the online game traffic to go through WOC in
nighttime before it is carried by low latency connection.</t>
<t><figure>
<artwork><![CDATA[{
Policy policy3_id
Appliesto flow2_id
Condition {Time>18:00 or Time< 2:00}
Action "gothrough",{woc_node_id ,link2_id}
}
]]></artwork>
</figure></t>
</section>
<section anchor="Security" title="Security Considerations">
<t>Because the network customers are allowed to customize their own
services, they may bring potentially big impacts to a running IP
network. A strong user authentication mechanism is needed for the
northbound interface of the SDN controller. User authorization should be
carefully managed by the network administrator to avoid any dangerous
operations and prevent any abuse of network resources.</t>
</section>
<section anchor="IANA" title="IANA Considerations">
<t>This memo includes no request to IANA.</t>
</section>
<section anchor="Acknowledgements" title="Acknowledgements">
<t>The authors would like to thanks the valuable comments made by Wei
Cao, Xiaofei Xu, Fuyou Miao and Wenyang Lei.</t>
<t>This document was produced using the xml2rfc tool <xref
target="RFC2629"></xref>.</t>
</section>
</middle>
<back>
<references title="Informative References">
<?rfc include='reference.RFC.2629'?>
<?rfc include='reference.RFC.2119'?>
<?rfc include='reference.RFC.6020'?>
<reference anchor="TSFNet">
<front>
<title>Towards Software-Friendly Networks, APSys 2010, pp:49-54,
2010, New Delhi, India.</title>
<author fullname="Kok-Kiong Yap" initials="K." surname=" Yap">
<organization></organization>
</author>
<author fullname="Te-Yuan" initials="T." surname=" Huang">
<organization></organization>
<address>
<postal>
<street></street>
<city></city>
<region></region>
<code></code>
<country></country>
</postal>
<phone></phone>
<facsimile></facsimile>
<email></email>
<uri></uri>
</address>
</author>
<author fullname="Ben" initials="B. " surname="Dodson">
<organization></organization>
<address>
<postal>
<street></street>
<city></city>
<region></region>
<code></code>
<country></country>
</postal>
<phone></phone>
<facsimile></facsimile>
<email></email>
<uri></uri>
</address>
</author>
<author fullname="Monica S." initials="M. " surname="Lam">
<organization></organization>
<address>
<postal>
<street></street>
<city></city>
<region></region>
<code></code>
<country></country>
</postal>
<phone></phone>
<facsimile></facsimile>
<email></email>
<uri></uri>
</address>
</author>
<author fullname="Nick" initials="N." surname="McKeown">
<organization></organization>
<address>
<postal>
<street></street>
<city></city>
<region></region>
<code></code>
<country></country>
</postal>
<phone></phone>
<facsimile></facsimile>
<email></email>
<uri></uri>
</address>
</author>
<date />
</front>
</reference>
<reference anchor="Frenetic">
<front>
<title>Frenetic: A Network Programming Languages, ICFP' 11</title>
<author fullname="Nate" initials="N." surname="Foster">
<organization></organization>
</author>
<author fullname="Rob" initials="R." surname="Harrison">
<organization></organization>
<address>
<postal>
<street></street>
<city></city>
<region></region>
<code></code>
<country></country>
</postal>
<phone></phone>
<facsimile></facsimile>
<email></email>
<uri></uri>
</address>
</author>
<author fullname="Michael J." initials="M. " surname="Freedman">
<organization></organization>
<address>
<postal>
<street></street>
<city></city>
<region></region>
<code></code>
<country></country>
</postal>
<phone></phone>
<facsimile></facsimile>
<email></email>
<uri></uri>
</address>
</author>
<author fullname="Christopher" initials="C." surname="Monsanto">
<organization></organization>
<address>
<postal>
<street></street>
<city></city>
<region></region>
<code></code>
<country></country>
</postal>
<phone></phone>
<facsimile></facsimile>
<email></email>
<uri></uri>
</address>
</author>
<author fullname="Jennifer" initials="J." surname="Rexford">
<organization></organization>
<address>
<postal>
<street></street>
<city></city>
<region></region>
<code></code>
<country></country>
</postal>
<phone></phone>
<facsimile></facsimile>
<email></email>
<uri></uri>
</address>
</author>
<author fullname="Alec " initials="A." surname="Story">
<organization></organization>
<address>
<postal>
<street></street>
<city></city>
<region></region>
<code></code>
<country></country>
</postal>
<phone></phone>
<facsimile></facsimile>
<email></email>
<uri></uri>
</address>
</author>
<author fullname="David" initials="D." surname="Walker">
<organization></organization>
<address>
<postal>
<street></street>
<city></city>
<region></region>
<code></code>
<country></country>
</postal>
<phone></phone>
<facsimile></facsimile>
<email></email>
<uri></uri>
</address>
</author>
<date />
</front>
</reference>
<reference anchor="PBNM">
<front>
<title>Policy-Based Network Management: Solutions for the Next
Generation, Morgan Kaufmann Publishers Inc. San Francisco, CA,
USA.</title>
<author fullname="John" initials="J." surname="Strassner">
<organization></organization>
</author>
<date year="2003" />
</front>
</reference>
<reference anchor="I-D.sdnrg-service-description-language">
<front>
<title abbrev="draft-xia-nai-modeling-language-00">Requirements for
a Service Description Language and Design Considerations,
draft-xia-sdnrg-service-description-language-00, Work in
progress</title>
<author fullname="Yinben" initials="Y." surname="Xia">
<organization>Huawei Technologies Co., Ltd</organization>
</author>
<author fullname="Sheng" initials="S." surname="Jiang">
<organization>Huawei Technologies Co., Ltd</organization>
</author>
<author fullname="Susan Hares" initials="S." surname="Hares">
<organization>Huawei Technologies Co., Ltd</organization>
</author>
<date month="July" year="2014" />
</front>
</reference>
</references>
</back>
</rfc>
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