| Internet Engineering Task Force | B. Zhuge |
| Internet-Draft | Y. Qi |
| Intended status: Standards Track | W. Wang |
| Expires: June 23, 2018 | M. Gao |
| Zhejiang Gongshang University | |
| December 20, 2017 |
Intelligent SDN Architecture based on Meta-Model
draft-zhuge-sdn-00
This document defines a notion called Software-Defined Pricing (SDP) and introduces it into a Software-Defined Networks (SDN) framework. The SDN system with SDP inside is expected to promote the efficiency on SDN resources usage and ease management for service providers.This document also defines a mechanism that can efficiently mannage SDN framework orderly and intelligently.
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Software-Defined Networks(SDN) is in the research process. With the idea of SDN, networking resources like switches, routers and types of Network Elements (NEs)are managed as kinds of virtual resources, forming virtual networks so as to provide rather flexible services to network users. In this research process, we noticed that how to price the services and the use of virtual network resources in an SDN is as critical as how the SDN is defined. We consider that it seems a precious idea to treat a service pricing mechanism as part of the SDN framework and to manage it in a software-defined way.
Network service prices are traditionally determined by service providers in a rather rigid way, which lacks of flexibility and sometimes even fairness to resources users. By means of the idea of SDP, it is able to treat service pricing as a part of SDN, forming a service pricing model flexible to time, traffic and other network factors and status. In this way, it is expected to promote the efficiency of SDN resources usage and ease the management for service providers.
Due to the ever increasing network complexity, the operators of intelligent network are driven toward a virtualization of network functionality that calls for a paradigm shift from a hardware-based approach to a software-based approach. We will correspondingly develop an intelligent management framework based on the concept of SDN, which is featured by the decoupling of control plane from data plane.The intelligent SDN framework aims to provide a viable way to solve the existing challenges in a unified manner.
Software-Defined Pricing (SDP) is an idea specific to network management, whose core is that the service prices of network resources are determined by means of software-defined algorithms and/or mechanisms, which figure the prices according to various factors and status of the network resources. In contrast to SDP, service prices may be pre-determined rigidly by service providers.
An SDP Protocol is an instance of SDP implementation shown in a way of protocol, which specifically defines algorithms and/or mechanisms to price specific services and use of network resources. An SDP protocol may be a private protocol if it is defined by a service provider personally, or a public protocol if defined publicly by standardization organizations.
By use of the software-defined mechanism, SDP essentially supports automatic negotiations of prices in a pricing process. Automatic resource and price negotiation features a Guaranteed Service (GS). As a result, SDN with SDP essentially supports GS services.
Network users must accept and abide by the network SDP protocol when they use the network resources and the services.
An SDP protocol usually includes trading partners, trading content, obligations and other transaction costs. Service providers can make provisions for users in terms of workload and resource use.
As an example, we present a typical process for an SDP protocol. When users expect to use resources from a virtual network by a service provider, users first query prices of various resources and services by means of the SDP protocol. The service provider returns the resource prices to users. Then, users will start up a price negotiation process with the service provider by use of the SDP protocol. Both the user and the service provider will proceed the price negotiation process based on their specific price negotiation algorithms. The negotiation process will be ended only from the user with the SDP protocol. It will end with an agreement is either met or not. The SDP protocol process is shown in Figure 1. Usually, in a negotiation algorithm, the user or the service provider are able to take into consideration of current network status and other network factors, which make the price negotiation process much more efficient and flexible than traditional pricing methods.
+------+ + + +-----------+ | | | --------SDP protocol------->| -----------------+ | | | | | | search price | | | | | | <-------SDP protocol--------|<-----------------+ | | | | | --------SDP protocol------->|------------------+ | service | | user | | | price negotiation| | sprovider | | | | <-------SDP protocol--------|<-----------------+ | | | | | --------SDP protocol------->|------------------+ | | | | | | negotiation ends | | | | | | <-------SDP protocol--------|<-----------------+ | | +------+ + + +-----------+
Figure 1: Process of an SDP Protocol
To fulfill above process, an SDP protocol header may usually include fields like shown in Figure 2, where:
+----------------------------------------------------------------------+
| ID | Level | Expression | TimeSpec | Price | ContractTime | State |
+------------|------------|----------|---------------------------------+
| |
| +----------------------+
V |
+------------------------+ |
| ID | Type | Properties | |
+-----------|------------+ V
| +-------------------------------------+
| | Y/M/D | Mon-Fri/Weekend | 8:00-0:00 |
V +-------------------------------------+
+-----------------------------------------+
| rate | delay | shake | etc. |
+-----------------------------------------+
Figure 2: An SDP Protocol Header
(TBD)
SDP can be applied to SDN architecture well because of its natural software-defined feature.
In SDN architecture, control plane and data plane are separated to achieve the segregation of the control and forwarding. A typical SDN architecture usually includes: application layer, control layer, and infrastructure (forwarding) layer. To adopt SDP in SDN, an SDP module is applied. An SDP module implements the SDP protocol and corresponding negotiation algorithms/mechanisms. An SDP module can be applied to any layer in the SDN, where resources need to be priced. In this way, theoretically, all kinds of network resources and services can be programmed in terms of use prices as well as resources functions. This makes SDN more complete regarding its software-defining characters.
In SDN application market, resource providers and resource consumers actually hardly know each other fully for the value of resources and services. Hence, the trade between them is an information asymmetry game. To take this into consideration, an SDP module with its protocol and associated negotiation mechanisms applied to an SDN system is usually of the following features:
As mentioned, a typical SDN framework usually includes Application Layer, Control Layer, and Infrastructure (forwarding) Layer. In SDN Application Layer, things like virtual servers and other SDN personalized services will be presented as individual SDN Applications. Based on the idea above on adopting SDP to SDN, a typical framework of an SDN system which adopts SDP module is as shown in Figure 3.In this framework, the SDP-App includes an SDP module inside and makes the module support software-defined pricing function.
SDP-App may exist in each layer of the SDN framework. Note that, SDN Application communicates with SDN controllers via the AD-SAL and Service Interface.Either should require that the AD-SAL and Service Interface must support SDP protocol to support the SDN with SDP. Also note that, SDN Control Layer includes the network service, SDP-App, and control abstraction Layer(CAL), it is defined to communicate with SDN forwarding layer by means of the resource abstraction layer(RAL) and the uniformly defined SDN southern interface protocols like ForCES ,OpenFlow, etc. To support SDN with SDP, SDP protocol must be designed supportable by these protocols for messaging purpose. This may become a key question for the design of an SDP protocol. The SDN Forwarding Layer includes the network element, and SDP-App. It is exposed via the Resource Abstraction Layer (RAL), which may be expressed by one or more abstraction models.
(TBD)
o--------------------------------o
| |
| +-------------+ +----------+ |
| | Application | | SDP-App | |
| +-------------+ +----------+ |
| Application Layer |
o---------------Y----------------o
|
*-----------------------------Y---------------------------------*
| Application-Driven Services Abstraction Layer (AD-SAL) |
*-----------------------------Y---------------------------------*
|
|Service
|Interface
|
o-----------------------------Y--------------------------------o
| Control | Layer |
| +----------Y--------+ +---------+ |
| | Network Service | | SDP-App | |
| +----------Y--------+ +----Y----+ |
| | | |
| *------------Y----------------Y------* |
| | Control Abstraction Layer (CAL) | |
| *------------Y-----------------------* |
| | |
o-----------------------------|--------------------------------o
|
| Southbound
| Interface
|
*-----------------------------Y---------------------------------*
| Resource Abstraction Layer (RAL) |
*-----------------------------Y---------------------------------*
| | |
| o--------Y-----------o +----------+ |
| | Network Element | | SDP-App | |
| o--------------------o +----------+ |
| Forwarding Layer |
+---------------------------------------------------------------+
Figure 3: An SDN Framework with SDP
As another example, we try to present an SDN application which uses SDP to access network resources so as to get optimal resources use price. We call the SDN application a 'Chat' App, which is to construct a social App platform to connect, communicate and share among people and things by means of Guaranteed-Service (GS) rather than Best-Efforts (BE) services to users. Hence, the App needs to hire network resources from cloud network service providers to provide virtual server and Guaranteed Service (GS) resources.
Fig 4 shown the process for 'Chat' to access the GS Resources by use of SDP. 'Chat' client and 'Chat' Server makes service agreement via SDP module. 'Chat' server may be implemented as a virtual server, whose pricing is also implemented by SDP module. Further more, resources to support the virtual server and the 'chat' message forwarding are used based on SDP negotiations. As shown inFigure 4 , in this case, SDN controller inside the virtual server of 'chat' may send requests to multiple cloud platforms by SDP module(such as Sina cloud, Baidu cloud and Ali cloud in the figure). All the cloud service providers return with resource prices, and SDN controller inside the 'chat' server select or negotiate with the cloud service providers. SDN controller finally may select or get a successful or failed negotiation results and returns to the 'chat' client via SDP protocols. As a result, a transaction for a GS service pricing ends.
+---------------------+
| 'Chat' client |
| ( With SDP ) |
+---------------------+
A
|
V
+---------------------+
| 'Chat' server |
| ( With SDP ) |
+---------------------+
A
|
V
+---------------------+
| virtual server |
| ( With SDP ) |
+---------------------+
A
|
V
+---------------------+
| SDN controller |
| ( With SDP ) |
+---------------------+
A
|
+----------------------------------------------+
| | |
V V V
+----------------+ +---------------+ +-------------+
| Sina cloud | | Baidu cloud | | Ali cloud |
| (With SDP) | | (With SDP ) | | (With SDP |
+----------------+ +---------------+ +-------------+
Figure 4: The Process for 'Chat' Accessing Resources by Use of SDP
A Meta-Model is a model architecture in which each defined layer will supply services and functions that built in a meta-model, to be exactly, APP-likely way. Then all of APPs could be refactoried and combined to satisfied sorts of diversified needs from users in upper layer. To be more precisely to defined the meta-model, the following elements will be invoked:
Based on the idea above on Meta-Model to SDN, a typical framework of an SDN with SDP bases on Meta-Model system is as shown in Figure 5.In this framework, the application layer includes a meta-app part inside and makes the module support dividing and refactoring the meta-service .
(TBD)
o---------------------------------------------------------------o
| |
| +-------------+ +----------+ +----------+ +----------+ |
| | Meta-App | | SDP-App | | Meta-APP | | Meta-App | |
| +-------------+ +----------+ +----------+ +----------+ |
| Application Layer |
o---------------------------------------------------------------o
|
*-----------------------------Y---------------------------------*
| Business Abstraction Layer |
*-----------------------------Y---------------------------------*
|
|Service
|Interface
|
o-----------------------------Y--------------------------------o
| Control | Layer |
| +----------Y--------+ +---------+ |
| | Meta-Service | | SDP-App | |
| +----------Y--------+ +----Y----+ |
| | | |
| | +-----------+ |
| | | |
| *------Y----Y-* |
| | Con-App | |
| *------Y------* |
| | |
o-----------------------------Y--------------------------------o
|
| Southbound
| Interface
|
*-----------------------------Y---------------------------------*
| Service Abstraction Layer |
*----Y-------------Y----------Y-----------Y-------Y---------Y---*
| | | | | |
*----Y-----* *----Y--* *----Y----* *---Y--* *--Y--* *---Y----*
| OpenFlow | | OVSDB | | NETCONF | | LISP | | BGP | | ForCES |
*----Y-----* *----Y--* *----Y----* *---Y--* *--Y--* *---Y----*
| | | | | |
*----Y-------------Y----------Y-----------Y-------Y---------Y---*
| Resource Abstraction Layer (RAL) |
*---------------------------------------------------------------*
| |
| o--------------o o----------------o +----------+ |
| | Meta-Ability | | Meta-Ability | | SDP-App | |
| o--------------o o----------------o +----------+ |
| Forwarding Layer |
+---------------------------------------------------------------+
Figure 5: An SDN Framework with SDP Bases on Meta-Model
As the mentioned definiton of SDN framework with SDP bases on Meta-Model above, the minimum units of application are meta-app, which of control layer are meta-service, and the minimum units in forwarding layer are meta-ability. Meanwhile, Refering to the idea of reconfigurable network architecture, The features of business and the load capacity of network could be abstract as a chained model like "Application -> Meta-App -> Meta-Service -> Meta-Ability" which be showed in Figure 6. A complicated network application can be divided to amounts of meta-app abstractly, and each meta-app contains features and functions of network applications. In this case, The meta-app is also combined by a series of fine-grained meta-service sets that called network fundamental function components. In addition, A set of meta-abilities can combine a series of fundamental load components of network, which can associate meta-service.
Conceptually, the meta-ability is a tiny unit defined by fundamental network, which having the abilities to certain capacity and function information. By using meta-abilities, The core of internet can be abstracted to lots of distinct LFBs (Logical Functional Block) which combined by the set of meta-abilities. Meanwhile, This also allows the core of internet to add new meta-ability extensions for promoting network extensibility.
Meta-Abilities are described as senary struction including type, mark, attribute set, operation, vendor and price. This "type" element specified the type of meta-abilities for classifying the meta-abilities with similar network function into separate type class. This "mark" element should be defined as natural number. Via type and mark element, the unique identity of meta-abilities can be defined within the scope of world-wide network. This "attribute set" element includes parameters about targets and relevant capacity of those targets. This targets in attribute set can specify the targets that meta-abilities should deal with. And this relevant capacity in attribute set can indicates the parameterized capacity goal of meta-abilities. This "operation" element indicates the operation that meta-ability can implemente to targets. This "vendor" element on behalf of the vendors of this meta-ability (e.g., telecom operators). This "price" element state the cost in the process of using this meta-ability.
(TBD)
Service Service Application
Abstract Map Abstract
o---------------o o---------------o o-----------o
| | | | | |
| +-----------+ | | +-----------+ | | +-------+ |
| | M-ability |->------->-| M-service |->-+----->-| M-App |->---+
| +-----------+ | +----->-+-----------+ | | | +-------+ | |
| | | | | | | | | |
| +-----------+ | | | +-----------+ | +----->-+-------+ | |
| | M-ability |->-+----->-| M-service |->---+--->-| M-App |->-+ |
| +-----------+ | | +--->-+-----------+ | | +->-+-------+ | | |
| | | | | | | | | | | +->o-----o
| +-----------+ | | | | +-----------+ | +-|->-+-------+ | +--->| App |
| | M-ability |->-|-+--->-| M-service |->-+---|->-| M-App | | +-->o-----o
| +-----------+ | | +-->-+-----------+ | | | | +-------+ | |
| . | | | | . | | +-+ | | |
| . | | | | . | | | | | |
| . | | | | . | | | | | |
| . | | | | . | | | | | |
| +-----------+ | +--|-->-+-----------+ | +-|--->-+-------+ | |
| | M-ability |->----+ | | M-service |->---+--->-| M-App |->--+
| +-----------+ | | +-----------+ | | +-------+ |
| | | | | |
o---------------o o---------------o o-----------o
where:
M-ability = Meta-ability
M-service = Meta-service
M-App = Meta-App
Figure 6: The Relationship between Meta-Model Layers
As shown inFigure 7A complete SDN environment is made up of application layer, control layer, data forwarding plane, if regard SDN environment as an economy market ,Then corresponding to the three layers structure of SDN environment, the economy market can be divided into: user layer, trading platform and provider layer. But each layer is embedded with the pricing model and consumption pattern which is apply to this layer , the communication between each other is accomplished by special protocol, each of them is independent but closely linked.In application layer, there are many users, the users were independent of each other, and they belonged to different platforms.In control layer there are multiple platforms, on the two ends of platform respectively connected to different users and providers, the existence of multiple platforms can solve the monopoly of a single platform and the problem that users and providers'choice unicity.In fowarding layer,there are many providers, they can offer different types of resources for each platform.
*------------------------------------------------------------------------*
|Application +--------------+ +---------------+ +---------------+ |
| Layer | Application 1| | Application 2 | ... | Application n | |
| +--------------+ +---------------+ +---------------+ |
*--------------Y-Y-Y---------------Y-Y--Y--------------------Y--Y--Y-----*
| | | +-------------+ | | +---------------+ | |
| | | | +-----------|--|----|------------------+ |
| | +-|---|-----------|--|----|----------------+ |
| +---|---|-------+ | +----|-----------+ | |
| | | | | | | | |
*--------------V-----V---V-------V---V-------V-----------V----V----V-----*
| Control +--------------+ +---------------+ +---------------+ |
| Layer |Control Plane1| |Control Plane2 | ... |Control Plane n| |
| +--------------+ +---------------+ +---------------+ |
*--------------Y-Y-Y---------------Y-Y--Y--------------------Y--Y--Y-----*
| | | +-------------+ | | +---------------+ | |
| | | | +-----------|--|----|------------------+ |
| | +-|---|-----------|--|----|----------------+ |
| +---|---|-------+ | +----|-----------+ | |
| | | | | | | | |
*--------------V-----V---V-------V---V-------V-----------V----V----V---------*
|Forwarding +-----------------+ +-----------------+ +------------------+ |
| Layer |Forwarding Plane1| |Forwarding Plane2| ... |Forwarding Plane n| |
| +-----------------+ +-----------------+ +------------------+ |
*----------------------------------------------------------------------------*
Figure 7: Multi-Ownership Combinatorial Double Auction Model
We summarize the differences of three kinds of trading pattern and the position of SDN architecture which applied them , as shown in Figure 8:
-----------------------------------------------------------------------------------
Trading | Product | Trading| Trading Risk | Trading price | Location
Pattern | Pattern | market | | | of SDN
-----------|------------|--------|---------------|-----------------|---------------
spot | Retail | No |Greater risk | Negotiation | Application
trading | Commodity| | |non-standard | layer
-----------|------------|--------|---------------|-----------------|---------------
Futures | A kind of | Future | Has margin, |Settlement based |
trading | products as| | less risk |on the price |Data forwarding
| a unit | | |of the exchange |layer
-----------|------------|--------|---------------|-----------------|---------------
Planned |Goods in any| Overall|PlannedSpending| Control price, | Entire
trading | combination| market |almost no risk |according to |architecture
| | | |supply and demand|
-----------|------------|--------|---------------|-----------------|---------------
Figure 8: the Differences among Three Trading Patterns
The commodities mode, trading market and other factors of planned trading decides it apply to the entire SDN market; the commodities mode of spot trading determines which is suitable for small number of resources trading, and it has some risks, therefore it works in the application layer of SDN architecture; the commodities mode of futures trading trade in a kind of resource as a unit, and the risk is small, possess the futures market, so it works in data forwarding layer of SDN architecture.
As shown inFigure 9We defines a advenced mechanism of SDN framework, the primary module sustains the speciality of intelligence and smart, which composed by three main components, including network sense function, SDP module, and policy control.
The network sence function, within this intelligence mechanism, in change of preceiving each details , monitoring network state on a domain scale, to be special, bandwidth, quality of service, line loading, besides, node capacities of calculation, storage and speed. While network sence function learns those information from SDN south interface, they could analyze and encapsulate them with an overlay, following, send encapsulated message to SDP module though inner port.
The SDP module porvides pre-customized algorithm based upon SDP protocol, which would operated in encapsulated message processing, consists the interaction and the relation between meta-abilities and requirements of applicatoin, and manages preliminary SFC policies, overviewed of RFC 7665, to construct meta-abilities with knowledge reasoning.
Policy, in contrast, interacts with the system in other places.Policies and SDP module may monitor meta-abilities to decide if additional (or fewer) instances of services are needed. When applicable, those decisions may in turn result in interactions that direct the control logic to change the placement of meta-abilities service function chain,in short, MSFC.
The policy control module is part of the overall intelligent mechanism, and is responsible for constructing MSFCs, translating MSFCs to forwarding paths, and propagating path information to participating meta-ability nodes to achieve requisite forwarding behavior to construct the service overlay and qualify the requirements of application. For instance, the physical placement of meta-ability nodes may be static; selecting exactly which MSFCs and which meta-abilities from those MSFCs are to be used, or it may be dynamic, allowing the network to perform some or all of the choices of MSFC or meta-abilities to use to deliver the selected service chain within the constraints represented by the service path. While, within this mechanism, physical resource and logicl meta models state are permitted to be registered on the policy control module.
Architecturally, within the same policy control module domain, some MSFCs may be fully specified, selecting exactly which MSFC and which meta-abilities are to be visited by packets using that MSFC, while other MSFCs may be quite vague, deferring to the traffic the decisions about the exact sequence of steps to be used to realize the MSFC.
o . . . . . . . . . . . . . . . . . . . . . . .
. +------------+
. + | SDP Module |+ + -----------------------
South . +---------+ / +------------+ \ | Policy +----+ +----+
Intf . | Network | / +| Control |SFC1|...|SFCn|
+--------->| Sence |+ +--------------+ | Module +----+ +----+
Network. | Function| |Kernel Control| +------------V--------V---
State . +---------+ | Module | / /
. +--------------+<-------------+--------+
o . . . . . . . . Y . . . . . . . . . . . . . .
+-------------+
| |
V V
Meta-Ability1...Meta-Abilityn
Figure 9: Composite Intelligent and Software-Defined-Price Mechanism Model
Intelligent mechanism bases on meta-model is predicated on several key architectural principles:
TBD
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