idnits 2.17.00 (12 Aug 2021) /tmp/idnits9192/draft-xia-sdnrg-nemo-language-03.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- -- The document has examples using IPv4 documentation addresses according to RFC6890, but does not use any IPv6 documentation addresses. Maybe there should be IPv6 examples, too? Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year == Line 136 has weird spacing: '...service also ...' == Line 142 has weird spacing: '...rk user also ...' == Line 582 has weird spacing: '... Type l3gr...' == Line 584 has weird spacing: '...roperty locat...' == Line 641 has weird spacing: '...roperty band...' == (5 more instances...) -- The document date (October 14, 2015) is 2411 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) -- Obsolete informational reference (is this intentional?): RFC 2629 (Obsoleted by RFC 7749) Summary: 0 errors (**), 0 flaws (~~), 7 warnings (==), 3 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 SDNRG Y. Xia, Ed. 3 Internet-Draft S. Jiang, Ed. 4 Intended status: Standards Track T. Zhou, Ed. 5 Expires: April 16, 2016 S. Hares 6 Huawei Technologies Co., Ltd 7 October 14, 2015 9 NEMO (NEtwork MOdeling) Language 10 draft-xia-sdnrg-nemo-language-03 12 Abstract 14 The North-Bound Interface (NBI), located between the control plane 15 and the applications, is essential to enable the application 16 innovations and nourish the eco-system of SDN. 18 While most of the NBIs are provided in the form of API, this document 19 proposes the NEtwork MOdeling (NEMO) language which is intent based 20 interface with novel language fashion. Concept, model and syntax are 21 introduced in the document. 23 Status of This Memo 25 This Internet-Draft is submitted in full conformance with the 26 provisions of BCP 78 and BCP 79. 28 Internet-Drafts are working documents of the Internet Engineering 29 Task Force (IETF). Note that other groups may also distribute 30 working documents as Internet-Drafts. The list of current Internet- 31 Drafts is at http://datatracker.ietf.org/drafts/current/. 33 Internet-Drafts are draft documents valid for a maximum of six months 34 and may be updated, replaced, or obsoleted by other documents at any 35 time. It is inappropriate to use Internet-Drafts as reference 36 material or to cite them other than as "work in progress." 38 This Internet-Draft will expire on April 16, 2016. 40 Copyright Notice 42 Copyright (c) 2015 IETF Trust and the persons identified as the 43 document authors. All rights reserved. 45 This document is subject to BCP 78 and the IETF Trust's Legal 46 Provisions Relating to IETF Documents 47 (http://trustee.ietf.org/license-info) in effect on the date of 48 publication of this document. Please review these documents 49 carefully, as they describe your rights and restrictions with respect 50 to this document. Code Components extracted from this document must 51 include Simplified BSD License text as described in Section 4.e of 52 the Trust Legal Provisions and are provided without warranty as 53 described in the Simplified BSD License. 55 Table of Contents 57 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 58 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 59 3. Requirements for the Intent Based NBI Language . . . . . . . 4 60 4. Related work . . . . . . . . . . . . . . . . . . . . . . . . 5 61 5. The NEMO Language Specifications . . . . . . . . . . . . . . 6 62 5.1. Network Model of the NEMO Language . . . . . . . . . . . 6 63 5.2. Notation . . . . . . . . . . . . . . . . . . . . . . . . 7 64 5.3. NEMO Language Overview . . . . . . . . . . . . . . . . . 8 65 5.4. Model Definition . . . . . . . . . . . . . . . . . . . . 9 66 5.4.1. Data Types . . . . . . . . . . . . . . . . . . . . . 9 67 5.4.2. Model Definition and Description Statement . . . . . 10 68 5.5. Resource Access Statements . . . . . . . . . . . . . . . 12 69 5.5.1. Node Operations . . . . . . . . . . . . . . . . . . . 12 70 5.5.2. Connection Operations . . . . . . . . . . . . . . . . 13 71 5.5.3. Flow Operations . . . . . . . . . . . . . . . . . . . 14 72 5.6. Behavior Statements . . . . . . . . . . . . . . . . . . . 15 73 5.6.1. Query Behavior . . . . . . . . . . . . . . . . . . . 16 74 5.6.2. Operation Behavior . . . . . . . . . . . . . . . . . 16 75 5.6.3. Notification Behavior . . . . . . . . . . . . . . . . 19 76 5.7. Transaction Statements . . . . . . . . . . . . . . . . . 20 77 6. The NEMO Language Examples . . . . . . . . . . . . . . . . . 20 78 7. Security Considerations . . . . . . . . . . . . . . . . . . . 21 79 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21 80 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 22 81 10. Informative References . . . . . . . . . . . . . . . . . . . 22 82 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 23 84 1. Introduction 86 While SDN (Software Defined Network) is becoming one of the most 87 important directions of network evolution, the essence of SDN is to 88 make the network more flexible and easy to use. The North-Bound 89 Interface (NBI), located between the control plane and the 90 applications, is essential to enable the application innovations and 91 nourish the eco-system of SDN by abstracting the network 92 capabilities/information and opening the abstract/logic network to 93 applications. 95 The NBI is usually provided in the form of API (Application 96 Programming Interface). Different vendors provide self-defined API 97 sets. Each API set, such as OnePK from Cisco and OPS from Huawei, 98 often contains hundreds of specific APIs. Diverse APIs without 99 consistent style are hard to remember and use, and nearly impossible 100 to be standardized. 102 In addition, most of those APIs are designed by network domain 103 experts, who are used to thinking from the network system 104 perspective. The interface designer does not know how the users will 105 use the device and exposes information details as much as possible. 106 It enables better control of devices, but leaves huge burden of 107 selecting useful information to users without well training. Since 108 the NBI is used by network users, a more appropriate design is to 109 express user intent and abstract the network from the top down. 111 To implement such an NBI design, we can learn from the successful 112 case of SQL (Structured Query Language), which simplified the 113 complicated data operation to a unified and intuitive way in the form 114 of language. Applications do not care about the way of data storage 115 and data operation, but to describe the demand for the data storage 116 and operation and then get the result. As a data domain DSL, SQL is 117 simple and intuitive, and can be embedded in applications. So what 118 we need for the network NBI is a set of "network domain SQL". 119 [I-D.xia-sdnrg-service-description-language] describe the 120 requirements for a service description language and the design 121 considerations. 123 This document will introduce an intent based NBI with novel language 124 fashion. 126 2. Terminology 128 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 129 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 130 "OPTIONAL" in this document are to be interpreted as described in 131 [RFC2119] when they appear in ALL CAPS. When these words are not in 132 ALL CAPS (such as "should" or "Should"), they have their usual 133 English meanings, and are not to be interpreted as [RFC2119] key 134 words. 136 Network service also "service" for short, is the service logic that 137 contains network operation requirements; 139 Network APP also "APP" for short, is the application to implement 140 the network service; 142 Network user also "user" for short, is the network administrator or 143 operator. 145 3. Requirements for the Intent Based NBI Language 147 An intent based NBI language design contains following features: 149 o Express user intent 151 To simplify the operation, applications or users can use the NBI 152 directly to describe their requirements for the network without 153 taking care of the implementation. All the parameters without 154 user concern will be concealed by the NBI. 156 o Platform independent 158 With the NBI, the application or user can description of network 159 demand in a generic way, so that any platform or system can get 160 the identical knowledge and consequently execute to the same 161 result. Any low-level and device/vendor specific configurations 162 and dependencies should be avoided. 164 o Intuitive Domain Specific Language (DSL) for network 166 The expression of the DSL should be human-friendly and be easily 167 understood by network operators. DSL should be directly used by 168 the system. 170 o Privilege control 172 Every application or user is authorized within a specific network 173 domain, which can be physical or virtual. While different network 174 domains are isolated without impact, the application or user may 175 have access to all the resource and capabilities within its 176 domain. The user perception of the network does not have to be 177 the same as the network operators. The NBI language works on the 178 user's view so the users can create topologies based on the 179 resources the network-operators allow them to have. 181 o Declarative style 183 As described above, the NBI language is designed to help defining 184 service requirement to network, detailed configurations and 185 instructions performed by network devices are opaque to network 186 operators. So the NBI language should be declarative rather than 187 imperative. 189 4. Related work 191 YANG [RFC6020] is a data modeling language used to model 192 configuration and state data manipulated by the Network Configuration 193 Protocol (NETCONF) [RFC6241], NETCONF remote procedure calls, and 194 NETCONF notifications. 196 UML (Unified Modeling Language) is a powerful modeling language, 197 which is domain agnostic. YANG and UML all focus on syntax 198 specification which formulate grammatical structure of NBI language, 199 however, they do not have the ability to express users' real 200 semantics. NBI language should facilitate users to express their own 201 intent explicitly, instead of general complying with grammar syntax. 202 So YANG and UML is appropriate to describe the model behind the NBI 203 language not the NBI itself. 205 With the emergence of the SDN concept, it is a consensus to simplify 206 the network operation, which leads to many cutting-edge explorations 207 in the academic area. 209 Nick McKeown from Stanford University proposed the SFNet [TSFNet], 210 which translated the high level network demand to the underlying 211 controller interfaces. By concealing the low level network details, 212 the controller simplified the operation of resource, flow, and 213 information for applications. The SFNet is used for the SDN 214 architecture design, and does not go into the NBI design. 216 Jennifer Rexford from Princeton University designed the Frenetic 217 [Frenetic] based on the OpenFlow protocol. It is an advanced 218 language for flow programming, and systematically defines the 219 operating model and mode for the flow. However, the network 220 requirement from the service is not only the flow operations, but 221 also includes operations of resource, service conditions, and service 222 logic. 224 In the book [PBNM], John Strassner defined the policy concept and 225 proposed the formal description for network operations by using the 226 policy. The method for querying network information is absent in the 227 book. Virtual tenant network and operations to the tenant network 228 are not considered. 230 All these investigations direct to the future SDN that use simple and 231 intuitive interfaces to describe the network demands without complex 232 programming. 234 5. The NEMO Language Specifications 236 NEMO language is a domain specific language (DSL) based on 237 abstraction of network models and conclusion of operation patterns. 238 It provides NBI fashion in the form of language. Instead of tons of 239 abstruse APIs, with limited number of key words and expressions, NEMO 240 language enables network users/applications to describe their demands 241 for network resources, services and logical operations in an 242 intuitive way. And finally the NEMO language description can be 243 explained and executed by a language engine. 245 5.1. Network Model of the NEMO Language 247 Behind the NEMO language, there is a set of basic network models 248 abstracting the network demands from the top down according to the 249 service requirement. Those demands can be divided into two types: 250 the demand for network resources and the demands for network 251 behaviors. 253 The network resource is composed of three kinds of entities: node, 254 connection and flow. Each entity contains property and statistic 255 information. With a globally unique identifier, the network entity 256 is the basic object for operation. Users can construct their own 257 topology or network traffic arbitrarily with these basic objects 258 without considering about real physical topology. In addition, NEMO 259 Engine also has the ability of obtaining available resources 260 automatically as operation objects when users don't define them. 262 o Node model: describes the entity with the capability of packet 263 processing. According to the functionality, there are two types 264 of node 266 * The function node (FN) provides network services or forwarding 267 with user concern, such as, firewall, load balance, vrouter, 268 etc. 270 * The business node (BN) describes a set of network elements and 271 their connections, such as subnet, autonomous system, and 272 internet. It conceals the internal topology and exposes 273 properties as one entity. It also enables iteration, i.e., a 274 network entity may include other network entities. 276 o Connection model: describes the connectivity network resource 277 between node entities. With Connection model, user could apply 278 for link resources between nodes and user can assign specific 279 bandwidth for them. Connection constructs the foundation of 280 communication, namely, the necessary condition for communications 281 between nodes is there are available resources between them. By 282 default, the communication is allowed if there are direct 283 connections between them. The Connection is not limited to the 284 connectivity between single entity and single entity, but it can 285 also express the connectivity between single entity and multiply 286 entities, or multiply entities and multiply entities. 288 o Flow model: describes a sequence of packets with certain common 289 characters, such as source/destination IP address, port, and 290 protocol. From the northbound perspective, flow is the special 291 traffic with user concern, which may be per device or across many 292 devices. So the flow characters also include ingress/egress node, 293 and so on. The Flow model together with the associated operations 294 describe reachability of specific traffic between nodes in the 295 virtual network, which is different from the connection resource 296 between nodes. 298 Network behavior includes the information aquisition and the control 299 operations. 301 The NEMO language provides two methods to get the network information 302 for users. 304 o Query: a synchronous mode to get the information, i.e., one can 305 get the response when a request is sent out. 307 o Notification: an asynchronous mode to get the information, i.e., 308 with one request, one or multiple responses will be sent to the 309 subscriber automatically whenever trigger conditions meet. 311 The NEMO language uses operations to control the network. 313 o Operation: control the behavior of specific entities by APP, such 314 as flow operation, node operation. All the operations follow the 315 same pattern "when , do , with ", 316 and can be applied to any entity. But some of operation elements 317 can be omitted according to users' requirement. Operation has the 318 similar meaning with policy in some sense which also emphasizes 319 the dynamic adjustment of objects. 321 5.2. Notation 323 The syntactic notation used in this specification is an extended 324 version of BNF ("Backus Naur Form" or "Backus Normal Form"). In BNF, 325 each syntactic element of the language is defined by means of a 326 production rule. This defines the element in terms of a formula 327 consisting of the characters, character strings, and syntactic 328 elements that can be used to form an instance of it. The version of 329 BNF used in this specification makes use of the following symbols: 331 < > 333 Angle brackets delimit character strings that are the names of 334 syntactic elements. 336 ::= 338 The definition operator. This is used in a production rule to 339 separate the element defined by the rule from its definition. The 340 element being defined appears to the left of the operator and the 341 formula that defines the element appears to the right. 343 [ ] 345 Square brackets indicate optional elements in a formula. The portion 346 of the formula within the brackets may be explicitly specified or may 347 be omitted. 349 { } 351 Braces group elements in a formula. The portion of the formula 352 within the braces shall be explicitly specified. 354 | 356 The alternative operator. The vertical bar indicates that the 357 portion of the formula following the bar is an alternative to the 358 portion preceding the bar. If the vertical bar appears at a position 359 where it is not enclosed in braces or square brackets, it specifies a 360 complete alternative for the element defined by the production rule. 361 If the vertical bar appears in a portion of a formula enclosed in 362 braces or square brackets, it specifies alternatives for the contents 363 of the innermost pair of such braces or brackets. 365 !! 367 Introduces ordinary English text. This is used when the definition 368 of a syntactic element is not expressed in BNF. 370 5.3. NEMO Language Overview 372 NEMO language provides 5 classes of commands: model definition, 373 resource access, behavior, connection management, transaction to 374 facilitate the user intent description. 376 := | | 377 378 := | | 379 | 380 := | | | 381 | | 382 | | 383 | | 384 := | | 385 | | | 386 | 387 := | 389 NEMO language provides limited number of key words to enables network 390 users/applications to describe their intent. The key words supported 391 by the language are as follows: 393 := Boolean | Integer | String | Date | UUID | EthAddr | 394 IPPrefix | NodeModel | ConnectionModel | FlowModel | 395 ActionModel | Description | Porperty | Node | Connection| 396 Flow | EndNodes | Type | Contain | Match | List | 397 Range| Query | From | Notification | Listener | 398 Operation | Target | Priority | Condition | Action | 399 Transaction | Commit | CREATE | IMPORT | UPDATE | DELETE 401 5.4. Model Definition 403 5.4.1. Data Types 405 NEMO language provides several build-in data types: 407 Boolean This data type is used for simple flags that track true/ 408 false conditions. There are only two possible values: true and 409 false. The Boolean literal is represented by the token . 411 Integer A number with an integer value, within the range from 412 -(2^63) to +(2^63)-1. The Integer literal is represented by the 413 token . 415 String A sequence of characters. The string is always in the 416 quotation marks. The String literal is represented by the token 417 . 419 Date A string in the format yyyy-mm-dd hh:mm:ss, or yyyy-mm-dd, or 420 hh:mm:ss. The Date literal is represented by the token . 422 UUID A string in the form of Universally Unique IDentifier 423 [RFC4122], e.g. "6ba7b814-9dad-11d1-80b4-00c04fd430c8". A 424 typical usage of the UUID is to identify network entities, 425 policies, actions and so on. The UUID literal is represented by 426 the token . 428 EthAddr A string in the form of MAC address, e.g. 429 "00:00:00:00:00:01". The EthAddr literal is represented by the 430 token . 432 IPPrefix A string in the form of IP address, e.g. "192.0.2.1". The 433 mask can be used in the IP address description, e.g. 434 "192.0.2.0/24". The IPPrefix literal is represented by the token 435 . 437 The token can be defined as follows: 439 := Boolean | Integer | String | Date | UUID | 440 EthAddr | IPPrefix 442 And a generic literal is represented by the token 444 := | | | | | 445 | 447 5.4.2. Model Definition and Description Statement 449 In addition to default build-in network models, NEMO language 450 facilitates users to define new model types. 452 The token is a string that MUST start with a letter and 453 followed by any number of letters and digits. More specific naming 454 can be defined as follows: 456 := !!type name of the node model 457 := !!type name of the connection model 458 := !!type name of the flow model 459 := | | 460 := !!type name of the action model 461 := | 462 := !!name of the property in a model 464 The statement is used to create a node model: 466 := NodeModel 467 Property { : }; 469 The NodeModel specifies a new node type. 471 The Property is followed by a list of " : " 472 pairs to specify properties for the new node type. Since belonging 473 network is the intrinsic property for a node model, there is no need 474 to redefine the belonging network in the property list. 476 Example: 478 NodeModel "DPI" Property String : "name", Boolean : "is_enable"; The 479 statement generates a new node model named DPI with two properties, 480 "name" and "is_enable". 482 The statement is used to create a connection 483 model: 485 := ConnectionModel 486 Property { : }; 488 The ConnectionModel specifies a new connection type. 490 The Property is followed by a list of " : " 491 pairs to specify properties for the new connection type. Since end 492 nodes are intrinsic properties for a connection model, there is no 493 need to redefine the end nodes in the property list. 495 The statement is used to create a flow model: 497 := FlowModel 498 Property { : }; 500 The FlowModel specifies a new flow type. 502 The Property is followed by a list of " : " 503 pairs to specify fields for the new flow type. The 504 statement is used to create an action model: 506 := ActionModel 507 Property { : }; 509 The ActionModel specifies a new action type. 511 The Property is followed by a list of " : " 512 pairs to specify properties for the new action. 514 NEMO language also supports querying the description of a defined 515 model by using the statement: 517 := Description ; 518 The keyword Description is followed by a model type name. The 519 description of the queried model will return from the language 520 engine. 522 5.5. Resource Access Statements 524 In NEMO language, each resource entity instance is identified by a 525 which MUST be unique. We use the following token to 526 indicate the identifier given to the resource entity instance. 528 := !! name to identify the node instance 529 := !! name to identify the connection instance 530 := !! name to identify the flow instance 531 := || 533 5.5.1. Node Operations 535 NEMO model defines basic method for the node instances, and uses 536 intuitive keyword to indicate the specific method. User could 537 create, import, update and delete a node instance. 539 The statement is used to create or update a node 540 instance: 542 := CREATE Node Type 543 [Contain {}] 544 [Property {: }]; 546 The statement is used to import an existing external 547 node instance: 549 := IMPORT Node Type 550 [Contain {}] 551 [Property {: }]; 553 The statement is used to update an existing node 554 instance: 556 := UPDATE Node 557 [Contain {}] 558 [Property {: }]; 560 In all the above three statements, the Node is followed by a user 561 specified . According to the method, system will take 562 corresponding action for the node instance. If the method is CREATE 563 or IMPORT and the is new in the system, a new node will be 564 created automatically. If the method is UPDATE and the 565 exists in the system, the corresponding node identified by 566 will be updated with the following information. 568 The Type specifies the type of the node to operate. 570 The Contain is an optional keyword specifying the internal nodes 571 which are included in this node instance. 573 The Property is an optional keyword followed by a list of 574 ": " pairs. Multiple ": 575 " pairs are separated by commas. The MUST be 576 selected from the property definition of the corresponding node 577 definition. 579 An example of creating a node instance is as follows: 581 CREATE Node Headquarter 582 Type l3group 583 Contain LN-1 584 Property location : "Beijing"; 586 The statement creates a layer 3 virtual network which contains a 587 predefined node "LN-1". The l3 virtual network is located in 588 Beijing. 590 The statement is used to delete a node instance: 592 := DELETE Node ; 594 The DELETE Node is to delete a node in user's network. 596 5.5.2. Connection Operations 598 NEMO model defines basic method for the connection instances, and use 599 intuitive keyword to indicate the specific method. User could 600 create, update and delete a connection instance. 602 The statement is used to create a connection: 604 := CREATE Connection 605 Type 606 EndNodes , 607 [Property {: }]; 609 The statement is used to update a connection: 611 := UPDATE Connection 612 [EndNodes {}, {}] 613 [Property {: }]; 615 The Connection is followed by a user specified . If 616 the method is CREATE and the is new in the system, a 617 new connection will be created automatically. If the method is 618 UPDATE and the exists in the system, the 619 corresponding connection identified by the will be 620 updated with the following information. 622 The Type specifies the type of the connection to use. For example 623 there will be point to point connection, or point to multiple points 624 connection. 626 The EndNodes specifies the end nodes of a connection. For each 627 connection there will be left nodes and right nodes stand for the two 628 ends. 630 The Property is an optional keyword followed by a list of 631 ": " pairs. Multiple ": 632 " pairs are separated by commas. The MUST be 633 selected from the property definition of the corresponding connection 634 definition. 636 An example of creating a connection instance is as follows: 638 CREATE Connection connection-1 639 Type p2p 640 EndNodes S1, S2 641 Property bandwidth : 1000, delay : 40; 643 The statement creates a connection between two nodes, and sets the 644 connection property. 646 The statement is used to delete a connection 647 instance: 649 := DELETE Connection ; 651 The DELETE Connection is to delete a connection in user's network. 653 5.5.3. Flow Operations 655 NEMO model defines basic method for the flow instances, and use 656 intuitive keyword to indicate the specific method. User could 657 create, update and delete a flow instance. 659 The statement is used to create a flow: 661 := CREATE Flow 662 Match {: 663 | Range (, ) 664 | List({})} 666 The statement is used to update a flow: 668 := UPDATE Flow 669 Match {: 670 | Range (, ) 671 | List({})} 673 The Flow is followed by a user defined . If the method is 674 CREATE and the is new in the system, a new flow identifier 675 will be created automatically. If the method is UPDATE and the 676 exists in the system, the corresponding flow identified by 677 the will be updated with the following information. 679 The Match specifies a flow by indicate match fields. NEMO language 680 also provides two keywords to assist the expression of values: 682 o The List is used to store a collection of data with the same data 683 type. 685 o The Range is used to express a range of values. 687 An example of creating a flow instance is as follows: 689 CREATE Flow flow-1 690 Match src_ip : Range ("192.0.2.1", "192.0.2.243"); 692 The statement describes a flow with the source IP address ranging 693 from 192.0.2.1 to 192.0.2.243. 695 The statement is used to delete a flow instance: 697 := DELETE Flow ; 699 The DELETE Flow is to delete a flow in user's network. 701 5.6. Behavior Statements 702 5.6.1. Query Behavior 704 The query statement is to retrieve selected data from specified model 705 object. 707 The generate a query: 709 := Query {} 710 From {|} 712 The Query is followed by one or more s which are 713 defined properties of the object to be queried. 715 The From is followed by the one or more queried objects. NENO 716 language support query operation to network entities and the policy. 718 5.6.2. Operation Behavior 720 NEMO model defines basic method for the operation instances, and use 721 intuitive keyword to indicate the specific method. User could 722 create, update and delete a operation instance. 724 In NEMO language, each operation instance is identified by a 725 which MUST be unique. 727 := !! name to identify the operation instance 729 Create and update a policy 731 := CREATE Operation 732 Target 733 Priority 734 [Condition ] 735 Action { : {}}; 737 := UPDATE Operation 738 [Target ] 739 [Priority ] 740 [Condition ] 741 [Action { : {}}]; 743 The Operation is followed by a user defined . If the 744 method is CREATE and the is new in the system, a new 745 operation will be created automatically. If the method is UPDATE and 746 the exists in the system, the corresponding operation 747 identified by the will be updated with the following 748 information. 750 The Target specifies the entity to which the operation will apply. 752 The Priority specifies the globe priority of the operation in the 753 tenant name space. The with lower number has a higher 754 priority, i.e. priority 0 holds the highest priority. 756 The Condition is an optional keyword follow by an expression. It 757 tells your program to execute the following actions only if a 758 particular test described by the expression evaluates to true. And 759 users also can define which objects won't need to execute these 760 actions with Constraint. 762 A NEMO language expression is a construct made up of variables, 763 operators, and method invocations, which are constructed according to 764 the syntax of the language and evaluates to a single value. NEMO 765 language supports many operators to facilitate the construction of 766 expressions. Assume variable A holds 10 and variable B holds 0, 767 then: 769 +----------+----------------------------------------------+---------+ 770 | Operator | Description | Example | 771 +----------+----------------------------------------------+---------+ 772 | && | Called Logical AND operator. If both the | (A && | 773 | | operands are non-zero, then the condition | B) is | 774 | | becomes true. | false. | 775 | || | Called Logical OR Operator. If any of the | (A || | 776 | | two operands are non-zero, then the | B) is | 777 | | condition becomes true. | true. | 778 | ! | Called Logical NOT Operator. Use to reverses | !(A && | 779 | | the logical state of its operand. If a | B) is | 780 | | condition is true then Logical NOT operator | true. | 781 | | will make false. | | 782 | == | Checks if the values of two operands are | (A == | 783 | | equal or not, if yes then condition becomes | B) is | 784 | | true. | not | 785 | | | true. | 786 | != | Checks if the values of two operands are | (A != | 787 | | equal or not, if values are not equal then | B) is | 788 | | condition becomes true. | true. | 789 | > | Checks if the value of left operand is | (A > B) | 790 | | greater than the value of right operand, if | is not | 791 | | yes then condition becomes true. | true. | 792 | >= | Checks if the value of left operand is | (A >= | 793 | | greater than or equal to the value of right | B) is | 794 | | operand, if yes then condition becomes true. | not | 795 | | | true. | 796 | < | Checks if the value of left operand is less | (A < B) | 797 | | than the value of right operand, if yes then | is | 798 | | condition becomes true. | true. | 799 | <= | Checks if the value of left operand is less | (A <= | 800 | | than or equal to the value of right operand, | B) is | 801 | | if yes then condition becomes true. | true. | 802 +----------+----------------------------------------------+---------+ 804 The Action specifies the execution when conditions meet. 806 An example of creating anoperation is as follows: 808 CREATE Operation operation-1 809 Target flow-1 810 Priority 100 811 Condition (time>"18:00") || (time<"21:00") 812 Action redirect : "backup_connection"; 814 The statement creates an operation which indicates the flow to go 815 through backup connection from 18:00 to 21:00. 817 Delete an operation: 819 := DELETE Operation ; 821 The DELETE Operation is to delete a policy in user's network. 823 5.6.3. Notification Behavior 825 In NEMO language, each notification instance is identified by a 826 828 := !! name to identify the notification 829 instance 831 Create and update a notification 833 := CREATE Notification 834 [(Query {} 835 From {})] 836 Condition {} 837 Listener ; 839 := UPDATE Notification 840 [(Query {} 841 From {})] 842 Condition {} 843 Listener ; 845 The Notification is followed by a user defined . If 846 the method is CREATE and the is new in the system, 847 a new notification will be created automatically. If the method is 848 UPDATE and the exists in the system, the 849 corresponding notification identified by the will be 850 updated with the following information. 852 The Query clause is nested in the notification statement to indicate 853 the information acquisition. 855 The Condition clause is the same as in operation statement, which 856 triggers the notification. 858 The Listener specifies the callback function that is used to process 859 the notification. 861 Delete a notification: 863 := DELETE Notification ; 864 The DELETE Notification is to delete a notification in user's 865 network. 867 5.7. Transaction Statements 869 := Transaction 870 := Commit 872 The keywords Transaction and Commit are used to tag begin and end of 873 a transaction. The code between the two key words will be 874 interpreted as a transaction and executed by the NEMO language 875 engine. 877 6. The NEMO Language Examples 879 An enterprise with geographically distributed headquarter and branch 880 sites has the requirement to dynamically balance the backup traffic. 882 In order to implement this scenario, the virtual WAN tenant creates 883 two logicnw, and generates two connections with different SLA to 884 carry diverse service flows. One connection has 100M bandwidth with 885 less than 50ms delay, which is used for normal traffic. And the 886 other connection has 40G bandwidth with less than 400ms delay, which 887 is used for backup traffic after work (from 19:00 to 23:00). With 888 self defined flow operations, the tenant can manage the connection 889 load balancing conveniently. 891 Real-time Connection 892 +--------------------+ 893 192.0.2.0/24 198.51.100.0/24 894 +---------+ +-------------+ 895 | Branch |------------------| Headquarter | 896 +---------+ +-------------+ 897 | | 898 +--------------------+ 899 Broadband Connection 901 The detailed operation and code are shown as follows. 903 o Step1: Create two virtual logicnw nodes in the WAN 905 CREATE Node Branch 906 Type l2group 907 Property ipv4Prefix : 192.0.2.0/24; 909 CREATE Node Headquarter 910 Type l2group 911 Property ipv4Prefix : 198.51.100.0/24; 913 o Step2: Connect the two virtual nodes with two virtual connections 914 with different SLA. 916 CREATE Connection broadband_connection 917 EndNodes Branch, Headquater 918 Property bandwidth : 40000, delay : 400; 920 CREATE Connection realtime_connection 921 EndNodes Branch, Headquater 922 Property bandwidth : 100, delay : 50; 924 o Step3: Indicate the flow to be operated. 926 CREATE Flow flow_all 927 Match src_ip : "192.0.2.0/24", dst_ip: "198.51.100.0/24"; 929 CREATE Flow flow_backup 930 Match src_ip : "192.0.2.0/24", dst_ip: "198.51.100.0/24", 931 port: 55555; 933 o Step4: Apply policies to corresponding flows. 935 P1: 936 CREATE Operation operation4all 937 Target flow_all 938 Priority 200 939 Action redirect: "realtime_connection"; 940 P2: 941 CREATE Operation operation4backup 942 Target flow_backup 943 Priority 100 944 Condition (time>"19:00:00") || (time<"23:00:00") 945 Action redirect: "broadband_connection"; 947 7. Security Considerations 949 Because the network customers are allowed to customize their own 950 services, they may bring potentially big impacts to a running IP 951 network. A strong user authentication mechanism is needed for the 952 northbound interface of the SDN controller. User authorization 953 should be carefully managed by the network administrator to avoid any 954 dangerous operations and prevent any abuse of network resources. 956 8. IANA Considerations 958 This memo includes no request to IANA. 960 9. Acknowledgements 962 The authors would like to thanks the valuable comments made by Wei 963 Cao, Xiaofei Xu, Fuyou Miao, Yali Zhang and Wenyang Lei. 965 This document was produced using the xml2rfc tool [RFC2629]. 967 10. Informative References 969 [Frenetic] 970 Foster, N., Harrison, R., Freedman, M., Monsanto, C., 971 Rexford, J., Story, A., and D. Walker, "Frenetic: A 972 Network Programming Languages, ICFP' 11". 974 [I-D.xia-sdnrg-service-description-language] 975 Xia, Y., Jiang, S., and S. Hares, "Requirements for a 976 Service Description Language and Design Considerations", 977 draft-xia-sdnrg-service-description-language-02 (work in 978 progress), May 2015. 980 [PBNM] Strassner, J., "Policy-Based Network Management: Solutions 981 for the Next Generation, Morgan Kaufmann Publishers Inc. 982 San Francisco, CA, USA.", 2003. 984 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 985 Requirement Levels", BCP 14, RFC 2119, 986 DOI 10.17487/RFC2119, March 1997, 987 . 989 [RFC2629] Rose, M., "Writing I-Ds and RFCs using XML", RFC 2629, 990 DOI 10.17487/RFC2629, June 1999, 991 . 993 [RFC4122] Leach, P., Mealling, M., and R. Salz, "A Universally 994 Unique IDentifier (UUID) URN Namespace", RFC 4122, 995 DOI 10.17487/RFC4122, July 2005, 996 . 998 [RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for 999 the Network Configuration Protocol (NETCONF)", RFC 6020, 1000 DOI 10.17487/RFC6020, October 2010, 1001 . 1003 [RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed., 1004 and A. Bierman, Ed., "Network Configuration Protocol 1005 (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011, 1006 . 1008 [TSFNet] Yap, K., Huang, T., Dodson, B., Lam, M., and N. McKeown, 1009 "Towards Software-Friendly Networks, APSys 2010, pp:49-54, 1010 2010, New Delhi, India.". 1012 Authors' Addresses 1014 Yinben Xia (editor) 1015 Huawei Technologies Co., Ltd 1016 Q14, Huawei Campus, No.156 Beiqing Road 1017 Hai-Dian District, Beijing, 100095 1018 P.R. China 1020 Email: xiayinben@huawei.com 1022 Sheng Jiang (editor) 1023 Huawei Technologies Co., Ltd 1024 Q14, Huawei Campus, No.156 Beiqing Road 1025 Hai-Dian District, Beijing, 100095 1026 P.R. China 1028 Email: jiangsheng@huawei.com 1030 Tianran Zhou (editor) 1031 Huawei Technologies Co., Ltd 1032 Q14, Huawei Campus, No.156 Beiqing Road 1033 Hai-Dian District, Beijing, 100095 1034 P.R. China 1036 Email: zhoutianran@huawei.com 1038 Susan Hares 1039 Huawei Technologies Co., Ltd 1040 7453 Hickory Hill 1041 Saline, CA 48176 1042 USA 1044 Email: shares@ndzh.com