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Hadi Salim 3 Internet-Draft Mojatatu Networks 4 Intended status: Informational January 5, 2014 5 Expires: July 9, 2014 7 ForCES Protocol Extensions 8 draft-jhs-forces-protoextenstion-02 10 Abstract 12 Experience in implementing and deploying ForCES architecture has 13 demonstrated need for a few small extensions both to ease 14 programmability and to improve wire efficiency of some transactions. 15 This document describes extensions to the ForCES Protocol 16 Specification[RFC 5810] semantics to achieve that end goal. 18 Status of This Memo 20 This Internet-Draft is submitted in full conformance with the 21 provisions of BCP 78 and BCP 79. 23 Internet-Drafts are working documents of the Internet Engineering 24 Task Force (IETF). Note that other groups may also distribute 25 working documents as Internet-Drafts. The list of current Internet- 26 Drafts is at http://datatracker.ietf.org/drafts/current/. 28 Internet-Drafts are draft documents valid for a maximum of six months 29 and may be updated, replaced, or obsoleted by other documents at any 30 time. It is inappropriate to use Internet-Drafts as reference 31 material or to cite them other than as "work in progress." 33 This Internet-Draft will expire on July 9, 2014. 35 Copyright Notice 37 Copyright (c) 2014 IETF Trust and the persons identified as the 38 document authors. All rights reserved. 40 This document is subject to BCP 78 and the IETF Trust's Legal 41 Provisions Relating to IETF Documents 42 (http://trustee.ietf.org/license-info) in effect on the date of 43 publication of this document. Please review these documents 44 carefully, as they describe your rights and restrictions with respect 45 to this document. Code Components extracted from this document must 46 include Simplified BSD License text as described in Section 4.e of 47 the Trust Legal Provisions and are provided without warranty as 48 described in the Simplified BSD License. 50 Table of Contents 52 1. Terminology and Conventions . . . . . . . . . . . . . . . . . 2 53 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 2 54 1.2. Definitions . . . . . . . . . . . . . . . . . . . . . . . 2 55 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4 56 3. Problem Overview . . . . . . . . . . . . . . . . . . . . . . 4 57 3.1. Table Ranges . . . . . . . . . . . . . . . . . . . . . . 4 58 3.2. Error codes . . . . . . . . . . . . . . . . . . . . . . . 5 59 4. Protocol Update Proposal . . . . . . . . . . . . . . . . . . 5 60 4.1. Table Ranges . . . . . . . . . . . . . . . . . . . . . . 5 61 4.2. Error Codes . . . . . . . . . . . . . . . . . . . . . . . 6 62 4.2.1. New Codes . . . . . . . . . . . . . . . . . . . . . . 7 63 4.2.2. Vendor Codes . . . . . . . . . . . . . . . . . . . . 7 64 4.2.3. Extended Result TLV . . . . . . . . . . . . . . . . . 7 65 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 66 6. Security Considerations . . . . . . . . . . . . . . . . . . . 9 67 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 68 7.1. Normative References . . . . . . . . . . . . . . . . . . 9 69 7.2. Informative References . . . . . . . . . . . . . . . . . 9 70 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 9 72 1. Terminology and Conventions 74 1.1. Requirements Language 76 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 77 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 78 document are to be interpreted as described in [RFC2119]. 80 1.2. Definitions 82 This document reiterates the terminology defined by the ForCES 83 architecture in various documents for the sake of clarity. 85 FE Model - The FE model is designed to model the logical 86 processing functions of an FE. The FE model proposed in this 87 document includes three components; the LFB modeling of individual 88 Logical Functional Block (LFB model), the logical interconnection 89 between LFBs (LFB topology), and the FE-level attributes, 90 including FE capabilities. The FE model provides the basis to 91 define the information elements exchanged between the CE and the 92 FE in the ForCES protocol [RFC5810]. 94 LFB (Logical Functional Block) Class (or type) - A template that 95 represents a fine-grained, logically separable aspect of FE 96 processing. Most LFBs relate to packet processing in the data 97 path. LFB classes are the basic building blocks of the FE model. 99 LFB Instance - As a packet flows through an FE along a data path, 100 it flows through one or multiple LFB instances, where each LFB is 101 an instance of a specific LFB class. Multiple instances of the 102 same LFB class can be present in an FE's data path. Note that we 103 often refer to LFBs without distinguishing between an LFB class 104 and LFB instance when we believe the implied reference is obvious 105 for the given context. 107 LFB Model - The LFB model describes the content and structures in 108 an LFB, plus the associated data definition. XML is used to 109 provide a formal definition of the necessary structures for the 110 modeling. Four types of information are defined in the LFB model. 111 The core part of the LFB model is the LFB class definitions; the 112 other three types of information define constructs associated with 113 and used by the class definition. These are reusable data types, 114 supported frame (packet) formats, and metadata. 116 LFB Metadata - Metadata is used to communicate per-packet state 117 from one LFB to another, but is not sent across the network. The 118 FE model defines how such metadata is identified, produced, and 119 consumed by the LFBs, but not how the per-packet state is 120 implemented within actual hardware. Metadata is sent between the 121 FE and the CE on redirect packets. 123 ForCES Component - A ForCES Component is a well-defined, uniquely 124 identifiable and addressable ForCES model building block. A 125 component has a 32-bit ID, name, type, and an optional synopsis 126 description. These are often referred to simply as components. 128 LFB Component - An LFB component is a ForCES component that 129 defines the Operational parameters of the LFBs that must be 130 visible to the CEs. 132 ForCES Protocol - Protocol that runs in the Fp reference points in 133 the ForCES Framework [RFC3746]. 135 ForCES Protocol Layer (ForCES PL) - A layer in the ForCES protocol 136 architecture that defines the ForCES protocol messages, the 137 protocol state transfer scheme, and the ForCES protocol 138 architecture itself as defined in the ForCES Protocol 139 Specification [RFC5810]. 141 ForCES Protocol Transport Mapping Layer (ForCES TML) - A layer in 142 ForCES protocol architecture that uses the capabilities of 143 existing transport protocols to specifically address protocol 144 message transportation issues, such as how the protocol messages 145 are mapped to different transport media (like TCP, IP, ATM, 146 Ethernet, etc.), and how to achieve and implement reliability, 147 ordering, etc. the ForCES SCTP TML [RFC5811] describes a TML that 148 is mandated for ForCES. 150 2. Introduction 152 Experience in implementing and deploying ForCES architecture has 153 demonstrated need for a few small extensions both to ease 154 programmability and to improve wire efficiency of some transactions. 155 This document describes a few extensions to the ForCES Protocol 156 Specification [RFC5810] semantics to achieve that end goal. 158 This document describes and justifies the need for 2 small extensions 159 which are backward compatible. 161 1. A table range operation to allow a controller or control 162 application to request an arbitrary range of table rows. 164 2. Improved Error codes returned to the controller (or control 165 application) to improve granularity of existing defined error 166 codes. 168 3. Problem Overview 170 In this section we present sample use cases to illustrate the 171 challenge being addressed. 173 3.1. Table Ranges 175 Consider, for the sake of illustration, an FE table with 1 million 176 reasonably sized table rows which are sparsely populated. Assume, 177 again for the sake of illustration, that there are 2000 table rows 178 sparsely populated between the row indices 23-10023. 180 ForCES GET and DEL requests sent from a controller (or control app) 181 are prepended with a path to a component and sent to the FE. In the 182 case of indexed tables, the component path can either be to a table 183 or a table row index. The approaches for retrieving or deleting a 184 sizeable number of table rows is at the programmatically (from an 185 application point of view unfriendly, tedious, and abusive of both 186 compute and bandwidth resources. 188 As an example, a control application attempting to retrieve the first 189 2000 table rows appearing between row indices 23 and 10023 can 190 achieve its goal in one of: 192 o Dump the whole table and filter for the needed 2000 table rows. 194 o Send upto 10000 ForCES PL requests with monotonically incrementing 195 indices and stop when the needed 2000 entries are retrieved. 197 o If the application had knowledge of which table rows existed (not 198 unreasonable given the controller is supposed to be aware of state 199 within an NE), then the application could take advantage of ForCES 200 batching to send fewer large messages (each with different path 201 entries for a total of two thousand). 203 As argued, while the above options exist - all are tedious. 205 3.2. Error codes 207 [RFC5810] has defined a generic set of error codes that are to be 208 returned to the CE from an FE. Deployment experience has shown that 209 it would be useful to have more fine grained error codes. As an 210 example, the error code E_NOT_SUPPORTED could be mapped to many FE 211 error source possibilities that need to be then interpreted by the 212 caller based on some understanding of the nature of the sent request. 213 This makes debugging more time consuming. 215 4. Protocol Update Proposal 217 This section describes proposals to update the protocol for issues 218 discussed in Section 3 220 4.1. Table Ranges 222 We propose to add a Table-range TLV (type ID 0x117) that will be 223 associated with the PATH-DATA TLV in the same manner the KEYINFO-TLV 224 is. 226 OPER = GET 227 PATH-DATA: 228 flags = F_SELTABRANGE, IDCount = 2, IDs = {1,6} 229 TABLERANGE-TLV content = {11,23} 231 Figure 1: ForCES table range request 233 Figure 1 illustrates a GET request for a range of rows 11 to 23 of a 234 table with component path of "1/6". 236 Path flag of F_SELTABRANGE (0x2 i.e bit 1, where bit 0 is F_SELKEY as 237 defined in RFC 5810) is set to indicate the presence of the Table- 238 range TLV. The pathflag bit F_SELTABRANGE can only be used in a GET 239 or DEL and is mutually exclusive with F_SELKEY. The FE MUST enforce 240 those constraints and reject a request with an error code of 241 E_INVALID_TFLAGS with a description of what the problem is (refer to 242 Section 4.2). 244 The Table-range TLV contents constitute: 246 o A 32 bit start index. An index of 0 implies the beggining of the 247 table row. 249 o A 32 bit end index. A value of 0xFFFFFFFFFFFFFFFF implies the 250 last entry. XXX: Do we need to define the "end wildcard"? 252 The response for a table range query will either be: 254 o The requested table data returned (when at least one referenced 255 row is available); in such a case, a response with a path pointing 256 to the table and whose data content contain the row(s) will be 257 sent to the CE. The data content MUST be encapsulated in 258 sparsedata TLV. The sparse data TLV content will have the "I" (in 259 ILV) for each table row indicating the table indices. 261 o An Extended result TLV when: 263 * Response is to a range delete request. The Result will either 264 be: 266 + A success if any of the requested for rows is deleted 268 + A proper error code if none of the requested for rows cannot 269 be deleted 271 * data is absent where the result code of E_EMPTY with an 272 optional content string describing the nature of the error 273 (refer to Section 4.2). 275 * When both a path key and path table range are reflected on the 276 the pathflags, an error code of E_INVALID_TFLAGS with an 277 optional content string describing the nature of the error 278 (refer to Section 4.2). 280 * other standard ForCES errors (such as ACL constraints trying to 281 retrieve contents of an unreadable table), accessing unknown 282 components etc. 284 4.2. Error Codes 286 We propose several things: 288 1. A new set of error codes. 290 2. Allocating currently reserved codes for vendor use. 292 3. A new TLV, EXTENDED-RESULT-TLV (0x118) that will carry a code 293 (which will be a superset of what is currently specified in RFC 294 5812) but also an optional cause content. This is illustrated in 295 Figure 2. 297 4.2.1. New Codes 299 Extended-Result TLV Result Value is 32 bits and is a superset of RFC 300 5810 Result TLV Result Value. The new version code space is 32 bits 301 as opposed to the RFC 5810 code size of 8 bits. 303 +-------------+--------------------+--------------------------------+ 304 | Code | Mnemonic | Details | 305 +-------------+--------------------+--------------------------------+ 306 | 0x100 | E_EMPTY | Table is empty | 307 | 0x101 | E_INVALID_TFLAGS | Invalid table flags | 308 | 0x102 | E_INVALID_OP | Requested operation is invalid | 309 | 0x103 | E_CONGEST_NT | Node Congestion notification | 310 +-------------+--------------------+--------------------------------+ 312 Table 1: New codes 314 4.2.2. Vendor Codes 316 Codes 0x18-0xFE are reserved for use as vendor codes. Since these 317 are freely available it is expected that the FE and CE side will both 318 understand the semantics of any used codes. 320 4.2.3. Extended Result TLV 322 0 1 2 3 323 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 324 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 325 | Type = EXTENDED-RESULT-TLV | Length | 326 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 327 | Result Value | 328 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 329 | Optional Cause content | 330 . . 331 | | 332 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 334 Figure 2: Extended Result TLV 336 o Like all other ForCES TLVs, the Extended Result TLV is expected to 337 be 32 bit aligned. 339 o The Result Value derives and extends from the same current 340 namespace as specified in RFC 5810, section 7.1.7. The main 341 difference is that we now have 32 bit result value (as opposed to 342 the old 8 bit). 344 o The optional result content is defined to further disambiguate the 345 result value. It is expected Utf-8 values to be used. However, 346 vendor specific error codes may choose to specify different 347 contents. Additionally, future codes may specify cause contents 348 to be of types other than string.. 350 o It is recommended that the maximum size of the cause string should 351 not exceed 32 bytes. We do not propose the cause string be 352 standardized. 354 XXX: Backward compatibility may require that we add a FEPO capability 355 to advertise ability to do extended results so that the CE is able to 356 interpret the results and a FEPO compatibility flag to define what 357 TLV setting would be used. Alternatively, the backward compatibility 358 can be made a configuration option (which helps reduce clutter on 359 FEPO LFB given that it is expected that in the future it makes sense 360 for implementations to support only extended Result TLVs). 362 5. IANA Considerations 364 This document registers two new top Level TLVs and two new path 365 flags. 367 The following new TLVs are defined: 369 o Table-range TLV (type ID 0x117) 371 o EXTENDED-RESULT-TLV (type ID 0x118) 373 The following new path flags are defined: 375 o F_SELTABRANGE (value 0x2 i.e bit 1) 377 The Defined Result Values are changed: 379 o codes 0x18-0xFE are reserved for vendor use. 381 o codes 0x100-102 are defined by this document. 383 6. Security Considerations 385 TBD 387 7. References 389 7.1. Normative References 391 [RFC3746] Yang, L., Dantu, R., Anderson, T., and R. Gopal, 392 "Forwarding and Control Element Separation (ForCES) 393 Framework", RFC 3746, April 2004. 395 [RFC5810] Doria, A., Hadi Salim, J., Haas, R., Khosravi, H., Wang, 396 W., Dong, L., Gopal, R., and J. Halpern, "Forwarding and 397 Control Element Separation (ForCES) Protocol 398 Specification", RFC 5810, March 2010. 400 [RFC5811] Hadi Salim, J. and K. Ogawa, "SCTP-Based Transport Mapping 401 Layer (TML) for the Forwarding and Control Element 402 Separation (ForCES) Protocol", RFC 5811, March 2010. 404 [RFC5812] Halpern, J. and J. Hadi Salim, "Forwarding and Control 405 Element Separation (ForCES) Forwarding Element Model", RFC 406 5812, March 2010. 408 7.2. Informative References 410 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 411 Requirement Levels", BCP 14, RFC 2119, March 1997. 413 Author's Address 415 Jamal Hadi Salim 416 Mojatatu Networks 417 Suite 400, 303 Moodie Dr. 418 Ottawa, Ontario K2H 9R4 419 Canada 421 Email: hadi@mojatatu.com