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Checking references for intended status: Informational ---------------------------------------------------------------------------- No issues found here. Summary: 0 errors (**), 0 flaws (~~), 2 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 ICNRG I. Moiseenko 3 Internet-Draft Cisco Systems 4 Intended status: Informational D. Oran 5 Expires: January 16, 2019 Network Systems Research and Design 6 July 15, 2018 8 Flow Classification in Information Centric Networking 9 draft-moiseenko-icnrg-flowclass-02 11 Abstract 13 For the ubiquitous and highly important Internet protocols (TCP, UDP, 14 IP), flows are conventionally identified by the "5-tuple" of source 15 and destination IP addresses, source and destination port, and 16 protocol type in an IP packet. Information Centric Networking (ICN) 17 is a new paradigm where network communications are accomplished by 18 requesting named content, instead of sending packets to destination 19 addresses. This document describes mechanisms allowing ICN 20 forwarders, consumers, producers and other ICN nodes to encode, 21 decode, and process equivalence class identifiers (flows) at any 22 desired granularity of a routable name prefix and beyond the routable 23 name prefix. This document is a product of the IRTF Information- 24 Centric Networking Research Group (ICNRG). 26 Status of This Memo 28 This Internet-Draft is submitted in full conformance with the 29 provisions of BCP 78 and BCP 79. 31 Internet-Drafts are working documents of the Internet Engineering 32 Task Force (IETF). Note that other groups may also distribute 33 working documents as Internet-Drafts. The list of current Internet- 34 Drafts is at https://datatracker.ietf.org/drafts/current/. 36 Internet-Drafts are draft documents valid for a maximum of six months 37 and may be updated, replaced, or obsoleted by other documents at any 38 time. It is inappropriate to use Internet-Drafts as reference 39 material or to cite them other than as "work in progress." 41 This Internet-Draft will expire on January 16, 2019. 43 Copyright Notice 45 Copyright (c) 2018 IETF Trust and the persons identified as the 46 document authors. All rights reserved. 48 This document is subject to BCP 78 and the IETF Trust's Legal 49 Provisions Relating to IETF Documents 50 (https://trustee.ietf.org/license-info) in effect on the date of 51 publication of this document. Please review these documents 52 carefully, as they describe your rights and restrictions with respect 53 to this document. Code Components extracted from this document must 54 include Simplified BSD License text as described in Section 4.e of 55 the Trust Legal Provisions and are provided without warranty as 56 described in the Simplified BSD License. 58 Table of Contents 60 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 61 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 62 2. Flow Identification Challenges and Opportunities in ICN . . . 3 63 3. Flow Encoding Schemes . . . . . . . . . . . . . . . . . . . . 4 64 3.1. Equivalence class component count (EC3) . . . . . . . . . 5 65 3.2. Equivalence class name component type (ECNCT) . . . . . . 6 66 4. Producer operation . . . . . . . . . . . . . . . . . . . . . 7 67 5. Consumer operation . . . . . . . . . . . . . . . . . . . . . 8 68 6. Forwarder operation . . . . . . . . . . . . . . . . . . . . . 8 69 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 70 8. Security Considerations . . . . . . . . . . . . . . . . . . . 9 71 9. Normative References . . . . . . . . . . . . . . . . . . . . 9 72 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 74 1. Introduction 76 The problem of identifying groups of packets that get consistent 77 treatment in a network and allowing that treatment to be independent 78 and isolated from the treatment of other groups of packets, is 79 ubiquitous and long-standing. The purposes to which this 80 identification can be put is highly varied, including such functions 81 are providing differentiated quality of service, traffic engineering, 82 traffic filtering for security functions like intrusion detection and 83 firewalling, etc. 85 Providing the capability to apply different functions to groupings 86 (formally equivalence classes) of packets is generally known as the 87 "flow identification problem" where the definition of what 88 constitutes a "flow" is highly dependent on the particular protocol 89 or protocols carrying the packets. Some of the above uses of flows 90 also bring a mechanism requirement that the flow identification 91 technique be useful to have not just equivalence classes, but the 92 ability to apply some useful notion of fairness among the instances 93 of each equivalence class. There are many possible flow 94 identification techniques that are either too granular (spatially or 95 temporally) to establish fairness, or conversely too coarse and 96 cannot separate traffic a fine enough level to have useful fairness. 98 For the ubiquitous and highly important Internet protocols (TCP, UDP, 99 IP), flows are conventionally identified by the "5-tuple" of source 100 and destination IP addresses, source and destination port, and 101 protocol type in an IP packet. Some systems augment this by further 102 distinguishing equivalence classes by the TOS/DSCP field, but this is 103 secondary to the 5-tuple methods. 2-party flows are present where the 104 source and destination addresses are unicast IP addresses. Multi- 105 party flows can exist when the destination IP address is a multicast 106 address. One key common characteristic is that the identification of 107 flows depends in a very deep way on the presence of source addresses 108 in the packets, and the limited richness of IP addresses is 109 correspondingly constraining as a means to classify traffic in a 110 semantically meaningful way. 112 The purpose of this document is to devise a mechanism allowing ICN 113 forwarders, consumers, producers and other ICN nodes to encode, 114 decode, and process equivalence class identifiers (flows) at any 115 desired granularity of a routable name prefix and beyond the routable 116 name prefix. 118 1.1. Requirements Language 120 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 121 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 122 document are to be interpreted as described in RFC 2119 [RFC2119]. 124 2. Flow Identification Challenges and Opportunities in ICN 126 ICN systems differ from IP-based designs in a number of ways, three 127 of which are quite fundamental. 129 1. The packets are addressed to a rich namespace of packets, which 130 is hierarchical and carry semantic information that can be useful 131 for classification of flows. 133 2. Conversely, the packets do not contain source addresses of any 134 kind, which means that identifying flows as groups of packets 135 between a single pair of endpoints (in the unicast case) is not 136 possible for intermediate forwarders (other than possibly the 137 first-hop forwarder if it serves a single consumer per 138 interface). 140 3. Instead of group-based multicast, ICN systems use multi- 141 destination delivery semantics. This allows a different way to 142 map packets to flows, and in fact in the IP world multicast has 143 been difficult to use partly because there is no good way to make 144 use of flow identification for multicast flows (for a variety of 145 reasons). 147 These differences lead to a need to find a different method to 148 identify flows than used in the IP protocol suite. Ideally, the 149 method would provide semantics that map well with the expected uses 150 of ICN to build applications. It would also use native capabilities 151 in the ICN protocols rather than having to change the protocol 152 architecture in ways that affect the semantics or utility of an ICN 153 approach to networking. 155 In NDN and CCN protocols, Interest and Data names are the only 156 identifiers in the network; neither source addresses nor destination 157 addresses are employed. Each Interest packet is responded by exactly 158 one Data packet, producing a useful property known as "flow balance". 159 This means that flow identification can be tied directly to the 160 Interest/Data exchanges. The key to having useful flow 161 identification is for the equivalence classes to be associated with 162 the names in the corresponding Interest and Data packets, and to be 163 stable over multiple exchanges using different names that share some 164 common "handle" that can be used to separate the names into 165 equivalence classes. As mentioned above, simply using the routing 166 state that maps name prefixes to routes does not provide a useful set 167 of equivalence classes, because: 169 o in general, routing prefixes are too coarse; many equivalence 170 classes of packets are generally covered by a single routing 171 prefix because they are present at the same set of destinations 172 from a routing perspective; 174 o practical, scalable routing needs to do route aggregation, which 175 further blurs the discrimination of the equivalence classes. 177 Therefore, NDN and CCN protocols need to have something that both 178 relates to the name structure but provides finer granularity for flow 179 classification purposes. This document describes two alternative 180 mechanisms addressing these issues. 182 3. Flow Encoding Schemes 184 Flow encoding schemes described in this document allow ICN systems to 185 perform flow identification at any desired granularity of a routable 186 name prefix and beyond the routable name prefix. Techniques 187 described herein permit both consumer nodes and forwarders to use 188 equivalence classes to perform per-flow functions. The encoding to 189 achieve the flow classification is lightweight and does not require 190 changes to the protocol architecture in ways that affect the 191 semantics or utility of an ICN approach to networking. Furthermore, 192 equivalence classes can be specified by the data producer, in 193 contrast to IP protocols in which the data producer can only control 194 the destination port as an equivalence-class discriminator. 196 No matter what method is used to identify equivalence classes that 197 can be treated as flows, there is the independent but critically 198 important issue of how to scale any state that is kept on a per-flow 199 basis when the flow count is very high. For consumers and producers, 200 this state scales naturally with the number of applications and 201 application interactions are going on simultaneously. Therefore the 202 scaling limit is not likely to be in the producers or consumers. For 203 ICN forwarders that are operating at high speed and/or handling the 204 traffic of many producers and consumers however, this state can scale 205 quadratically or worse. If the ICN forwarder cannot keep all the 206 state due to memory or processing limitations, it faces the common 207 problem of which flows to remember and which to forget. This 208 document does not solve this problem, which is fundamental. Flow 209 encoding schemes described in this document provide a method for 210 identifying equivalence classes using protocol machinery that already 211 has to scale (e.g. name parsing and lookup) and hence does not 212 introduce a new class of problems not inherently present. 214 3.1. Equivalence class component count (EC3) 216 For this encoding scheme a new field called equivalence class 217 component count (EC3) is introduced into the Data packets. It is set 218 by a producer and counts the number of name components in the 219 corresponding name that are to be considered, when grouped together 220 under the same prefix part of the name, to be one equivalence class 221 instance. This allows either finer (or coarser) granularity than 222 provided by routing prefixes. Because the EC3 is a separate field of 223 the packet (Figure 1), producers can "regroup" equivalence classes 224 dynamically by including more or fewer levels of the name hierarchy 225 when they respond to Interests for the corresponding Data packets. 226 Therefore, the behavior of EC3 encoding scheme is somewhat different 227 from ECNCT encoding scheme and has both advantages and disadvantages. 228 The advantage is flexibility in re-grouping equivalence classes, 229 especially in aggregating flows at different granularities. The 230 disadvantage is that the binding of the equivalence class into the 231 namespace is not explicit, and hence it is harder to enforce 232 consistent interpretations. 234 An additional consideration with the EC3 encoding scheme is whether 235 or not the field is inside or outside the security envelope that 236 provides cryptographic packet integrity to the name and data in the 237 data packet. Either approach is possible; however having the field 238 outside the security envelope would allow ICN forwarders to modify 239 it, allowing the aggregation/disaggregation of flows to be performed 240 by the forwarders as well as the consumers. Conversely, leaving the 241 field outside the security envelope may enhance certain attack 242 scenarios against flow classification for quality of service or 243 firewall filtering. 245 +-------------------------------------------------------------------+ 246 | /youtube | / | /video OR | | | 247 | | | /audio | | | 248 +-----------+--------------+-------------+-------------+------------+ 249 | Name | Name | Name | Name | Segment | 250 | component | component | component | component | component | 251 | type | type | type | type | type | 252 +-----------+--------------+-------------+-------------+------------+ 253 | | 254 | Equivalence Class Component Count = 2 (up to MediaID stream) | 255 | OR | 256 | Equivalence Class Component Count = 3 (video or audio substream) | 257 +-------------------------------------------------------------------+ 259 An example of EC3 encoding of flow information. 261 Figure 1 263 3.2. Equivalence class name component type (ECNCT) 265 For this scheme the equivalence class information is encoded directly 266 in the name, by adding a name component to the name of the Interest 267 and Data packets. This new typed named component is called 268 equivalence class name component type (ECNCT). It is set by the 269 producer as part of constructing all Data packets in the desired 270 equivalence class and is therefore immutable for the lifetime of the 271 associated named data. A consequence of this is that the ECNCT is 272 present in Interest packets as well, and hence may affect both PIT 273 matching and FIB matching. The Equivalence Class name component both 274 names the equivalence class explicitly, and implicitly makes all Data 275 packets named below it in the hierarchy part of that equivalence 276 class. In other words, the name can have multiple equivalence class 277 (e.g. flow and subflows) markings using this scheme (Figure 2). As 278 in EC3 encoding scheme, depending where in the name component 279 hierarchy the ECNCT is placed, one can have either finer or coarser 280 granularity than provided by routing prefixes. 282 The exact details of how to encode the ECNCT name component may 283 differ among ICN architectures. The CCN design has explicitly typed 284 name components, so for that protocol an explicit name component type 285 can be assigned straightforwardly. The NDN design eschews typed name 286 components and instead uses textual naming conventions for name 287 components. In that case an architectural constant string would be 288 chosen to distinguish ECNCT from other name component semantics. 290 +------------------------------------------------------------+ 291 | /youtube | / | /video OR | | | 292 | | | /audio | | | 293 +----------+------------+-----------+-----------+------------+ 294 | Name | Flow | Flow | Name | Segment | 295 | component| component | component | component | component | 296 | type | type | type | type | type | 297 +----------+------------+-----------+-----------+------------+ 299 An example of ECNCT encoding of flow information. 301 Figure 2 303 When an ICN forwarder receives a packet with a name carrying 304 ECNCT(s), it can be processed on a component-by-component basis, and 305 substreams can be identified according to name prefixes indicated by 306 the equivalence class identifiers. The identification of substreams 307 enables special treatment of selected substreams. For example, video 308 substreams can be discriminated from other substreams, such as audio 309 substreams. In the example in Figure 2, two name components include 310 equivalence class identifiers to define a hierarchy of flows (or 311 substreams). Specifically, two flow components are encoded to define 312 the following hierarchy of flows: 314 First level name prefix: /youtube/ 316 Second level name prefix: /youtube//video 318 Second level name prefix: /youtube//audio 320 4. Producer operation 322 In ECNCT encoding scheme, an ICN producer receives an Interest packet 323 carrying equivalence class identifiers in the name. A producer might 324 use the equivalence class identifiers for demultiplexing, load 325 sharding and other purposes, and reply with a Data packet matching 326 the Interest name. 328 In EC3 encoding scheme, an ICN producer receives an Interest packet 329 that might not carry an equivalence class identifier. In such case, 330 the producer may refer to the name schemas used in a particular 331 application to dynamically determine the equivalence class identifier 332 for Interest demultiplexing, load sharding and other purposes, and 333 for replying with a Data packet carring the equivalence class 334 identifer in EC3 field. 336 5. Consumer operation 338 An ICN consumer may also use the knowledge of equivalence classes of 339 packets to take certain actions. For example, when a Data packet 340 with a name specifying a particular equivalence class arrives at a 341 consumer in response to a previously sent Interest packet, the 342 consumer can associate the data packet with the correct equivalence 343 class. Consequently, the consumer can manage subsequent Interest/ 344 Data exchanges with the same name prefix and equivalence class 345 identifier (e.g., EC3 or ECNCT) as one flow. Associated measurements 346 such as round trip time (RTT) or marginal delay can be leveraged to 347 perform flow and congestion management for the equivalence class as a 348 whole. 350 6. Forwarder operation 352 A flow table may be provisioned in ICN node to enable the node to 353 make decisions about performing actions on Interest and/or Data 354 packets based on one or more equivalence classes. The flow table can 355 include name prefixes mapped to equivalence class identifiers 356 obtained from previous Interest-Data exchanges. In ECNCT encoding 357 scheme, Interest packets carry the equivalence class identifier, 358 therefore flow table may only include name prefixes. Typically, name 359 prefixes in flow table are more granular than prefixes in the FIB, 360 but less granular than names in the PIT. Flow table could be 361 separate from other elements of ICN node or could be integrated with 362 FIB or PIT. 364 Flow management logic can be configured to treat flows having the 365 same equivalence class similarly. Actions taken that are related to 366 flows or objects having a similar equivalence class can include, but 367 are not limited to, dropping a packet, using a particular interface 368 for a packet, security related actions (e.g., filtering traffic for 369 security functions like intrusion detection and firewalling), quality 370 of service (QoS) related actions (e.g., types of resources to 371 allocate to the packets, moving a packet up in the queue for 372 forwarding purposes, etc.), and/or traffic engineering (e.g., 373 selecting one path over another path). Flow management logic can 374 enable such actions to be taken on a particular flow based on the 375 equivalence class associated with the flow or object and policies 376 related to the equivalence class. 378 Specific examples of how ICN node can use the knowledge of 379 equivalence classes of packets include, but are not limited to, the 380 following: 382 1. Enforce rate control for the equivalence class as a whole (e.g., 383 dropping packets, queuing packets, etc.); 385 2. Estimate the number of simultaneous flows traversing a bottleneck 386 link, which can improve the performance of many congestion 387 control schemes; and 389 3. Make more intelligent selections of which packets to cache at the 390 ICN forwarder, for example, to prefer to cache many packets of 391 the same equivalence class. 393 7. IANA Considerations 395 This memo includes no request to IANA. 397 8. Security Considerations 399 Certain attack scenarios against flow classification for quality of 400 service or firewall filtering may be prevented if the EC3 field 401 located inside the security envelope. ICN forwarders can read, but 402 not change, the EC3 value, because the EC3 field is covered by a 403 security signature and not encrypted. 405 If the EC3 field is outside of the security envelope, it can be 406 placed in the hop-by-hop headers and, therefore, be modified by the 407 transit ICN forwarders. This allows the transit ICN forwarders to 408 override the flow definitions set by the producer applications, but 409 opens the system to various attack scenarios. 411 Modification of equivalence class identifiers in ECNCT encoding 412 scheme effectively modifies the packet name, and therefore, ECNCT 413 does not introduce any additional security threats. 415 9. Normative References 417 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 418 Requirement Levels", BCP 14, RFC 2119, 419 DOI 10.17487/RFC2119, March 1997, 420 . 422 Authors' Addresses 424 Ilya Moiseenko 425 Cisco Systems 426 USA 428 Email: ilmoisee@cisco.com 429 Dave Oran 430 Network Systems Research and Design 431 4 Shady Hill Square 432 Cambridge, MA 02138 433 USA 435 Email: daveoran@orandom.net