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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 IDR Working Group C. Loibl 3 Internet-Draft next layer Telekom GmbH 4 Obsoletes: 5575,7674 (if approved) S. Hares 5 Intended status: Standards Track Huawei 6 Expires: October 30, 2020 R. Raszuk 7 Bloomberg LP 8 D. McPherson 9 Verisign 10 M. Bacher 11 T-Mobile Austria 12 April 28, 2020 14 Dissemination of Flow Specification Rules 15 draft-ietf-idr-rfc5575bis-24 17 Abstract 19 This document defines a Border Gateway Protocol Network Layer 20 Reachability Information (BGP NLRI) encoding format that can be used 21 to distribute traffic Flow Specifications. This allows the routing 22 system to propagate information regarding more specific components of 23 the traffic aggregate defined by an IP destination prefix. 25 It also specifies BGP Extended Community encoding formats, that can 26 be used to propagate Traffic Filtering Actions along with the Flow 27 Specification NLRI. Those Traffic Filtering Actions encode actions a 28 routing system can take if the packet matches the Flow Specification. 30 Additionally, it defines two applications of that encoding format: 31 one that can be used to automate inter-domain coordination of traffic 32 filtering, such as what is required in order to mitigate 33 (distributed) denial-of-service attacks, and a second application to 34 provide traffic filtering in the context of a BGP/MPLS VPN service. 35 Other applications (e.g. centralized control of traffic in a SDN or 36 NFV context) are also possible. Other documents may specify Flow 37 Specification extensions. 39 The information is carried via BGP, thereby reusing protocol 40 algorithms, operational experience, and administrative processes such 41 as inter-provider peering agreements. 43 This document obsoletes both RFC5575 and RFC7674. 45 Status of This Memo 47 This Internet-Draft is submitted in full conformance with the 48 provisions of BCP 78 and BCP 79. 50 Internet-Drafts are working documents of the Internet Engineering 51 Task Force (IETF). Note that other groups may also distribute 52 working documents as Internet-Drafts. The list of current Internet- 53 Drafts is at https://datatracker.ietf.org/drafts/current/. 55 Internet-Drafts are draft documents valid for a maximum of six months 56 and may be updated, replaced, or obsoleted by other documents at any 57 time. It is inappropriate to use Internet-Drafts as reference 58 material or to cite them other than as "work in progress." 60 This Internet-Draft will expire on October 30, 2020. 62 Copyright Notice 64 Copyright (c) 2020 IETF Trust and the persons identified as the 65 document authors. All rights reserved. 67 This document is subject to BCP 78 and the IETF Trust's Legal 68 Provisions Relating to IETF Documents 69 (https://trustee.ietf.org/license-info) in effect on the date of 70 publication of this document. Please review these documents 71 carefully, as they describe your rights and restrictions with respect 72 to this document. Code Components extracted from this document must 73 include Simplified BSD License text as described in Section 4.e of 74 the Trust Legal Provisions and are provided without warranty as 75 described in the Simplified BSD License. 77 Table of Contents 79 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 80 2. Definitions of Terms Used in This Memo . . . . . . . . . . . 5 81 3. Flow Specifications . . . . . . . . . . . . . . . . . . . . . 5 82 4. Dissemination of IPv4 Flow Specification Information . . . . 6 83 4.1. Length Encoding . . . . . . . . . . . . . . . . . . . . . 7 84 4.2. NLRI Value Encoding . . . . . . . . . . . . . . . . . . . 7 85 4.2.1. Operators . . . . . . . . . . . . . . . . . . . . . . 7 86 4.2.2. Components . . . . . . . . . . . . . . . . . . . . . 9 87 4.3. Examples of Encodings . . . . . . . . . . . . . . . . . . 14 88 5. Traffic Filtering . . . . . . . . . . . . . . . . . . . . . . 16 89 5.1. Ordering of Flow Specifications . . . . . . . . . . . . . 17 90 6. Validation Procedure . . . . . . . . . . . . . . . . . . . . 18 91 7. Traffic Filtering Actions . . . . . . . . . . . . . . . . . . 19 92 7.1. Traffic Rate in Bytes (traffic-rate-bytes) sub-type 0x06 21 93 7.2. Traffic Rate in Packets (traffic-rate-packets) sub-type 94 TBD . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 95 7.3. Traffic-action (traffic-action) sub-type 0x07 . . . . . . 21 96 7.4. RT Redirect (rt-redirect) sub-type 0x08 . . . . . . . . . 22 97 7.5. Traffic Marking (traffic-marking) sub-type 0x09 . . . . . 23 98 7.6. Interaction with other Filtering Mechanisms in Routers . 23 99 7.7. Considerations on Traffic Filtering Action Interference . 24 100 8. Dissemination of Traffic Filtering in BGP/MPLS VPN Networks . 24 101 9. Traffic Monitoring . . . . . . . . . . . . . . . . . . . . . 25 102 10. Error Handling . . . . . . . . . . . . . . . . . . . . . . . 25 103 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 25 104 11.1. AFI/SAFI Definitions . . . . . . . . . . . . . . . . . . 25 105 11.2. Flow Component Definitions . . . . . . . . . . . . . . . 26 106 11.3. Extended Community Flow Specification Actions . . . . . 27 107 12. Security Considerations . . . . . . . . . . . . . . . . . . . 30 108 13. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 31 109 14. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 31 110 15. References . . . . . . . . . . . . . . . . . . . . . . . . . 32 111 15.1. Normative References . . . . . . . . . . . . . . . . . . 32 112 15.2. Informative References . . . . . . . . . . . . . . . . . 34 113 15.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 34 114 Appendix A. Example Python code: flow_rule_cmp . . . . . . . . . 35 115 Appendix B. Comparison with RFC 5575 . . . . . . . . . . . . . . 37 116 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 38 118 1. Introduction 120 This document obsoletes "Dissemination of Flow Specification Rules" 121 [RFC5575] (see Appendix B for the differences). This document also 122 obsoletes "Clarification of the Flowspec Redirect Extended Community" 123 [RFC7674] since it incorporates the encoding of the BGP Flow 124 Specification Redirect Extended Community in Section 7.4. 126 Modern IP routers have the capability to forward traffic and to 127 classify, shape, rate limit, filter, or redirect packets based on 128 administratively defined policies. These traffic policy mechanisms 129 allow the operator to define match rules that operate on multiple 130 fields of the packet header. Actions such as the ones described 131 above can be associated with each rule. 133 The n-tuple consisting of the matching criteria defines an aggregate 134 traffic Flow Specification. The matching criteria can include 135 elements such as source and destination address prefixes, IP 136 protocol, and transport protocol port numbers. 138 Section 4 of this document defines a general procedure to encode Flow 139 Specifications for aggregated traffic flows so that they can be 140 distributed as a BGP [RFC4271] NLRI. Additionally, Section 7 of this 141 document defines the required Traffic Filtering Actions BGP Extended 142 Communities and mechanisms to use BGP for intra- and inter-provider 143 distribution of traffic filtering rules to filter (distributed) 144 denial-of-service (DoS) attacks. 146 By expanding routing information with Flow Specifications, the 147 routing system can take advantage of the ACL (Access Control List) or 148 firewall capabilities in the router's forwarding path. Flow 149 Specifications can be seen as more specific routing entries to a 150 unicast prefix and are expected to depend upon the existing unicast 151 data information. 153 A Flow Specification received from an external autonomous system will 154 need to be validated against unicast routing before being accepted 155 (Section 6). The Flow Specification received from an internal BGP 156 peer within the same autonomous system [RFC4271] is assumed to have 157 been validated prior to transmission within the internal BGP (iBGP) 158 mesh of an autonomous system. If the aggregate traffic flow defined 159 by the unicast destination prefix is forwarded to a given BGP peer, 160 then the local system can install more specific Flow Specifications 161 that may result in different forwarding behavior, as requested by 162 this system. 164 From an operational perspective, the utilization of BGP as the 165 carrier for this information allows a network service provider to 166 reuse both internal route distribution infrastructure (e.g., route 167 reflector or confederation design) and existing external 168 relationships (e.g., inter-domain BGP sessions to a customer 169 network). 171 While it is certainly possible to address this problem using other 172 mechanisms, this solution has been utilized in deployments because of 173 the substantial advantage of being an incremental addition to already 174 deployed mechanisms. 176 In current deployments, the information distributed by this extension 177 is originated both manually as well as automatically, the latter by 178 systems that are able to detect malicious traffic flows. When 179 automated systems are used, care should be taken to ensure the 180 correctness of the automated system. The the limitations of the 181 receiving systems that need to process these automated Flow 182 Specifications need to be taken in consideration as well (see also 183 Section 12). 185 This specification defines required protocol extensions to address 186 most common applications of IPv4 unicast and VPNv4 unicast filtering. 187 The same mechanism can be reused and new match criteria added to 188 address similar filtering needs for other BGP address families such 189 as IPv6 families [I-D.ietf-idr-flow-spec-v6]. 191 2. Definitions of Terms Used in This Memo 193 AFI - Address Family Identifier. 195 AS - Autonomous System. 197 Loc-RIB - The Loc-RIB contains the routes that have been selected 198 by the local BGP speaker's Decision Process [RFC4271]. 200 NLRI - Network Layer Reachability Information. 202 PE - Provider Edge router. 204 RIB - Routing Information Base. 206 SAFI - Subsequent Address Family Identifier. 208 VRF - Virtual Routing and Forwarding instance. 210 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 211 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 212 "OPTIONAL" in this document are to be interpreted as described in BCP 213 14 [RFC2119] [RFC8174] when, and only when, they appear in all 214 capitals, as shown here. 216 3. Flow Specifications 218 A Flow Specification is an n-tuple consisting of several matching 219 criteria that can be applied to IP traffic. A given IP packet is 220 said to match the defined Flow Specification if it matches all the 221 specified criteria. This n-tuple is encoded into a BGP NLRI defined 222 below. 224 A given Flow Specification may be associated with a set of 225 attributes, depending on the particular application; such attributes 226 may or may not include reachability information (i.e., NEXT_HOP). 227 Well-known or AS-specific community attributes can be used to encode 228 a set of predetermined actions. 230 A particular application is identified by a specific (Address Family 231 Identifier, Subsequent Address Family Identifier (AFI, SAFI)) pair 232 [RFC4760] and corresponds to a distinct set of RIBs. Those RIBs 233 should be treated independently from each other in order to assure 234 non-interference between distinct applications. 236 BGP itself treats the NLRI as a key to an entry in its databases. 237 Entries that are placed in the Loc-RIB are then associated with a 238 given set of semantics, which is application dependent. This is 239 consistent with existing BGP applications. For instance, IP unicast 240 routing (AFI=1, SAFI=1) and IP multicast reverse-path information 241 (AFI=1, SAFI=2) are handled by BGP without any particular semantics 242 being associated with them until installed in the Loc-RIB. 244 Standard BGP policy mechanisms, such as UPDATE filtering by NLRI 245 prefix as well as community matching and must apply to the Flow 246 specification defined NLRI-type. Network operators can also control 247 propagation of such routing updates by enabling or disabling the 248 exchange of a particular (AFI, SAFI) pair on a given BGP peering 249 session. 251 4. Dissemination of IPv4 Flow Specification Information 253 This document defines a Flow Specification NLRI type (Figure 1) that 254 may include several components such as destination prefix, source 255 prefix, protocol, ports, and others (see Section 4.2 below). 257 This NLRI information is encoded using MP_REACH_NLRI and 258 MP_UNREACH_NLRI attributes as defined in [RFC4760]. When advertising 259 Flow Specifications, the Length of Next Hop Network Address SHOULD be 260 set to 0. The Network Address of Next Hop field MUST be ignored. 262 The NLRI field of the MP_REACH_NLRI and MP_UNREACH_NLRI is encoded as 263 one or more 2-tuples of the form . It consists 264 of a 1- or 2-octet length field followed by a variable-length NLRI 265 value. The length is expressed in octets. 267 +-------------------------------+ 268 | length (0xnn or 0xfnnn) | 269 +-------------------------------+ 270 | NLRI value (variable) | 271 +-------------------------------+ 273 Figure 1: Flow Specification NLRI for IPv4 275 Implementations wishing to exchange Flow Specification MUST use BGP's 276 Capability Advertisement facility to exchange the Multiprotocol 277 Extension Capability Code (Code 1) as defined in [RFC4760]. The 278 (AFI, SAFI) pair carried in the Multiprotocol Extension Capability 279 MUST be (AFI=1, SAFI=133) for IPv4 Flow Specification, and (AFI=1, 280 SAFI=134) for VPNv4 Flow Specification. 282 4.1. Length Encoding 284 o If the NLRI length is smaller than 240 (0xf0 hex) octets, the 285 length field can be encoded as a single octet. 287 o Otherwise, it is encoded as an extended-length 2-octet value in 288 which the most significant nibble has the hex value 0xf. 290 In Figure 1 above, values less-than 240 are encoded using two hex 291 digits (0xnn). Values above 239 are encoded using 3 hex digits 292 (0xfnnn). The highest value that can be represented with this 293 encoding is 4095. For example the length value of 239 is encoded as 294 0xef (single octet) while 240 is encoded as 0xf0f0 (2-octet). 296 4.2. NLRI Value Encoding 298 The Flow Specification NLRI value consists of a list of optional 299 components and is encoded as follows: 301 Encoding: <[component]+> 303 A specific packet is considered to match the Flow Specification when 304 it matches the intersection (AND) of all the components present in 305 the Flow Specification. 307 Components MUST follow strict type ordering by increasing numerical 308 order. A given component type MAY (exactly once) be present in the 309 Flow Specification. If present, it MUST precede any component of 310 higher numeric type value. 312 All combinations of components within a single Flow Specification are 313 allowed. However, some combinations cannot match any packets (e.g. 314 "ICMP Type AND Port" will never match any packets), and thus SHOULD 315 NOT be propagated by BGP. 317 A NLRI value not encoded as specified specified here is considered 318 malformed and error handling according to Section 10 is performed. 320 4.2.1. Operators 322 Most of the components described below make use of comparison 323 operators. Which of the two operators is used is defined by the 324 components in Section 4.2.2. The operators are encoded as a single 325 octet. 327 4.2.1.1. Numeric Operator (numeric_op) 329 This operator is encoded as shown in Figure 2. 331 0 1 2 3 4 5 6 7 332 +---+---+---+---+---+---+---+---+ 333 | e | a | len | 0 |lt |gt |eq | 334 +---+---+---+---+---+---+---+---+ 336 Figure 2: Numeric Operator (numeric_op) 338 e - end-of-list bit: Set in the last {op, value} pair in the list. 340 a - AND bit: If unset, the result of the previous {op, value} pair 341 is logically ORed with the current one. If set, the operation is 342 a logical AND. In the first operator octet of a sequence it 343 SHOULD be encoded as unset and MUST be treated as always unset on 344 decoding. The AND operator has higher priority than OR for the 345 purposes of evaluating logical expressions. 347 len - length: The length of the value field for this operator given 348 as (1 << len). This encodes 1 (len=00), 2 (len=01), 4 (len=10), 8 349 (len=11) octets. 351 0 - SHOULD be set to 0 on NLRI encoding, and MUST be ignored during 352 decoding 354 lt - less than comparison between data and value. 356 gt - greater than comparison between data and value. 358 eq - equality between data and value. 360 The bits lt, gt, and eq can be combined to produce common relational 361 operators such as "less or equal", "greater or equal", and "not equal 362 to" as shown in Table 1. 364 +----+----+----+-----------------------------------+ 365 | lt | gt | eq | Resulting operation | 366 +----+----+----+-----------------------------------+ 367 | 0 | 0 | 0 | false (independent of the value) | 368 | 0 | 0 | 1 | == (equal) | 369 | 0 | 1 | 0 | > (greater than) | 370 | 0 | 1 | 1 | >= (greater than or equal) | 371 | 1 | 0 | 0 | < (less than) | 372 | 1 | 0 | 1 | <= (less than or equal) | 373 | 1 | 1 | 0 | != (not equal value) | 374 | 1 | 1 | 1 | true (independent of the value) | 375 +----+----+----+-----------------------------------+ 377 Table 1: Comparison operation combinations 379 4.2.1.2. Bitmask Operator (bitmask_op) 381 This operator is encoded as shown in Figure 3. 383 0 1 2 3 4 5 6 7 384 +---+---+---+---+---+---+---+---+ 385 | e | a | len | 0 | 0 |not| m | 386 +---+---+---+---+---+---+---+---+ 388 Figure 3: Bitmask Operator (bitmask_op) 390 e, a, len - Most significant nibble: (end-of-list bit, AND bit, and 391 length field), as defined in the Numeric Operator format in 392 Section 4.2.1.1. 394 not - NOT bit: If set, logical negation of operation. 396 m - Match bit: If set, this is a bitwise match operation defined as 397 "(data AND value) == value"; if unset, (data AND value) evaluates 398 to TRUE if any of the bits in the value mask are set in the data 400 0 - all 0 bits: SHOULD be set to 0 on NLRI encoding, and MUST be 401 ignored during decoding 403 4.2.2. Components 405 The encoding of each of the components begins with a type field (1 406 octet) followed by a variable length parameter. The following 407 sections define component types and parameter encodings for the IPv4 408 IP layer and transport layer headers. IPv6 NLRI component types are 409 described in [I-D.ietf-idr-flow-spec-v6]. 411 4.2.2.1. Type 1 - Destination Prefix 413 Encoding: 415 Defines the destination prefix to match. The length and prefix 416 fields are encoded as in BGP UPDATE messages [RFC4271] 418 4.2.2.2. Type 2 - Source Prefix 420 Encoding: 422 Defines the source prefix to match. The length and prefix fields are 423 encoded as in BGP UPDATE messages [RFC4271] 425 4.2.2.3. Type 3 - IP Protocol 427 Encoding: 429 Contains a list of {numeric_op, value} pairs that are used to match 430 the IP protocol value octet in IP packet header (see [RFC0791] 431 Section 3.1). 433 This component uses the Numeric Operator (numeric_op) described in 434 Section 4.2.1.1. Type 3 component values SHOULD be encoded as single 435 octet (numeric_op len=00). 437 4.2.2.4. Type 4 - Port 439 Encoding: 441 Defines a list of {numeric_op, value} pairs that matches source OR 442 destination TCP/UDP ports (see [RFC0793] Section 3.1 and [RFC0768] 443 Section "Format"). This component matches if either the destination 444 port OR the source port of a IP packet matches the value. 446 This component uses the Numeric Operator (numeric_op) described in 447 Section 4.2.1.1. Type 4 component values SHOULD be encoded as 1- or 448 2-octet quantities (numeric_op len=00 or len=01). 450 In case of the presence of the port (destination-port 451 Section 4.2.2.5, source-port Section 4.2.2.6) component only TCP or 452 UDP packets can match the entire Flow Specification. The port 453 component, if present, never matches when the packet's IP protocol 454 value is not 6 (TCP) or 17 (UDP), if the packet is fragmented and 455 this is not the first fragment, or if the system is unable to locate 456 the transport header. Different implementations may or may not be 457 able to decode the transport header in the presence of IP options or 458 Encapsulating Security Payload (ESP) NULL [RFC4303] encryption. 460 4.2.2.5. Type 5 - Destination Port 462 Encoding: 464 Defines a list of {numeric_op, value} pairs used to match the 465 destination port of a TCP or UDP packet (see also [RFC0793] 466 Section 3.1 and [RFC0768] Section "Format"). 468 This component uses the Numeric Operator (numeric_op) described in 469 Section 4.2.1.1. Type 5 component values SHOULD be encoded as 1- or 470 2-octet quantities (numeric_op len=00 or len=01). 472 The last paragraph of Section 4.2.2.4 also applies to this component. 474 4.2.2.6. Type 6 - Source Port 476 Encoding: 478 Defines a list of {numeric_op, value} pairs used to match the source 479 port of a TCP or UDP packet (see also [RFC0793] Section 3.1 and 480 [RFC0768] Section "Format"). 482 This component uses the Numeric Operator (numeric_op) described in 483 Section 4.2.1.1. Type 6 component values SHOULD be encoded as 1- or 484 2-octet quantities (numeric_op len=00 or len=01). 486 The last paragraph of Section 4.2.2.4 also applies to this component. 488 4.2.2.7. Type 7 - ICMP type 490 Encoding: 492 Defines a list of {numeric_op, value} pairs used to match the type 493 field of an ICMP packet (see also [RFC0792] Section "Message 494 Formats"). 496 This component uses the Numeric Operator (numeric_op) described in 497 Section 4.2.1.1. Type 7 component values SHOULD be encoded as single 498 octet (numeric_op len=00). 500 In case of the presence of the ICMP type component only ICMP packets 501 can match the entire Flow Specification. The ICMP type component, if 502 present, never matches when the packet's IP protocol value is not 1 503 (ICMP), if the packet is fragmented and this is not the first 504 fragment, or if the system is unable to locate the transport header. 505 Different implementations may or may not be able to decode the 506 transport header in the presence of IP options or Encapsulating 507 Security Payload (ESP) NULL [RFC4303] encryption. 509 4.2.2.8. Type 8 - ICMP code 511 Encoding: 513 Defines a list of {numeric_op, value} pairs used to match the code 514 field of an ICMP packet (see also [RFC0792] Section "Message 515 Formats"). 517 This component uses the Numeric Operator (numeric_op) described in 518 Section 4.2.1.1. Type 8 component values SHOULD be encoded as single 519 octet (numeric_op len=00). 521 In case of the presence of the ICMP code component only ICMP packets 522 can match the entire Flow Specification. The ICMP code component, if 523 present, never matches when the packet's IP protocol value is not 1 524 (ICMP), if the packet is fragmented and this is not the first 525 fragment, or if the system is unable to locate the transport header. 526 Different implementations may or may not be able to decode the 527 transport header in the presence of IP options or Encapsulating 528 Security Payload (ESP) NULL [RFC4303] encryption. 530 4.2.2.9. Type 9 - TCP flags 532 Encoding: 534 Defines a list of {bitmask_op, bitmask} pairs used to match TCP 535 Control Bits (see also [RFC0793] Section 3.1). 537 This component uses the Bitmask Operator (bitmask_op) described in 538 Section 4.2.1.2. Type 9 component bitmasks MUST be encoded as 1- or 539 2-octet bitmask (bitmask_op len=00 or len=01). 541 When a single octet (bitmask_op len=00) is specified, it matches 542 octet 14 of the TCP header (see also [RFC0793] Section 3.1), which 543 contains the TCP Control Bits. When a 2-octet (bitmask_op len=01) 544 encoding is used, it matches octets 13 and 14 of the TCP header with 545 the data offset (leftmost 4 bits) always treated as 0. 547 In case of the presence of the TCP flags component only TCP packets 548 can match the entire Flow Specification. The TCP flags component, if 549 present, never matches when the packet's IP protocol value is not 6 550 (TCP), if the packet is fragmented and this is not the first 551 fragment, or if the system is unable to locate the transport header. 552 Different implementations may or may not be able to decode the 553 transport header in the presence of IP options or Encapsulating 554 Security Payload (ESP) NULL [RFC4303] encryption. 556 4.2.2.10. Type 10 - Packet length 558 Encoding: 560 Defines a list of {numeric_op, value} pairs used to match on the 561 total IP packet length (excluding Layer 2 but including IP header). 563 This component uses the Numeric Operator (numeric_op) described in 564 Section 4.2.1.1. Type 10 component values SHOULD be encoded as 1- or 565 2-octet quantities (numeric_op len=00 or len=01). 567 4.2.2.11. Type 11 - DSCP (Diffserv Code Point) 569 Encoding: 571 Defines a list of {numeric_op, value} pairs used to match the 6-bit 572 DSCP field (see also [RFC2474]). 574 This component uses the Numeric Operator (numeric_op) described in 575 Section 4.2.1.1. Type 11 component values MUST be encoded as single 576 octet (numeric_op len=00). 578 The six least significant bits contain the DSCP value. All other 579 bits SHOULD be treated as 0. 581 4.2.2.12. Type 12 - Fragment 583 Encoding: 585 Defines a list of {bitmask_op, bitmask} pairs used to match specific 586 IP fragments. 588 This component uses the Bitmask Operator (bitmask_op) described in 589 Section 4.2.1.2. The Type 12 component bitmask MUST be encoded as 590 single octet bitmask (bitmask_op len=00). 592 0 1 2 3 4 5 6 7 593 +---+---+---+---+---+---+---+---+ 594 | 0 | 0 | 0 | 0 |LF |FF |IsF|DF | 595 +---+---+---+---+---+---+---+---+ 597 Figure 4: Fragment Bitmask Operand 599 Bitmask values: 601 DF - Don't fragment - match if [RFC0791] IP Header Flags Bit-1 (DF) 602 is 1 604 IsF - Is a fragment - match if [RFC0791] IP Header Fragment Offset 605 is not 0 607 FF - First fragment - match if [RFC0791] IP Header Fragment Offset 608 is 0 AND Flags Bit-2 (MF) is 1 610 LF - Last fragment - match if [RFC0791] IP Header Fragment Offset is 611 not 0 AND Flags Bit-2 (MF) is 0 613 0 - SHOULD be set to 0 on NLRI encoding, and MUST be ignored during 614 decoding 616 4.3. Examples of Encodings 618 4.3.1. Example 1 620 An example of a Flow Specification NLRI encoding for: "all packets to 621 192.0.2.0/24 and TCP port 25". 623 +--------+----------------+----------+----------+ 624 | length | destination | protocol | port | 625 +--------+----------------+----------+----------+ 626 | 0x0b | 01 18 c0 00 02 | 03 81 06 | 04 81 19 | 627 +--------+----------------+----------+----------+ 629 Decoded: 631 +-------+------------+-------------------------------+ 632 | Value | | | 633 +-------+------------+-------------------------------+ 634 | 0x0b | length | 11 octets (len<240 1-octet) | 635 | 0x01 | type | Type 1 - Destination Prefix | 636 | 0x18 | length | 24 bit | 637 | 0xc0 | prefix | 192 | 638 | 0x00 | prefix | 0 | 639 | 0x02 | prefix | 2 | 640 | 0x03 | type | Type 3 - IP Protocol | 641 | 0x81 | numeric_op | end-of-list, value size=1, == | 642 | 0x06 | value | 6 (TCP) | 643 | 0x04 | type | Type 4 - Port | 644 | 0x81 | numeric_op | end-of-list, value size=1, == | 645 | 0x19 | value | 25 | 646 +-------+------------+-------------------------------+ 648 This constitutes a NLRI with a NLRI length of 11 octets. 650 4.3.2. Example 2 652 An example of a Flow Specification NLRI encoding for: "all packets to 653 192.0.2.0/24 from 203.0.113.0/24 and port {range [137, 139] or 654 8080}". 656 +--------+----------------+----------------+-------------------------+ 657 | length | destination | source | port | 658 +--------+----------------+----------------+-------------------------+ 659 | 0x12 | 01 18 c0 00 02 | 02 18 cb 00 71 | 04 03 89 45 8b 91 1f 90 | 660 +--------+----------------+----------------+-------------------------+ 662 Decoded: 664 +--------+------------+-------------------------------+ 665 | Value | | | 666 +--------+------------+-------------------------------+ 667 | 0x12 | length | 18 octets (len<240 1-octet) | 668 | 0x01 | type | Type 1 - Destination Prefix | 669 | 0x18 | length | 24 bit | 670 | 0xc0 | prefix | 192 | 671 | 0x00 | prefix | 0 | 672 | 0x02 | prefix | 2 | 673 | 0x02 | type | Type 2 - Source Prefix | 674 | 0x18 | length | 24 bit | 675 | 0xcb | prefix | 203 | 676 | 0x00 | prefix | 0 | 677 | 0x71 | prefix | 113 | 678 | 0x04 | type | Type 4 - Port | 679 | 0x03 | numeric_op | value size=1, >= | 680 | 0x89 | value | 137 | 681 | 0x45 | numeric_op | "AND", value size=1, <= | 682 | 0x8b | value | 139 | 683 | 0x91 | numeric_op | end-of-list, value size=2, == | 684 | 0x1f90 | value | 8080 | 685 +--------+------------+-------------------------------+ 687 This constitutes a NLRI with a NLRI length of 18 octets. 689 4.3.3. Example 3 691 An example of a Flow Specification NLRI encoding for: "all packets to 692 192.0.2.1/32 and fragment { DF or FF } (matching packet with DF bit 693 set or First Fragments) 694 +--------+-------------------+----------+ 695 | length | destination | fragment | 696 +--------+-------------------+----------+ 697 | 0x09 | 01 20 c0 00 02 01 | 0c 80 05 | 698 +--------+-------------------+----------+ 700 Decoded: 702 +-------+------------+------------------------------+ 703 | Value | | | 704 +-------+------------+------------------------------+ 705 | 0x09 | length | 9 octets (len<240 1-octet) | 706 | 0x01 | type | Type 1 - Destination Prefix | 707 | 0x20 | length | 32 bit | 708 | 0xc0 | prefix | 192 | 709 | 0x00 | prefix | 0 | 710 | 0x02 | prefix | 2 | 711 | 0x01 | prefix | 1 | 712 | 0x0c | type | Type 12 - Fragment | 713 | 0x80 | bitmask_op | end-of-list, value size=1 | 714 | 0x05 | bitmask | DF=1, FF=1 | 715 +-------+------------+------------------------------+ 717 This constitutes a NLRI with a NLRI length of 9 octets. 719 5. Traffic Filtering 721 Traffic filtering policies have been traditionally considered to be 722 relatively static. Limitations of these static mechanisms caused 723 this new dynamic mechanism to be designed for the three new 724 applications of traffic filtering: 726 o Prevention of traffic-based, denial-of-service (DOS) attacks. 728 o Traffic filtering in the context of BGP/MPLS VPN service. 730 o Centralized traffic control for SDN/NFV networks. 732 These applications require coordination among service providers and/ 733 or coordination among the AS within a service provider. 735 The Flow Specification NLRI defined in Section 4 conveys information 736 about traffic filtering rules for traffic that should be discarded or 737 handled in a manner specified by a set of pre-defined actions (which 738 are defined in BGP Extended Communities). This mechanism is 739 primarily designed to allow an upstream autonomous system to perform 740 inbound filtering in their ingress routers of traffic that a given 741 downstream AS wishes to drop. 743 In order to achieve this goal, this document specifies two 744 application-specific NLRI identifiers that provide traffic filters, 745 and a set of actions encoding in BGP Extended Communities. The two 746 application-specific NLRI identifiers are: 748 o IPv4 Flow Specification identifier (AFI=1, SAFI=133) along with 749 specific semantic rules for IPv4 routes, and 751 o VPNv4 Flow Specification identifier (AFI=1, SAFI=134) value, which 752 can be used to propagate traffic filtering information in a BGP/ 753 MPLS VPN environment. 755 Encoding of the NLRI is described in Section 4 for IPv4 Flow 756 Specification and in Section 8 for VPNv4 Flow Specification. The 757 filtering actions are described in Section 7. 759 5.1. Ordering of Flow Specifications 761 More than one Flow Specification may match a particular traffic flow. 762 Thus, it is necessary to define the order in which Flow 763 Specifications get matched and actions being applied to a particular 764 traffic flow. This ordering function is such that it does not depend 765 on the arrival order of the Flow Specification via BGP and thus is 766 consistent in the network. 768 The relative order of two Flow Specifications is determined by 769 comparing their respective components. The algorithm starts by 770 comparing the left-most components (lowest component type value) of 771 the Flow Specifications. If the types differ, the Flow Specification 772 with lowest numeric type value has higher precedence (and thus will 773 match before) than the Flow Specification that doesn't contain that 774 component type. If the component types are the same, then a type- 775 specific comparison is performed (see below). If the types are equal 776 the algorithm continues with the next component. 778 For IP prefix values (IP destination or source prefix): If one of the 779 two prefixes to compare is a more specific prefix of the other, the 780 more specific prefix has higher precedence. Otherwise the one with 781 the lowest IP value has higher precedence. 783 For all other component types, unless otherwise specified, the 784 comparison is performed by comparing the component data as a binary 785 string using the memcmp() function as defined by [ISO_IEC_9899]. For 786 strings with equal lengths the lowest string (memcmp) has higher 787 precedence. For strings of different lengths, the common prefix is 788 compared. If the common prefix is not equal the string with the 789 lowest prefix has higher precedence. If the common prefix is equal, 790 the longest string is considered to have higher precedence than the 791 shorter one. 793 The code in Appendix A shows a Python3 implementation of the 794 comparison algorithm. The full code was tested with Python 3.6.3 and 795 can be obtained at 796 https://github.com/stoffi92/rfc5575bis/tree/master/flowspec-cmp [1]. 798 6. Validation Procedure 800 Flow Specifications received from a BGP peer that are accepted in the 801 respective Adj-RIB-In are used as input to the route selection 802 process. Although the forwarding attributes of two routes for the 803 same Flow Specification prefix may be the same, BGP is still required 804 to perform its path selection algorithm in order to select the 805 correct set of attributes to advertise. 807 The first step of the BGP Route Selection procedure (Section 9.1.2 of 808 [RFC4271] is to exclude from the selection procedure routes that are 809 considered non-feasible. In the context of IP routing information, 810 this step is used to validate that the NEXT_HOP attribute of a given 811 route is resolvable. 813 The concept can be extended, in the case of the Flow Specification 814 NLRI, to allow other validation procedures. 816 The validation process described below validates Flow Specifications 817 against unicast routes received over the same AFI but the associated 818 unicast routing information SAFI: 820 Flow Specification received over SAFI=133 will be validated 821 against routes received over SAFI=1 823 Flow Specification received over SAFI=134 will be validated 824 against routes received over SAFI=128 826 In the absence of explicit configuration a Flow Specification NLRI 827 MUST be validated such that it is considered feasible if and only if 828 all of the conditions below are true: 830 a) A destination prefix component is embedded in the Flow 831 Specification. 833 b) The originator of the Flow Specification matches the originator 834 of the best-match unicast route for the destination prefix 835 embedded in the Flow Specification (this is the unicast route with 836 the longest possible prefix length covering the destination prefix 837 embedded in the Flow Specification). 839 c) There are no "more-specific" unicast routes, when compared with 840 the flow destination prefix, that have been received from a 841 different neighboring AS than the best-match unicast route, which 842 has been determined in rule b). 844 However, rule a) MAY be relaxed by explicit configuration, permitting 845 Flow Specifications that include no destination prefix component. If 846 such is the case, rules b) and c) are moot and MUST be disregarded. 848 By "originator" of a BGP route, we mean either the address of the 849 originator in the ORIGINATOR_ID Attribute [RFC4456], or the source IP 850 address of the BGP peer, if this path attribute is not present. 852 BGP implementations MUST also enforce that the AS_PATH attribute of a 853 route received via the External Border Gateway Protocol (eBGP) 854 contains the neighboring AS in the left-most position of the AS_PATH 855 attribute. While this rule is optional in the BGP specification, it 856 becomes necessary to enforce it here for security reasons. 858 The best-match unicast route may change over the time independently 859 of the Flow Specification NLRI. Therefore, a revalidation of the 860 Flow Specification NLRI MUST be performed whenever unicast routes 861 change. Revalidation is defined as retesting rules a) to c) as 862 described above. 864 Explanation: 866 The underlying concept is that the neighboring AS that advertises the 867 best unicast route for a destination is allowed to advertise Flow 868 Specification information that conveys a destination prefix that is 869 more or equally specific. Thus, as long as there are no "more- 870 specific" unicast routes, received from a different neighboring AS, 871 which would be affected by that Flow Specification, the Flow 872 Specification is validated successfully. 874 The neighboring AS is the immediate destination of the traffic 875 described by the Flow Specification. If it requests these flows to 876 be dropped, that request can be honored without concern that it 877 represents a denial of service in itself. The reasoning is that this 878 is as if the traffic is being dropped by the downstream autonomous 879 system, and there is no added value in carrying the traffic to it. 881 7. Traffic Filtering Actions 883 This document defines a minimum set of Traffic Filtering Actions that 884 it standardizes as BGP extended communities [RFC4360]. This is not 885 meant to be an inclusive list of all the possible actions, but only a 886 subset that can be interpreted consistently across the network. 888 Additional actions can be defined as either requiring standards or as 889 vendor specific. 891 The default action for a matching Flow Specification is to accept the 892 packet (treat the packet according to the normal forwarding behaviour 893 of the system). 895 This document defines the following extended communities values shown 896 in Table 2 in the form 0xttss where tt indicates the type and ss 897 indicates the sub-type of the extended community. Encodings for 898 these extended communities are described below. 900 +-------------+---------------------------+-------------------------+ 901 | community | action | encoding | 902 | 0xttss | | | 903 +-------------+---------------------------+-------------------------+ 904 | 0x8006 | traffic-rate-bytes | 2-octet AS, 4-octet | 905 | | (Section 7.1) | float | 906 | TBD | traffic-rate-packets | 2-octet AS, 4-octet | 907 | | (Section 7.1) | float | 908 | 0x8007 | traffic-action | bitmask | 909 | | (Section 7.3) | | 910 | 0x8008 | rt-redirect AS-2octet | 2-octet AS, 4-octet | 911 | | (Section 7.4) | value | 912 | 0x8108 | rt-redirect IPv4 | 4-octet IPv4 address, | 913 | | (Section 7.4) | 2-octet value | 914 | 0x8208 | rt-redirect AS-4octet | 4-octet AS, 2-octet | 915 | | (Section 7.4) | value | 916 | 0x8009 | traffic-marking | DSCP value | 917 | | (Section 7.5) | | 918 +-------------+---------------------------+-------------------------+ 920 Table 2: Traffic Filtering Action Extended Communities 922 Multiple Traffic Filtering Actions defined in this document may be 923 present for a single Flow Specification and SHOULD be applied to the 924 traffic flow (for example traffic-rate-bytes and rt-redirect can be 925 applied to packets at the same time). If not all of the Traffic 926 Filtering Actions can be applied to a traffic flow they should be 927 treated as interfering Traffic Filtering Actions (see below). 929 Some Traffic Filtering Actions may interfere with each other or even 930 contradict. Section 7.7 of this document provides general 931 considerations on such Traffic Filtering Action interference. Any 932 additional definition of Traffic Filtering Actions SHOULD specify the 933 action to take if those Traffic Filtering Actions interfere (also 934 with existing Traffic Filtering Actions). 936 All Traffic Filtering Actions are specified as transitive BGP 937 Extended Communities. 939 7.1. Traffic Rate in Bytes (traffic-rate-bytes) sub-type 0x06 941 The traffic-rate-bytes extended community uses the following extended 942 community encoding: 944 The first two octets carry the 2-octet id, which can be assigned from 945 a 2-octet AS number. When a 4-octet AS number is locally present, 946 the 2 least significant octets of such an AS number can be used. 947 This value is purely informational and SHOULD NOT be interpreted by 948 the implementation. 950 The remaining 4 octets carry the maximum rate information in IEEE 951 floating point [IEEE.754.1985] format, units being bytes per second. 952 A traffic-rate of 0 should result on all traffic for the particular 953 flow to be discarded. On encoding the traffic-rate MUST NOT be 954 negative. On decoding negative values MUST be treated as zero 955 (discard all traffic). 957 Interferes with: May interfere with the traffic-rate-packets (see 958 Section 7.2). A policy may allow both filtering by traffic-rate- 959 packets and traffic-rate-bytes. If the policy does not allow this, 960 these two actions will conflict. 962 7.2. Traffic Rate in Packets (traffic-rate-packets) sub-type TBD 964 The traffic-rate-packets extended community uses the same encoding as 965 the traffic-rate-bytes extended community. The floating point value 966 carries the maximum packet rate in packets per second. A traffic- 967 rate-packets of 0 should result in all traffic for the particular 968 flow to be discarded. On encoding the traffic-rate-packets MUST NOT 969 be negative. On decoding negative values MUST be treated as zero 970 (discard all traffic). 972 Interferes with: May interfere with the traffic-rate-bytes (see 973 Section 7.1). A policy may allow both filtering by traffic-rate- 974 packets and traffic-rate-bytes. If the policy does not allow this, 975 these two actions will conflict. 977 7.3. Traffic-action (traffic-action) sub-type 0x07 979 The traffic-action extended community consists of 6 octets of which 980 only the 2 least significant bits of the 6th octet (from left to 981 right) are defined by this document as shown in Figure 5. 983 0 1 2 3 984 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 1 985 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 986 | Traffic Action Field | 987 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 988 | Tr. Action Field (cont.) |S|T| 989 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 991 Figure 5: Traffic-action Extended Community Encoding 993 where S and T are defined as: 995 o T: Terminal Action (bit 47): When this bit is set, the traffic 996 filtering engine will evaluate any subsequent Flow Specifications 997 (as defined by the ordering procedure Section 5.1). If not set, 998 the evaluation of the traffic filters stops when this Flow 999 Specification is evaluated. 1001 o S: Sample (bit 46): Enables traffic sampling and logging for this 1002 Flow Specification (only effective when set). 1004 o Traffic Action Field: Other Traffic Action Field (see Section 11) 1005 bits unused in this specification. These bits SHOULD be set to 0 1006 on encoding, and MUST be ignored during decoding. 1008 The use of the Terminal Action (bit 47) may result in more than one 1009 Flow Specification matching a particular traffic flow. All the 1010 Traffic Filtering Actions from these Flow Specifications shall be 1011 collected and applied. In case of interfering Traffic Filtering 1012 Actions it is an implementation decision which Traffic Filtering 1013 Actions are selected. See also Section 7.7. 1015 Interferes with: No other BGP Flow Specification Traffic Filtering 1016 Action in this document. 1018 7.4. RT Redirect (rt-redirect) sub-type 0x08 1020 The redirect extended community allows the traffic to be redirected 1021 to a VRF routing instance that lists the specified route-target in 1022 its import policy. If several local instances match this criteria, 1023 the choice between them is a local matter (for example, the instance 1024 with the lowest Route Distinguisher value can be elected). 1026 This Extended Community allows 3 different encodings formats for the 1027 route-target (type 0x80, 0x81, 0x82). It uses the same encoding as 1028 the Route Target Extended Community in Sections 3.1 (type 0x80: 1029 2-octet AS, 4-octet value), 3.2 (type 0x81: 4-octet IPv4 address, 1030 2-octet value) and 4 of [RFC4360] and Section 2 (type 0x82: 4-octet 1031 AS, 2-octet value) of [RFC5668] with the high-order octet of the Type 1032 field 0x80, 0x81, 0x82 respectively and the low-order of the Type 1033 field (Sub-Type) always 0x08. 1035 Interferes with: No other BGP Flow Specification Traffic Filtering 1036 Action in this document. 1038 7.5. Traffic Marking (traffic-marking) sub-type 0x09 1040 The traffic marking extended community instructs a system to modify 1041 the DSCP bits in the IP header ([RFC2474] Section 3) of a transiting 1042 IP packet to the corresponding value encoded in the 6 least 1043 significant bits of the extended community value as shown in 1044 Figure 6. 1046 The extended is encoded as follows: 1048 0 1 2 3 1049 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 1050 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1051 | reserved | reserved | reserved | reserved | 1052 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1053 | reserved | r.| DSCP | 1054 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1056 Figure 6: Traffic Marking Extended Community Encoding 1058 o DSCP: new DSCP value for the transiting IP packet. 1060 o reserved, r.: SHOULD be set to 0 on encoding, and MUST be ignored 1061 during decoding. 1063 Interferes with: No other BGP Flow Specification Traffic Filtering 1064 Action in this document. 1066 7.6. Interaction with other Filtering Mechanisms in Routers 1068 Implementations should provide mechanisms that map an arbitrary BGP 1069 community value (normal or extended) to Traffic Filtering Actions 1070 that require different mappings on different systems in the network. 1071 For instance, providing packets with a worse-than-best-effort per-hop 1072 behavior is a functionality that is likely to be implemented 1073 differently in different systems and for which no standard behavior 1074 is currently known. Rather than attempting to define it here, this 1075 can be accomplished by mapping a user-defined community value to 1076 platform-/network-specific behavior via user configuration. 1078 7.7. Considerations on Traffic Filtering Action Interference 1080 Since Traffic Filtering Actions are represented as BGP extended 1081 community values, Traffic Filtering Actions may interfere with each 1082 other (e.g. there may be more than one conflicting traffic-rate-bytes 1083 Traffic Filtering Action associated with a single Flow 1084 Specification). Traffic Filtering Action interference has no impact 1085 on BGP propagation of Flow Specifications (all communities are 1086 propagated according to policies). 1088 If a Flow Specification associated with interfering Traffic Filtering 1089 Actions is selected for packet forwarding, it is an implementation 1090 decision which of the interfering Traffic Filtering Actions are 1091 selected. Implementors of this specification SHOULD document the 1092 behaviour of their implementation in such cases. 1094 Operators are encouraged to make use of the BGP policy framework 1095 supported by their implementation in order to achieve a predictable 1096 behaviour. See also Section 12. 1098 8. Dissemination of Traffic Filtering in BGP/MPLS VPN Networks 1100 Provider-based Layer 3 VPN networks, such as the ones using a BGP/ 1101 MPLS IP VPN [RFC4364] control plane, may have different traffic 1102 filtering requirements than Internet service providers. But also 1103 Internet service providers may use those VPNs for scenarios like 1104 having the Internet routing table in a VRF, resulting in the same 1105 traffic filtering requirements as defined for the global routing 1106 table environment within this document. This document defines an 1107 additional BGP NLRI type (AFI=1, SAFI=134) value, which can be used 1108 to propagate Flow Specification in a BGP/MPLS VPN environment. 1110 The NLRI format for this address family consists of a fixed-length 1111 Route Distinguisher field (8 octets) followed by the Flow 1112 Specification NLRI value (Section 4.2). The NLRI length field shall 1113 include both the 8 octets of the Route Distinguisher as well as the 1114 subsequent Flow Specification NLRI value. The resulting encoding is 1115 shown in Figure 7. 1117 +--------------------------------+ 1118 | length (0xnn or 0xfn nn) | 1119 +--------------------------------+ 1120 | Route Distinguisher (8 octets) | 1121 +--------------------------------+ 1122 | NLRI value (variable) | 1123 +--------------------------------+ 1125 Figure 7: Flow Specification NLRI for MPLS 1127 Propagation of this NLRI is controlled by matching Route Target 1128 extended communities associated with the BGP path advertisement with 1129 the VRF import policy, using the same mechanism as described in BGP/ 1130 MPLS IP VPNs [RFC4364]. 1132 Flow Specifications received via this NLRI apply only to traffic that 1133 belongs to the VRF(s) in which it is imported. By default, traffic 1134 received from a remote PE is switched via an MPLS forwarding decision 1135 and is not subject to filtering. 1137 Contrary to the behavior specified for the non-VPN NLRI, Flow 1138 Specifications are accepted by default, when received from remote PE 1139 routers. 1141 The validation procedure (Section 6) and Traffic Filtering Actions 1142 (Section 7) are the same as for IPv4. 1144 9. Traffic Monitoring 1146 Traffic filtering applications require monitoring and traffic 1147 statistics facilities. While this is an implementation specific 1148 choice, implementations SHOULD provide: 1150 o A mechanism to log the packet header of filtered traffic. 1152 o A mechanism to count the number of matches for a given Flow 1153 Specification. 1155 10. Error Handling 1157 Error handling according to [RFC7606] and [RFC4760] applies to this 1158 specification. 1160 This document introduces Traffic Filtering Action Extended 1161 Communities. Malformed Traffic Filtering Action Extended Communities 1162 in the sense of [RFC7606] Section 7.14. are Extended Community values 1163 that cannot be decoded according to Section 7 of this document. 1165 11. IANA Considerations 1167 This section complies with [RFC7153]. 1169 11.1. AFI/SAFI Definitions 1171 IANA maintains a registry entitled "SAFI Values". For the purpose of 1172 this work, IANA is requested to update the following SAFIs to read 1173 according to the table below (Note: This document obsoletes both 1174 RFC7674 and RFC5575 and all references to those documents should be 1175 deleted from the registry below): 1177 +-------+------------------------------------------+----------------+ 1178 | Value | Name | Reference | 1179 +-------+------------------------------------------+----------------+ 1180 | 133 | Dissemination of Flow Specification | [this | 1181 | | rules | document] | 1182 | 134 | L3VPN Dissemination of Flow | [this | 1183 | | Specification rules | document] | 1184 +-------+------------------------------------------+----------------+ 1186 Table 3: Registry: SAFI Values 1188 The above textual changes clarify the definition of the SAFIs rather 1189 than change its underlying meaning. Therefore, based on 1190 "The YANG 1.1 Data Modeling Language" [RFC7950], the above text 1191 implies that the following YANG descriptions from 1192 "Common YANG Data Types for the Routing Area" [RFC8294] need to have 1193 their descriptions at https://www.iana.org/assignments/iana-routing- 1194 types [2] changed to: 1196 1197 enum ipv4-flow-spec-safi { 1198 value 133; 1199 description 1200 "Dissemination of Flow Specification rules SAFI."; 1201 } 1202 enum vpnv4-flow-spec-safi { 1203 value 134; 1204 description 1205 "L3VPN Dissemination of Flow Specification rules SAFI"; 1206 } 1207 1209 11.2. Flow Component Definitions 1211 A Flow Specification consists of a sequence of flow components, which 1212 are identified by an 8-bit component type. IANA has created and 1213 maintains a registry entitled "Flow Spec Component Types". IANA is 1214 requested to update the reference for this registry to [this 1215 document]. Furthermore the references to the values should be 1216 updated according to the table below (Note: This document obsoletes 1217 both RFC7674 and RFC5575 and all references to those documents should 1218 be deleted from the registry below). 1220 +-------+--------------------+-----------------+ 1221 | Value | Name | Reference | 1222 +-------+--------------------+-----------------+ 1223 | 1 | Destination Prefix | [this document] | 1224 | 2 | Source Prefix | [this document] | 1225 | 3 | IP Protocol | [this document] | 1226 | 4 | Port | [this document] | 1227 | 5 | Destination port | [this document] | 1228 | 6 | Source port | [this document] | 1229 | 7 | ICMP type | [this document] | 1230 | 8 | ICMP code | [this document] | 1231 | 9 | TCP flags | [this document] | 1232 | 10 | Packet length | [this document] | 1233 | 11 | DSCP | [this document] | 1234 | 12 | Fragment | [this document] | 1235 +-------+--------------------+-----------------+ 1237 Table 4: Registry: Flow Spec Component Types 1239 In order to manage the limited number space and accommodate several 1240 usages, the following policies defined by [RFC8126] are used: 1242 +--------------+-------------------------------+ 1243 | Type Values | Policy | 1244 +--------------+-------------------------------+ 1245 | 0 | Reserved | 1246 | [1 .. 12] | Defined by this specification | 1247 | [13 .. 127] | Specification required | 1248 | [128 .. 255] | First Come First Served | 1249 +--------------+-------------------------------+ 1251 Table 5: Flow Spec Component Types Policies 1253 11.3. Extended Community Flow Specification Actions 1255 The Extended Community Flow Specification Action types defined in 1256 this document consist of two parts: 1258 Type (BGP Transitive Extended Community Type) 1260 Sub-Type 1262 For the type-part, IANA maintains a registry entitled "BGP Transitive 1263 Extended Community Types". For the purpose of this work (Section 7), 1264 IANA is requested to update the references to the following entries 1265 according to the table below (Note: This document obsoletes both 1266 RFC7674 and RFC5575 and all references to those documents should be 1267 deleted in the registry below): 1269 +-------+-----------------------------------------------+-----------+ 1270 | Type | Name | Reference | 1271 | Value | | | 1272 +-------+-----------------------------------------------+-----------+ 1273 | 0x81 | Generic Transitive Experimental | [this | 1274 | | Use Extended Community Part 2 (Sub-Types are | document] | 1275 | | defined in the "Generic Transitive | | 1276 | | Experimental Use Extended Community Part 2 | | 1277 | | Sub-Types" Registry) | | 1278 | 0x82 | Generic Transitive Experimental | [this | 1279 | | Use Extended Community Part 3 | document] | 1280 | | (Sub-Types are defined in the "Generic | | 1281 | | Transitive Experimental Use | | 1282 | | Extended Community Part 3 Sub-Types" | | 1283 | | Registry) | | 1284 +-------+-----------------------------------------------+-----------+ 1286 Table 6: Registry: BGP Transitive Extended Community Types 1288 For the sub-type part of the extended community Traffic Filtering 1289 Actions IANA maintains the following registries. IANA is requested 1290 to update all names and references according to the tables below and 1291 assign a new value for the "Flow spec traffic-rate-packets" Sub-Type 1292 (Note: This document obsoletes both RFC7674 and RFC5575 and all 1293 references to those documents should be deleted from the registries 1294 below). 1296 +----------+--------------------------------------------+-----------+ 1297 | Sub-Type | Name | Reference | 1298 | Value | | | 1299 +----------+--------------------------------------------+-----------+ 1300 | 0x06 | Flow spec traffic-rate-bytes | [this | 1301 | | | document] | 1302 | TBD | Flow spec traffic-rate-packets | [this | 1303 | | | document] | 1304 | 0x07 | Flow spec traffic-action (Use | [this | 1305 | | of the "Value" field is defined in the | document] | 1306 | | "Traffic Action Fields" registry) | | 1307 | 0x08 | Flow spec rt-redirect | [this | 1308 | | AS-2octet format | document] | 1309 | 0x09 | Flow spec traffic-remarking | [this | 1310 | | | document] | 1311 +----------+--------------------------------------------+-----------+ 1313 Table 7: Registry: Generic Transitive Experimental Use Extended 1314 Community Sub-Types 1316 +------------+----------------------------------------+-------------+ 1317 | Sub-Type | Name | Reference | 1318 | Value | | | 1319 +------------+----------------------------------------+-------------+ 1320 | 0x08 | Flow spec rt-redirect IPv4 | [this | 1321 | | format | document] | 1322 +------------+----------------------------------------+-------------+ 1324 Table 8: Registry: Generic Transitive Experimental Use Extended 1325 Community Part 2 Sub-Types 1327 +------------+-----------------------------------------+------------+ 1328 | Sub-Type | Name | Reference | 1329 | Value | | | 1330 +------------+-----------------------------------------+------------+ 1331 | 0x08 | Flow spec rt-redirect | [this | 1332 | | AS-4octet format | document] | 1333 +------------+-----------------------------------------+------------+ 1335 Table 9: Registry: Generic Transitive Experimental Use Extended 1336 Community Part 3 Sub-Types 1338 Furthermore IANA is requested to update the reference for the 1339 registries "Generic Transitive Experimental Use Extended Community 1340 Part 2 Sub-Types" and "Generic Transitive Experimental Use Extended 1341 Community Part 3 Sub-Types" to [this document]. 1343 The "traffic-action" extended community (Section 7.3) defined in this 1344 document has 46 unused bits, which can be used to convey additional 1345 meaning. IANA created and maintains a registry entitled: "Traffic 1346 Action Fields". IANA is requested to update the reference for this 1347 registry to [this document]. Furthermore IANA is requested to update 1348 the references according to the table below. These values should be 1349 assigned via IETF Review rules only (Note: This document obsoletes 1350 both RFC7674 and RFC5575 and all references to those documents should 1351 be deleted from the registry below). 1353 +-----+-----------------+-----------------+ 1354 | Bit | Name | Reference | 1355 +-----+-----------------+-----------------+ 1356 | 47 | Terminal Action | [this document] | 1357 | 46 | Sample | [this document] | 1358 +-----+-----------------+-----------------+ 1360 Table 10: Registry: Traffic Action Fields 1362 12. Security Considerations 1364 As long as Flow Specifications are restricted to match the 1365 corresponding unicast routing paths for the relevant prefixes 1366 (Section 6), the security characteristics of this proposal are 1367 equivalent to the existing security properties of BGP unicast 1368 routing. Any relaxation of the validation procedure described in 1369 Section 6 may allow unwanted Flow Specifications to be propagated and 1370 thus unwanted Traffic Filtering Actions may be applied to flows. 1372 Where the above mechanisms are not in place, this could open the door 1373 to further denial-of-service attacks such as unwanted traffic 1374 filtering, remarking or redirection. 1376 Deployment of specific relaxations of the validation within an 1377 administrative boundary of a network are useful in some networks for 1378 quickly distributing filters to prevent denial-of-service attacks. 1379 For a network to utilize this relaxation, the BGP policies must 1380 support additional filtering since the origin AS field is empty. 1381 Specifications relaxing the validation restrictions MUST contain 1382 security considerations that provide details on the required 1383 additional filtering. For example, the use of Origin validation can 1384 provide enhanced filtering within an AS confederation. 1386 Inter-provider routing is based on a web of trust. Neighboring 1387 autonomous systems are trusted to advertise valid reachability 1388 information. If this trust model is violated, a neighboring 1389 autonomous system may cause a denial-of-service attack by advertising 1390 reachability information for a given prefix for which it does not 1391 provide service (unfiltered address space hijack). Since validation 1392 of the Flow Specification is tied to the announcement of the best 1393 unicast route, the failure in the validation of best path route may 1394 prevent the Flow Specificaiton from being used by a local router. 1395 Possible mitigations are [RFC6811] and [RFC8205]. 1397 On IXPs routes are often exchanged via route servers which do not 1398 extend the AS_PATH. In such cases it is not possible to enforce the 1399 left-most AS in the AS_PATH to be the neighbor AS (the AS of the 1400 route server). Since the validation of Flow Specification 1401 (Section 6) depends on this, additional care must be taken. It is 1402 advised to use a strict inbound route policy in such scenarios. 1404 Enabling firewall-like capabilities in routers without centralized 1405 management could make certain failures harder to diagnose. For 1406 example, it is possible to allow TCP packets to pass between a pair 1407 of addresses but not ICMP packets. It is also possible to permit 1408 packets smaller than 900 or greater than 1000 octets to pass between 1409 a pair of addresses, but not packets whose length is in the range 1410 900- 1000. Such behavior may be confusing and these capabilities 1411 should be used with care whether manually configured or coordinated 1412 through the protocol extensions described in this document. 1414 Flow Specification BGP speakers (e.g. automated DDoS controllers) not 1415 properly programmed, algorithms that are not performing as expected, 1416 or simply rogue systems may announce unintended Flow Specifications, 1417 send updates at a high rate or generate a high number of Flow 1418 Specifications. This may stress the receiving systems, exceed their 1419 capacity, or lead to unwanted Traffic Filtering Actions being applied 1420 to flows. 1422 While the general verification of the Flow Specification NLRI is 1423 specified in this document (Section 6) the Traffic Filtering Actions 1424 received by a third party may need custom verification or filtering. 1425 In particular all non traffic-rate actions may allow a third party to 1426 modify packet forwarding properties and potentially gain access to 1427 other routing-tables/VPNs or undesired queues. This can be avoided 1428 by proper filtering/screening of the Traffic Filtering Action 1429 communities at network borders and only exposing a predefined subset 1430 of Traffic Filtering Actions (see Section 7) to third parties. One 1431 way to achieve this is by mapping user-defined communities, that can 1432 be set by the third party, to Traffic Filtering Actions and not 1433 accepting Traffic Filtering Action extended communities from third 1434 parties. 1436 This extension adds additional information to Internet routers. 1437 These are limited in terms of the maximum number of data elements 1438 they can hold as well as the number of events they are able to 1439 process in a given unit of time. Service providers need to consider 1440 the maximum capacity of their devices and may need to limit the 1441 number of Flow Specifications accepted and processed. 1443 13. Contributors 1445 Barry Greene, Pedro Marques, Jared Mauch and Nischal Sheth were 1446 authors on [RFC5575], and therefore are contributing authors on this 1447 document. 1449 14. Acknowledgements 1451 The authors would like to thank Yakov Rekhter, Dennis Ferguson, Chris 1452 Morrow, Charlie Kaufman, and David Smith for their comments for the 1453 comments on the original [RFC5575]. Chaitanya Kodeboyina helped 1454 design the flow validation procedure; and Steven Lin and Jim Washburn 1455 ironed out all the details necessary to produce a working 1456 implementation in the original [RFC5575]. 1458 A packet rate Traffic Filtering Action was also described in a Flow 1459 Specification extension draft and the authors like to thank Wesley 1460 Eddy, Justin Dailey and Gilbert Clark for their work. 1462 Additionally, the authors would like to thank Alexander Mayrhofer, 1463 Nicolas Fevrier, Job Snijders, Jeffrey Haas and Adam Chappell for 1464 their comments and review. 1466 15. References 1468 15.1. Normative References 1470 [IEEE.754.1985] 1471 IEEE, "Standard for Binary Floating-Point Arithmetic", 1472 IEEE 754-1985, August 1985. 1474 [ISO_IEC_9899] 1475 ISO, "Information technology -- Programming languages -- 1476 C", ISO/IEC 9899:2018, June 2018. 1478 [RFC0768] Postel, J., "User Datagram Protocol", STD 6, RFC 768, 1479 DOI 10.17487/RFC0768, August 1980, 1480 . 1482 [RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791, 1483 DOI 10.17487/RFC0791, September 1981, 1484 . 1486 [RFC0792] Postel, J., "Internet Control Message Protocol", STD 5, 1487 RFC 792, DOI 10.17487/RFC0792, September 1981, 1488 . 1490 [RFC0793] Postel, J., "Transmission Control Protocol", STD 7, 1491 RFC 793, DOI 10.17487/RFC0793, September 1981, 1492 . 1494 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1495 Requirement Levels", BCP 14, RFC 2119, 1496 DOI 10.17487/RFC2119, March 1997, 1497 . 1499 [RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black, 1500 "Definition of the Differentiated Services Field (DS 1501 Field) in the IPv4 and IPv6 Headers", RFC 2474, 1502 DOI 10.17487/RFC2474, December 1998, 1503 . 1505 [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A 1506 Border Gateway Protocol 4 (BGP-4)", RFC 4271, 1507 DOI 10.17487/RFC4271, January 2006, 1508 . 1510 [RFC4360] Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended 1511 Communities Attribute", RFC 4360, DOI 10.17487/RFC4360, 1512 February 2006, . 1514 [RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private 1515 Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February 1516 2006, . 1518 [RFC4456] Bates, T., Chen, E., and R. Chandra, "BGP Route 1519 Reflection: An Alternative to Full Mesh Internal BGP 1520 (IBGP)", RFC 4456, DOI 10.17487/RFC4456, April 2006, 1521 . 1523 [RFC4760] Bates, T., Chandra, R., Katz, D., and Y. Rekhter, 1524 "Multiprotocol Extensions for BGP-4", RFC 4760, 1525 DOI 10.17487/RFC4760, January 2007, 1526 . 1528 [RFC5668] Rekhter, Y., Sangli, S., and D. Tappan, "4-Octet AS 1529 Specific BGP Extended Community", RFC 5668, 1530 DOI 10.17487/RFC5668, October 2009, 1531 . 1533 [RFC7153] Rosen, E. and Y. Rekhter, "IANA Registries for BGP 1534 Extended Communities", RFC 7153, DOI 10.17487/RFC7153, 1535 March 2014, . 1537 [RFC7606] Chen, E., Ed., Scudder, J., Ed., Mohapatra, P., and K. 1538 Patel, "Revised Error Handling for BGP UPDATE Messages", 1539 RFC 7606, DOI 10.17487/RFC7606, August 2015, 1540 . 1542 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 1543 Writing an IANA Considerations Section in RFCs", BCP 26, 1544 RFC 8126, DOI 10.17487/RFC8126, June 2017, 1545 . 1547 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 1548 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 1549 May 2017, . 1551 15.2. Informative References 1553 [I-D.ietf-idr-flow-spec-v6] 1554 Loibl, C., Raszuk, R., and S. Hares, "Dissemination of 1555 Flow Specification Rules for IPv6", draft-ietf-idr-flow- 1556 spec-v6-10 (work in progress), November 2019. 1558 [RFC4303] Kent, S., "IP Encapsulating Security Payload (ESP)", 1559 RFC 4303, DOI 10.17487/RFC4303, December 2005, 1560 . 1562 [RFC5575] Marques, P., Sheth, N., Raszuk, R., Greene, B., Mauch, J., 1563 and D. McPherson, "Dissemination of Flow Specification 1564 Rules", RFC 5575, DOI 10.17487/RFC5575, August 2009, 1565 . 1567 [RFC6811] Mohapatra, P., Scudder, J., Ward, D., Bush, R., and R. 1568 Austein, "BGP Prefix Origin Validation", RFC 6811, 1569 DOI 10.17487/RFC6811, January 2013, 1570 . 1572 [RFC7674] Haas, J., Ed., "Clarification of the Flowspec Redirect 1573 Extended Community", RFC 7674, DOI 10.17487/RFC7674, 1574 October 2015, . 1576 [RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language", 1577 RFC 7950, DOI 10.17487/RFC7950, August 2016, 1578 . 1580 [RFC8205] Lepinski, M., Ed. and K. Sriram, Ed., "BGPsec Protocol 1581 Specification", RFC 8205, DOI 10.17487/RFC8205, September 1582 2017, . 1584 [RFC8294] Liu, X., Qu, Y., Lindem, A., Hopps, C., and L. Berger, 1585 "Common YANG Data Types for the Routing Area", RFC 8294, 1586 DOI 10.17487/RFC8294, December 2017, 1587 . 1589 15.3. URIs 1591 [1] https://github.com/stoffi92/rfc5575bis/tree/master/flowspec-cmp 1593 [2] https://www.iana.org/assignments/iana-routing-types 1595 Appendix A. Example Python code: flow_rule_cmp 1597 1598 """ 1599 Copyright (c) 2020 IETF Trust and the persons identified as authors 1600 of draft-ietf-idr-rfc5575bis. All rights reserved. 1602 Redistribution and use in source and binary forms, with or without 1603 modification, is permitted pursuant to, and subject to the license 1604 terms contained in, the Simplified BSD License set forth in Section 1605 4.c of the IETF Trust's Legal Provisions Relating to IETF Documents 1606 (http://trustee.ietf.org/license-info). 1607 """ 1609 import itertools 1610 import collections 1611 import ipaddress 1613 EQUAL = 0 1614 A_HAS_PRECEDENCE = 1 1615 B_HAS_PRECEDENCE = 2 1616 IP_DESTINATION = 1 1617 IP_SOURCE = 2 1619 FS_component = collections.namedtuple('FS_component', 1620 'component_type op_value') 1622 class FS_nlri(object): 1623 """ 1624 FS_nlri class implementation that allows sorting. 1626 By calling .sort() on a array of FS_nlri objects these will be 1627 sorted according to the flow_rule_cmp algorithm. 1629 Example: 1630 nlri = [ FS_nlri(components=[ 1631 FS_component(component_type=IP_DESTINATION, 1632 op_value=ipaddress.ip_network('10.1.0.0/16') ), 1633 FS_component(component_type=4, 1634 op_value=bytearray([0,1,2,3,4,5,6])), 1635 ]), 1636 FS_nlri(components=[ 1637 FS_component(component_type=5, 1638 op_value=bytearray([0,1,2,3,4,5,6])), 1639 FS_component(component_type=6, 1640 op_value=bytearray([0,1,2,3,4,5,6])), 1642 ]), 1643 ] 1644 nlri.sort() # sorts the array accorinding to the algorithm 1645 """ 1646 def __init__(self, components = None): 1647 """ 1648 components: list of type FS_component 1649 """ 1650 self.components = components 1652 def __lt__(self, other): 1653 # use the below algorithm for sorting 1654 result = flow_rule_cmp(self, other) 1655 if result == B_HAS_PRECEDENCE: 1656 return True 1657 else: 1658 return False 1660 def flow_rule_cmp(a, b): 1661 """ 1662 Example of the flowspec comparison algorithm. 1663 """ 1664 for comp_a, comp_b in itertools.zip_longest(a.components, 1665 b.components): 1666 # If a component type does not exist in one rule 1667 # this rule has lower precedence 1668 if not comp_a: 1669 return B_HAS_PRECEDENCE 1670 if not comp_b: 1671 return A_HAS_PRECEDENCE 1672 # Higher precedence for lower component type 1673 if comp_a.component_type < comp_b.component_type: 1674 return A_HAS_PRECEDENCE 1675 if comp_a.component_type > comp_b.component_type: 1676 return B_HAS_PRECEDENCE 1677 # component types are equal -> type specific comparison 1678 if comp_a.component_type in (IP_DESTINATION, IP_SOURCE): 1679 # assuming comp_a.op_value, comp_b.op_value of 1680 # type ipaddress.IPv4Network 1681 if comp_a.op_value.overlaps(comp_b.op_value): 1682 # longest prefixlen has precedence 1683 if comp_a.op_value.prefixlen > \ 1684 comp_b.op_value.prefixlen: 1685 return A_HAS_PRECEDENCE 1686 if comp_a.op_value.prefixlen < \ 1687 comp_b.op_value.prefixlen: 1688 return B_HAS_PRECEDENCE 1690 # components equal -> continue with next component 1691 elif comp_a.op_value > comp_b.op_value: 1692 return B_HAS_PRECEDENCE 1693 elif comp_a.op_value < comp_b.op_value: 1694 return A_HAS_PRECEDENCE 1695 else: 1696 # assuming comp_a.op_value, comp_b.op_value of type 1697 # bytearray 1698 if len(comp_a.op_value) == len(comp_b.op_value): 1699 if comp_a.op_value > comp_b.op_value: 1700 return B_HAS_PRECEDENCE 1701 if comp_a.op_value < comp_b.op_value: 1702 return A_HAS_PRECEDENCE 1703 # components equal -> continue with next component 1704 else: 1705 common = min(len(comp_a.op_value), len(comp_b.op_value)) 1706 if comp_a.op_value[:common] > comp_b.op_value[:common]: 1707 return B_HAS_PRECEDENCE 1708 elif comp_a.op_value[:common] < \ 1709 comp_b.op_value[:common]: 1710 return A_HAS_PRECEDENCE 1711 # the first common bytes match 1712 elif len(comp_a.op_value) > len(comp_b.op_value): 1713 return A_HAS_PRECEDENCE 1714 else: 1715 return B_HAS_PRECEDENCE 1716 return EQUAL 1717 1719 Appendix B. Comparison with RFC 5575 1721 This document includes numerous editorial changes to [RFC5575]. It 1722 also completely incorporates the redirect action clarification 1723 document [RFC7674]. It is recommended to read the entire document. 1724 The authors, however want to point out the following technical 1725 changes to [RFC5575]: 1727 Section 1 introduces the Flow Specification NLRI. In [RFC5575] 1728 this NLRI was defined as an opaque-key in BGPs database. This 1729 specification has removed all references to an opaque-key 1730 property. BGP implementations are able to understand the NLRI 1731 encoding. 1733 Section 4.2.1.1 defines a numeric operator and comparison bit 1734 combinations. In [RFC5575] the meaning of those bit combination 1735 was not explicitly defined and left open to the reader. 1737 Section 4.2.2.3 - Section 4.2.2.8, Section 4.2.2.10, 1738 Section 4.2.2.11 make use of the above numeric operator. The 1739 allowed length of the comparison value was not consistently 1740 defined in [RFC5575]. 1742 Section 7 defines all Traffic Filtering Action Extended 1743 communities as transitive extended communities. [RFC5575] defined 1744 the traffic-rate action to be non-transitive and did not define 1745 the transitivity of the other Traffic Filtering Action communities 1746 at all. 1748 Section 7.2 introduces a new Traffic Filtering Action (traffic- 1749 rate-packets). This action did not exist in [RFC5575]. 1751 Section 7.4 contains the same redirect actions already defined in 1752 [RFC5575] however, these actions have been renamed to "rt- 1753 redirect" to make it clearer that the redirection is based on 1754 route-target. This section also completely incorporates the 1755 [RFC7674] clarifications of the Flowspec Redirect Extended 1756 Community. 1758 Section 7.7 contains general considerations on interfering traffic 1759 actions. Section 7.3 also cross-references Section 7.7. 1760 [RFC5575] did not mention this. 1762 Section 10 contains new error handling. 1764 Authors' Addresses 1766 Christoph Loibl 1767 next layer Telekom GmbH 1768 Mariahilfer Guertel 37/7 1769 Vienna 1150 1770 AT 1772 Phone: +43 664 1176414 1773 Email: cl@tix.at 1775 Susan Hares 1776 Huawei 1777 7453 Hickory Hill 1778 Saline, MI 48176 1779 USA 1781 Email: shares@ndzh.com 1782 Robert Raszuk 1783 Bloomberg LP 1784 731 Lexington Ave 1785 New York City, NY 10022 1786 USA 1788 Email: robert@raszuk.net 1790 Danny McPherson 1791 Verisign 1792 USA 1794 Email: dmcpherson@verisign.com 1796 Martin Bacher 1797 T-Mobile Austria 1798 Rennweg 97-99 1799 Vienna 1030 1800 AT 1802 Email: mb.ietf@gmail.com