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Haas, Ed. 3 Internet-Draft Juniper Networks 4 Updates: 5575 (if approved) October 20, 2014 5 Intended status: Standards Track 6 Expires: April 23, 2015 8 Clarification of the Flowspec Redirect Extended Community 9 draft-ietf-idr-flowspec-redirect-rt-bis-01 11 Abstract 13 This document clarifies the formatting of the the BGP Flowspec 14 Redirect Extended Community, originally documented in RFC 5575 15 (Dissemination of Flow Specification Rules). 17 Status of This Memo 19 This Internet-Draft is submitted in full conformance with the 20 provisions of BCP 78 and BCP 79. 22 Internet-Drafts are working documents of the Internet Engineering 23 Task Force (IETF). Note that other groups may also distribute 24 working documents as Internet-Drafts. The list of current Internet- 25 Drafts is at http://datatracker.ietf.org/drafts/current/. 27 Internet-Drafts are draft documents valid for a maximum of six months 28 and may be updated, replaced, or obsoleted by other documents at any 29 time. It is inappropriate to use Internet-Drafts as reference 30 material or to cite them other than as "work in progress." 32 This Internet-Draft will expire on April 23, 2015. 34 Copyright Notice 36 Copyright (c) 2014 IETF Trust and the persons identified as the 37 document authors. All rights reserved. 39 This document is subject to BCP 78 and the IETF Trust's Legal 40 Provisions Relating to IETF Documents 41 (http://trustee.ietf.org/license-info) in effect on the date of 42 publication of this document. Please review these documents 43 carefully, as they describe your rights and restrictions with respect 44 to this document. Code Components extracted from this document must 45 include Simplified BSD License text as described in Section 4.e of 46 the Trust Legal Provisions and are provided without warranty as 47 described in the Simplified BSD License. 49 Table of Contents 51 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 52 2. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 53 3. Security Considerations . . . . . . . . . . . . . . . . . . . 4 54 4. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4 55 5. Normative References . . . . . . . . . . . . . . . . . . . . 5 56 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 5 58 1. Introduction 60 Dissemination of Flow Specification Rules [RFC5575], commonly known 61 as BGP Flowspec, provided for a BGP Extended Community [RFC4360] that 62 served to redirect traffic to a VRF routing instance that matched the 63 flow specification NLRI. In that RFC, the Redirect Extended 64 Community was documented as follows: 66 : +--------+--------------------+--------------------------+ 67 : | type | extended community | encoding | 68 : +--------+--------------------+--------------------------+ 69 : | 0x8008 | redirect | 6-byte Route Target | 70 : +--------+--------------------+--------------------------+ 71 : 72 : [...] 73 : 74 : Redirect: The redirect extended community allows the traffic to be 75 : redirected to a VRF routing instance that lists the specified 76 : route-target in its import policy. If several local instances 77 : match this criteria, the choice between them is a local matter 78 : (for example, the instance with the lowest Route Distinguisher 79 : value can be elected). This extended community uses the same 80 : encoding as the Route Target extended community [RFC4360]. 81 : [...] 82 : 83 : 11. IANA Considerations 84 : [...] 85 : 86 : The following traffic filtering flow specification rules have been 87 : allocated by IANA from the "BGP Extended Communities Type - 88 : Experimental Use" registry as follows: 89 : [...] 90 : 91 : 0x8008 - Flow spec redirect 93 The IANA registry of BGP Extended Communities clearly identifies 94 communities of specific formats. For example, "Two-octet AS Specific 95 Extended Community" [RFC4360], "Four-octet AS Specific Extended 96 Community" [RFC5668] and "IPv4 Address Specific Extended Community" 98 [RFC4360]. Route Targets [RFC4360] identify this format in the high- 99 order (Type) octet of the Extended Community and set the value of the 100 low-order (Sub-Type) octet to 0x02. The Value field of the Route 101 Target Extended Community is intended to be interpreted in the 102 context of its format. 104 Since the Redirect Extended Community only registered a single code- 105 point in the IANA BGP Extended Community registry, a common 106 interpretation of the redirect extended community's "6-byte route 107 target" has been to look, at a receiving router, for a route target 108 value that matches the route target value in the received redirect 109 extended community, and import the advertised route to the 110 corresponding VRF instance subject to the rules defined in RFC 5575 111 [RFC 5575]. However, because the route target format in the redirect 112 extended community is not clearly defined, the wrong match may occur. 114 This "value wildcard" matching behavior, that does not take into 115 account the format of the route target defined for a local VRF and 116 may result in the wrong matching decision, does not match deployed 117 implementations of BGP flowspec. Deployed implementations of BGP 118 flowspec solve this problem by defining different redirect extended 119 communities that are specific to the format of the route target 120 value. This document defines the following redirect extended 121 communities: 123 +--------+--------------------+-------------------------------------+ 124 | type | extended community | encoding | 125 +--------+--------------------+-------------------------------------+ 126 | 0x8008 | redirect AS-2byte | 2-octet AS, 4-octet Value | 127 | 0x8108 | redirect IPv4 | 4-octet IPv4 Address, 2-octet Value | 128 | 0x8208 | redirect AS-4byte | 4-octet AS, 2-octet Value | 129 +--------+--------------------+-------------------------------------+ 131 It should be noted that the low-order nybble of the Redirect's Type 132 field corresponds to the Route Target Extended Community format field 133 (Type). (See [RFC4360], Secs. 3.1, 3.2 and [RFC5668], Sec. 2.) The 134 low order octet (Sub-Type) of the Redirect Extended Community remains 135 0x08, contrasted to 0x02 for Route Targets. 137 The IANA Registries for BGP Extended Communities [RFC7153] document 138 was written to update the previously-mentioned IANA registries to 139 better document BGP Extended Community formats. The IANA 140 Considerations section below further amends those registry updates in 141 order to properly document the flowspec redirect communities. 143 2. IANA Considerations 145 IANA is requested to update the BGP GENERIC TRANSITIVE EXPERIMENTAL 146 USE EXTENDED COMMUNITY SUB-TYPES registry as follows: 148 0x08 - Flow spec redirect AS-2byte format. 150 IANA is requested to update the BGP TRANSITIVE EXTENDED COMMUNITY 151 TYPES registry as follows: 153 0x81 - Generic Transitive Experimental Use Extended Community 154 Part 2 (Sub-Types are defined in the "Generic Transitive 155 Experimental Extended Community Part 2 Sub-Types" Registry) 156 0x82 - Generic Transitive Experimental Use Extended Community 157 Part 3 (Sub-Types are defined in the "Generic Transitive 158 Experimental Extended Community Part 3 Sub-Types" Registry) 160 IANA is requested to create the GENERIC TRANSITIVE EXPERIMENTAL USE 161 EXTENDED COMMUNITY PART 2 SUB-TYPES registry. It should be seeded 162 with the following Sub-Type: 164 0x08 - Flow spec redirect IPv4 format. 166 IANA is requested to create the GENERIC TRANSITIVE EXPERIMENTAL USE 167 EXTENDED COMMUNITY PART 3 SUB-TYPES registry. It should be seeded 168 with the following Sub-Type: 170 0x08 - Flow spec redirect AS-4byte format. 172 3. Security Considerations 174 This document introduces no additional security considerations than 175 those already covered in [RFC5575]. 177 4. Acknowledgements 179 The contents of this document was raised as part of implementation 180 discussions of BGP Flowspec with the following individuals: 182 Andrew Karch (Cisco) 184 Robert Raszuk 186 Adam Simpson (Alcatel-Lucent) 188 Matthieu Texier (Arbor Networks) 190 Kaliraj Vairavakkalai (Juniper) 192 5. Normative References 194 [RFC4360] Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended 195 Communities Attribute", RFC 4360, February 2006. 197 [RFC5575] Marques, P., Sheth, N., Raszuk, R., Greene, B., Mauch, J., 198 and D. McPherson, "Dissemination of Flow Specification 199 Rules", RFC 5575, August 2009. 201 [RFC5668] Rekhter, Y., Sangli, S., and D. Tappan, "4-Octet AS 202 Specific BGP Extended Community", RFC 5668, October 2009. 204 [RFC7153] Rosen, E. and Y. Rekhter, "IANA Registries for BGP 205 Extended Communities", RFC 7153, March 2014. 207 Author's Address 209 Jeffrey Haas (editor) 210 Juniper Networks 211 1194 N. Mathida Ave. 212 Sunnyvale, CA 94089 213 US 215 Email: jhaas@juniper.net