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(The document does seem to have the reference to RFC 2119 which the ID-Checklist requires). -- The document date (October 31, 2016) is 2734 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) ** Downref: Normative reference to an Informational RFC: RFC 7368 == Outdated reference: A later version (-08) exists of draft-ietf-bier-architecture-01 == Outdated reference: A later version (-12) exists of draft-ietf-bier-mpls-encapsulation-02 Summary: 1 error (**), 0 flaws (~~), 4 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group P. Pfister 3 Internet-Draft IJ. Wijnands 4 Intended status: Standards Track Cisco Systems 5 Expires: May 4, 2017 October 31, 2016 7 An IPv6 based BIER Encapsulation and Encoding 8 draft-pfister-bier-over-ipv6-01 10 Abstract 12 This document specifies the packet format and procedures for 13 transporting IPv6 payloads to multiple IPv6 destinations using the 14 Bit Index Explicit Replication (BIER). The BIER BitString is stored 15 within the low-order bits of the IPv6 destination address while the 16 high-order bits are used for unicast forwarding before entering the 17 destination BIER domain, identifying whether a packet is a BIER 18 packet, the destination Sub-Domain, the Set Identifier and the 19 BitString length. 21 Status of This Memo 23 This Internet-Draft is submitted in full conformance with the 24 provisions of BCP 78 and BCP 79. 26 Internet-Drafts are working documents of the Internet Engineering 27 Task Force (IETF). Note that other groups may also distribute 28 working documents as Internet-Drafts. The list of current Internet- 29 Drafts is at http://datatracker.ietf.org/drafts/current/. 31 Internet-Drafts are draft documents valid for a maximum of six months 32 and may be updated, replaced, or obsoleted by other documents at any 33 time. It is inappropriate to use Internet-Drafts as reference 34 material or to cite them other than as "work in progress." 36 This Internet-Draft will expire on May 4, 2017. 38 Copyright Notice 40 Copyright (c) 2016 IETF Trust and the persons identified as the 41 document authors. All rights reserved. 43 This document is subject to BCP 78 and the IETF Trust's Legal 44 Provisions Relating to IETF Documents 45 (http://trustee.ietf.org/license-info) in effect on the date of 46 publication of this document. Please review these documents 47 carefully, as they describe your rights and restrictions with respect 48 to this document. Code Components extracted from this document must 49 include Simplified BSD License text as described in Section 4.e of 50 the Trust Legal Provisions and are provided without warranty as 51 described in the Simplified BSD License. 53 Table of Contents 55 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 56 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 57 3. IPv6 BIER Packet Format . . . . . . . . . . . . . . . . . . . 3 58 4. Multicast Flow Overlay Operations . . . . . . . . . . . . . . 4 59 5. Bier Layer Forwarding Operations . . . . . . . . . . . . . . 4 60 6. Applicability Statement . . . . . . . . . . . . . . . . . . . 4 61 7. Security Considerations . . . . . . . . . . . . . . . . . . . 5 62 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 63 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 64 9.1. Normative References . . . . . . . . . . . . . . . . . . 5 65 9.2. Informative References . . . . . . . . . . . . . . . . . 6 66 Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 6 67 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 69 1. Introduction 71 The Bit Index Explicit Replication (BIER - 72 [I-D.ietf-bier-architecture]) forwarding technique enables IP 73 multicast transport across a BIER domain. Its architecture is based 74 on three different layers, a multicast flow overlay, a BIER Layer, 75 and a routing underlay. This document specifies the packet format 76 and procedures enabling IPv6 payload transport to multiple 77 destinations, hence defining the transport part of a BIER layer. 79 BIER BitString is encoded in the low-order bits of the IPv6 80 destination address of each packet. The high-order bits of the IPv6 81 destination address are used by intermediate routers for unicast 82 forwarding, deciding whether a packet is a BIER packet, and if so, to 83 identify the BIER Sub-Domain, Set Identifier and BitString length. 85 Transported payloads can be of various types such as IPv6 or IPv4, 86 unicast or multicast (e.g. using generic packet tunnelling 87 [RFC2473]), or transported data (e.g. using UDP). Any data that can 88 be used as payload to an IPv6 packet can be encapsulated, but special 89 care must be taken when forwarding some types of payloads. For 90 example, the UDP checksum may become invalid as the BIER BitString is 91 modified. 93 This technique is an alternative to the MPLS encapsulation 94 [I-D.ietf-bier-mpls-encapsulation]. It may be appropriate when 95 deploying an MPLS network is not an option, e.g., in some data 96 centers, or in home networks [RFC7368]. It also offers some 97 interesting properties with regard to host compatibility (see 98 Section 6). 100 2. Terminology 102 In this document, the key words "MAY", "MUST", "MUST NOT", 103 "RECOMMENDED", and "SHOULD", are to be interpreted as described in 104 [RFC2119]. 106 3. IPv6 BIER Packet Format 108 Payload to be sent to multiple destinations is encapsulated within an 109 IPv6 packet with no additional extension or encapsulation header. 110 Information required by BIER to operate is stored in the destination 111 IP address of the IPv6 header. The BIER BitString is encoded in the 112 low-order bits of the IPv6 destination address of the packet while 113 the high-order bits are used by intermediate BIER routers to identify 114 that the forwarded packet is an IPv6 BIER packet, its BIER sub- 115 domain, its associated BIER Set Identifier, and the BitString length. 117 | p bits | 128-p bits | 118 +---------------------------------------------------------+ 119 | BIER IPv6 Prefix | BitString bits | 120 +---------------------------------------------------------+ 122 Figure 1: IPv6 BIER destination address format 124 BIER IPv6 Prefix: This is a prefix used for BIER forwarding within 125 the domain. BIER routers will consider all packets sent to 126 this prefix as an IPv6 BIER packets. Each BIER IPv6 Prefix is 127 associated with a Sub-Domain, a Set Identifier, and a BitString 128 length. 130 BitString bits: These bits are used to encode the BIER BitString. 131 It encodes the set of BFERs the packet should be sent to. 132 Those bits are modified as the packet is replicated by 133 intermediate BIER routers. 135 The mapping between a BIER IPv6 Prefix and the BIER parameters may be 136 implemented using either algorithmic mapping (e.g., by including the 137 Sub-Domain and the Set Identifier in the low-order bits of the 138 prefix), by using a binding table (e.g., by associated each prefix 139 with configuration parameters), or using a combination of the two. 140 Although an algorithmic mapping might be advantageous in certain 141 scenarios, only the binding table model can interoperate with any 142 other operating mode. Therefore, implementations SHOULD support the 143 binding table model (in order to interoperate with any other 144 operating modes), and MAY provide other operating modes too. 146 4. Multicast Flow Overlay Operations 148 When a multicast packet enters the BIER domain, the BFIR first 149 consults the multicast flow overlay and obtains the Sub-Domain 150 Identifier and the set of BFERs the packet must be sent to. This set 151 is used in order to compute the set of bit indexes representing the 152 set of destination BFERs. All indexes that have the same Set 153 Identifier are grouped in order to create a set of BitStrings 154 associated with their respective SI. For each SI, the multicast 155 packet is encapsulated within an IPv6 BIER packet, as specified in 156 Section 3. 158 The same process is used when a given IPv6 payload is sent to a set 159 of destinations. But instead of encapsulating the packet, the 160 payload is attached to the BIER IPv6 header and the IPv6 protocol 161 number is set to the type of the payload. 163 5. Bier Layer Forwarding Operations 165 Each BIER IPv6 Prefix is inserted in the IPv6 FIB. When a packet is 166 received, a longest prefix match is performed on the destination IPv6 167 address. If the result of the lookup returns a BIER entry, the BIER 168 Sub-Domain, Set Identifier and BitString length are retrieved. The 169 packet is then processed according to the BIER forwarding algorithm. 170 For each replicated packet, the BitString, included in the IPv6 171 destination address is modified and the packet is sent on the 172 outgoing interface. 174 It is worth noting that this algorithm may interact with unicast 175 forwarding. For example, BIER IPv6 Prefixes corresponding to a sub- 176 domain in which a BIER router is not included in MAY be implemented 177 as a unicast forwarding FIB entry. 179 6. Applicability Statement 181 The technique described in this document enables transport of IPv6 182 payloads towards multiple destinations using BIER. The information 183 required by BIER is stored in the destination IPv6 address. In 184 particular, the length of the BIER BitString is limited by the prefix 185 length assigned to BIER forwarding. For example, lengths from 16 to 186 72 could be used while lengths of 128 or greater are impractical. 187 Therefore, this proposal does not comply with the current version of 188 the BIER architecture document [I-D.ietf-bier-architecture] which 189 mandates fixed, power of 2, values from 64 to 4096, with a minimal 190 supported value of 256. It appears to the authors that such values 191 depend on the underlying technology that is used. In particular, 192 mandated values seem to fit MPLS [I-D.ietf-bier-mpls-encapsulation] 193 requirements, but may be impractical in other scenarios. 195 Past the BitString length limitation, this proposal offers different 196 advantages: 198 BIER IPv6 packets are not different from IPv6 unicast packets. If 199 the BIER IPv6 Prefix is a globally unique IPv6 prefix, reachable 200 from outside the BIER domain, it is possible to send a packet from 201 outside the BIER domain to multiple destinations within the BIER 202 domain. 204 It may be used for transporting IP multicast packets, but also for 205 sending IP payloads directly to multiple destinations. 207 It does not rely on a new IPv6 extension header, which simplifies 208 deployment and is likely to improve performances. 210 It is possible to configure a host with an address which 211 corresponds to a BIER address with a single bit set. From the 212 host perspective, such address is not different from a unicast 213 IPv6 address. Which means a BIER-unaware host may receive BIER 214 packets transparently. As an example, if multicast traffic is 215 being transported over BIER using standard IP-in-IPv6 216 encapsulation, an end-host could behave as tunnel end-point for 217 this traffic without requiring any BIER specific configuration. 219 Finally, it is worth mentioning that this proposal relies on routers 220 modifying the IPv6 destination address from IPv6 packets. Just like 221 other BIER encapsulations, this technique will likely require the 222 development of specific monitoring tools and techniques. 224 7. Security Considerations 226 This technique allows IPv6 BIER packets to be sent across the 227 internet toward multiple destination located in a given BIER domain. 228 If this is considered a threat, a firewall at the entrance of the 229 BIER domain in order to avoid BIER packets from being injected and 230 replicated within the network. 232 8. IANA Considerations 234 This specification does not require any action from IANA. 236 9. References 238 9.1. Normative References 240 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 241 Requirement Levels", BCP 14, RFC 2119, March 1997. 243 [RFC2473] Conta, A. and S. Deering, "Generic Packet Tunneling in 244 IPv6 Specification", RFC 2473, DOI 10.17487/RFC2473, 245 December 1998, . 247 [RFC7368] Chown, T., Arkko, J., Brandt, A., Troan, O., and J. Weil, 248 "IPv6 Home Networking Architecture Principles", RFC 7368, 249 October 2014. 251 9.2. Informative References 253 [I-D.ietf-bier-architecture] 254 Wijnands, I., Rosen, E., Dolganow, A., Przygienda, T., and 255 S. Aldrin, "Multicast using Bit Index Explicit 256 Replication", draft-ietf-bier-architecture-01 (work in 257 progress), June 2015. 259 [I-D.ietf-bier-mpls-encapsulation] 260 Wijnands, I., Rosen, E., Dolganow, A., Tantsura, J., and 261 S. Aldrin, "Encapsulation for Bit Index Explicit 262 Replication in MPLS Networks", draft-ietf-bier-mpls- 263 encapsulation-02 (work in progress), August 2015. 265 Appendix A. Acknowledgements 267 The authors would like to thank the BIER Interim Meeting participants 268 as well as Eric Rosen, Toerless Eckert and Xiaohu Xu for their 269 comments on the mailing list. 271 Authors' Addresses 273 Pierre Pfister 274 Cisco Systems 275 Paris 276 France 278 Email: pierre.pfister@darou.fr 280 IJsbrand Wijnands 281 Cisco Systems 282 De Kleetlaan 6a 283 Diegem 1831 284 Belgium 286 Email: ice@cisco.com