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Checking references for intended status: Informational ---------------------------------------------------------------------------- ** Obsolete normative reference: RFC 2460 (Obsoleted by RFC 8200) == Outdated reference: A later version (-02) exists of draft-herbert-gue-fragmentation-00 == Outdated reference: A later version (-05) exists of draft-ietf-nvo3-gue-01 == Outdated reference: A later version (-82) exists of draft-templin-aerolink-61 == Outdated reference: A later version (-04) exists of draft-templin-intarea-grefrag-00 Summary: 2 errors (**), 0 flaws (~~), 5 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group F. Templin, Ed. 3 Internet-Draft Boeing Research & Technology 4 Intended status: Informational August 5, 2015 5 Expires: February 6, 2016 7 AERO Minimal Encapsulation 8 draft-templin-aeromin-01.txt 10 Abstract 12 Asymmetric Extended Route Optimization (AERO) specifies both a 13 control messaging and data packet forwarding facility for managing 14 tunnels over an enterprise network or other Internetwork. Although 15 AERO can operate with any tunnel encapsulation format, the base 16 document considers Generic UDP Encapsulation (GUE) as the default. 17 This document presents a minimal encapsulation format for AERO for 18 use when a UDP header is not needed. 20 Status of This Memo 22 This Internet-Draft is submitted in full conformance with the 23 provisions of BCP 78 and BCP 79. 25 Internet-Drafts are working documents of the Internet Engineering 26 Task Force (IETF). Note that other groups may also distribute 27 working documents as Internet-Drafts. The list of current Internet- 28 Drafts is at http://datatracker.ietf.org/drafts/current/. 30 Internet-Drafts are draft documents valid for a maximum of six months 31 and may be updated, replaced, or obsoleted by other documents at any 32 time. It is inappropriate to use Internet-Drafts as reference 33 material or to cite them other than as "work in progress." 35 This Internet-Draft will expire on February 6, 2016. 37 Copyright Notice 39 Copyright (c) 2015 IETF Trust and the persons identified as the 40 document authors. All rights reserved. 42 This document is subject to BCP 78 and the IETF Trust's Legal 43 Provisions Relating to IETF Documents 44 (http://trustee.ietf.org/license-info) in effect on the date of 45 publication of this document. Please review these documents 46 carefully, as they describe your rights and restrictions with respect 47 to this document. Code Components extracted from this document must 48 include Simplified BSD License text as described in Section 4.e of 49 the Trust Legal Provisions and are provided without warranty as 50 described in the Simplified BSD License. 52 Table of Contents 54 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 55 2. Minimal Encapsulation Format . . . . . . . . . . . . . . . . 3 56 3. When to Insert the IPv6 Fragment Header . . . . . . . . . . . 3 57 4. Considerations for Using Minimal Encapsulation . . . . . . . 4 58 5. Minimal Encapsulation using GRE . . . . . . . . . . . . . . . 4 59 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 60 7. Security Considerations . . . . . . . . . . . . . . . . . . . 5 61 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5 62 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 63 9.1. Normative References . . . . . . . . . . . . . . . . . . 5 64 9.2. Informative References . . . . . . . . . . . . . . . . . 6 65 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 7 67 1. Introduction 69 Asymmetric Extended Route Optimization (AERO) [I-D.templin-aerolink] 70 specifies both a control messaging and data packet forwarding 71 facility for forwarding Internet Protocol (IP) packets [RFC0791] 72 [RFC2460] over an enterprise network or other Internetwork through a 73 process known as tunneling. Although AERO can operate with any 74 tunnel encapsulation format, the base document specifies the 75 insertion of a User Datagram Protocol (UDP) header [RFC0768] with 76 port 8060 between the inner and outer IP headers per the Generic UDP 77 Encapsulation (GUE) [I-D.ietf-nvo3-gue] specification. This document 78 presents a minimal encapsulation format for AERO for use when a UDP 79 header is not needed. 81 In its minimal form, AERO can use direct IP-in-IP encapsulation 82 [RFC2003][RFC2473][RFC4213] or Generic Routing Encapsulation (GRE) 83 [RFC2784][RFC2890] for interior routing and addressing services. The 84 encapsulation is therefore only differentiated from other tunnel 85 types through the application of AERO control messaging. 87 However, the tunnel fragmentation required by AERO to support a 88 guaranteed minimum 1500 bytes requires a different fragment header 89 than the one offered by GUE [I-D.herbert-gue-fragmentation] . 90 Instead, for simple IP-in-IP encapsulation an IPv6 fragment header is 91 inserted directly between the inner and outer IP headers when needed, 92 i.e., even if the outer header is IPv4. The IPv6 Fragment Header is 93 identified to the outer IP layer by its IP protocol number, and the 94 Next Header field in the IPv6 Fragment Header identifies the inner IP 95 header version. 97 2. Minimal Encapsulation Format 99 Figure 1 shows the AERO minimal encapsulation format before any 100 fragmentation is applied: 102 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 103 | Outer IPv4 Header | | Outer IPv6 Header | 104 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 105 |IPv6 Fragment Header (optional)| |IPv6 Fragment Header (optional)| 106 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 107 | Inner IP Header | | Inner IP Header | | 108 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 109 | | | | 110 ~ ~ ~ ~ 111 ~ Inner Packet Body ~ ~ Inner Packet Body ~ 112 ~ ~ ~ ~ 113 | | | | 114 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 116 Minimal Encapsulation in IPv4 Minimal Encapsulation in IPv6 118 Figure 1: Minimal Encapsulation Format 120 3. When to Insert the IPv6 Fragment Header 122 The IPv6 Fragment Header is inserted whenever the AERO tunnel ingress 123 needs to apply fragmentation to accommodate packets no larger than 124 1500 bytes. Fragmentation is performed on the inner packet while 125 encapsulating each inner packet fragment in identical outer IP and 126 IPv6 Fragment Headers. Fragmentation therefore follows the same 127 procedure as for the case when a UDP header is included, which 128 follows the same procedure as for standard IPv6 fragmentation. 130 The IPv6 Fragment Header can also be inserted in order to include a 131 coherent Identification value with each packet, e.g., to aid in 132 Duplicate Packet Detection (DPD). In this way, networking devices 133 can cache the Identification values of recently-seen packets and use 134 the cached values to determine whether a newly-arrived packet is in 135 fact a duplicate. 137 Finally, the Identification value within each packet could provide a 138 rough indicator of packet reordering, e.g., in cases when the tunnel 139 egress wishes to discard packets that are grossly out of order. 141 4. Considerations for Using Minimal Encapsulation 143 Minimal encapsulation is preferred in environments where UDP 144 encapsulation would add unnecessary overhead. For example, certain 145 low-bandwidth wireless data links may benefit from an 8-byte-per- 146 packet overhead reduction. This is not likely to be a prime 147 consideration for many modern wireless data links nor for most modern 148 wired-line data links. 150 UDP encapsulation can traverse network paths that are inaccessible to 151 minimal encapsulation, e.g., for crossing Network Address Translators 152 (NATs). More and more, network middleboxes are also being configured 153 to discard packets that include anything other than a well-known IP 154 protocol such as UDP and TCP. It may therefore be necessary to 155 consider the potential for middlebox filtering before enabling 156 minimal encapsulation in a given environment. 158 Evidence seems to suggest that IPv6 fragmentation does not work along 159 all paths, since well-meaning network middleboxes may consider it as 160 an attack. 162 5. Minimal Encapsulation using GRE 164 GRE encapsulation can be used instead of simple IP-in-IP 165 encapsulation when GRE facilities such as keys and checksums are 166 desired. In that case, AERO can include a GRE fragmentation header 167 in the encpasulation [I-D.templin-intarea-grefrag] as shown in 168 Figure 2: 170 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 171 | Outer IP Header | 172 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 173 | GRE Header | 174 | (with checksum, key, etc..) | 175 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 176 | GRE Framgent Header | 177 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 178 | Inner IP Header | 179 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 180 | | 181 ~ ~ 182 ~ Inner Packet Body ~ 183 ~ ~ 184 | | 185 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 187 Minimal Encapsulation Using GRE 189 Figure 2: Minimal Encapsulation Using GRE 191 6. IANA Considerations 193 This document introduces no IANA considerations. 195 7. Security Considerations 197 Security considerations are discussed in the base AERO specification 198 [I-D.templin-aerolink]. 200 8. Acknowledgements 202 TBD 204 9. References 206 9.1. Normative References 208 [RFC0768] Postel, J., "User Datagram Protocol", STD 6, RFC 768, 209 DOI 10.17487/RFC0768, August 1980, 210 . 212 [RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791, 213 DOI 10.17487/RFC0791, September 1981, 214 . 216 [RFC2003] Perkins, C., "IP Encapsulation within IP", RFC 2003, 217 DOI 10.17487/RFC2003, October 1996, 218 . 220 [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 221 (IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460, 222 December 1998, . 224 [RFC2473] Conta, A. and S. Deering, "Generic Packet Tunneling in 225 IPv6 Specification", RFC 2473, DOI 10.17487/RFC2473, 226 December 1998, . 228 [RFC2784] Farinacci, D., Li, T., Hanks, S., Meyer, D., and P. 229 Traina, "Generic Routing Encapsulation (GRE)", RFC 2784, 230 DOI 10.17487/RFC2784, March 2000, 231 . 233 [RFC2890] Dommety, G., "Key and Sequence Number Extensions to GRE", 234 RFC 2890, DOI 10.17487/RFC2890, September 2000, 235 . 237 [RFC4213] Nordmark, E. and R. Gilligan, "Basic Transition Mechanisms 238 for IPv6 Hosts and Routers", RFC 4213, 239 DOI 10.17487/RFC4213, October 2005, 240 . 242 9.2. Informative References 244 [I-D.herbert-gue-fragmentation] 245 Herbert, T. and F. Templin, "Fragmentation option for 246 Generic UDP Encapsulation", draft-herbert-gue- 247 fragmentation-00 (work in progress), March 2015. 249 [I-D.ietf-nvo3-gue] 250 Herbert, T., Yong, L., and O. Zia, "Generic UDP 251 Encapsulation", draft-ietf-nvo3-gue-01 (work in progress), 252 June 2015. 254 [I-D.templin-aerolink] 255 Templin, F., "Asymmetric Extended Route Optimization 256 (AERO)", draft-templin-aerolink-61 (work in progress), 257 August 2015. 259 [I-D.templin-intarea-grefrag] 260 Templin, F., "GRE Tunnel Fragmentation", draft-templin- 261 intarea-grefrag-00 (work in progress), April 2015. 263 Author's Address 265 Fred L. Templin (editor) 266 Boeing Research & Technology 267 P.O. Box 3707 268 Seattle, WA 98124 269 USA 271 Email: fltemplin@acm.org