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Checking references for intended status: Informational ---------------------------------------------------------------------------- ** Obsolete normative reference: RFC 2460 (Obsoleted by RFC 8200) == Outdated reference: A later version (-05) exists of draft-ietf-nvo3-gue-02 == Outdated reference: A later version (-82) exists of draft-templin-aerolink-63 == Outdated reference: A later version (-04) exists of draft-templin-intarea-grefrag-01 Summary: 1 error (**), 0 flaws (~~), 4 warnings (==), 1 comment (--).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 F. Templin, Ed. 3 Internet-Draft Boeing Research & Technology 4 Intended status: Informational January 08, 2016 5 Expires: July 11, 2016 7 AERO Minimal Encapsulation 8 draft-templin-aeromin-03.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 minimal encapsulation formats for AERO using 18 other encapsulation types. 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 July 11, 2016. 37 Copyright Notice 39 Copyright (c) 2016 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 AERO Encapsulation . . . . . . . . . . . . . . . . . 3 56 3. When to Insert an Encapsulation Fragment Header . . . . . . . 4 57 4. Considerations for Using Minimal Encapsulation . . . . . . . 5 58 5. AERO Operation Over Native Links . . . . . . . . . . . . . . 5 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] between 76 the inner and outer IP headers per the Generic UDP Encapsulation 77 (GUE) [I-D.ietf-nvo3-gue] specification. This document presents 78 minimal encapsulation formats for AERO using other encapsulation 79 types. 81 AERO can use common minimal encapsulations such as IP-in-IP 82 [RFC2003][RFC2473][RFC4213], Generic Routing Encapsulation (GRE) 83 [RFC2784][RFC2890] and others. The encapsulation is therefore only 84 differentiated from non-AERO tunnels through the application of AERO 85 control messaging. 87 In certain use cases, AERO minimal encapsulation formats may require 88 encapsulation layer fragmentation in the same manner as for GUE 89 fragmentation [I-D.herbert-gue-fragmentation] . For simple IP-in-IP 90 encapsulation, an IPv6 fragment header is inserted directly between 91 the inner and outer IP headers when needed, i.e., even if the outer 92 header is IPv4. The IPv6 Fragment Header is identified to the outer 93 IP layer by its IP protocol number, and the Next Header field in the 94 IPv6 Fragment Header identifies the inner IP header version. For GRE 95 encapsulation, a GRE fragment header is inserted within the GRE 96 header [I-D.templin-intarea-grefrag]. 98 2. Minimal AERO Encapsulation 100 Figure 1 shows the AERO IP-in-IP minimal encapsulation format before 101 any fragmentation is applied: 103 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 104 | Outer IPv4 Header | | Outer IPv6 Header | 105 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 106 |IPv6 Frag Header (optional)| |IPv6 Frag Header (optional)| 107 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 108 | Inner IP Header | | Inner IP Header | 109 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 110 | | | | 111 ~ ~ ~ ~ 112 ~ Inner Packet Body ~ ~ Inner Packet Body ~ 113 ~ ~ ~ ~ 114 | | | | 115 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 117 Minimal Encapsulation in IPv4 Minimal Encapsulation in IPv6 119 Figure 1: Minimal Encapsulation Format using IP-in-IP 121 GRE encapsulation can be used instead of simple IP-in-IP 122 encapsulation when GRE facilities such as keys and checksums are 123 desired. In that case, AERO can include a GRE fragment header in the 124 encapsulation [I-D.templin-intarea-grefrag] as shown in Figure 2: 126 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 127 | Outer IP Header | 128 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 129 | GRE Header | 130 | (with checksum, key, etc..) | 131 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 132 | GRE Fragment Header (optional)| 133 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 134 | Inner IP Header | 135 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 136 | | 137 ~ ~ 138 ~ Inner Packet Body ~ 139 ~ ~ 140 | | 141 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 143 Minimal Encapsulation in GRE 145 Figure 2: Minimal Encapsulation Using GRE 147 3. When to Insert an Encapsulation Fragment Header 149 An encapsulation fragment header is inserted when the AERO tunnel 150 ingress needs to apply fragmentation to accommodate packets that must 151 be delivered without loss due to a size restriction. Fragmentation 152 is performed on the inner packet while encapsulating each inner 153 packet fragment in identical outer IP and encapsulation layer 154 headers. 156 The fragment header can also be inserted in order to include a 157 coherent Identification value with each packet, e.g., to aid in 158 Duplicate Packet Detection (DPD). In this way, network nodes can 159 cache the Identification values of recently-seen packets and use the 160 cached values to determine whether a newly-arrived packet is in fact 161 a duplicate. The Identification value within each packet could 162 further provide a rough indicator of packet reordering, e.g., in 163 cases when the tunnel egress wishes to discard packets that are 164 grossly out of order. 166 In some use cases, there may be operational assurance that no 167 fragmentation of any kind will be necessary, or that only occasional 168 large control messages will require fragmentation. In that case, the 169 encapsulation fragment header can be omitted and ordinary 170 fragmentation of the outer IP protocol version can be applied when 171 necessary. 173 4. Considerations for Using Minimal Encapsulation 175 Minimal encapsulation is preferred in environments where GUE 176 encapsulation would add unnecessary overhead. For example, certain 177 low-bandwidth wireless data links may benefit from a reduced 178 encapsulation overhead. This is not likely to be a prime 179 consideration for many modern wireless data links nor for most modern 180 wired-line data links. 182 GUE encapsulation can traverse network paths that are inaccessible to 183 minimal encapsulation, e.g., for crossing Network Address Translators 184 (NATs). More and more, network middleboxes are also being configured 185 to discard packets that include anything other than a well-known IP 186 protocol such as UDP and TCP. It may therefore be necessary to 187 determine the potential for middlebox filtering before enabling 188 minimal encapsulation in a given environment. 190 5. AERO Operation Over Native Links 192 AERO can also operate over native links using no encapsulation at 193 all. In that case, AERO Clients can identify AERO Servers on the 194 link through their link-layer addresses, and the AERO prefix 195 delegation, mobility management, fault tolerance and route 196 optimization facilities operate on the native link the same as over 197 an NBMA tunnel overlay. 199 6. IANA Considerations 201 This document introduces no IANA considerations. 203 7. Security Considerations 205 Security considerations are discussed in the base AERO specification 206 [I-D.templin-aerolink]. 208 8. Acknowledgements 210 TBD 212 9. References 214 9.1. Normative References 216 [RFC0768] Postel, J., "User Datagram Protocol", STD 6, RFC 768, 217 DOI 10.17487/RFC0768, August 1980, 218 . 220 [RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791, 221 DOI 10.17487/RFC0791, September 1981, 222 . 224 [RFC2003] Perkins, C., "IP Encapsulation within IP", RFC 2003, 225 DOI 10.17487/RFC2003, October 1996, 226 . 228 [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 229 (IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460, 230 December 1998, . 232 [RFC2473] Conta, A. and S. Deering, "Generic Packet Tunneling in 233 IPv6 Specification", RFC 2473, DOI 10.17487/RFC2473, 234 December 1998, . 236 [RFC2784] Farinacci, D., Li, T., Hanks, S., Meyer, D., and P. 237 Traina, "Generic Routing Encapsulation (GRE)", RFC 2784, 238 DOI 10.17487/RFC2784, March 2000, 239 . 241 [RFC2890] Dommety, G., "Key and Sequence Number Extensions to GRE", 242 RFC 2890, DOI 10.17487/RFC2890, September 2000, 243 . 245 [RFC4213] Nordmark, E. and R. Gilligan, "Basic Transition Mechanisms 246 for IPv6 Hosts and Routers", RFC 4213, 247 DOI 10.17487/RFC4213, October 2005, 248 . 250 9.2. Informative References 252 [I-D.herbert-gue-fragmentation] 253 Herbert, T. and F. Templin, "Fragmentation option for 254 Generic UDP Encapsulation", draft-herbert-gue- 255 fragmentation-02 (work in progress), October 2015. 257 [I-D.ietf-nvo3-gue] 258 Herbert, T., Yong, L., and O. Zia, "Generic UDP 259 Encapsulation", draft-ietf-nvo3-gue-02 (work in progress), 260 December 2015. 262 [I-D.templin-aerolink] 263 Templin, F., "Asymmetric Extended Route Optimization 264 (AERO)", draft-templin-aerolink-63 (work in progress), 265 August 2015. 267 [I-D.templin-intarea-grefrag] 268 Templin, F., "GRE Tunnel Fragmentation", draft-templin- 269 intarea-grefrag-01 (work in progress), August 2015. 271 Author's Address 273 Fred L. Templin (editor) 274 Boeing Research & Technology 275 P.O. Box 3707 276 Seattle, WA 98124 277 USA 279 Email: fltemplin@acm.org