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Boucadair 3 Internet-Draft Orange 4 Updates: 7296 (if approved) December 17, 2020 5 Intended status: Standards Track 6 Expires: June 20, 2021 8 IKEv2 Notification Status Types for IPv4/IPv6 Coexistence 9 draft-ietf-ipsecme-ipv6-ipv4-codes-06 11 Abstract 13 This document specifies new IKEv2 notification status types to better 14 manage IPv4 and IPv6 co-existence by allowing the responder to signal 15 to the initiator which address families are allowed. 17 This document updates RFC7296. 19 Status of This Memo 21 This Internet-Draft is submitted in full conformance with the 22 provisions of BCP 78 and BCP 79. 24 Internet-Drafts are working documents of the Internet Engineering 25 Task Force (IETF). Note that other groups may also distribute 26 working documents as Internet-Drafts. The list of current Internet- 27 Drafts is at https://datatracker.ietf.org/drafts/current/. 29 Internet-Drafts are draft documents valid for a maximum of six months 30 and may be updated, replaced, or obsoleted by other documents at any 31 time. It is inappropriate to use Internet-Drafts as reference 32 material or to cite them other than as "work in progress." 34 This Internet-Draft will expire on June 20, 2021. 36 Copyright Notice 38 Copyright (c) 2020 IETF Trust and the persons identified as the 39 document authors. All rights reserved. 41 This document is subject to BCP 78 and the IETF Trust's Legal 42 Provisions Relating to IETF Documents 43 (https://trustee.ietf.org/license-info) in effect on the date of 44 publication of this document. Please review these documents 45 carefully, as they describe your rights and restrictions with respect 46 to this document. Code Components extracted from this document must 47 include Simplified BSD License text as described in Section 4.e of 48 the Trust Legal Provisions and are provided without warranty as 49 described in the Simplified BSD License. 51 Table of Contents 53 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 54 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 55 3. Why Not INTERNAL_ADDRESS_FAILURE? . . . . . . . . . . . . . . 3 56 4. IP6_ALLOWED and IP4_ALLOWED Status Types . . . . . . . . . . 4 57 5. An Update to RFC7296 . . . . . . . . . . . . . . . . . . . . 4 58 6. Security Considerations . . . . . . . . . . . . . . . . . . . 6 59 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 60 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 61 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 62 9.1. Normative References . . . . . . . . . . . . . . . . . . 6 63 9.2. Informative References . . . . . . . . . . . . . . . . . 7 64 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 7 66 1. Introduction 68 As described in [RFC7849], if the subscription data or network 69 configuration allows only one IP address family (IPv4 or IPv6), the 70 cellular host must not request a second PDP-Context (Section 3.2 of 71 [RFC6459]) to the same Access Point Name (APN) for the other IP 72 address family (AF). The Third Generation Partnership Project (3GPP) 73 network informs the cellular host about allowed Packet Data Protocol 74 (PDP) types by means of Session Management (SM) cause codes. In 75 particular, the following cause codes can be returned: 77 o cause #50 "PDP type IPv4 only allowed": This cause code is used by 78 the network to indicate that only PDP type IPv4 is allowed for the 79 requested Public Data Network (PDN) connectivity. 81 o cause #51 "PDP type IPv6 only allowed": This cause code is used by 82 the network to indicate that only PDP type IPv6 is allowed for the 83 requested PDN connectivity. 85 o cause #52 "single address bearers only allowed": This cause code 86 is used by the network to indicate that the requested PDN 87 connectivity is accepted with the restriction that only single IP 88 version bearers are allowed. 90 If the requested IPv4v6 PDP-Context is not supported by the network 91 but IPv4 and IPv6 PDP types are allowed, then the cellular host will 92 be configured with an IPv4 address or an IPv6 prefix by the network. 93 It must initiate another PDP-Context activation of the other address 94 family in addition to the one already activated for a given APN. The 95 purpose of initiating a second PDP-Context is to achieve dual-stack 96 connectivity (that is, IPv4 and IPv6 connectivity) by means of two 97 PDP-Contexts. 99 When the User Equipment (UE) attaches to the 3GPP network using a 100 non-3GPP access network (e.g., Wireless Local Area Network (WLAN)), 101 there are no equivalent Internet Key Exchange Protocol Version 2 102 (IKEv2) capabilities [RFC7296] notification codes for the 3GPP 103 network to inform the UE why an IP address family is not assigned or 104 whether that UE should retry with another address family. 106 This document fills that void by introducing new IKEv2 notification 107 status types for the sake of deterministic UE behaviors (Section 4). 109 These notification status types are not specific to 3GPP 110 architectures, but can be used in other deployment contexts. 111 Cellular networks are provided as an illustration example. 113 2. Terminology 115 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 116 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 117 "OPTIONAL" in this document are to be interpreted as described in BCP 118 14 [RFC2119][RFC8174] when, and only when, they appear in all 119 capitals, as shown here. 121 This document makes use of the terms defined in [RFC7296]. In 122 particular, readers should be familiar with "initiator" and 123 "responder" terms used in that document. 125 3. Why Not INTERNAL_ADDRESS_FAILURE? 127 The following address assignment failures may be encountered when an 128 initiator requests assignment of IP addresses/prefixes: 130 o An initiator asks for IPvx, but IPvx address assignment is not 131 supported by the responder. 133 o An initiator requests both IPv4 and IPv6 addresses, but only IPv4 134 address assignment is supported by the responder. 136 o An initiator requests both IPv4 and IPv6 addresses, but only IPv6 137 prefix assignment is supported by the responder. 139 o An initiator asks for both IPv4 and IPv6 addresses, but only one 140 address family can be assigned by the responder for policy 141 reasons. 143 Section 3.15.4 of [RFC7296] defines a generic notification error type 144 (INTERNAL_ADDRESS_FAILURE) that is related to a failure to handle an 145 address assignment request. The responder sends 146 INTERNAL_ADDRESS_FAILURE only if no addresses can be assigned. This 147 behavior does not explicitly allow an initiator to determine why a 148 given address family is not assigned, nor whether it should try using 149 another address family. INTERNAL_ADDRESS_FAILURE is a catch-all 150 error type when an address-related issue is encountered by an IKEv2 151 responder. 153 INTERNAL_ADDRESS_FAILURE does not provide sufficient hints to the 154 IKEv2 initiator to adjust its behavior. 156 4. IP6_ALLOWED and IP4_ALLOWED Status Types 158 IP6_ALLOWED and IP4_ALLOWED notification status types (see Section 7) 159 are defined to inform the initiator about the responder's address 160 family assignment support capabilities, and to report to the 161 initiator the reason why an address assignment failed. These 162 notification status types are used by the initiator to adjust its 163 behavior accordingly (Section 5). 165 No data is associated with these notifications. 167 5. An Update to RFC7296 169 If the initiator is dual-stack (i.e., supports both IPv4 and IPv6), 170 it MUST include both address families configuration attributes in its 171 configuration request (absent explicit policy/configuration 172 otherwise). More details about IPv4 and IPv6 configuration 173 attributes are provided in Section 3.15 of [RFC7296]. These 174 attributes are used to infer the requested/assigned AFs listed in 175 Table 1. 177 The responder MUST include IP6_ALLOWED and/or IP4_ALLOWED 178 notification status type in a response to an address assignment 179 request as indicated in Table 1. 181 +----------------+----------------+---------------+-----------------+ 182 | | | | Returned | 183 | Requested | Supported | Assigned | Notification | 184 | AF(s) | AF(s) | AF(s) | Status Type(s) | 185 | (Initiator) | (Responder) | (Responder) | (Responder) | 186 +----------------+----------------+---------------+-----------------+ 187 | IPv4 | IPv6 | None | IP6_ALLOWED | 188 | IPv4 | IPv4 | IPv4 | IP4_ALLOWED | 189 | IPv4 | IPv4 and IPv6 | IPv4 | IP4_ALLOWED, | 190 | | | | IP6_ALLOWED | 191 | IPv6 | IPv6 | IPv6 | IP6_ALLOWED | 192 | IPv6 | IPv4 | None | IP4_ALLOWED | 193 | IPv6 | IPv4 and IPv6 | IPv6 | IP4_ALLOWED, | 194 | | | | IP6_ALLOWED | 195 | IPv4 and IPv6 | IPv4 | IPv4 | IP4_ALLOWED | 196 | IPv4 and IPv6 | IPv6 | IPv6 | IP6_ALLOWED | 197 | IPv4 and IPv6 | IPv4 and IPv6 | IPv4 and IPv6 | IP4_ALLOWED, | 198 | | | | IP6_ALLOWED | 199 | IPv4 and IPv6 | IPv4 or IPv6 | IPv4 or IPv6 | IP4_ALLOWED, | 200 | | (Policy-based) | | IP6_ALLOWED | 201 +----------------+----------------+---------------+-----------------+ 203 Table 1: Returned Notification Status Types 205 If the initiator only receives one single notification IP4_ALLOWED or 206 IP6_ALLOWED from the responder, the initiator MUST NOT send a 207 subsequent request for an alternate address family not supported by 208 the responder. 210 If a dual-stack initiator requests only an IPv6 prefix (or an IPv4 211 address) but only receives IP4_ALLOWED (or IP6_ALLOWED) notification 212 status type from the responder, the initiator MUST send a request for 213 IPv4 address(es) (or IPv6 prefix(es)). 215 If a dual-stack initiator requests both an IPv6 prefix and an IPv4 216 address but receives an IPv6 prefix (or an IPv4 address) only with 217 both IP4_ALLOWED and IP6_ALLOWED notification status types from the 218 responder, the initiator MAY send a request for the other AF (i.e., 219 IPv4 address (or IPv6 prefix)). In such case, the initiator MUST 220 create a new IKE Security Association (SA) and request that another 221 address family using the new IKE SA. 223 For other address-related error cases that have not been covered by 224 the aforementioned notification status types, the responder/initiator 225 MUST follow the procedure defined in Section 3.15.4 of [RFC7296]. 227 6. Security Considerations 229 Since the IPv4/IPv6 capabilities of a node are readily determined 230 from the traffic it generates, this document does not introduce any 231 new security considerations compared to the ones described in 232 [RFC7296], which continue to apply. 234 7. IANA Considerations 236 This document requests IANA to update the "IKEv2 Notify Message Types 237 - Status Types" registry available at: 238 https://www.iana.org/assignments/ikev2-parameters/ 239 ikev2-parameters.xhtml with the following status types: 241 Value NOTIFY MESSAGES - STATUS TYPES Reference 242 TBD IP4_ALLOWED [This-Document] 243 TBD IP6_ALLOWED [This-Document] 245 8. Acknowledgements 247 Many thanks to Christian Jacquenet for the review. 249 Thanks to Paul Wouters, Yaov Nir, Valery Smyslov, Daniel Migault, 250 Tero Kivinen, and Michael Richardson for the comments and review. 252 Thanks to Benjamin Kaduk for the AD review. 254 Thanks to Murray Kucherawy, Eric Vyncke, and Robert Wilton for the 255 IESG review. 257 9. References 259 9.1. Normative References 261 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 262 Requirement Levels", BCP 14, RFC 2119, 263 DOI 10.17487/RFC2119, March 1997, 264 . 266 [RFC7296] Kaufman, C., Hoffman, P., Nir, Y., Eronen, P., and T. 267 Kivinen, "Internet Key Exchange Protocol Version 2 268 (IKEv2)", STD 79, RFC 7296, DOI 10.17487/RFC7296, October 269 2014, . 271 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 272 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 273 May 2017, . 275 9.2. Informative References 277 [RFC6459] Korhonen, J., Ed., Soininen, J., Patil, B., Savolainen, 278 T., Bajko, G., and K. Iisakkila, "IPv6 in 3rd Generation 279 Partnership Project (3GPP) Evolved Packet System (EPS)", 280 RFC 6459, DOI 10.17487/RFC6459, January 2012, 281 . 283 [RFC7849] Binet, D., Boucadair, M., Vizdal, A., Chen, G., Heatley, 284 N., Chandler, R., Michaud, D., Lopez, D., and W. Haeffner, 285 "An IPv6 Profile for 3GPP Mobile Devices", RFC 7849, 286 DOI 10.17487/RFC7849, May 2016, 287 . 289 Author's Address 291 Mohamed Boucadair 292 Orange 293 Rennes 35000 294 France 296 Email: mohamed.boucadair@orange.com