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Boucadair 3 Internet-Draft Orange 4 Updates: 7296 (if approved) October 21, 2020 5 Intended status: Standards Track 6 Expires: April 24, 2021 8 IKEv2 Notification Status Types for IPv4/IPv6 Coexistence 9 draft-ietf-ipsecme-ipv6-ipv4-codes-05 11 Abstract 13 This document specifies new IKEv2 notification status types to better 14 manage IPv4 and IPv6 co-existence. 16 This document updates RFC7296. 18 Status of This Memo 20 This Internet-Draft is submitted in full conformance with the 21 provisions of BCP 78 and BCP 79. 23 Internet-Drafts are working documents of the Internet Engineering 24 Task Force (IETF). Note that other groups may also distribute 25 working documents as Internet-Drafts. The list of current Internet- 26 Drafts is at https://datatracker.ietf.org/drafts/current/. 28 Internet-Drafts are draft documents valid for a maximum of six months 29 and may be updated, replaced, or obsoleted by other documents at any 30 time. It is inappropriate to use Internet-Drafts as reference 31 material or to cite them other than as "work in progress." 33 This Internet-Draft will expire on April 24, 2021. 35 Copyright Notice 37 Copyright (c) 2020 IETF Trust and the persons identified as the 38 document authors. All rights reserved. 40 This document is subject to BCP 78 and the IETF Trust's Legal 41 Provisions Relating to IETF Documents 42 (https://trustee.ietf.org/license-info) in effect on the date of 43 publication of this document. Please review these documents 44 carefully, as they describe your rights and restrictions with respect 45 to this document. Code Components extracted from this document must 46 include Simplified BSD License text as described in Section 4.e of 47 the Trust Legal Provisions and are provided without warranty as 48 described in the Simplified BSD License. 50 Table of Contents 52 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 53 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 54 3. Why Not INTERNAL_ADDRESS_FAILURE? . . . . . . . . . . . . . . 3 55 4. IP6_ALLOWED and IP4_ALLOWED Status Types . . . . . . . . . . 4 56 5. An Update to RFC7296 . . . . . . . . . . . . . . . . . . . . 4 57 6. Security Considerations . . . . . . . . . . . . . . . . . . . 6 58 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 59 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 60 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 61 9.1. Normative References . . . . . . . . . . . . . . . . . . 6 62 9.2. Informative References . . . . . . . . . . . . . . . . . 7 63 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 7 65 1. Introduction 67 As described in [RFC7849], if the subscription data or network 68 configuration allows only one IP address family (IPv4 or IPv6), the 69 cellular host must not request a second PDP-Context to the same 70 Access Point Name (APN) for the other IP address family (AF). The 71 Third Generation Partnership Project (3GPP) network informs the 72 cellular host about allowed Packet Data Protocol (PDP) types by means 73 of Session Management (SM) cause codes. In particular, the following 74 cause codes can be returned: 76 o cause #50 "PDP type IPv4 only allowed": This cause code is used by 77 the network to indicate that only PDP type IPv4 is allowed for the 78 requested Public Data Network (PDN) connectivity. 80 o cause #51 "PDP type IPv6 only allowed": This cause code is used by 81 the network to indicate that only PDP type IPv6 is allowed for the 82 requested PDN connectivity. 84 o cause #52 "single address bearers only allowed": This cause code 85 is used by the network to indicate that the requested PDN 86 connectivity is accepted with the restriction that only single IP 87 version bearers are allowed. 89 If the requested IPv4v6 PDP-Context is not supported by the network 90 but IPv4 and IPv6 PDP types are allowed, then the cellular host will 91 be configured with an IPv4 address or an IPv6 prefix by the network. 92 It must initiate another PDP-Context activation of the other address 93 family in addition to the one already activated for a given APN. The 94 purpose of initiating a second PDP-Context is to achieve dual-stack 95 connectivity (that is, IPv4 and IPv6 connectivity) by means of two 96 PDP-Contexts. 98 When the User Equipment (UE) attaches the network using a Wireless 99 Local Area Network (WLAN) access by means of Internet Key Exchange 100 Protocol Version 2 (IKEv2) capabilities [RFC7296], there are no 101 equivalent notification codes to inform the UE why an IP address 102 family is not assigned or whether that UE should retry with another 103 address family. 105 This document fills that void by introducing new IKEv2 notification 106 status types for the sake of deterministic UE behaviors (Section 4). 108 These notification status types are not specific to 3GPP 109 architectures, but can be used in other deployment contexts. 110 Cellular networks are provided as an illustration example. 112 2. Terminology 114 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 115 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 116 "OPTIONAL" in this document are to be interpreted as described in BCP 117 14 [RFC2119][RFC8174] when, and only when, they appear in all 118 capitals, as shown here. 120 This document makes use of the terms defined in [RFC7296]. In 121 particular, readers should be familiar with "initiator" and 122 "responder" terms used in that document. 124 3. Why Not INTERNAL_ADDRESS_FAILURE? 126 The following address assignment failures may be encountered when an 127 initiator requests assignment of IP addresses/prefixes: 129 o An initiator asks for IPvx, but IPvx address assignment is not 130 supported by the responder. 132 o An initiator requests both IPv4 and IPv6 addresses, but only IPv4 133 address assignment is supported by the responder. 135 o An initiator requests both IPv4 and IPv6 addresses, but only IPv6 136 prefix assignment is supported by the responder. 138 o An initiator asks for both IPv4 and IPv6 addresses, but only one 139 address family can be assigned by the responder for policy 140 reasons. 142 Section 3.15.4 of [RFC7296] defines a generic notification error type 143 (INTERNAL_ADDRESS_FAILURE) that is related to a failure to handle an 144 address assignment request. The responder sends 145 INTERNAL_ADDRESS_FAILURE only if no addresses can be assigned. This 146 behavior does not explicitly allow an initiator to determine why a 147 given address family is not assigned, nor whether it should try using 148 another address family. INTERNAL_ADDRESS_FAILURE is a catch-all 149 error type when an address-related issue is encountered by an IKEv2 150 responder. 152 INTERNAL_ADDRESS_FAILURE does not provide sufficient hints to the 153 IKEv2 initiator to adjust its behavior. 155 4. IP6_ALLOWED and IP4_ALLOWED Status Types 157 IP6_ALLOWED and IP4_ALLOWED notification status types (see Section 7) 158 are defined to inform the initiator about the responser's address 159 family assignment support capabilities, and to report to the 160 initiator the reason why an address assignment failed. These 161 notification status types are used by the initiator to adjust its 162 behavior accordingly (Section 5). 164 No data is associated with these notifications. 166 5. An Update to RFC7296 168 If the initiator is dual-stack (i.e., supports both IPv4 and IPv6), 169 it MUST include both address families configuration attributes in its 170 configuration request (absent explicit policy/configuration 171 otherwise). More details about IPv4 and IPv6 configuration 172 attributes are provided in Section 3.15 of [RFC7296]. These 173 attributes are used to infer the requested/assigned AFs listed in 174 Table 1. 176 The responder MUST include IP6_ALLOWED and/or IP4_ALLOWED 177 notification status type in a response to an address assignment 178 request as indicated in Table 1. 180 +----------------+----------------+---------------+-----------------+ 181 | | | | Returned | 182 | Requested | Supported | Assigned | Notification | 183 | AF(s) | AF(s) | AF(s) | Status Type(s) | 184 | (Initiator) | (Responder) | (Responder) | (Responder) | 185 +----------------+----------------+---------------+-----------------+ 186 | IPv4 | IPv6 | None | IP6_ALLOWED | 187 | IPv4 | IPv4 | IPv4 | IP4_ALLOWED | 188 | IPv4 | IPv4 and IPv6 | IPv4 | IP4_ALLOWED, | 189 | | | | IP6_ALLOWED | 190 | IPv6 | IPv6 | IPv6 | IP6_ALLOWED | 191 | IPv6 | IPv4 | None | IP4_ALLOWED | 192 | IPv6 | IPv4 and IPv6 | IPv6 | IP4_ALLOWED, | 193 | | | | IP6_ALLOWED | 194 | IPv4 and IPv6 | IPv4 | IPv4 | IP4_ALLOWED | 195 | IPv4 and IPv6 | IPv6 | IPv6 | IP6_ALLOWED | 196 | IPv4 and IPv6 | IPv4 and IPv6 | IPv4 and IPv6 | IP4_ALLOWED, | 197 | | | | IP6_ALLOWED | 198 | IPv4 and IPv6 | IPv4 or IPv6 | IPv4 or IPv6 | IP4_ALLOWED, | 199 | | (Policy-based) | | IP6_ALLOWED | 200 +----------------+----------------+---------------+-----------------+ 202 Table 1: Returned Notification Status Types 204 If the initiator only receives one single notification IP4_ALLOWED or 205 IP6_ALLOWED from the responder, the initiator MUST NOT send a 206 subsequent request for an alternate address family not supported by 207 the responder. 209 If a dual-stack initiator requests only an IPv6 prefix (or an IPv4 210 address) but only receives IP4_ALLOWED (or IP6_ALLOWED) notification 211 status type from the responder, the initiator MUST send a request for 212 IPv4 address(es) (or IPv6 prefix(es)). 214 If a dual-stack initiator requests both an IPv6 prefix and an IPv4 215 address but receives an IPv6 prefix (or an IPv4 address) only with 216 both IP4_ALLOWED and IP6_ALLOWED notification status types from the 217 responder, the initiator MAY send a request for the other AF (i.e., 218 IPv4 address (or IPv6 prefix)). In such case, the initiator MUST 219 create a new IKE Security Association (SA) and request that another 220 address family using the new IKE SA. 222 For other address-related error cases that have not been covered by 223 the aforementioned notification status types, the repsonder/initiator 224 MUST follow the procedure defined in Section 3.15.4 of [RFC7296]. 226 6. Security Considerations 228 Since the IPv4/IPv6 capabilities of a node are readily determined 229 from the traffic it generates, this document does not introduce any 230 new security considerations compared to the ones described in 231 [RFC7296], which continue to apply. 233 7. IANA Considerations 235 This document requests IANA to update the "IKEv2 Notify Message Types 236 - Status Types" registry available at: 237 https://www.iana.org/assignments/ikev2-parameters/ 238 ikev2-parameters.xhtml with the following status types: 240 Value NOTIFY MESSAGES - STATUS TYPES Reference 241 TBD IP4_ALLOWED [This-Document] 242 TBD IP6_ALLOWED [This-Document] 244 8. Acknowledgements 246 Many thanks to Christian Jacquenet for the review. 248 Thanks to Paul Wouters, Yaov Nir, Valery Smyslov, Daniel Migault, 249 Tero Kivinen, and Michael Richardson for the comments and review. 251 Thanks to Benjamin Kaduk for the AD review. 253 9. References 255 9.1. Normative References 257 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 258 Requirement Levels", BCP 14, RFC 2119, 259 DOI 10.17487/RFC2119, March 1997, 260 . 262 [RFC7296] Kaufman, C., Hoffman, P., Nir, Y., Eronen, P., and T. 263 Kivinen, "Internet Key Exchange Protocol Version 2 264 (IKEv2)", STD 79, RFC 7296, DOI 10.17487/RFC7296, October 265 2014, . 267 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 268 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 269 May 2017, . 271 9.2. Informative References 273 [RFC7849] Binet, D., Boucadair, M., Vizdal, A., Chen, G., Heatley, 274 N., Chandler, R., Michaud, D., Lopez, D., and W. Haeffner, 275 "An IPv6 Profile for 3GPP Mobile Devices", RFC 7849, 276 DOI 10.17487/RFC7849, May 2016, 277 . 279 Author's Address 281 Mohamed Boucadair 282 Orange 283 Rennes 35000 284 France 286 Email: mohamed.boucadair@orange.com