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Boucadair 3 Internet-Draft Orange 4 Updates: 7296 (if approved) April 29, 2019 5 Intended status: Standards Track 6 Expires: October 31, 2019 8 IKEv2 Notification Status Types for IPv4/IPv6 Coexistence 9 draft-ietf-ipsecme-ipv6-ipv4-codes-03 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 October 31, 2019. 35 Copyright Notice 37 Copyright (c) 2019 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 . . . . . . . . . . . . . . . . . 6 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 by means of two PDP-Contexts. 97 When the User Equipment (UE) attaches the network using a Wireless 98 Local Area Network (WLAN) access by means of Internet Key Exchange 99 Protocol Version 2 (IKEv2) capabilities [RFC7296], there are no 100 equivalent notification codes to inform the UE why an IP address 101 family is not assigned or whether that UE should retry with another 102 address family. 104 This document fills that void by introducing new IKEv2 notification 105 status types for the sake of deterministic UE behaviors (Section 4). 107 These notification status types are not specific to 3GPP 108 architectures, but can be used in other deployment contexts. 109 Cellular networks are provided as an illustration example. 111 2. Terminology 113 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 114 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 115 "OPTIONAL" in this document are to be interpreted as described in BCP 116 14 [RFC2119][RFC8174] when, and only when, they appear in all 117 capitals, as shown here. 119 This document makes use of the terms defined in [RFC7296]. In 120 particular, readers should be familiar with "initiator" and 121 "responder" terms used in that document. 123 3. Why Not INTERNAL_ADDRESS_FAILURE? 125 The following address assignment failures may be encountered when an 126 initiator requests assignment of IP addresses/prefixes: 128 o An initiator asks for IPvx, but IPvx address assignment is not 129 supported by the responder. 131 o An initiator requests both IPv4 and IPv6 addresses, but only IPv4 132 address assignment is supported by the responder. 134 o An initiator requests both IPv4 and IPv6 addresses, but only IPv6 135 prefix assignment is supported by the responder. 137 o An initiator asks for both IPv4 and IPv6 addresses, but only one 138 address family can be assigned by the responder for policy 139 reasons. 141 Section 3.15.4 of [RFC7296] defines a generic notification error type 142 that is related to a failure to handle an address assignment request. 143 That error type does not explicitly allow an initiator to determine 144 why a given address family is not assigned, nor whether it should try 145 using another address family. INTERNAL_ADDRESS_FAILURE is a catch- 146 all error type when an address-related issue is encountered by an 147 IKEv2 responder. 149 INTERNAL_ADDRESS_FAILURE does not provide sufficient hints to the 150 IKEv2 initiator to adjust its behavior. 152 4. IP6_ALLOWED and IP4_ALLOWED Status Types 154 IP6_ALLOWED and IP4_ALLOWED status types (see Section 7) are defined 155 to inform the initiator about the responser's address family 156 assignment support capabilities, and to report to the initiator the 157 reason why an address assignment failed. These notification status 158 types are used by the initiator to adjust its behavior accordingly 159 (Section 5). 161 No data is associated with these notifications. 163 5. An Update to RFC7296 165 If the initiator is dual-stack, it MUST include both address families 166 in its request (absent explicit policy/configuration otherwise). 168 The responder MUST include IP6_ALLOWED and/or IP4_ALLOWED status type 169 in a response to an address assignment request as indicated in 170 Table 1. 172 +----------------+----------------+---------------+-----------------+ 173 | | | | Returned | 174 | Requested | Supported | Assigned | Notification | 175 | AF(s) | AF(s) | AF(s) | Status Type(s) | 176 | (Initiator) | (Responder) | (Responder) | (Responder) | 177 +----------------+----------------+---------------+-----------------+ 178 | IPv4 | IPv6 | None | IP6_ALLOWED | 179 | IPv4 | IPv4 | IPv4 | IP4_ALLOWED | 180 | IPv4 | IPv4 and IPv6 | IPv4 | IP4_ALLOWED, | 181 | | | | IP6_ALLOWED | 182 | IPv6 | IPv6 | IPv6 | IP6_ALLOWED | 183 | IPv6 | IPv4 | None | IP4_ALLOWED | 184 | IPv6 | IPv4 and IPv6 | IPv6 | IP4_ALLOWED, | 185 | | | | IP6_ALLOWED | 186 | IPv4 and IPv6 | IPv4 | IPv4 | IP4_ALLOWED | 187 | IPv4 and IPv6 | IPv6 | IPv6 | IP6_ALLOWED | 188 | IPv4 and IPv6 | IPv4 and IPv6 | IPv4 and IPv6 | IP4_ALLOWED, | 189 | | | | IP6_ALLOWED | 190 | IPv4 and IPv6 | IPv4 or IPv6 | IPv4 or IPv6 | IP4_ALLOWED, | 191 | | (Policy-based) | | IP6_ALLOWED | 192 +----------------+----------------+---------------+-----------------+ 194 Table 1: Returned Notification Status Types 196 If the initiator only receives one single notification IP4_ALLOWED or 197 IP6_ALLOWED from the responder, the initiator MUST NOT send a request 198 for an alternate address family not supported by the responder. 200 If a dual-stack initiator requests only an IPv6 prefix (or an IPv4 201 address) but only receives IP4_ALLOWED (or IP6_ALLOWED) notification 202 status type from the responder, the initiator MUST send a request for 203 IPv4 address(es) (or IPv6 prefix(es)). 205 If a dual-stack initiator requests both an IPv6 prefix and an IPv4 206 address but receives an IPv6 prefix (or an IPv4 address) only with 207 both IP4_ALLOWED and IP6_ALLOWED notification status types from the 208 responder, the initiator MAY send a request for the other AF (i.e., 209 IPv4 address (or IPv6 prefix)). In such case, the initiator MUST 210 create a new IKE Security Association (SA) and request that another 211 address family using the new IKE SA. 213 For other address-related error cases that have not been covered by 214 the aforementioned notification status types, the repsonder/initiator 215 MUST follow the procedure defined in Section 3.15.4 of [RFC7296]. 217 6. Security Considerations 219 This document adheres to the security considerations defined in 220 [RFC7296]. 222 7. IANA Considerations 224 This document requests IANA to update the "IKEv2 Notify Message Types 225 - Status Types" registry available at: 226 https://www.iana.org/assignments/ikev2-parameters/ 227 ikev2-parameters.xhtml with the following status types: 229 Value NOTIFY MESSAGES - STATUS TYPES Reference 230 TBD IP4_ALLOWED [This-Document] 231 TBD IP6_ALLOWED [This-Document] 233 8. Acknowledgements 235 Many thanks to Christian Jacquenet for the review. 237 Thanks to Paul Wouters, Yaov Nir, Valery Smyslov, Daniel Migault, 238 Tero Kivinen, and Michael Richardson for the comments and review. 240 9. References 242 9.1. Normative References 244 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 245 Requirement Levels", BCP 14, RFC 2119, 246 DOI 10.17487/RFC2119, March 1997, 247 . 249 [RFC7296] Kaufman, C., Hoffman, P., Nir, Y., Eronen, P., and T. 250 Kivinen, "Internet Key Exchange Protocol Version 2 251 (IKEv2)", STD 79, RFC 7296, DOI 10.17487/RFC7296, October 252 2014, . 254 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 255 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 256 May 2017, . 258 9.2. Informative References 260 [RFC7849] Binet, D., Boucadair, M., Vizdal, A., Chen, G., Heatley, 261 N., Chandler, R., Michaud, D., Lopez, D., and W. Haeffner, 262 "An IPv6 Profile for 3GPP Mobile Devices", RFC 7849, 263 DOI 10.17487/RFC7849, May 2016, 264 . 266 Author's Address 268 Mohamed Boucadair 269 Orange 270 Rennes 35000 271 France 273 Email: mohamed.boucadair@orange.com