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Checking references for intended status: Informational ---------------------------------------------------------------------------- -- Obsolete informational reference (is this intentional?): RFC 3633 (Obsoleted by RFC 8415) -- Obsolete informational reference (is this intentional?): RFC 4941 (Obsoleted by RFC 8981) Summary: 0 errors (**), 0 flaws (~~), 1 warning (==), 3 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 V6OPS Working Group C. Byrne 3 Internet-Draft T-Mobile USA 4 Intended Status: Informational D. Drown 5 Expires: April 9, 2014 A. Vizdal 6 Deutsche Telekom AG 7 October 6, 2013 9 Extending an IPv6 /64 Prefix from a 3GPP Mobile Interface to a LAN link 10 draft-ietf-v6ops-64share-09 12 Abstract 14 This document describes requirements for extending an IPv6 /64 prefix 15 from a User Equipment 3GPP radio interface to a LAN link as well as 16 two implementation examples. 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 http://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 6, 2014. 35 Copyright and License Notice 37 Copyright (c) 2013 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 (http://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 . . . . . . . . . . . . . . . . . . . . . . . . . 3 53 1.2 Special Language . . . . . . . . . . . . . . . . . . . . . . 3 54 2. The Challenge of Providing IPv6 Addresses to a LAN link via a 55 3GPP UE . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 56 3. Requirements for Extending the 3GPP Interface /64 IPv6 Prefix 57 to a LAN link . . . . . . . . . . . . . . . . . . . . . . . . . 4 58 4. Example Methods for Extending the 3GPP Interface /64 IPv6 59 Prefix to a LAN link . . . . . . . . . . . . . . . . . . . . . 4 60 4.1 General Behavior for All Example Scenarios . . . . . . . . . 4 61 4.2 Example Scenario 1: Global Address Only Assigned to LAN 62 link . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 63 4.3 Example Scenario 2: A Single Global Address Assigned to 64 3GPP Radio and LAN link . . . . . . . . . . . . . . . . . . 6 65 5. Security Considerations . . . . . . . . . . . . . . . . . . . . 7 66 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7 67 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 7 68 8. Informative References . . . . . . . . . . . . . . . . . . . . 7 69 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8 71 1. Introduction 73 3GPP mobile cellular networks such as GSM, UMTS, and LTE have 74 architectural support for IPv6 [RFC6459] , but only 3GPP Release-10 75 and onwards of the 3GPP specification supports DHCPv6 Prefix 76 Delegation [RFC3633] for delegating IPv6 prefixes to a single LAN 77 link. To facilitate the use of IPv6 in a LAN prior to the deployment 78 of DHCPv6 Prefix Delegation in 3GPP networks and in User Equipment 79 (UE), this document describes requirements and provides examples on 80 how the 3GPP UE radio interface assigned global /64 prefix may be 81 extended from the 3GPP radio interface to a LAN link. 83 This can be achieved by receiving the Router Advertisement (RA) 84 [RFC4861] announced globally unique /64 IPv6 prefix from the 3GPP 85 radio interface and then advertising the same IPv6 prefix to the LAN 86 link with RA. For all of the cases in the scope of this document, 87 the UE may be any device that functions as an IPv6 router between the 88 3GPP network and a LAN. 90 This document describes requirements for achieving IPv6 prefix 91 extension from a 3GPP radio interface to a LAN link including two 92 practical implementation examples: 94 1) The 3GPP UE only has a global scope address on the LAN link 95 2) The 3GPP UE maintains the same consistent 128 bit global scope 96 IPv6 anycast address [RFC4291] on the 3GPP radio interface and the 97 LAN link. The LAN link is configured as a /64 and the 3GPP radio 98 interface is configured as a /128. 100 Section 3 describes the characteristics of each of the two example 101 approaches. 103 1.2 Special Language 105 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 106 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 107 document are to be interpreted as described in RFC 2119 [RFC2119]. 109 NOTE WELL: This document is not a standard, and conformance with 110 it is not required in order to claim conformance with IETF 111 standards for IPv6. 113 This document uses the normative keywords only for precision. 115 2. The Challenge of Providing IPv6 Addresses to a LAN link via a 3GPP UE 117 As described in [RFC6459], 3GPP networks assign a /64 global scope 118 prefix to each UE using RA. DHCPv6 Prefix Delegation is an optional 119 part of 3GPP Release-10 and is not covered by any earlier releases. 120 Neighbor Discovery Proxy (ND Proxy) [RFC4389] functionality has been 121 suggested as an option for extending the assigned /64 from the 3GPP 122 radio interface to the LAN link, but ND Proxy is an experimental 123 protocol and has some limitations with loop-avoidance. 125 DHCPv6 is the best way to delegate a prefix to a LAN link. The 126 methods described in this document should only be applied when 127 deploying DHCPv6 Prefix Delegation is not achievable in the 3GPP 128 network and the UE. The methods described in this document are at 129 various stages of implementation and deployment planning. The goal 130 of this memo is to document the available methods which may be used 131 prior to DHCPv6 deployment. 133 3. Requirements for Extending the 3GPP Interface /64 IPv6 Prefix to a 134 LAN link 136 R-1: The 3GPP network provided /64 prefix MUST be made available on 137 the LAN link. 139 LAN attached devices shall be able to use the 3GPP network 140 assigned IPv6 prefix (e.g. using SLAAC [RFC4862]). 142 R-2: The UE MUST defend all its IPv6 addresses on the LAN link. 144 In case a LAN attached node will e.g. autoconfigure the same 145 global IPv6 address as used on the 3GPP interface, the UE must 146 fail the Duplicate Address Detection process run by the LAN node. 148 R-3: The LAN link configuration MUST be tightly coupled with the 3GPP 149 link state. 151 R-4: The UE MUST decrement the TTL when passing packets between IPv6 152 links across the UE. 154 4. Example Methods for Extending the 3GPP Interface /64 IPv6 Prefix to a 155 LAN link 157 4.1 General Behavior for All Example Scenarios 159 As [RFC6459] describes, the 3GPP network assigned /64 is completely 160 dedicated to the UE and the gateway does not consume any of the /64 161 addresses. The gateway routes the entire /64 to the UE and does not 162 perform ND or Network Unreachability Detection (NUD) [RFC4861]. 163 Communication between the UE and the gateway is only done using link- 164 local addresses and the link is point-to-point. This allows for the 165 UE to reliably manipulate the /64 from the 3GPP radio interface 166 without negatively impacting the point-to-point 3GPP radio link 167 interface. The LAN link RA configuration must be tightly coupled 168 with the 3GPP link state. If the 3GPP link goes down or changes the 169 IPv6 prefix, that state should be reflected in the LAN link IPv6 170 configuration. Just as in a standard IPv6 router, the packet TTL 171 will be decremented when passing packets between IPv6 links across 172 the UE. The UE is employing the weak host model [RFC1122]. The RA 173 function on the UE is exclusively run on the LAN link. 175 The LAN link originated RA message carries a copy of the following 176 3GPP radio link received RA message option fields: 178 o MTU (if not provided by the 3GPP network, the UE will provide its 179 3GPP link MTU size) 180 o Prefix Information 182 4.2 Example Scenario 1: Global Address Only Assigned to LAN link 184 For this case, the UE receives the RA from the 3GPP network but does 185 not use a global address on the 3GPP interface. The 3GPP RA /64 186 prefix information is used to configure NDP on the LAN and assigns 187 itself an address on the LAN link. The LAN link uses RA to announce 188 the prefix to the LAN. The UE LAN link interface defends its LAN 189 IPv6 address with DAD. The UE shall not run Stateless Address 190 Autoconfiguration [RFC4862] to assign a global address on the 3GPP 191 radio interface while routing is enabled. 193 This method allows the UE to originate and terminate IPv6 194 communications as a host while acting as an IPv6 router. The 195 movement of the IPv6 prefix from the 3GPP radio interface to the LAN 196 link may result in long-lived data connections being terminated 197 during the transition from a host-only mode to router-and-host mode. 198 Connections which are likely to be affected are ones that have been 199 specifically bound to the 3GPP radio interface. This method is 200 appropriate if the UE or software on the UE cannot support multiple 201 interfaces with the same anycast IPv6 address and the UE requires 202 global connectivity while acting as a router. 204 Below is the general procedure for this scenario: 206 1. The user activates router functionality for a LAN on the UE. 208 2. The UE checks to make sure the 3GPP interface is active and has 209 an IPv6 address. If the interface does not have an IPv6 address, 210 an attempt will be made to acquire one, or else the procedure 211 will terminate. 213 3. In this example, the UE finds the 3GPP interface has the IPv6 214 address 2001:db8:ac10:f002:1234:4567:0:9 assigned and active. 216 4. The UE moves the address 2001:db8:ac10:f002:1234:4567:0:9 as a 217 /64 from the 3GPP interfaces to the LAN link interface, disables 218 the IPv6 SLAAC feature on the 3GPP radio interface to avoid 219 address autoconfiguration, and begins announcing the prefix 220 2001:db8:ac10:f002::/64 via RA to the LAN. For this example, the 221 LAN has 2001:db8:ac10:f002:1234:4567:0:9/64 and the 3GPP radio 222 only has a link-local address. 224 5. The UE directly processes all packets destined to itself at 225 2001:db8:ac10:f002:1234:4567:0:9. 227 6. The UE, acting as a router running NDP on the LAN, will route 228 packets to and from the LAN. IPv6 packets passing between 229 interfaces will have the TTL decremented. 231 7. On the LAN link interface, there is no chance of address conflict 232 since the address is defended using DAD. The 3GPP radio 233 interface only has a link-local address. 235 4.3 Example Scenario 2: A Single Global Address Assigned to 3GPP Radio 236 and LAN link 238 In this method, the UE assigns itself one address from the 3GPP 239 network RA announced /64. This one address is configured as anycast 240 [RFC4291] on both the 3GPP radio link as a /128 and on the LAN link 241 as a /64. This allows the UE to maintain long lived data connections 242 since the 3GPP radio interface address does not change when the 243 router function is activated. This method may cause complications 244 for certain software that may not support multiple interfaces with 245 the same anycast IPv6 address or are sensitive to prefix length 246 changes. This method also creates complications for ensuring 247 uniqueness for Privacy Extensions [RFC4941]. When Privacy Extensions 248 are in use all temporary addresses will be copied from the 3GPP radio 249 interface to the LAN link and the preferred and valid lifetimes will 250 be synchronized, such that the temporary anycast addresses on both 251 interfaces expire simultaneously. 253 There might also be more complex scenarios in which the prefix length 254 is not changed and privacy extensions are supported by having the 255 subnet span multiple interfaces, as ND Proxy does [RFC4389]. Further 256 elaboration is out of scope of the present document. 258 Below is the general procedure for this scenario: 260 1. The user activates router functionality for a LAN on the UE. 262 2. The UE checks to make sure the 3GPP interface is active and has 263 an IPv6 address. If the interface does not have an IPv6 address, 264 an attempt will be made to acquire one, or else the procedure 265 will terminate. 267 3. In this example, the UE finds the 3GPP interface has the IPv6 268 address 2001:db8:ac10:f002:1234:4567:0:9 assigned and active. 270 4. The UE moves the address 2001:db8:ac10:f002:1234:4567:0:9 as an 271 anycast /64 from the 3GPP interface to the LAN interface and 272 begins announcing the prefix 2001:db8:ac10:f002::/64 via RA to 273 the LAN. The 3GPP interface maintains the same IPv6 anycast 274 address with a /128. For this example, the LAN has 275 2001:db8:ac10:f002:1234:4567:0:9/64 and the 3GPP radio interface 276 has 2001:db8:ac10:f002:1234:4567:0:9/128. 278 5. The UE directly processes all packets destined to itself at 279 2001:db8:ac10:f002:1234:4567:0:9. 281 6. On the LAN interface, there is no chance of address conflict 282 since the address is defended using DAD. The 3GPP radio 283 interface only has a /128 and no other systems on the 3GPP radio 284 point-to-point link may use the global /64. 286 5. Security Considerations 288 Since the UE will be switched from an IPv6 host mode to an IPv6 289 router-and-host mode a basic IPv6 CPE security functions [RFC6092] 290 shall be considered. 292 6. IANA Considerations 294 This document does not require any action from IANA. 296 7. Acknowledgments 298 Many thanks for review and discussion from Dave Thaler, Sylvain 299 Decremps, Mark Smith, Dmitry Anipko, Masanobu Kawashima, Teemu 300 Savolainen, Mikael Abrahamsson, Eric Vyncke, Alexandru Petrescu, 301 Jouni Korhonen, Lorenzo Colitti, Julien Laganier, Owen DeLong and 302 Holger Metschulat. 304 8. Informative References 306 [RFC1122] Braden, R., Ed., "Requirements for Internet Hosts - 307 Communication Layers", STD 3, RFC 1122, October 1989. 309 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 310 Requirement Levels", BCP 14, RFC 2119, March 1997. 312 [RFC3633] Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic 313 Host Configuration Protocol (DHCP) version 6", RFC 3633, 314 December 2003. 316 [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing 317 Architecture", RFC 4291, February 2006. 319 [RFC4389] Thaler, D., Talwar, M., and C. Patel, "Neighbor Discovery 320 Proxies (ND Proxy)", RFC 4389, April 2006. 322 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, 323 "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, 324 September 2007. 326 [RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless 327 Address Autoconfiguration", RFC 4862, September 2007. 329 [RFC4941] Narten, T., Draves, R., and S. Krishnan, "Privacy 330 Extensions for Stateless Address Autoconfiguration in 331 IPv6", RFC 4941, September 2007. 333 [RFC6092] Woodyatt, J., Ed., "Recommended Simple Security 334 Capabilities in Customer Premises Equipment (CPE) for 335 Providing Residential IPv6 Internet Service", RFC 6092, 336 January 2011. 338 [RFC6459] Korhonen, J., Ed., Soininen, J., Patil, B., Savolainen, 339 T., Bajko, G., and K. Iisakkila, "IPv6 in 3rd Generation 340 Partnership Project (3GPP) Evolved Packet System (EPS)", 341 RFC 6459, January 2012. 343 Authors' Addresses 345 Cameron Byrne 346 T-Mobile USA 347 Bellevue, Washington, USA 348 EMail: Cameron.Byrne@T-Mobile.com 350 Dan Drown 351 Email: Dan@Drown.org 353 Ales Vizdal 354 Deutsche Telekom AG 355 Tomickova 2144/1 356 Prague, 149 00 357 Czech Republic 358 EMail: Ales.Vizdal@T-Mobile.cz