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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: October 4, 2014 A. Vizdal 6 Deutsche Telekom AG 7 April 2, 2014 9 Extending an IPv6 /64 Prefix from a 3GPP Mobile Interface to a LAN link 10 draft-ietf-v6ops-64share-10 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) 2014 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 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 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 . . . . . . . . . . . . . . . . . . . . . 5 60 4.1 General Behavior for All Example Scenarios . . . . . . . . . 5 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 . . . . . . . . . . . . . . . . . . . . . . 8 67 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 8 68 8. Informative References . . . . . . . . . . . . . . . . . . . . 8 69 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9 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 [TS.23401] supports DHCPv6 76 Prefix Delegation [RFC3633] for delegating IPv6 prefixes to a single 77 LAN link. 79 To facilitate the use of IPv6 in a LAN prior to the deployment of 80 DHCPv6 Prefix Delegation in 3GPP networks and in User Equipment (UE), 81 this document describes requirements and provides examples on how the 82 3GPP UE radio interface assigned global /64 prefix may be extended 83 from the 3GPP radio interface to a LAN link. 85 There are two scenarios where this might be done. The first is where 86 the 3GPP node sets up and manages its own LAN (e.g., an IEEE 802.11 87 SSID) and provides single-homed service to hosts that connect to this 88 LAN. A second scenario is where the 3GPP node connects to an 89 existing LAN and acts as a router in order to provide redundant or 90 multi-homed IPv6 service. 92 This document is intended to address the first scenario, and is not 93 applicable to the second scenario, because the operational 94 complexities of the second scenario are not addressed. 96 This can be achieved by receiving the Router Advertisement (RA) 97 [RFC4861] announced globally unique /64 IPv6 prefix from the 3GPP 98 radio interface by the UE and then advertising the same IPv6 prefix 99 to the LAN link with RA. For all of the cases in the scope of this 100 document, the UE may be any device that functions as an IPv6 router 101 between the 3GPP network and a LAN. 103 This document describes requirements for achieving IPv6 prefix 104 extension from a 3GPP radio interface to a LAN link including two 105 practical implementation examples: 107 1) The 3GPP UE only has a global scope address on the LAN link 108 2) The 3GPP UE maintains the same consistent 128 bit global scope 109 IPv6 anycast address [RFC4291] on the 3GPP radio interface and the 110 LAN link. The LAN link is configured as a /64 and the 3GPP radio 111 interface is configured as a /128. 113 Section 3 describes the characteristics of each of the two example 114 approaches. 116 1.2 Special Language 118 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 119 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 120 document are to be interpreted as described in RFC 2119 [RFC2119]. 122 NOTE WELL: This document is not a standard, and conformance with 123 it is not required in order to claim conformance with IETF 124 standards for IPv6. 126 This document uses the normative keywords only for precision. 128 2. The Challenge of Providing IPv6 Addresses to a LAN link via a 3GPP UE 130 As described in [RFC6459], 3GPP networks assign a /64 global scope 131 prefix to each UE using RA. DHCPv6 Prefix Delegation is an optional 132 part of 3GPP Release-10 and is not covered by any earlier releases. 133 Neighbor Discovery Proxy (ND Proxy) [RFC4389] functionality has been 134 suggested as an option for extending the assigned /64 from the 3GPP 135 radio interface to the LAN link, but ND Proxy is an experimental 136 protocol and has some limitations with loop-avoidance. 138 DHCPv6 is the best way to delegate a prefix to a LAN link. The 139 methods described in this document SHOULD only be applied when 140 deploying DHCPv6 Prefix Delegation is not achievable in the 3GPP 141 network and the UE. The methods described in this document are at 142 various stages of implementation and deployment planning. The goal 143 of this memo is to document the available methods which may be used 144 prior to DHCPv6 deployment. 146 3. Requirements for Extending the 3GPP Interface /64 IPv6 Prefix to a 147 LAN link 149 R-1: The 3GPP network provided /64 prefix MUST be made available on 150 the LAN link. 152 LAN attached devices shall be able to use the 3GPP network 153 assigned IPv6 prefix (e.g. using IPv6 Stateless Address 154 Autoconfiguration - SLAAC [RFC4862]). 156 R-2: The UE MUST defend all its IPv6 addresses on the LAN link. 158 In case a LAN attached node will e.g. autoconfigure the same 159 global IPv6 address as used on the 3GPP interface, the UE must 160 fail the Duplicate Address Detection (DAD) [RFC4862] process run 161 by the LAN node. 163 R-3: The LAN link configuration MUST be tightly coupled with the 3GPP 164 link state. 166 R-4: The UE MUST decrement the TTL when passing packets between IPv6 167 links across the UE. 169 4. Example Methods for Extending the 3GPP Interface /64 IPv6 Prefix to a 170 LAN link 172 4.1 General Behavior for All Example Scenarios 174 As [RFC6459] describes, the 3GPP network assigned /64 is completely 175 dedicated to the UE and the gateway does not consume any of the /64 176 addresses. The gateway routes the entire /64 to the UE and does not 177 perform ND or Network Unreachability Detection (NUD) [RFC4861]. 178 Communication between the UE and the gateway is only done using link- 179 local addresses and the link is point-to-point. This allows for the 180 UE to reliably manipulate the /64 from the 3GPP radio interface 181 without negatively impacting the point-to-point 3GPP radio link 182 interface. The LAN link Router Advertisement (RA) configuration must 183 be tightly coupled with the 3GPP link state. If the 3GPP link goes 184 down or changes the IPv6 prefix, that state should be reflected in 185 the LAN link IPv6 configuration. Just as in a standard IPv6 router, 186 the packet TTL will be decremented when passing packets between IPv6 187 links across the UE. The UE is employing the weak host model 188 [RFC1122]. The RA function on the UE is exclusively run on the LAN 189 link. 191 The LAN link originated RA message carries a copy of the following 192 3GPP radio link received RA message option fields: 194 o MTU (if not provided by the 3GPP network, the UE will provide its 195 3GPP link MTU size) 196 o Prefix Information 198 4.2 Example Scenario 1: Global Address Only Assigned to LAN link 200 For this case, the UE receives the RA from the 3GPP network but does 201 not use a global address on the 3GPP interface. The 3GPP interface 202 received RA /64 prefix information is used to configure NDP on the 203 LAN. The UE assigns itself an IPv6 address on the LAN link from the 204 3GPP interface received RA. The LAN link uses RA to announce the 205 prefix to the LAN. The UE LAN link interface defends its LAN IPv6 206 address with DAD. The UE shall not run SLAAC to assign a global 207 address on the 3GPP radio interface while routing is enabled. 209 This method allows the UE to originate and terminate IPv6 210 communications as a host while acting as an IPv6 router. The 211 movement of the IPv6 prefix from the 3GPP radio interface to the LAN 212 link may result in long-lived data connections being terminated 213 during the transition from a host-only mode to router-and-host mode. 215 Connections which are likely to be affected are ones that have been 216 specifically bound to the 3GPP radio interface. This method is 217 appropriate if the UE or software on the UE cannot support multiple 218 interfaces with the same anycast IPv6 address and the UE requires 219 global connectivity while acting as a router. 221 Below is the general procedure for this scenario: 223 1. The user activates router functionality for a LAN on the UE. 225 2. The UE checks to make sure the 3GPP interface is active and has 226 an IPv6 address. If the interface does not have an IPv6 address, 227 an attempt will be made to acquire one, or else the procedure 228 will terminate. 230 3. In this example, the UE finds the 3GPP interface has the IPv6 231 address 2001:db8:ac10:f002:1234:4567:0:9 assigned and active. 233 4. The UE moves the address 2001:db8:ac10:f002:1234:4567:0:9 as a 234 /64 from the 3GPP interfaces to the LAN link interface, disables 235 the IPv6 SLAAC feature on the 3GPP radio interface to avoid 236 address autoconfiguration, and begins announcing the prefix 237 2001:db8:ac10:f002::/64 via RA to the LAN. For this example, the 238 LAN has 2001:db8:ac10:f002:1234:4567:0:9/64 and the 3GPP radio 239 only has a link-local address. 241 5. The UE directly processes all packets destined to itself at 242 2001:db8:ac10:f002:1234:4567:0:9. 244 6. The UE, acting as a router running NDP on the LAN, will route 245 packets to and from the LAN. IPv6 packets passing between 246 interfaces will have the TTL decremented. 248 7. On the LAN link interface, there is no chance of address conflict 249 since the address is defended using DAD. The 3GPP radio 250 interface only has a link-local address. 252 4.3 Example Scenario 2: A Single Global Address Assigned to 3GPP Radio 253 and LAN link 255 In this method, the UE assigns itself one address from the 3GPP 256 network RA announced /64. This one address is configured as anycast 257 [RFC4291] on both the 3GPP radio link as a /128 and on the LAN link 258 as a /64. This allows the UE to maintain long lived data connections 259 since the 3GPP radio interface address does not change when the 260 router function is activated. This method may cause complications 261 for certain software that may not support multiple interfaces with 262 the same anycast IPv6 address, or are sensitive to prefix length 263 changes. This method also creates complications for ensuring 264 uniqueness for Privacy Extensions [RFC4941]. When Privacy Extensions 265 are in use all temporary addresses will be copied from the 3GPP radio 266 interface to the LAN link. The preferred and valid lifetimes will be 267 synchronized, such that the temporary anycast addresses on both 268 interfaces expire simultaneously. 270 There might also be more complex scenarios in which the prefix length 271 is not changed and privacy extensions are supported by having the 272 subnet span multiple interfaces, as ND Proxy does [RFC4389]. Further 273 elaboration is out of scope of the present document. 275 Below is the general procedure for this scenario: 277 1. The user activates router functionality for a LAN on the UE. 279 2. The UE checks to make sure the 3GPP interface is active and has 280 an IPv6 address. If the interface does not have an IPv6 address, 281 an attempt will be made to acquire one, or else the procedure 282 will terminate. 284 3. In this example, the UE finds the 3GPP interface has the IPv6 285 address 2001:db8:ac10:f002:1234:4567:0:9 assigned and active. 287 4. The UE moves the address 2001:db8:ac10:f002:1234:4567:0:9 as an 288 anycast /64 from the 3GPP interface to the LAN interface and 289 begins announcing the prefix 2001:db8:ac10:f002::/64 via RA to 290 the LAN. The 3GPP interface maintains the same IPv6 anycast 291 address with a /128. For this example, the LAN has 292 2001:db8:ac10:f002:1234:4567:0:9/64 and the 3GPP radio interface 293 has 2001:db8:ac10:f002:1234:4567:0:9/128. 295 5. The UE directly processes all packets destined to itself at 296 2001:db8:ac10:f002:1234:4567:0:9. 298 6. On the LAN interface, there is no chance of address conflict 299 since the address is defended using DAD. The 3GPP radio 300 interface only has a /128 and no other systems on the 3GPP radio 301 point-to-point link may use the global /64. 303 5. Security Considerations 305 Since the UE will be switched from an IPv6 host mode to an IPv6 306 router-and-host mode, a basic IPv6 CPE security functions [RFC6092] 307 SHOULD be applied. 309 Despite the use of temporary IPv6 addresses, the mobile network 310 provided /64 prefix is common to all the LAN attached devices 311 potentially concerning privacy. A nomadic device (e.g. a smartphone) 312 provided IPv6 prefix is not a long lived one due to re-attaches 313 caused by a device reload, traveling through loosely covered areas, 314 etc. The network will provide a new IPv6 prefix after a successful 315 re-attach. 317 3GPP mobile network capable CPEs (e.g. a router) are likely to keep 318 the mobile network data connection up for a longer time. Some mobile 319 networks may be re-setting the mobile network connection regularly 320 (e.g. every 24 hours) others may not. Privacy concerned users shall 321 take appropriate measures to not to keep their IPv6 prefixes long- 322 lived. 324 6. IANA Considerations 326 This document does not require any action from IANA. 328 7. Acknowledgments 330 Many thanks for review and discussion from Dave Thaler, Sylvain 331 Decremps, Mark Smith, Dmitry Anipko, Masanobu Kawashima, Teemu 332 Savolainen, Mikael Abrahamsson, Eric Vyncke, Alexandru Petrescu, 333 Jouni Korhonen, Lorenzo Colitti, Julien Laganier, Owen DeLong, Holger 334 Metschulat, Yaron Sheffer and Victor Kuarsingh. Special thanks to Ann 335 Cerveny for her language review. 337 8. Informative References 339 [RFC1122] Braden, R., Ed., "Requirements for Internet Hosts - 340 Communication Layers", STD 3, RFC 1122, October 1989. 342 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 343 Requirement Levels", BCP 14, RFC 2119, March 1997. 345 [RFC3633] Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic 346 Host Configuration Protocol (DHCP) version 6", RFC 3633, 347 December 2003. 349 [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing 350 Architecture", RFC 4291, February 2006. 352 [RFC4389] Thaler, D., Talwar, M., and C. Patel, "Neighbor Discovery 353 Proxies (ND Proxy)", RFC 4389, April 2006. 355 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, 356 "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, 357 September 2007. 359 [RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless 360 Address Autoconfiguration", RFC 4862, September 2007. 362 [RFC4941] Narten, T., Draves, R., and S. Krishnan, "Privacy 363 Extensions for Stateless Address Autoconfiguration in 364 IPv6", RFC 4941, September 2007. 366 [RFC6092] Woodyatt, J., Ed., "Recommended Simple Security 367 Capabilities in Customer Premises Equipment (CPE) for 368 Providing Residential IPv6 Internet Service", RFC 6092, 369 January 2011. 371 [RFC6459] Korhonen, J., Ed., Soininen, J., Patil, B., Savolainen, 372 T., Bajko, G., and K. Iisakkila, "IPv6 in 3rd Generation 373 Partnership Project (3GPP) Evolved Packet System (EPS)", 374 RFC 6459, January 2012. 376 [TS.23401] 3GPP, "General Packet Radio Service (GPRS) enhancements 377 for Evolved Universal Terrestrial Radio Access Network (E- 378 UTRAN) access", 3GPP TS 23.401 10.0.0, June 2010. 380 Authors' Addresses 382 Cameron Byrne 383 T-Mobile USA 384 Bellevue, Washington, USA 385 EMail: Cameron.Byrne@T-Mobile.com 387 Dan Drown 388 EMail: Dan@Drown.org 390 Ales Vizdal 391 Deutsche Telekom AG 392 Tomickova 2144/1 393 Prague, 149 00 394 Czech Republic 395 EMail: Ales.Vizdal@T-Mobile.cz