idnits 2.17.1 draft-ietf-v6ops-3gpp-cases-00.txt: -(176): Line appears to be too long, but this could be caused by non-ascii characters in UTF-8 encoding Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- ** Looks like you're using RFC 2026 boilerplate. This must be updated to follow RFC 3978/3979, as updated by RFC 4748. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- == There are 2 instances of lines with non-ascii characters in the document. == No 'Intended status' indicated for this document; assuming Proposed Standard Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- ** The document seems to lack an IANA Considerations section. (See Section 2.2 of https://www.ietf.org/id-info/checklist for how to handle the case when there are no actions for IANA.) ** The document seems to lack separate sections for Informative/Normative References. All references will be assumed normative when checking for downward references. Miscellaneous warnings: ---------------------------------------------------------------------------- -- The document seems to lack a disclaimer for pre-RFC5378 work, but may have content which was first submitted before 10 November 2008. If you have contacted all the original authors and they are all willing to grant the BCP78 rights to the IETF Trust, then this is fine, and you can ignore this comment. If not, you may need to add the pre-RFC5378 disclaimer. (See the Legal Provisions document at https://trustee.ietf.org/license-info for more information.) -- The document date (September 2002) is 7887 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-01) exists of draft-ietf-ipv6-3gpp-recommend-00 ** Downref: Normative reference to an Informational draft: draft-ietf-ipv6-3gpp-recommend (ref. '1') -- Possible downref: Non-RFC (?) normative reference: ref. '2' -- Possible downref: Non-RFC (?) normative reference: ref. '3' -- Possible downref: Non-RFC (?) normative reference: ref. '4' -- Possible downref: Non-RFC (?) normative reference: ref. '5' Summary: 4 errors (**), 0 flaws (~~), 3 warnings (==), 6 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Internet Draft J. Soininen, 3 Document: draft-ietf-v6ops-3gpp-cases-00.txt Editor 4 Expires: March 2003 Nokia 5 September 2002 7 Transition Scenarios for 3GPP Networks 9 Status of this Memo 11 This document is an Internet-Draft and is in full conformance with 12 all provisions of Section 10 of RFC2026. 14 Internet-Drafts are working documents of the Internet Engineering 15 Task Force (IETF), its areas, and its working groups. Note that 16 other groups may also distribute working documents as Internet- 17 Drafts. 19 Internet-Drafts are draft documents valid for a maximum of six months 20 and may be updated, replaced, or obsoleted by other documents at any 21 time. It is inappropriate to use Internet-Drafts as reference 22 material or to cite them other than as "work in progress." 24 The list of current Internet-Drafts can be accessed at 25 http://www.ietf.org/ietf/1id-abstracts.txt 26 The list of Internet-Draft Shadow Directories can be accessed at 27 http://www.ietf.org/shadow.html. 29 Abstract 31 This document describes different scenarios in Third Generation 32 Partnership Project (3GPP) defined packet network, i.e. General 33 Packet Radio Service (GPRS) that would need IP version 6 and IP 34 version 4 transition. The focus of this document is on the scenarios 35 where the User Equipment (UE) connects to nodes in other networks, 36 e.g. in the Internet. GPRS network internal transition scenarios, 37 i.e. between different GPRS elements in the network, are out of scope 38 of this document. 40 The purpose of the document is to list the scenarios for further 41 discussion and study. 43 Table of Contents 45 1. Introduction...................................................2 46 2. Scope of the document..........................................2 47 3. Brief description of the 3GPP network environment..............2 48 3.1 GPRS architecture basics...................................3 49 3.2 IP Multimedia Core Network Subsystem (IMS).................3 50 4. Transition scenarios...........................................5 51 4.1 GPRS Scenarios.............................................5 52 4.2 Transition scenarios with IMS..............................8 53 5. Security Considerations........................................8 54 6. Changes from Last version......................................9 55 Authors...........................................................9 56 References.......................................................10 57 Editor's Address.................................................10 59 Copyright 61 (C) The Internet Society (2002). All Rights Reserved. 63 1. Introduction 65 This document will describe the transition scenarios in 3GPP packet 66 data networks that might come up in the deployment phase of IPv6. 67 The main purpose of this document is to identify, and document those 68 scenarios for further discussion, and for study in the V6OPS working 69 group. 71 This document gives neither an overview, nor an explanation of 3GPP 72 or the 3GPP packet data network, GPRS. A good overview of the 3GPP 73 specified GPRS can be found from [1]. The GPRS architecture 74 specification is defined in [2]. 76 2. Scope of the document 78 The scope of this document is to describe the possible transition 79 scenarios in the 3GPP defined GPRS network where a UE connects to, or 80 is contacted from, the Internet or another UE. The document describes 81 scenarios with and without the usage of the SIP based IP Multimedia 82 Core Network Subsystem (IMS). 84 The scope of this document does not include scenarios inside the GPRS 85 network, i.e. on the different interfaces of the GPRS network. This 86 document neither changes 3GPP specifications, nor proposes changes to 87 the current specifications. 89 In addition, this document describes the possible transition 90 scenarios. The solutions will be documented in a separate document. 92 These scenarios may or may not be found feasible, or even likely in 93 further study. 95 3. Brief description of the 3GPP network environment 97 This section describes the most important concepts of the 3GPP 98 environment for understanding the transition scenarios. The first 99 part of the description gives a brief overview to the GPRS network as 100 such. The second part concentrates on the IP Multimedia Core Network 101 Subsystem (IMS). 103 3.1 GPRS architecture basics 105 This section gives an overview to the most important concepts of the 106 3GPP packet architecture. For more detailed description, please see 107 [2]. 109 From the point of view of this document, the most relevant 3GPP 110 architectural elements are the User Equipment (UE), and the Gateway 111 GPRS Support Node (GGSN). A simplified picture of the architecture is 112 shown in Figure 1. 114 The UE is the mobile phone. It can either be an integrated device 115 comprised of a combined GPRS part, and the IP stack, or it might be a 116 separate GPRS device, and a separate equipment with the IP stack, 117 e.g. a laptop. 119 The GGSN serves as an anchor-point for the GPRS mobility management. 120 It also serves as the default router for the UE. 122 The Peer node mentioned in the picture refers to a node with which 123 the UE is communicating. 125 -- ---- ************ --------- 126 |UE|- ... -|GGSN|--+--* IPv4/v6 NW *--+--|Peer node| 127 -- ---- ************ --------- 128 Figure 1: Simplified GPRS Architecture 130 There is a dedicated link between the UE, and the GGSN called the 131 Packet Data Protocol (PDP) Context. This link is created through the 132 PDP Context activation process. During the activation the UE is 133 configured with its IP address, and other information needed to 134 maintain IP access, e.g. DNS server address. There are three 135 different types of PDP Contexts: IPv4, IPv6, and Point-to-Point 136 Protocol (PPP). 138 A UE can have one or more simultaneous PDP Contexts open to the same 139 or to different GGSNs. The PDP Context can be either of the same, or 140 different types. 142 3.2 IP Multimedia Core Network Subsystem (IMS) 144 IP Multimedia Core Network Subsystem (IMS) is a SIP based multimedia 145 service architecture. It is specified in Release 5 of 3GPP. This 146 section provides an overview of the 3GPP IMS and is not intended to 147 be comprehensive. A more detailed description can be found in [3], 148 [4] and [5]. 150 The IMS comprises a set of SIP proxies, servers, and registrars. In 151 addition, there are Media Gateways (MGWs) that offer connections to 152 non-IP networks such as the Public Switched Telephony Network (PSTN). 153 A simplified overview of the IMS is depicted in figure 2. 154 +-------------+ +-------------------------------------+ 155 | | | +------+ | 156 | | | |S-CSCF|--- 157 | | | | +------+ | 158 +-|+ | | | / | 159 | | | SIP Sig. | | +------+ +------+ | 160 | |----|------+------|--|----|P-CSCF|----------|I-CSCF| | 161 | | | | | +------+ +------+ | 162 | |-----------+------------------------------------------------ 163 +--+ | User traf. | | | 164 UE | | | | 165 | GPRS access | | IP Multimedia CN Subsystem | 166 +-------------+ +-------------------------------------+ 167 Figure 2: Overview of the 3GPP IMS architecture 169 The SIP proxies, servers, and registrars shown in Figure 2 are as 170 follows. 172 - P-CSCF (Proxy-Call Session Control Function) is the first 173 contact point within the IMS for the subscriber. 175 - I-CSCF (Interrogating-CSCF) is the contact point within an 176 operator�s network for all connections destined to a subscriber 177 of that network operator, or a roaming subscriber currently 178 located within that network operator�s service area. 180 - S-CSCF (Serving-CSCF) performs the session control services for 181 the subscriber. It also behaves as a SIP Registrar. 183 IMS UEs use the GPRS as an access network for the IMS. Thus, a UE has 184 to have an activated PDP Context to the IMS before it can proceed to 185 use the IMS services. The PDP Context activation is explained briefly 186 in section 3.1. 188 The IMS is exclusively IPv6. Thus, the activated PDP Context is of 189 PDP Type IPv6. This means that an 3GPP IP Multimedia terminal uses 190 exclusively IPv6 to access the IMS, and the IMS SIP server and proxy 191 support exclusively IPv6. Hence, all the traffic going to the IMS is 192 IPv6, even if the UE is dual stack capable - this comprises both 193 signaling and user traffic. 195 This, of course, does not prevent the usage of other unrelated 196 services (e.g. corporate access) on IPv4. 198 4. Transition scenarios 200 This section is divided into two main parts - GPRS scenarios, and 201 scenarios with the IP Multimedia Subsystem (IMS). The first part - 202 GPRS scenarios - concentrates on scenarios with a User Equipment (UE) 203 connecting to services in the Internet, e.g. mail, web. The second 204 part - IMS scenarios - then describes how an IMS capable UE can 205 connect to other SIP capable nodes in the Internet using the IMS 206 services. 208 4.1 GPRS Scenarios 210 This section describes the scenarios that might occur when a GPRS UE 211 contacts services, or nodes outside the GPRS network, e.g. web-server 212 in the Internet. 214 Transition scenarios of the GPRS internal interfaces are outside of 215 the scope of this document. 217 The following scenarios are described here. In all of the scenarios, 218 the UE is part of a network where there is at least one router of the 219 same IP version, i.e. GGSN, and it is connecting to a node in a 220 different network. 222 The scenarios here apply also for PDP Context type Point-to-Point 223 Protocol (PPP) where PPP is terminated at the GGSN. On the other 224 hand, where the PPP PDP Context is terminated e.g. at an external 225 ISP, the environment is the same as for general ISP cases. 227 1) Dual Stack UE connecting to IPv4 and IPv6 nodes 228 2) IPv6 UE connecting to an IPv6 node through an IPv4 network 229 3) IPv4 UE connecting to an IPv4 node through an IPv6 network 230 4) IPv6 UE connecting to an IPv4 node 231 5) IPv4 UE connecting to an IPv6 node 233 1) Dual Stack UE connecting to IPv4 and IPv6 nodes 235 The GPRS system has been designed in a manner that there is the 236 possibility to have simultaneous IPv4, and IPv6 PDP Contexts open. 237 Thus, in cases where the UE is dual stack capable, and in the network 238 there is a GGSN (or separate GGSNs) that supports both connection to 239 IPv4 and IPv6 networks, it is possible to connect to both at the same 240 time. Figure 3 depicts this scenario. 242 +-------------+ 243 | | 244 | UE | +------+ 245 | | | IPv4 | 246 | | /| | 247 |------|------+ / +------+ 248 | IPv6 | IPv4 | +--------+ / 249 +-------------+ IPv4 | | / 250 | |------------------------| |/ 251 | | | 252 | IPv6 | GGSN |\ 253 |-------------------------------| | \ 254 +-----------+ | | \ +------+ 255 | GPRS Core | | | \ | IPv6 | 256 +-----------+ +--------+ | | 257 +------+ 258 Figure 3: Dual-Stack Case 260 However, the IPv4 addresses might be a scarce resource for the mobile 261 operator or an ISP. In that case, it might not be possible for the UE 262 to have a globally unique IPv4 address allocated all the time. Hence, 263 the UE should either activate the IPv4 PDP Context only when needed, 264 or be allocated an IPv4 address from a private address space. 266 2) IPv6 UE connecting to an IPv6 node through an IPv4 network 268 Especially in the first stages of IPv6 deployment, there are cases 269 where an IPv6 node would need to connect to the IPv6 Internet through 270 a network that is IPv4. For instance, this can be seen in current 271 fixed networks, where the access is provided in IPv4 only, but there 272 is an IPv6 network deeper in the Internet. This scenario is shown in 273 the Figure 4. 275 +------+ +------+ 276 | | | | +------+ 277 | UE |------------------| |-----------------| | 278 | | +-----------+ | GGSN | +---------+ | IPv6 | 279 | IPv6 | | GPRS Core | | | | IPv4 Net| | | 280 +------+ +-----------+ +------+ +---------+ +------+ 281 Figure 4: IPv6 nodes communicating over IPv4 283 In this case, in the GPRS system, the UE would be IPv6 capable, and 284 the GPRS network would provide an IPv6 capable GGSN in the network. 285 However, there is an IPv4 network between the GGSN, and the peer 286 node. 288 3) IPv4 UE connecting to an IPv4 node through an IPv6 network 290 Further in the future, there are cases where the legacy UEs are still 291 IPv4 only, capable of connecting only to the legacy IPv4 Internet. 292 However, the GPRS operator network has already been upgraded to IPv6. 293 Figure 5 represents this scenario. 295 +------+ +------+ 296 | | | | +------+ 297 | UE |------------------| |-----------------| | 298 | | +-----------+ | GGSN | +---------+ | IPv4 | 299 | IPv4 | | GPRS Core | | | | IPv6 Net| | | 300 +------+ +-----------+ +------+ +---------+ +------+ 301 Figure 5: IPv4 nodes communicating over IPv6 303 In this case, the operator would still provide an IPv4 capable GGSN, 304 and a connection through the IPv6 network to the IPv4 Internet. 306 4) IPv6 UE connecting to an IPv4 node 308 In this scenario an IPv6 UE connects to an IPv4 node in the IPv4 309 Internet. As an example, an IPv6 UE connects to an IPv4 web server in 310 the legacy Internet. In the figure 6, this kind of possible 311 installation is described. 313 +------+ +------+ 314 | | | | +---+ +------+ 315 | UE |------------------| |-----| |----| | 316 | | +-----------+ | GGSN | | ? | | IPv4 | 317 | IPv6 | | GPRS Core | | | | | | | 318 +------+ +-----------+ +------+ +---+ +------+ 319 Figure 6: IPv6 node communicating with IPv4 node 321 5) IPv4 UE connecting to an IPv6 node 323 This is similar to the case above, but in the opposite direction. 324 Here an IPv4 UE connects to an IPv6 node in the IPv6 Internet. As an 325 example, a legacy IPv4 UE is connected to an IPv6 server in the IPv6 326 Internet. Figure 7 depicts this configuration. 328 +------+ +------+ 329 | | | | +---+ +------+ 330 | UE |------------------| |-----| |----| | 331 | | +-----------+ | GGSN | | ? | | IPv6 | 332 | IPv4 | | GPRS Core | | | | | | | 333 +------+ +-----------+ +------+ +---+ +------+ 334 Figure 7: IPv4 node communicating with IPv6 node 336 4.2 Transition scenarios with IMS 338 As described in section 3.2, IMS is exclusively IPv6. Thus, the 339 number of possible transition scenarios is reduced dramatically. In 340 the following, the possible transition scenarios are listed. 342 1) UE connecting to a node in an IPv4 network through IMS 343 2) Two IPv6 IMS connected via an IPv4 network 345 1) UE connecting to a node in an IPv4 network through IMS 347 This scenario occurs when an IMS UE (IPv6) connects to a node in the 348 IPv4 Internet through the IMS, or vice versa. This happens when the 349 other node is a part of a different system than 3GPP, e.g. a fixed 350 PC, with only IPv4 capabilities. This scenario is shown in the Figure 351 8. 353 +------+ +------+ +-----+ 354 | | | | | | +---+ +------+ 355 | UE |-...-| |-----| IMS |--| |--| | 356 | | | GGSN | | | | ? | | IPv4 | 357 | IPv6 | | | | | | | | | 358 +------+ +------+ +-----+ +---+ +------+ 359 Figure 8: IMS UE connecting to an IPv4 node 361 2) Two IPv6 IMS connected via an IPv4 network 363 At the early stages of IMS deployment, there may be cases where two 364 IMS islands are only connected via an IPv4 network such as the legacy 365 Internet. See Figure 9 for illustration. 367 +------+ +------+ +-----+ +-----+ 368 | | | | | | | | 369 | UE |-...-| |-----| IMS |--------| | 370 | | | GGSN | | |+------+| IMS | 371 | IPv6 | | | | || IPv4 || | 372 +------+ +------+ +-----++------++-----+ 373 Figure 9: Two IMS islands connected over IPv4 375 5. Security Considerations 377 This document does not generate any additional security 378 considerations. 380 6. Changes from Last version 382 Description of the 3GPP environment has been added - brief overview 383 of both GPRS, and IMS. 385 Pictures added to scenarios for better explanation. 387 Authors deleted from the header, and design team members added to the 388 end of the document instead. 390 Authors 392 This is document is a result of a joint effort of a design team. The 393 members of the design team are listed in the following. 395 Alain Durand, Sun Microsystems 396 398 Karim El-Malki, Ericsson Radio Systems 399 401 Paul Francis, Tahoe Networks 402 404 Niall Richard Murphy, Enigma Consulting Limited 405 407 Hugh Shieh, AT&T Wireless 408 410 Jonne Soininen, Nokia 411 413 Hesham Soliman, Ericsson Radio Systems 414 416 Margaret Wasserman, Wind River 417 419 Juha Wiljakka, Nokia 420 422 Acknowledgements 424 The authors would like to thank Basavaraj Patil, Tuomo Sipila, Fred 425 Templin, Rod Van Meter, and Jens Staack for good input, and comments 426 that helped writing this document. 428 References 430 [1] Wasserman, M. et al, "Recommendations for IPv6 in 3GPP 431 Standards", January 2002, draft-ietf-ipv6-3gpp-recommend-00.txt. 433 [2] 3GPP TS 23.060 v 5.2.0, "General Packet Radio Service (GPRS); 434 Service description; Stage 2(Release 5)", June 2002. 436 [3] 3GPP TS 23.228 v 5.3.0, " IP Multimedia Subsystem (IMS); Stage 437 2(Release 5)", January 2002. 439 [4] 3GPP TS 24.228 V5.0.0, "Signalling flows for the IP multimedia 440 call control based on SIP and SDP; Stage 3 (Release 5)", March 441 2002. 443 [5] 3GPP TS 24.229 V5.0.0, "IP Multimedia Call Control Protocol 444 based on SIP and SDP; Stage 3 (Release 5)", March 2002. 446 Editor's Address 448 Jonne Soininen 449 Nokia 450 313 Fair Child Dr. Phone: +1-650-864-6794 451 Mountain View, CA, USA Email: jonne.Soininen@nokia.com