From 4bfd864f10b68b71482b35c818559068ef8d5797 Mon Sep 17 00:00:00 2001 From: Thomas Voss Date: Wed, 27 Nov 2024 20:54:24 +0100 Subject: doc: Add RFC documents --- doc/rfc/rfc3574.txt | 675 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 675 insertions(+) create mode 100644 doc/rfc/rfc3574.txt (limited to 'doc/rfc/rfc3574.txt') diff --git a/doc/rfc/rfc3574.txt b/doc/rfc/rfc3574.txt new file mode 100644 index 0000000..6be2be9 --- /dev/null +++ b/doc/rfc/rfc3574.txt @@ -0,0 +1,675 @@ + + + + + + +Network Working Group J. Soininen, Ed. +Request for Comments: 3574 Nokia +Category: Informational August 2003 + + + Transition Scenarios for 3GPP Networks + +Status of this Memo + + This memo provides information for the Internet community. It does + not specify an Internet standard of any kind. Distribution of this + memo is unlimited. + +Copyright Notice + + Copyright (C) The Internet Society (2003). All Rights Reserved. + +Abstract + + This document describes different scenarios in Third Generation + Partnership Project (3GPP) defined packet network, i.e., General + Packet Radio Service (GPRS) that would need IP version 6 and IP + version 4 transition. The focus of this document is on the scenarios + where the User Equipment (UE) connects to nodes in other networks, + e.g., in the Internet. GPRS network internal transition scenarios, + i.e., between different GPRS elements in the network, are out of + scope. The purpose of the document is to list the scenarios for + further discussion and study. + +Table of Contents + + 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2 + 2. Scope of the Document. . . . . . . . . . . . . . . . . . . . . 2 + 3. Brief Description of the 3GPP Network Environment. . . . . . . 2 + 3.1 GPRS Architecture Basics . . . . . . . . . . . . . . . . . 3 + 3.2 IP Multimedia Core Network Subsystem (IMS) . . . . . . . . 3 + 4. Transition Scenarios . . . . . . . . . . . . . . . . . . . . . 5 + 4.1 GPRS Scenarios . . . . . . . . . . . . . . . . . . . . . . 5 + 4.2 IMS Scenarios . . . . . . . . . . . . . . . . . . . . . . 8 + 5. Security Considerations. . . . . . . . . . . . . . . . . . . . 9 + 6. Contributing Authors . . . . . . . . . . . . . . . . . . . . . 10 + 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 10 + 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10 + 8.1. Normative References . . . . . . . . . . . . . . . . . . 10 + 8.2. Informative References . . . . . . . . . . . . . . . . . 11 + 9. Editor's Address . . . . . . . . . . . . . . . . . . . . . . . 11 + 10. Full Copyright Statement . . . . . . . . . . . . . . . . . . . 12 + + + + +Soininen Informational [Page 1] + +RFC 3574 Transition Scenarios for 3GPP Networks August 2003 + + +1. Introduction + + This document describes the transition scenarios in 3GPP packet data + networks that might come up in the deployment phase of IPv6. The + main purpose of this document is to identify and to document those + scenarios for further discussion and study them in the v6ops working + group. + + Just a brief overview of the 3GPP packet data network, GPRS, is given + to help the reader to better understand the transition scenarios. A + better overview of the 3GPP specified GPRS can be found for example + from [6]. The GPRS architecture is defined in [1]. + +2. Scope of the Document + + The scope is to describe the possible transition scenarios in the + 3GPP defined GPRS network where a UE connects to, or is contacted + from, the Internet or another UE. The document describes scenarios + with and without the usage of the SIP-based (Session Initiation + Protocol [5]) IP Multimedia Core Network Subsystem (IMS). The 3GPP + releases 1999, 4, and 5 are considered as the basis. + + Out of scope are scenarios inside the GPRS network, i.e., on the + different interfaces of the GPRS network. This document neither + changes 3GPP specifications, nor proposes changes to the current + specifications. + + In addition, the possible transition scenarios are described. The + solutions will be documented in a separate document. + + All the possible scenarios are listed here. Further analysis may + show that some of the scenarios are not actually relevant in this + context. + +3. Brief Description of the 3GPP Network Environment + + This section describes the most important concepts of the 3GPP + environment for understanding the transition scenarios. The first + part of the description gives a brief overview to the GPRS network as + such. The second part concentrates on the IP Multimedia Core Network + Subsystem (IMS). + + + + + + + + + + +Soininen Informational [Page 2] + +RFC 3574 Transition Scenarios for 3GPP Networks August 2003 + + +3.1. GPRS Architecture Basics + + This section gives an overview to the most important concepts of the + 3GPP packet architecture. For more detailed description, please see + [1]. + + From the point of view of this document, the most relevant 3GPP + architectural elements are the User Equipment (UE), and the Gateway + GPRS Support Node (GGSN). A simplified picture of the architecture + is shown in Figure 1. + + The UE is the mobile phone. It can either be an integrated device + comprising a combined GPRS part, and the IP stack, or it might be a + separate GPRS device, and separate equipment with the IP stack, e.g., + a laptop. + + The GGSN serves as an anchor-point for the GPRS mobility management. + It also serves as the default router for the UE. + + The Peer node mentioned in the picture refers to a node with which + the UE is communicating. + + -- ---- ************ --------- + |UE|- ... -|GGSN|--+--* IPv4/v6 NW *--+--|Peer node| + -- ---- ************ --------- + + Figure 1: Simplified GPRS Architecture + + There is a dedicated link between the UE and the GGSN called the + Packet Data Protocol (PDP) Context. This link is created through the + PDP Context activation process. During the activation the UE is + configured with its IP address and other information needed to + maintain IP access, e.g., DNS server address. There are three + different types of PDP Contexts: IPv4, IPv6, and Point-to-Point + Protocol (PPP). + + A UE can have one or more simultaneous PDP Contexts open to the same + or to different GGSNs. The PDP Context can be either of the same or + different types. + +3.2. IP Multimedia Core Network Subsystem (IMS) + + IP Multimedia Core Network Subsystem (IMS) is an architecture for + supporting multimedia services via a SIP infrastructure. It is + specified in 3GPP Release 5. This section provides an overview of + the 3GPP IMS and is not intended to be comprehensive. A more + detailed description can be found in [2], [3] and [4]. + + + + +Soininen Informational [Page 3] + +RFC 3574 Transition Scenarios for 3GPP Networks August 2003 + + + The IMS comprises a set of SIP proxies, servers, and registrars. In + addition, there are Media Gateways (MGWs) that offer connections to + non-IP networks such as the Public Switched Telephony Network (PSTN). + A simplified overview of the IMS is depicted in figure 2. + + +-------------+ +-------------------------------------+ + | | | +------+ | + | | | |S-CSCF|--- + | | | | +------+ | + +-|+ | | | / | + | | | SIP Sig. | | +------+ +------+ | + | |----|------+------|--|----|P-CSCF|----------|I-CSCF| | + | | | | | +------+ +------+ | + | |-----------+------------------------------------------------ + +--+ | User traf. | | | + UE | | | | + | GPRS access | | IP Multimedia CN Subsystem | + +-------------+ +-------------------------------------+ + + Figure 2: Overview of the 3GPP IMS architecture + + The SIP proxies, servers, and registrars shown in Figure 2 are as + follows. + + - P-CSCF (Proxy-Call Session Control Function) is the first + contact point within the IMS for the subscriber. + + - I-CSCF (Interrogating-CSCF) is the contact point within an + operator's network for all connections destined to a subscriber + of that network operator, or a roaming subscriber currently + located within that network operator's service area. + + - S-CSCF (Serving-CSCF) performs the session control services for + the subscriber. It also acts as a SIP Registrar. + + IMS capable UEs utilize the GPRS network as an access network for + accessing the IMS. Thus, a UE has to have an activated PDP Context + to the IMS before it can proceed to use the IMS services. The PDP + Context activation is explained briefly in section 3.1. + + The IMS is exclusively IPv6. Thus, the activated PDP Context is of + PDP Type IPv6. This means that a 3GPP IP Multimedia terminal uses + exclusively IPv6 to access the IMS, and the IMS SIP server and proxy + support exclusively IPv6. Hence, all the traffic going to the IMS is + IPv6, even if the UE is dual stack capable - this comprises both + signaling and user traffic. + + + + + +Soininen Informational [Page 4] + +RFC 3574 Transition Scenarios for 3GPP Networks August 2003 + + + This, of course, does not prevent the usage of other unrelated + services (e.g., corporate access) on IPv4. + +4. Transition Scenarios + + This section is divided into two main parts - GPRS scenarios, and + scenarios with the IP Multimedia Subsystem (IMS). The first part - + GPRS scenarios - concentrates on scenarios with a User Equipment (UE) + connecting to services in the Internet, e.g., mail, web. The second + part - IMS scenarios - then describes how an IMS capable UE can + connect to other SIP-capable nodes in the Internet using the IMS + services. + +4.1. GPRS Scenarios + + This section describes the scenarios that might occur when a GPRS UE + contacts services, or nodes outside the GPRS network, e.g., web- + server in the Internet. + + Transition scenarios of the GPRS internal interfaces are outside of + the scope of this document. + + The following scenarios are described here. In all of the scenarios, + the UE is part of a network where there is at least one router of the + same IP version, i.e., GGSN, and it is connecting to a node in a + different network. + + The scenarios here apply also for PDP Context type Point-to-Point + Protocol (PPP) where PPP is terminated at the GGSN. On the other + hand, where the PPP PDP Context is terminated e.g., at an external + ISP, the environment is the same as for general ISP cases. + + 1) Dual Stack UE connecting to IPv4 and IPv6 nodes + 2) IPv6 UE connecting to an IPv6 node through an IPv4 network + 3) IPv4 UE connecting to an IPv4 node through an IPv6 network + 4) IPv6 UE connecting to an IPv4 node + 5) IPv4 UE connecting to an IPv6 node + + 1) Dual Stack UE connecting to IPv4 and IPv6 nodes + + The GPRS system has been designed in a manner that there is the + possibility to have simultaneous IPv4, and IPv6 PDP Contexts open. + Thus, in cases where the UE is dual stack capable, and in the + network there is a GGSN (or separate GGSNs) that supports both + connections to IPv4 and IPv6 networks, it is possible to connect + to both at the same time. Figure 3 depicts this scenario. + + + + + +Soininen Informational [Page 5] + +RFC 3574 Transition Scenarios for 3GPP Networks August 2003 + + + +-------------+ + | | + | UE | +------+ + | | | IPv4 | + | | /| | + |------|------+ / +------+ + | IPv6 | IPv4 | +--------+ / + +-------------+ IPv4 | | / + | |------------------------| |/ + | | | + | IPv6 | GGSN |\ + |-------------------------------| | \ + +-----------+ | | \ +------+ + | GPRS Core | | | \ | IPv6 | + +-----------+ +--------+ \| | + +------+ + + Figure 3: Dual-Stack Case + + However, the IPv4 addresses may be a scarce resource for the + mobile operator or an ISP. In that case, it might not be possible + for the UE to have a globally unique IPv4 address allocated all + the time. Hence, the UE could either activate the IPv4 PDP + Context only when needed, or be allocated an IPv4 address from a + private address space. + + 2) IPv6 UE connecting to an IPv6 node through an IPv4 network + + Especially in the initial stages of IPv6 deployment, there are + cases where an IPv6 node would need to connect to the IPv6 + Internet through a network that is IPv4. For instance, this can + be seen in current fixed networks, where the access is provided + via IPv4 only, but there is an IPv6 network deeper in the + Internet. This scenario is shown in Figure 4. + + +------+ +------+ + | | | | +------+ + | UE |------------------| |-----------------| | + | | +-----------+ | GGSN | +---------+ | IPv6 | + | IPv6 | | GPRS Core | | | | IPv4 Net| | | + +------+ +-----------+ +------+ +---------+ +------+ + + Figure 4: IPv6 nodes communicating over IPv4 + + In this case, in the GPRS system, the UE would be IPv6 capable, + and the GPRS network would provide an IPv6 capable GGSN in the + network. However, there is an IPv4 network between the GGSN, and + the peer node. + + + +Soininen Informational [Page 6] + +RFC 3574 Transition Scenarios for 3GPP Networks August 2003 + + + 3) IPv4 UE connecting to an IPv4 node through an IPv6 network + + Further in the future, there are cases where the legacy UEs are + still IPv4 only, capable of connecting only to the legacy IPv4 + Internet. However, the GPRS operator network has already been + upgraded to IPv6. Figure 5 represents this scenario. + + +------+ +------+ + | | | | +------+ + | UE |------------------| |-----------------| | + | | +-----------+ | GGSN | +---------+ | IPv4 | + | IPv4 | | GPRS Core | | | | IPv6 Net| | | + +------+ +-----------+ +------+ +---------+ +------+ + + Figure 5: IPv4 nodes communicating over IPv6 + + In this case, the operator would still provide an IPv4 capable + GGSN, and a connection through the IPv6 network to the IPv4 + Internet. + + 4) IPv6 UE connecting to an IPv4 node + + In this scenario, an IPv6 UE connects to an IPv4 node in the IPv4 + Internet. As an example, an IPv6 UE connects to an IPv4 web + server in the legacy Internet. In the figure 6, this kind of + possible installation is described. + + +------+ +------+ + | | | | +---+ +------+ + | UE |------------------| |-----| |----| | + | | +-----------+ | GGSN | | ? | | IPv4 | + | IPv6 | | GPRS Core | | | | | | | + +------+ +-----------+ +------+ +---+ +------+ + + Figure 6: IPv6 node communicating with IPv4 node + + + + + + + + + + + + + + + + +Soininen Informational [Page 7] + +RFC 3574 Transition Scenarios for 3GPP Networks August 2003 + + + 5) IPv4 UE connecting to an IPv6 node + + This is similar to the case above, but in the opposite direction. + Here an IPv4 UE connects to an IPv6 node in the IPv6 Internet. As + an example, a legacy IPv4 UE is connected to an IPv6 server in the + IPv6 Internet. Figure 7 depicts this configuration. + + +------+ +------+ + | | | | +---+ +------+ + | UE |------------------| |-----| |----| | + | | +-----------+ | GGSN | | ? | | IPv6 | + | IPv4 | | GPRS Core | | | | | | | + +------+ +-----------+ +------+ +---+ +------+ + + Figure 7: IPv4 node communicating with IPv6 node + +4.2. IMS Scenarios + + As described in section 3.2, IMS is exclusively IPv6. Thus, the + number of possible transition scenarios is reduced dramatically. In + the following, the possible transition scenarios are listed. + + 1) UE connecting to a node in an IPv4 network through IMS + 2) Two IPv6 IMS connected via an IPv4 network + + 1) UE connecting to a node in an IPv4 network through IMS + + This scenario occurs when an IMS UE (IPv6) connects to a node in + the IPv4 Internet through the IMS, or vice versa. This happens + when the other node is a part of a different system than 3GPP, + e.g., a fixed PC, with only IPv4 capabilities. This scenario is + shown in the Figure 8. + + +------+ +------+ +-----+ + | | | | | | +---+ +------+ + | UE |-...-| |-----| IMS |--| |--| | + | | | GGSN | | | | ? | | IPv4 | + | IPv6 | | | | | | | | | + +------+ +------+ +-----+ +---+ +------+ + + Figure 8: IMS UE connecting to an IPv4 node + + + + + + + + + + +Soininen Informational [Page 8] + +RFC 3574 Transition Scenarios for 3GPP Networks August 2003 + + + 2) Two IPv6 IMS connected via an IPv4 network + + At the early stages of IMS deployment, there may be cases where + two IMS islands are only connected via an IPv4 network such as the + legacy Internet. See Figure 9 for illustration. + + +------+ +------+ +-----+ +-----+ + | | | | | | | | + | UE |-...-| |-----| IMS |----------| | + | | | GGSN | | | +------+ | IMS | + | IPv6 | | | | | | IPv4 | | | + +------+ +------+ +-----+ +------+ +-----+ + + Figure 9: Two IMS islands connected over IPv4 + +5. Security Considerations + + This document describes possible transition scenarios for 3GPP + networks for future study. Solutions and mechanism are explored in + other documents. The description of the 3GPP network scenarios does + not have any security issues. + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +Soininen Informational [Page 9] + +RFC 3574 Transition Scenarios for 3GPP Networks August 2003 + + +6. Contributing Authors + + This document is a result of a joint effort of a design team. The + members of the design team are listed in the following. + + Alain Durand, Sun Microsystems + + + Karim El-Malki, Ericsson Radio Systems + + + Niall Richard Murphy, Enigma Consulting Limited + + + Hugh Shieh, AT&T Wireless + + + Jonne Soininen, Nokia + + + Hesham Soliman, Ericsson Radio Systems + + + Margaret Wasserman, Wind River + + + Juha Wiljakka, Nokia + + +7. Acknowledgements + + The authors would like to thank Basavaraj Patil, Tuomo Sipila, Fred + Templin, Rod Van Meter, Pekka Savola, Francis Dupont, Christine + Fisher, Alain Baudot, Rod Walsh, and Jens Staack for good input, and + comments that helped writing this document. + +8. References + +8.1. Normative References + + [1] 3GPP TS 23.060 v 5.2.0, "General Packet Radio Service (GPRS); + Service description; Stage 2(Release 5)", June 2002. + + [2] 3GPP TS 23.228 v 5.3.0, " IP Multimedia Subsystem (IMS); Stage + 2(Release 5)", January 2002. + + + + + + +Soininen Informational [Page 10] + +RFC 3574 Transition Scenarios for 3GPP Networks August 2003 + + + [3] 3GPP TS 24.228 V5.0.0, "Signalling flows for the IP multimedia + call control based on SIP and SDP; Stage 3 (Release 5)", March + 2002. + + [4] 3GPP TS 24.229 V5.0.0, "IP Multimedia Call Control Protocol based + on SIP and SDP; Stage 3 (Release 5)", March 2002. + + [5] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A., + Peterson, J., Sparks, R., Handley, M. and E. Schooler, "SIP: + Session Initiation Protocol", RFC 3261, June 2002. + +8.2. Informative References + + [6] Wasserman, M., "Recommendations for IPv6 in Third Generation + Partnership Project (3GPP) Standards", RFC 3314, September 2002. + +9. Editor's Address + + Jonne Soininen + Nokia + 313 Fairchild Dr. + Mountain View, CA, USA + + Phone: +1-650-864-6794 + EMail: jonne.soininen@nokia.com + + + + + + + + + + + + + + + + + + + + + + + + + + +Soininen Informational [Page 11] + +RFC 3574 Transition Scenarios for 3GPP Networks August 2003 + + +10. Full Copyright Statement + + Copyright (C) The Internet Society (2003). All Rights Reserved. + + This document and translations of it may be copied and furnished to + others, and derivative works that comment on or otherwise explain it + or assist in its implementation may be prepared, copied, published + and distributed, in whole or in part, without restriction of any + kind, provided that the above copyright notice and this paragraph are + included on all such copies and derivative works. However, this + document itself may not be modified in any way, such as by removing + the copyright notice or references to the Internet Society or other + Internet organizations, except as needed for the purpose of + developing Internet standards in which case the procedures for + copyrights defined in the Internet Standards process must be + followed, or as required to translate it into languages other than + English. + + The limited permissions granted above are perpetual and will not be + revoked by the Internet Society or its successors or assignees. + + This document and the information contained herein is provided on an + "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING + TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING + BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION + HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF + MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. + +Acknowledgement + + Funding for the RFC Editor function is currently provided by the + Internet Society. + + + + + + + + + + + + + + + + + + + +Soininen Informational [Page 12] + -- cgit v1.2.3