Internet Draft J. Soininen Document: draft-soininen-ngtrans-3gpp-cases-00.txt J. Wiljakka Expires: October 2002 Nokia A.Durand Sun Microsystems P. Francis Tahoe Networks April 2002 Transition Scenarios for 3GPP Networks Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. 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 of this document. 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. Transition scenarios...........................................2 Soininen, et al. Expires - October 2002 [Page 1] Transition Scenarios for 3GPP Networks April 2002 3.1 GPRS Scenarios.............................................3 3.2 Transition scenarios with IMS..............................4 4. Security Considerations........................................5 Acknowledgements..................................................5 References........................................................5 Author's Addresses................................................5 Copyright (C) The Internet Society (2002). All Rights Reserved. 1. Introduction This document will describe 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 document those scenarios for further discussion, and for study in the NGTRANS working group. This document does give neither an overview, nor an explanation of 3GPP or the 3GPP packet data network - the GPRS. A good overview of the 3GPP specified GPRS can be found from [1]. The GPRS architecture specification is defined in [2]. 2. Scope of the document The scope of this document 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 IP Multimedia Core Network Subsystem (IMS). The scope of this document does not include scenarios inside the GPRS network, i.e. on the different interfaces of the GPRS network. In addition, this document does not identify solutions - just possible scenarios. These scenarios may, or may not be found feasible, or even likely in further study. 3. 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 - concentrate 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. Soininen, et al. Expires - October 2002 [Page 2] Transition Scenarios for 3GPP Networks April 2002 3.1 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. 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 connection to IPv4, and IPv6 networks, it is possible to connect to both at the same time. However, the IPv4 addresses might 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, either activating the IPv4 PDP Context only when needed, or having an IPv4 address from a private address space. 2) IPv6 UE connecting to an IPv6 node through an IPv4 network Especially in the first 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 in IPv4 only, but there is an IPv6 network deeper in the Internet. In this case, in the GPRS system, the UE would be IPv6 capable, and the GPRS network would be IPv6 capable of providing an IPv6 capable Soininen, et al. Expires - October 2002 [Page 3] Transition Scenarios for 3GPP Networks April 2002 GGSN in the network. However, the operator only has an IPv4 network as such. 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 to the legacy IPv4 Internet. However, the GPRS operator network has already been upgraded to IPv6. In this case, the operator would still provide the 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. 5) IPv4 UE connecting to an IPv6 node This is similar to the case above, but to 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. 3.2 Transition scenarios with IMS IP Multimedia Core Network Subsystem (IMS) is a SIP based multimedia service architecture. It is specified in the Release 5 of 3GPP. It 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). IMS is exclusively IPv6. Hence, all the traffic for the IMS is IPv6, even if the UE would be dual stack capable. More information on IMS can be found in [3]. As IMS is exclusively IPv6, 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 Soininen, et al. Expires - October 2002 [Page 4] Transition Scenarios for 3GPP Networks April 2002 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. 2) Two IPv6 IMS connected via an IPv4 At the early stages of IMS deployment, there may be cases where two IMS islands are separated on IPv4 network such as the legacy Internet. Here both the UEs are IPv6 and the IMSes where the UEs are IPv6. However, the IPv6 islands are not native IPv6 connected. 4. Security Considerations This document does not generate any additional security considerations. Acknowledgements The authors would like to thank Basavaraj Patil, Tuomo Sipila, and Jens Staack for good input, and comments that helped writing this document. References [1] Wasserman, M. et al, "Recommendations for IPv6 in 3GPP Standards", January 2002, draft-ietf-ipv6-3gpp-recommend-00.txt. [2] 3GPP TS 23.060 v 3.11.0, "General Packet Radio Service (GPRS); Service description; Stage 2(Release 1999)", March 2002. [3] 3GPP TS 23.228 v 5.3.0, " IP Multimedia Subsystem (IMS); Stage 2(Release 5)", January 2002. Author's Addresses Jonne Soininen Nokia 313 Fair Child Dr. Phone: +1-650-864-6794 Mountain View, CA, USA Email: jonne.Soininen@nokia.com Juha Wiljakka Nokia Visiokatu 3 Phone: +358 7180 47562 FIN-33720 TAMPERE, Finland Email: juha.wiljakka@nokia.com Soininen, et al. Expires - October 2002 [Page 5] Transition Scenarios for 3GPP Networks April 2002 Alain Durand Sun Microsystems 901 San Antonio rd UMPK17-202 Palo Alto, CA, USA Email: Alain.Durand@sun.com Paul Francis Tahoe Networks 3052 Orchard Dr. Phone: +1-408-944-8632 San Jose CA, USA Email: francis@tahoenetworks.com Soininen, et al. Expires - October 2002 [Page 6]