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
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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
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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.
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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
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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
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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
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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
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