1、 ETSI TR 1Digital cellular telecoUniversal Mobile TelDirect tunn(3GPP TR 23.9TECHNICAL REPORT 123 919 V13.0.0 (2016communications system (Phaelecommunications System (LTE; nnel deployment guideline .919 version 13.0.0 Release 1316-01) hase 2+); (UMTS); 13) ETSI ETSI TR 123 919 V13.0.0 (2016-01)13GPP
2、 TR 23.919 version 13.0.0 Release 13Reference RTR/TSGS-0223919vd00 Keywords GSM,LTE,UMTS ETSI 650 Route des Lucioles F-06921 Sophia Antipolis Cedex - FRANCE Tel.: +33 4 92 94 42 00 Fax: +33 4 93 65 47 16 Siret N 348 623 562 00017 - NAF 742 C Association but non lucratif enregistre la Sous-Prfecture
3、de Grasse (06) N 7803/88 Important notice The present document can be downloaded from: http:/www.etsi.org/standards-search The present document may be made available in electronic versions and/or in print. The content of any electronic and/or print versions of the present document shall not be modif
4、ied without the prior written authorization of ETSI. In case of any existing or perceived difference in contents between such versions and/or in print, the only prevailing document is the print of the Portable Document Format (PDF) version kept on a specific network drive within ETSI Secretariat. Us
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6、ment to one of the following services: https:/portal.etsi.org/People/CommiteeSupportStaff.aspx Copyright Notification No part may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm except as authorized by written permission of ETSI.
7、The content of the PDF version shall not be modified without the written authorization of ETSI. The copyright and the foregoing restriction extend to reproduction in all media. European Telecommunications Standards Institute 2016. All rights reserved. DECTTM, PLUGTESTSTM, UMTSTMand the ETSI logo are
8、 Trade Marks of ETSI registered for the benefit of its Members. 3GPPTM and LTE are Trade Marks of ETSI registered for the benefit of its Members and of the 3GPP Organizational Partners. GSM and the GSM logo are Trade Marks registered and owned by the GSM Association. ETSI ETSI TR 123 919 V13.0.0 (20
9、16-01)23GPP TR 23.919 version 13.0.0 Release 13Intellectual Property Rights IPRs essential or potentially essential to the present document may have been declared to ETSI. The information pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be f
10、ound in ETSI SR 000 314: “Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in respect of ETSI standards“, which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web server (https:/ipr.etsi.org/). Pursuant to the ETSI IPR
11、Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web server) which are, or may be, or may become, essential to the present document. Foreword This
12、Technical Report (TR) has been produced by ETSI 3rd Generation Partnership Project (3GPP). The present document may refer to technical specifications or reports using their 3GPP identities, UMTS identities or GSM identities. These should be interpreted as being references to the corresponding ETSI d
13、eliverables. The cross reference between GSM, UMTS, 3GPP and ETSI identities can be found under http:/webapp.etsi.org/key/queryform.asp. Modal verbs terminology In the present document “shall“, “shall not“, “should“, “should not“, “may“, “need not“, “will“, “will not“, “can“ and “cannot“ are to be i
14、nterpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of provisions). “must“ and “must not“ are NOT allowed in ETSI deliverables except when used in direct citation. ETSI ETSI TR 123 919 V13.0.0 (2016-01)33GPP TR 23.919 version 13.0.0 Release 13Contents In
15、tellectual Property Rights 2g3Foreword . 2g3Modal verbs terminology 2g3Foreword . 4g31 Scope 5g32 References 5g33 Abbreviations . 5g34 Direct Tunnel Feature . 5g34.1 General . 5g35 Impacts on Functions and Characteristics 6g35.1 Charging . 6g35.2 Lawful Interception 6g35.3 CAMEL 6g35.4 Error Handlin
16、g 6g36 Impacts on 3GPP Network Entities, Features and Transport Network 7g36.1 SGSN 7g36.2 GGSN . 7g36.3 RNC 8g36.4 IP Backbone Network 8g36.5 IP versions 9g36.6 QoS Architecture 9g37 Limitations of Direct Tunnel Solution . 9g38 Upgrade considerations 9g38.1 Interworking with Pre-DT GGSN 9g38.2 Inte
17、rworking with Pre-DT SGSN . 10g38.3 Interworking with Pre-Rel-7 RNC . 10g3Annex A: Change history 11g3History 12g3ETSI ETSI TR 123 919 V13.0.0 (2016-01)43GPP TR 23.919 version 13.0.0 Release 13Foreword This Technical Report has been produced by the 3rdGeneration Partnership Project (3GPP). The conte
18、nts of the present document are subject to continuing work within the TSG and may change following formal TSG approval. Should the TSG modify the contents of the present document, it will be re-released by the TSG with an identifying change of release date and an increase in version number as follow
19、s: Version x.y.z where: x the first digit: 1 presented to TSG for information; 2 presented to TSG for approval; 3 or greater indicates TSG approved document under change control. y the second digit is incremented for all changes of substance, i.e. technical enhancements, corrections, updates, etc. z
20、 the third digit is incremented when editorial only changes have been incorporated in the document. ETSI ETSI TR 123 919 V13.0.0 (2016-01)53GPP TR 23.919 version 13.0.0 Release 131 Scope The present document contains deployment guidelines for the use of direct tunnelling of user plane data between t
21、he RNC and the GGSN (earlier known as the One Tunnel approach). This report highlights the impacts of the 3GPP Release 7 Direct Tunnel solution to the current UMTS system in order to guide equipment development and network deployment. 2 References The following documents contain provisions which, th
22、rough reference in this text, constitute provisions of the present document. - References are either specific (identified by date of publication, edition number, version number, etc.) or non-specific. - For a specific reference, subsequent revisions do not apply. - For a non-specific reference, the
23、latest version applies. In the case of a reference to a 3GPP document (including a GSM document), a non-specific reference implicitly refers to the latest version of that document in the same Release as the present document. 1 3GPP TS 23.060: “General Packet Radio Service (GPRS); Service description
24、; Stage 2“. 2 3GPP TS 23.107: “ Quality of Service (QoS) concept and architecture“. 3 3GPP TS 23.203: “Policy and charging control architecture“. 4 3GPP TS 33.106: “Lawful interception requirements“. 5 3GPP TS 33.107: “3G security; Lawful interception architecture and functions“. 6 3GPP TS 33.108: “
25、3G security; Handover interface for Lawful Interception (LI)“. 3 Abbreviations For the purposes of the present document, the following abbreviations apply: DT Direct Tunnel LI Lawful Interception 4 Direct Tunnel Feature 4.1 General Direct Tunnel is an optional feature in Iu mode that allows the SGSN
26、 to establish a direct user plane tunnel between RAN and GGSN within the PS domain. The SGSN handles the control plane signalling and makes the decision when to establish a Direct Tunnel. In case of Direct Tunnel, the SGSN provides the RAN with the TEID and user plane address of the GGSN, and provid
27、es the GGSN with the TEID and user plane address of the RAN. The detailed procedures are specified in TS 23.060 1. ETSI ETSI TR 123 919 V13.0.0 (2016-01)63GPP TR 23.919 version 13.0.0 Release 13Figure 4-1: Direct Tunnel concept 5 Impacts on Functions and Characteristics 5.1 Charging When a Direct Tu
28、nnel is active, the SGSN will no longer be able to count data volumes associated with the PDP context for which the Direct Tunnel is established. As a result of activating a Direct Tunnel for a specific PDP context, an inconsistency in the data volumes captured by the SGSN and GGSN will arise for th
29、at PDP context. Hence, if Direct Tunnel is active, volume based charging can no longer operate when relying on SGSN charging information alone (e.g. CAMEL pre-paid service or charging only on S-CDRs). During an upgrade phase when there exist Pre-DT GGSN or Pre-DT RNC in the network there may in some
30、 error situations as described in clause 8 occur a discrepancy in CDR closure time between S-CDRs and G-CDRs. However, no impacts on flow based charging, as defined in TS 23.203 3, are foreseen. 5.2 Lawful Interception If a Direct Tunnel is in use, the LI system can only collect the communication co
31、ntent from the GGSN. When the LI function in the GGSN is used, some control plane related information, such as SMS and MM-related information can only be collected from the SGSN. Details for LI are specified in following documents: TS 33.106 4, TS 33.107 5, and TS 33.108 6. 5.3 CAMEL Direct Tunnel i
32、s not enabled for a subscriber that has controlling PS domain CAMEL services active. 5.4 Error Handling With the Rel-7 Direct Tunnel feature, the GTP-U related error handling has been slightly changed in the GGSN and RNC. For the Error Handling function to work fully correctly, the GGSN and RNC need
33、 to be upgraded to support Direct Tunnel. During a deployment phase, the Direct Tunnel feature may however be used without the GGSN and/or the RNC being upgraded. The shortcomings and issues related with this are mainly that the network may experience hanging PDP contexts or inconsistent PDP context
34、 data in some rare error cases, e.g. at node failures or restarts. This is further explained in clause 8. ETSI ETSI TR 123 919 V13.0.0 (2016-01)73GPP TR 23.919 version 13.0.0 Release 136 Impacts on 3GPP Network Entities, Features and Transport Network 6.1 SGSN The main principle is that whenever a R
35、AB is assigned for a PDP context (or re-assigned) the SGSN decides whether to use a direct user plane tunnel between RNC and GGSN, or, if it needs to handle user plane data and use two tunnels as in earlier 3GPP releases. Further, when a Direct Tunnel was in use and the RAB assigned for a PDP contex
36、t is released (i.e. the PDP context is preserved) the GTP-U tunnel is (re)established between the GGSN and SGSN in order to be able to handle the downlink packets. The SGSN needs to decide before every RAB assignment and every SRNS relocation if direct tunnel will be used or not. Figure 6-1: Connect
37、ed mode and Idle mode handling In the Intra SGSN Inter-system Change procedure from 3G to 2G, the SGSN needs to perform a PDP Context Update Procedure to establish the tunnel between the 2G SGSN and the GGSN and release the Direct Tunnel between RNC and GGSN. In the Intra SGSN Inter-system Change pr
38、ocedure from 2G to 3G, the SGSN provides to the RNC the GGSNs Address(es) for User Plane and TEID(s) for Uplink data in the RAB Assignment Request during the Service Request Procedure. Then the SGSN performs a PDP Context Update Procedure to establish the Direct Tunnel between the RNC and the GGSN a
39、nd release the tunnel between SGSN and GGSN. Toggling between 2G and 3G might (or might not) be frequent. This may effect the Gn signalling when Direct Tunnel is deployed. It is implementation specific how this is addressed. 6.2 GGSN In order to inform the GGSN of the IP address of the RNC and the T
40、EID for the active PDP context, the SGSN will send an Update PDP Context Request message to the GGSN during every PDP Context Activation procedure for which a Direct Tunnel is established. This message, which is an optional message in two-tunnel system, increases the signalling load on SGSN and GGSN
41、. RAB release and re-establishment procedures, which become visible to the GGSN in a Direct Tunnel system, also increase the signalling load on SGSN and GGSN. If the radio-link is bad, and the RNC releases the Iu connection, the frequent RAB release and re-establishment increases the signalling load
42、 on SGSN and GGSN. One consequence is that it is useful if the RNC utilises URA-PCH state. Some Intra SGSN procedures, such as Intra SGSN inter RNC, Intra SGSN Inter-system change, and possibly other procedures, which are invisible to the GGSN in two-tunnel system, will become visible to the GGSN an
43、d increase the signalling load on both SGSN and GGSN. ETSI ETSI TR 123 919 V13.0.0 (2016-01)83GPP TR 23.919 version 13.0.0 Release 13Receipt of the Direct Tunnel Indicator makes the GGSN aware that the SGSN is using a Direct Tunnel. When using Direct Tunnel, if the GGSN receives a GTP-U Error Indica
44、tion (from the RNC) it shall not release the related PDP context locally but the GGSN shall notify the SGSN that the RAB in RAN is invalid. This needs the GGSN to be updated. NOTE: During a deployment phase, the Direct Tunnel feature may however be used without the GGSN being upgraded. This is furth
45、er explained in clause 8.1. If, when using two tunnels transport network QoS was used on Iu-PS but not on Gn then moving to Direct Tunnel requires the GGSN to implement transport network QoS. 6.3 RNC RNCs that only support ATM transport should support IP transport for the Iu-PS interface. Alternativ
46、ely a solution as described below in clause 6.4 can be used. Due to this Direct Tunnel feature, the Error Handling Behaviour of Rel-7 RNC is changed. NOTE: During a deployment phase, the Direct Tunnel feature may however be used without the RNC being upgraded. This is further explained in clause 8.3
47、. If, when using two tunnels transport network QoS was used on Gn but not on Iu-PS then moving to Direct Tunnel requires the RNC to implement transport network QoS. 6.4 IP Backbone Network Within the network area where Direct Tunnel is used, the Iu-PS and Gn transport networks must be made visible t
48、o each other, this is a network configuration issue. This is minor security drawback. The risk could be reduced by using firewall between Iu-PS and Gn networks instead of simple router (this might impact user-plane latency). Only IP traffic to predefined IP-addresses/ports from predefined addresses/
49、ports would be allowed between Iu-PS and Gn networks. Considering network security, a firewall can be deployed between the RNC and the IP network. For an ATM based Iu-PS, the ATM connection needs to be terminated and “interworked“ to IP. The location of the interworking may be within the Iu-PS network or at the edge of the Iu-PS network. Figure 6-2 shows the connectivity between the Iu-PS network and the Gn (backbone) network. Figure 6-2: Connectivity with Iu-PS ETSI ETSI TR 123 919 V13.0.0 (2016-01)93GPP TR 23.919 version 13.0.0 Release 136.5 IP versio
