Service Function Chaining Sunil Kumar Sinha Internet-Draft Infinite Computing Solutions Intended status: Informational Amardeep Sinha Expires: December 7, 2018 Reliance Jio Infocomm Limited Dharmendra Dwivedi Ericsson Harsh Vardhan Singh Chauhan Nokia June 8, 2018 5G-System Bearer Offloading for Dual Connectivity for RAN draft-sfc-sinha-5g-bearer-dc-ran-00 Abstract This document attempts the case for new work that needs to be developed for 5G users to improve faster download and upload of the user's data in a scenario of dual-connectivity 3GPP access outlining the poor radio coverage issues. This document also outlines the faster user data mechanism accompanying 3GPP access of 5G user device via bearer offloading in case of a poor coverage. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at https://datatracker.ietf.org/drafts/current/. 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." This Internet-Draft will expire on December 7, 2018 Copyright Notice Copyright (c) 2018 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. sinha Expires December 7, 2018 [Page 1] Internet-Draft 5G Bearer Offloading DC for RAN June 2018 Table of Contents: 1. Introduction...................................................2 2. Conventions and Terminology....................................2 3. User data flow for Dual Connectivity for 3GPP access and problem statement..............................................2 3.1 5G System architecture.....................................2 3.2 QoS........................................................3 3.3 Dual Connectivity..........................................3 3.4 Problem Statement..........................................4 4. Proposal of Bearer Offloading Dual-Connectivity with 3GPP access ........................................................4 5. IANA Considerations............................................6 6. Security Considerations........................................6 7. Privacy Considerations ........................................6 8. Acknowledgements...............................................6 9. References.....................................................7 9.1 Normative References.......................................7 9.2 Informative References.....................................7 Authors' Addresses................................................8 1. Introduction 5G system has been evolved to serve the user in more efficient way of meeting higher download and upload of user data for 5G Users accessing the network via wireline and wireless, in addition to Residential Gateway RG and IoT support. In 5G system Access and user experience is challenging for poor radio coverage (for both wi-fi and RAN) and the proposal in this document addresses to the problem of dual-connectivity of 3GPP access with Master-gNB having poor coverage. 2. Conventions and Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [1]. 3. User data flow for Dual Connectivity for 3GPP access and problem statement 3.1 5G system architecture A simplified 5G-system architecture shown in Figure-1 in the case of UE in non-roaming scenario with RAN access(3GPP). sinha Expires December 7, 2018 [Page 2] Internet-Draft 5G Bearer Offloading DC for RAN June 2018 +-------------------------------+ | | | +------------------+ | | | | | | | |N8 |N15 | | | | +------+ | | +------+ N13 +-----+ | | NSSF |---+ | | | AUSF |-------| UDM | | +------+ | | | +------+ +-----+ | | | | | | | | | | | | | N22| | | |N12 |N10 +-----+ N5 +----+ | | | +---+ | | PCF |------| AF | | | | | | +-----+ +----+ | | | | | | | | | | | | +-----+ +-------+ +-----+ | UE---| RAN |-------| AMF |------------| SMF |-------+ +-----+ N2 +-------+ N11 +-----+ N7 | | | | | |N4 | | | | | N3 +-----+ N6 +-------------+ +-------------------------------| UPF |--------| Service N/W | +-----+ +-------------+ Figure 1 : Simplified 5G-system Architecture for RAN access For clarity in the current document proposal, multiple node/ function like UDSF, NRF, and interfaces N9, N14 are not shown. 3.2 QoS QFI is defined as Qos Flow ID is an identity to QoS flow in the 5G system. All data traffic within a PDU session are labelled or identified by QFI, it implies same QFI labelled data flow will receive same traffic forwarding treatment like scheduling, priority etc. Data flow is via N3 (N3 and N9) interface, being encapsulated end-to-end. This flow is controlled by SMF, who provides QoS profile during session establishment to R(AN) and provide the PDR to the UPF. Please Note that like 4G system, default QoS flow is applied to each PDU session and retain till lifetime span of connectivity. In case of non-3GPP access QFI is delivered to N3IWF entity (or NG-RAN) for every time User Plane of the PDU session is established, modified or activated. 3.3 Dual Connectivity sinha Expires December 7, 2018 [Page 3] Internet-Draft 5G Bearer Offloading DC for RAN June 2018 Dual connectivity (DC) concept developed for 3GPP access, functional support the network to make use of additional radio resource to achieve required throughput in downlink and uplink of user data. This was introduced in 4G system support 5G data speed by addition of dual connectivity of UE with eNBs , master eNB and Secondary eNB and /or eNodeB in congestion with gNB. This is achieved by addition of Secondary eNodeB to the Master eNodeB. Master-eNB has full control to add, delete and HO (handover) of eNodeBs as and when needed. 3.4 Problem Statement Problem statement 1: Inspite in a Dual connectivity of 5G system user experience is impacted because of Master-gNB may have degrade radio condition and another Master-gNB is not available for handover where as Secondary-gNB is available with sufficient radio resource. 4. Proposal of Bearer Offloading Dual-Connectivity with 3GPP access The solution proposed in this document to solve the degrade Rf condition at Master-gNB while handover to another Master-gNB is not possible and UE have better or improved Rf condition with Secondary-gNB(as compared to Master-gNB). Figure 2, show below shows how radio resource control can be handed over from Master-gNB to Secondary-gNB. - 5G user (UE) is being served by Master-gNB - Master-gNB adds Secondary-gNB for delivering user data to UE - UE is register to 5G-core via Master-gNB , whereas there is no user context available between Secondary-gNB and AMF - There is X2 interface between master-gNB and Secondary-gNB defined in 3GPP specification. - User data is deliver over N3 interface between UPF and Master-gNB - Master-gNB splits the partial User data over x2 interface to Secondary-gNB. sinha Expires December 7, 2018 [Page 4] Internet-Draft 5G Bearer Offloading DC for RAN June 2018 +--+ +-----+ +-----+ +---+ +---+ +---+ |UE| |M-gNB| |S-gNB| |AMF| |SMF| |UPF| +--+ +-----+ +-----+ +---+ +---+ +---+ | | | | | | | | | | | | |<==User Data==>|<==============User Data==============>| | | | | | | | Measurement | | | | | |<--------------| | | | | | Control | | | | | | | | | | | | Measurement | | | | | |-------------->| | | | | | Report | | | | | | | | | | | | ------------- | | | | | | HO Decision | | | | | | ------------- | | | | | | | | | | | | | | | | | | S-gNB HO Request | | | | |--------->| | | | | | (carry SCG configinfo) | | | | | | | | | | | | | | | | | | | | | | S-gNB HO Req.Ack | | | | |<---------| | | | | | | | | | | | | | | | |<-----RRC procedure------>| | | | | | | | | | | | | | | | | -------------------------------------------- | | PATH UPDATE PROCEDURE and FILTER | | -------------------------------------------- | | | |<========User Data=======>|<==========User Data=======>| | | | Figure 2: Bearer Offloading Dual-Connectivity with 3GPP access only - Based on Measurement report, Master-gNB take decision to execute a procedure of handover to Secondary-gNB with SCG configuration. - Secondary-gNB establish connection with AMF to cater user's all signalling and data traffic. - Master-gNB also provides a radio (Rf) bearer splitting template termed as 'FILTER'. This bearer template FILTER is delivered to UPF via SMF. - UPF now shift the user data on N3 interface from Master-gNB to Secondary-gNB. This Secondary-gNB will act as new Master-gNB. sinha Expires December 7, 2018 [Page 5] Internet-Draft 5G Bearer Offloading DC for RAN June 2018 Please note that this FILTER value in this scenario of handover from Master-gNB to Secondary-gNB MUST empty or NULL, implies that user traffic segregation is completely governed by AMF and SMF based on PCC rules and policies. 5. IANA Considerations None. 6. Security Considerations Security considerations related to the 5G systems are discussed in [NGMN]. Due to the request for intrinsic realization of security such aspects have to be considered by design for architecture and protocols. Especially as a joint usage of resources and network functions by different separate logical network slices (e.g. in terms of virtual network functions) seems to be inevitable in the framework of 5G the need for strong security measures in such an environment is a major challenge. 7. Privacy Considerations Support of full privacy of the users (customers and tenants / end service providers) is a basic feature of the next generation trusted and reliable communications offering system. Such a high degree of ensured privacy shall be reflected in the proposed architecture and protocol solutions. Especially as Identifiers and mapping of locators to them are addressed some privacy concerns arise. Mobility solutions tend to expose unique identifiers. A solution inside the mobile network exposes these identifiers to the network operator, which is not a big deal since the network operator already has information about the device's location. In contrast, an IP level solution exposes both the identifiers and the locations at the IP layer. That means that web sites, for example, can now track the device's successive locations by watching the IP address. Solutions such as transporting the identifiers not as part of the IP header should be considered. 8. Acknowledgements This work has been partially performed in the framework of the cooperation Config. Contributions of the project partners are gratefully acknowledged. The project consortium is not liable for any use that may be made of any of the information contained therein. Comments, constructive critisms from Karthik Palaniswamy and Nagesh V. J. are respectfully acknowledged. sinha Expires December 7, 2018 [Page 6] Internet-Draft 5G Bearer Offloading DC for RAN June 2018 9. References 9.1. Normative References [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . 9.2. Informative References [TS23.501] "3GPP TS23.501, System Architecture for the 5G System (Release 15)", March 2018. [TS36.300] "3GPP TS36.300, Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN); Overall description", March 2018. [TS23.502] "3Procedures for the 5G System", March 2018. [TS23.228] "IP Multimedia Subsystem (IMS)", March 2018. [TR38.801] "Study on new radio access technology: Radio access architecture and interfaces", March 2017. [TR23.793] "Study on Access Traffic Steering, Switch and Splitting support in the 5G system architecture.", April 2018. [TR23.793] "Study on Access Traffic Steering, Switch and Splitting support in the 5G system architecture.", April 2018. [ETSI GR NGP 004] "Next Generation Protocol (NGP):Evolved Architecture for mobility using. Identity Oriented Networks.",January 2018 [ETSI GR NGP 001] "Next Generation Protocol (NGP); Scenario Definitions". ,May 2017 [NGMN] NGMN Alliance, "NGMN White Paper", February 2015. sinha Expires December 7, 2018 [Page 7] Internet-Draft 5G Bearer Offloading DC for RAN June 2018 Authors' Addresses Sunil Kumar Sinha FF-01, Rainbow Residency, Green Glan layout, Bellandur, Bangalore Karnataka, India Email: sunilkumarsinha9@gmail.com Amardeep Sinha C-1003, Yashodeep Heights, Sec-29C, Airoli, Navi-Mumbai, Maharashtra India Email: sinha.amardeep@gmail.com Dharmendra Dwivedi Ericsson Global Service, India EGI, Mahadev Pura, EMC Square, Outer Ring Road, Bengaluru, India Email: dharmendra.dwivedi78@gmail.com Harsh Vardhan Singh Chauhan Gwalior, MP Email: vardhan.chauhan@gmail.com sinha Expires December 7, 2018 [Page 8]