Distributed Mobility Management Kyoungjae Sun Internet Draft Younghan Kim Intended status: Informational Soongsil University Expires: December 2017 Jaehwoon Lee Dongguk University June 28, 2017 Gap Analysis for Adapting the Distributed Mobility Management Models in 4G/5G Mobile Networks draft-kjsun-dmm-gap-analysis-3gpp-01.txt 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 http://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 27, 2017. Copyright Notice Copyright (c) 2017 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 (http://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. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. KJ Sun, et al. Expires December 27, 2017 [Page 1] Internet-Draft draft-kjsun-dmm-gap-analysis-3gpp-01 June 2017 Abstract In this document, we provide a gap analysis to apply DMM deplyment models to a 3GPP mobile core network. The DMM deployment models are described into five models for separation control and data plane, and the 3GPP mobile core network is a 4G-based extended architecture and 5G core network study architecture. We conduct the gap analysis to describe the technology that requires current standards-based applicability and extension for technical interoperability between two standardization organizations. Table of Contents 1. Introduction ................................................ 2 2. 3GPP 4G/5G Studies Overview ................................. 3 3. Gap Analysis for Adapting DMM in 4G/5G Mobile Core Network .. 4 3.1. Split Home Anchor Model ................................ 4 3.2. Separated Control and User Plane ....................... 5 3.3. Centralized Control Plane .............................. 5 3.4. Data Plane Abstraction ................................. 6 3.5. On-demand Control Plane Orchestration .................. 6 3.6. Mapping DMM Deployment Model in to 4G/5G Core Network Architecture ........................................... 7 4. Security Considerations...................................... 7 5. IANA Considerations ......................................... 7 6. References .................................................. 8 6.1. Normative References.................................... 8 6.2. Informative References.................................. 8 7. Acknowledgments ..............................................8 1. Introduction The Distributed Mobility Management (DMM) solution has been investigated to re-locate the current anchor functions in a distributed manner and to provide different IP session management characteristics for each mobile node session. For deploying DMM, five different models are described in [dmm-deployment-models] based on the network entities according to the location(access or home) and functionality(control or data). 3GPP has the responsibility to standardize cellular mobile networks, and the functional separation of the gateway in 4G Evolved Packet Core(EPC) netowrk has also been studied to divide the gateway into a control and data plane, defining an interface between them, and KJ Sun, et al. Expires December 27, 2017 [Page 2] Internet-Draft draft-kjsun-dmm-gap-analysis-3gpp-01 June 2017 configuring a data path from the control plane entities to the data plane entities by exchanging signaling messages between the control plane entities. Futhermore, future mobile core network architecture called 5G NextGen has been also studied. For flexible service continuity, 5G NextGen have integrated the current distributed gateway entities (SGW and PGW) that are deployed in a hierarchical manner into a combined gateway to separate the control and data plane function. In addition, to provide on-demand session management, they separate the attachment procedure of the mobile node and the session establishment procedure so that different sessions of the mobile node with different service characteristics can connect through a network slice. However, mobility management solution when the IP anchor function is changing is not decribed clearly yet. This document provides a gap analysis to adapt the DMM deployment model into the 4G/5G mobile network architectures studied in 3GPP. Based on studies of the network architecture evolution in 3GPP, we analyze whether each scenario of the DMM deployment model can be adapted to the 3GPP network architecture under study by showing the corresponding mapping table. 2. 3GPP 4G/5G Studies Overview The 4G EPC network includes several components that provide IP connectivity to mobile subscribers and accommodate the use of various network access technologies. In mobility management, many different kinds of handover can occur in the EPC network architecture. IP mobility is occurred in the Inter-MME handover, which occurs between different SGWs, the traffic forwarding path between the SGW and PGW should be changed, so the IP mobility scheme should be needed. For this, the 3GPP standard can use the GTP or PMIP protocol to update the location of the mobile node, establish the tunnel between the SGW and PGW, and forward data traffic. To improve the flexibility during deployment and operation of the mobile core network, 3GPP provides several options to modify the gateway deployment. First, the combined gateway entity is defined by integrating the SGW and PGW function into a single component in [3GPP TR 23.401]. Second, the control plane and the data plane are separated for the gateway functions in [3GPP TR 23.714]. The operation of the interface between control plane and data plane includes managing the state of the data plane in the control plane, configuring the session path between the GW-DPs according to the service request of the mobile node, and reporting the measurement information from the data plane to the control plane. KJ Sun, et al. Expires December 27, 2017 [Page 3] Internet-Draft draft-kjsun-dmm-gap-analysis-3gpp-01 June 2017 +-----+ +-----+ +-----+ +-----+ +----+ | NEF | | NRF | | PCI | | UDM | | AF | +-----+ +-----+ +-----+ +-----+ +----+ | | | | | ----------------------------------------------- | | | +-----+ +-----+ +-----+ | AUF | | AMF | | SMF | +-----+ +-----+ +-----+ : : : control-plane ==============:=====:=============:==================== : : : user-plane +----+ +-----+ +-----+ +----+ | UE |----| RAN |---------| UPF |-------| DN | +----+ +-----+ +-----+ +----+ Fig 1. 5G Core Network Architecture The 5G mobile core network architecture is designed in a service- oriented manner described in Fig.1. 5G mobile core network design separates control and user plane functions for allowing independent scaling of both functions and it allows control plane dynamically configures user-plane functions to provide the traffic handling functionality. Unlike SGW/PGW in 4G network, user plane function of 5G is defined as a unified entitiy. All the control plane functions are separated into different standlone entities to enable independent scalability and flexibility. For example, unlike the 4G mobile core network, authemtication and mobility management funtion which were combined into the MME are separated and also mobility management and session management function are separated. The interfaces between control functions are defined as a service-based interface which is independent on the communication protocol so that the interoperation in the control plane is more flexible that the 4G mobile core network. For the mobility management, since that mobility managment and session management functions are separated, they consider to support different levels of data session continuity based on the mobility on demand concept as similiar with DMM works. It allows selection of anchor point to achieve efficient user plane path, as well as enablement of reselection of anchor point to achieve efficient user plane path with minimum service interruption. In the 5G mobile core architecture, IP anchor function is separated into control and user plane function. Control plane of anchor function which is allocation of UE IP address is performed by the Session Management Function (SMF) and user plane of anchor functions such as external PDU session point, packet forwarding and anchor point for mobility are assigned to user plane function. When the IP mobility of the mobile KJ Sun, et al. Expires December 27, 2017 [Page 4] Internet-Draft draft-kjsun-dmm-gap-analysis-3gpp-01 June 2017 nodes traffic occurs between the different access networks or by changing the IP anchor in the core network, the SMF processes the signaling to provide session mobility for the mobile node and configures the forwarding policies to the data plane. There is more than one data plane functions in the core network, and these are included in the path of the mobile nodes traffic to the data network but it may not perform the separate roles as with the SGW/PGW in the existing 4G network. 3. Gap Analysis for Adapting DMM in 4G/5G Mobile Core Network Following five deployment models in [dmm-deployment-model], we provide a conformance and gap analysis to apply the IETF DMM deployment model to 4G/5G mobile network architectures. Detailed description of DMM deployment model is not provided in this document. 3.1. Split Home Anchor Model In the 4G EPC network, we can deploy the PGW as the home anchor with CP/DP separation and the SGW as an Access Node with a legacy entity without CP/DP separation. For that, terminology of Home-CPA is mapped to PGW-CP, Home-DPA to PGW-DP, Access-CPN to SGW-CP, and Access-CPN to SGW-DP. In this case, the current interface between SGW and PGW is separated into two interfaces for the control and data planes. However, since the SGW is implemented as an existing CP/DP combined entity, the destinations of the control and data packets must be set differently in the SGW. In the 5G core network study architecture, the data plane functions are not separated into Home and Access. Even though one or more data plane functions may be included in the data traffic path of the mobile node between the access network and the data network, it is not clear whether this separates the roles of Access and Home. 3.2. Separated Control and User Plane This model separates the control plane and the data plane from both the Access and Home nodes, and it can be applied as a CP/DP separation architecture between the SGW and the PGW when applied in the 4G EPC network. The parameters for the tunnel configuration, such as the TEID according to the bearer information generated through the control plane and the QoS-related information, are KJ Sun, et al. Expires December 27, 2017 [Page 5] Internet-Draft draft-kjsun-dmm-gap-analysis-3gpp-01 June 2017 transmitted to the data plane by using the interface between the control plane and the data plane, and traffic measurement information is transmitted to the control plane for billing and policy management. Since there is no definition for an access node in the 5G core architecture, we cannot find a clear adaptable scenario to apply that model. By considering the network slice concept, the 5G architecture separates the mobile node attachment and the service request process for the authentication and connection state management according to the attachment of the mobile node through the Common CP function and selects an appropriate network slice when the mobile node requests session connectivity to the network. In this case, several control planes can exist in the core network, but this is not related to mobility management and there is no data plane function that is mapped with the Common CP. 3.3. Centralized Control Plane In [3GPP TR 23.401], the 3GPP standard allows to integrate the SGW and PGW into a single entity called Combined GW. In the CP/DP separation architecture, each plane entity can be deployed as a combined or separated entity, and the architecture with a combined control plane and separate data plane entities can be applied. For the combined GW-CP function, the interface between control plane functions is no longer required because the SGW-CP and PGW-CP functions are combined as a single physical entity. With the 5G core architecture, there may be an architecture for a single control plane entity to manage multiple data plane entities, even without an access node definition. In particular, in a multi-homed PDU scenario to manage multiple parallel PDU sessions, [3GPP TR 23.799] defines a data plane branching a GW entity between the access network and the different data plane functions. The branching GW maintains the session between the respective anchor data plane nodes and uses the tunnels for traffic forwarding. 3.4. Data Plane Abstraction SDN-based EPC networks and forwarding configuration schemes between the data plane entities can be possible. In several studies, all EPC control plane functions, including the SGW-CP and the PGW-CP, are implemented in the SDN controller as an SDN application, and the KJ Sun, et al. Expires December 27, 2017 [Page 6] Internet-Draft draft-kjsun-dmm-gap-analysis-3gpp-01 June 2017 data traffic path in the data plane network is set utilizing southbound protocol such as the OpenFlow. The SDN-based EPC architecture has an advantage in that the traffic path between the data plane entities can be abstracted from the control plane while maintaining each GW role, so a flexible forwarding path configuration may be possible. The 5G core network architecture document also considers SDN-based data plane abstraction. Even though there is no definition for Anchor and Access node, the data plane GW entities and the switches in the core network are abstracted through the SDN controller to manage the traffic path from the access network to the data network. 3.5. On-demand Control Plane Orchestration This model can be deployed through an EPC network structure with an NFV-based virtualization environment and Management & Orchestration (MANO) function. In an NFV-based virtualized EPC (vEPC) environment, all control plane functions can be installed on a general-purpose cloud server using a Virtualized Network Function (VNF), and the data plane entities can be physically located in the switch or router. Regarding mobility, the Mobility Controller defined in the DMM deployment model is an entity that provides mapping information of the mobility control plane and data plane functions as needed. This is a method to generate mobility services by including VNFs according to the mobility in the network. The 5G architecture research also discusses methods to provide on-demand services in a virtualization-based environment. In particular, different sets of core network functions by selecting network slices according to the type of traffic for a given service, even if they are from the same mobile node. A network slice has the advantage of providing QoS to meet various service requirements. Although the reference architecture for 5G networks has been defined, a real deployment model and its details are still under consideration. KJ Sun, et al. Expires December 27, 2017 [Page 7] Internet-Draft draft-kjsun-dmm-gap-analysis-3gpp-01 June 2017 3.6. Mapping DMM Deployment Model in to 4G/5G Core Network Architecture Table 1 shows whether five DMM deployment models are applicable to the 4G EPC network and 5G core network study architecture. +==============+===================================================+ | | DMM Deployment Models (Described Chapter) | | 3GPP +---------------------------------------------------+ | | 3.1 | 3.2 | 3.3 | 3.4 | 3.5 | +========================+=========+=========+==========+==========+ | 4G EPC Core | | | | YES | YES | | with CP/DP | YES | YES | YES | with | with | | Separation | | | | SDN | NFV | +--------------+---------+---------+---------+----------+----------+ | 5G Core | | | | YES | YES | | Network Study| NO | NO | YES | with | with | | Architecture | | | | SDN | NFV | +==============+=========+=========+=========+==========+==========+ Table 1: Mapping DMM Deployment Model in to 3GPP Mobile Core Network 4. Security Considerations T.B.D 5. IANA Considerations T.B.D 6. References 6.1. Normative References [dmm-deployment-models] S. Gundavelli, and S. Jeon, "DMM Deployment Models and Architectural Considerations", I.D. draft-ietf -dmm-deployment-models-01, Feb. 2017. [3GPP TR 23.401] 3GPP, "LTE: General Packet Radio Service(GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access", 3GPP TR 23.401 (v.14.2.0), Dec. 2016. [3GPP TR 23.714] 3GPP, "Study on Control and User Plane Separation of EPC nodes", 3GPP TR 23.714 (v.14.0.0). Jun.2016. KJ Sun, et al. Expires December 27, 2017 [Page 8] Internet-Draft draft-kjsun-dmm-gap-analysis-3gpp-01 June 2017 [3GPP TR 23.799] 3GPP, "Study on Architecture for Next Generation System", 3GPP TR 23.799 (v.1.0.2), Sep. 2016. 6.2. Informative References 7. Acknowledgments KJ Sun, et al. Expires December 27, 2017 [Page 9] Internet-Draft draft-kjsun-dmm-gap-analysis-3gpp-01 June 2017 Authors' Addresses Kyoungjae Sun Soongsil University 369, Sangdo-ro, Dongjak-gu Seoul 156-743, Korea Email: gomjae@ssu.ac.kr Jaehwoon Lee Dongguk University 26, 3-ga Pil-dong, Chung-gu Seoul 100-715, KOREA Email: jaehwoon@dongguk.edu Younghan Kim Soongsil University 369, Sangdo-ro, Dongjak-gu Seoul 156-743, Korea Email: younghak@dcn.ssu.ac.kr KJ Sun, et al. Expires December 27, 2017 [Page 10]