Network Working Group D. von Hugo Internet-Draft Telekom Innovation Laboratories Intended status: Informational B. Sarikaya Expires: September 14, 2017 Huawei March 13, 2017 Review on issues in discussion of next generation converged networks (5G) from an IP point of view draft-vonhugo-5gangip-ip-issues-03 Abstract This document presents considerations related to open issues with upcoming new communication systems denoted as 5G aiming to set a basis for documenting problem space, use-cases, and potential solutions related to next-generation network infrastructure. The draft reviews currently investigated topics, including both inputs from IETF and from other SDOs as well as research activities. Further the outcome of recent discussions at side sessions during IETF meetings are recaptured to help identifying a starting point for future thoughts. 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 September 14, 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 von Hugo & Sarikaya Expires September 14, 2017 [Page 1] Internet-Draft 5G IP Issues March 2017 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. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Problem Space and Typical Use Cases . . . . . . . . . . . . . 4 2.1. Ubiquitous Broadband Access Use Case . . . . . . . . . . 4 2.2. Massive Deployment of Machines Use Case . . . . . . . . . 4 2.3. Critical Communications Use Case . . . . . . . . . . . . 4 3. Requirements to Future Communication Systems . . . . . . . . 4 4. Current Activities and Areas of Work within IETF/IRTF . . . . 5 5. Future Internet Architecture . . . . . . . . . . . . . . . . 6 6. Edge Network with no Tunneling . . . . . . . . . . . . . . . 8 7. Logical Network Isolation (Slicing) Concepts . . . . . . . . 9 8. Towards Converged Access-Agnostic Core Network . . . . . . . 10 9. Session Management Architecture . . . . . . . . . . . . . . . 12 10. Investigations in 5G IP Protocols . . . . . . . . . . . . . . 14 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16 12. Security Considerations . . . . . . . . . . . . . . . . . . . 16 13. Privacy Considerations . . . . . . . . . . . . . . . . . . . 16 14. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 16 15. References . . . . . . . . . . . . . . . . . . . . . . . . . 17 15.1. Normative References . . . . . . . . . . . . . . . . . . 17 15.2. Informative References . . . . . . . . . . . . . . . . . 17 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19 1. Introduction This document focuses on IP architecture and protocol aspects related to upcoming new communication system infrastructure. This envisaged 5G system is foreseen to be available from 2020 onwards to provide a converged Information and Communication Technology (ICT) ecosystem. The offered broad spectrum of fixed and mobile services will be characterised mainly by improved flexibility and efficient usage of available resources to support services' demands with partially contradicting requirements. A new highly re-configurable architecture in both heterogeneous access and a converged core network shall allow for key features as o Stable selectable low latency o Granted reliability and availability according to user and service demands von Hugo & Sarikaya Expires September 14, 2017 [Page 2] Internet-Draft 5G IP Issues March 2017 o Potential (adaptive) mobility support (i.e. on demand): in case of change in device or service location or as countermeasure to partial failures /outage o Low cost (i.e. affordable and related to service characteristics) with respect to both investment and operational expenses: efficiency in terms of resource consumption and effort o Adaptive support of service quality in terms of (raw network) performance (Quality of Service, QoS) and individual user experience (Quality of Experience, QoE) requiring end-to-end monitoring and feedback o Selectable inbuilt security: different measures to be chosen from a tool box o Improved resource efficiency (e.g. in terms of energy consumption, processing power, data storage, and radio spectrum usage) o High flexibility for new services (and service features) introduction and deployment o Much better scalability in terms of amount of supported end devices and transferred data rates and volume o Higher bandwidth, data rate and throughput shall be achieved with new radio technologies (multiple antennas) o multiple heterogeneous technologies in concurrence (multiaccess) o Bandwidth/ broadband access values exceeding 1Gbps. A network to serve diverse demands ranging between very strict and quite relaxed requirements asks for dynamic feature selection per network functionality and thus will be much more software centric. Only an architecture with modular control plane functions will enable service tailored selection or adaptation of network characteristics in terms of functionalities. Also the expected high flexibility and resource efficiency demands for exploitation of SDN and NFV together with computation and storage space provision in central or distributed cloud environments. In addition a new architecture with modular control plane functions is required to enable service tailored selection or adaptation of network characteristics in terms of functionalities. von Hugo & Sarikaya Expires September 14, 2017 [Page 3] Internet-Draft 5G IP Issues March 2017 Decoupling and abstraction of access and core domains to allow for heterogeneity enabling higher flexibility and resource usage efficiency is a request to 5G systems. 2. Problem Space and Typical Use Cases The design of the new 5G system faces challenging requirements which are derived from potential prospective services to be provisioned via the 5G ecosystem. To illustrate the broad range of diverse demands out of the plentitude of use cases as identified e.g. in [NGMN] a set of three exemplary use case families is presented below following [METIS]. Generally all such services cannot and have not to be provided within one specifically configured logical network. Flexibility to allow different adaptations of the same physical infrastructure to fulfill one tenants or verticals (service providers) requests is essential for an appropriate 5G system concept. 2.1. Ubiquitous Broadband Access Use Case This group of use cases covers fixed, portable, and mobile applications between user equipment and servers in the network which may be characterized by large bandwidth requirements, support of mobile devices, typical multimedia services between humans and between humans and content in the network to only name a few. 2.2. Massive Deployment of Machines Use Case The Machine Type Communication (MTC) or Internet of Things (IoT) use cases cover generally a large amount and dense deployment of devices (sensors, metering) as smart grid or of Industry 4.0 type, but also vehicular communication. 2.3. Critical Communications Use Case Here a strict latency and reliability limit has to be considered since services are time-critical or need high delivery probability. 3. Requirements to Future Communication Systems Derived from the use case scenarios a list of requirements for 5G has been established by several organisations as e.g. NGMN or 3GPP denoting as key issues or key design principles or key drivers, for details see e.g. 3GPP [TR23.799]. Also ITU has identified key capabilities of IMT-2020, i.e. the International Mobile Telecommunications (IMT) system for 2020 and beyond, which can be found in [M.2083]. von Hugo & Sarikaya Expires September 14, 2017 [Page 4] Internet-Draft 5G IP Issues March 2017 Beside quantitatively measurable expected enhancement of performance parameters as o User experienced data rate: 100 vs. 10 Mbit/s o Spectrum efficiency 3 times that of IMT Advanced o Mobility support for up to 500 km/h instead of 350 km/h (only) o Latency (of 1 vs. 10 ms), Latency down to 1ms could be foreseen for 5G o Connection density of 1 Million vs. 100000 devices/km o Network energy efficiency of 100 times improved o Area traffic capacity of 10 vs. 0.1 Mbit/s/m2 o Peak data rate of 20 instead of below 1 Gbit/s Other key improvements which are not always direct quantitatively measurable cover so-called soft features are also essential for 5G: o Network scalability and flexibility o Logical network separation (slicing) o Consistent customer experience o Service and network trust, reliability and security o Operational efficiency o Openness for innovation 4. Current Activities and Areas of Work within IETF/IRTF Although a vertical topic as 5G is seen not as IETF topic ( providing standardized building blocks for specific engineering challenges "horizontals." IETF does not define or adapt "vertical" frameworks like "Smart Cities," "Internet of Things," or "5G networks." It is implicitly assumed that the participants will apply the building blocks within the verticals [I-D.arkko-ietf-trends-and-observations].), the topic creates issues on multiple horizontal levels as is reflected within drafts and discussions in WGs such as LISP (Locator/Identifier Separation Protocol), NVO3 (Network Virtualization Overlays). Furthermore IRTF RGs with focus on 5G topics are NFV(Network Function Virtualization), von Hugo & Sarikaya Expires September 14, 2017 [Page 5] Internet-Draft 5G IP Issues March 2017 SDN (Software Defined Networking), and ICN (Information Centric Networking). There is also a rich set of Mobile IP based mobility approaches which also can be viewed as identifier locator separation protocol with home address as the identifier and care-of address as the locator. Original Mobile IP used tunneling and a fixed anchor called Home Agent (HA) or Local Mobility Anchor (LMA). However more recently extensions for distributed anchoring were designed. The current activities there contribute to one or more of the following issues addressed in more detail during the preceding side meetings of the 5GangIP mailing list archive. 5. Future Internet Architecture Currently, the efforts towards the Next Generation System have defined architectural requirements as outlined in [TR23.799] and design of specific network entities as network functions (NFs or VNFs) and interfaces between them, protocols and procedures both for 5G Access Network for various different accesses and a common core network is ongoing. Aim is specifying and optimizing protocols for a more efficient internet to provide mobility, scale, security and ease of deployment required for a connected society beyond the year 2020. But the industry seems to be divided by what should qualify as a true 5G. One approach to 5G is: 5G radio / enhanced LTE + 5G core This new core shall both meet the 5G requirements and allow for connection via enhanced 4G radio for reasons of operational continuity. The current IP is connectivity-centric. Additional features such as mobility and security are added as optional patches and fix-ups. Moreover, protocols have been designed in a segmented way instead of an architectural way. Future Internet Architecture attempts to look at the current user/ data plane protocol stack that is in use in both fixed and mobile networks and redesign it. One issue the future internet architecture addresses is the number of layers below the IP layer. If we consider the current LTE radio protocol stack, we can easily find that there are 6-plus layers, with PDCP, RLC, MAC and PHY being the ones below IP layer. Each layer adds some bytes to the header, some layers have their own checksums, i.e. more overhead. However, in cellular Internet of Things, (IoT) a packet may have only 1 byte von Hugo & Sarikaya Expires September 14, 2017 [Page 6] Internet-Draft 5G IP Issues March 2017 payload. In this case, we would not call it efficient, the efficiency rate is less than 1%, with the efficiency rate defined as (payload length)/(packet size). Future internet architecture deals with data plane protocol stack reduction issues like: o Which layers could be reduced? o How can we deal with multiple checksums, since it is very expensive to compute checksums, remembering we aim at 1ms latency budget? o Should we design a new type of protocol that does not reuse the existing ones to make the network more efficient? Such a clean slate approach would expose a high degree of disruption. o What would happen if we take away GTP, LTE's tunneling protocol? For more discussion on this see Section 6. Future internet architecture proposes a unified layering for both fixed and mobile networks. In the IP layer, we have Identifier Oriented Networking or IP protocol. Below this, we have the next generation medium access control protocol providing a unified medium access to 5G radio, 802.11 or Wi-Fi and Ethernet type of fixed access technologies. The lowest layer is the next generation physical layer protocol unifying all physical accesses to 5G-era. In the control plane, more need to be considered. For example, the current internet is operated by routing protocols and their extensions. These protocols are usually driven by Command Line Interfaces (CLIs) on the first hand, e.g. for protocols like OSPF [RFC5340] will work as instructed by the commands in CLI. However, in 5G, there will be many mobile nodes, perhaps with low- power so that at one instant they are up and at the next instant they are down. The traditional operation model won't work any more, since we can't easily configure them and we don't want their mobility and status change affecting the routing tables, Routing Information Base (RIB) frequently. In this case, mobility issue will arise. A cell phone moves, but its identifier (ID) does not change. Can 5G network mobility protocols (see Section 10) be used for this use case, i.e. also handle e.g. session continuity in case of multi-connectivity? Which further extensions and modifications might be needed to re-scope the approach to apply for the required mobility? ID plays a central role in mobility. Can we design a new protocol, say ID-Oriented Networking von Hugo & Sarikaya Expires September 14, 2017 [Page 7] Internet-Draft 5G IP Issues March 2017 Protocol? In future, more and more mobile things are connected to the internet which may not yet have proper identifiers available compared to cell phones (see e.g. [I-D.ietf-dmm-4283mnids]): things like connected cars, connected drones, etc. For more discussion on this see Section 10. 6. Edge Network with no Tunneling In fixed network, PPPoE protocol [RFC2516] is used between the residential gateway and broadband network gateway to transport the residential users IP packets to the fixed network gateway to the Internet. PPPoE protocol requires 8 octets of header in every IP packet, thereby reducing the MTU size by 8 octets to usually 1492 octets. PPPoE protocol is carried in Ethernet frames with 18 octet headers where the destination address is the broadband network gateway address. Aiming at an IP protocol unaware/agnostic/overarching control plane logic multiple protocol approches can be deployed depending on actual service and slice demands, such as e.g. those based on low-overhead translation mechanisms and encapsulation-based ones on the other hand. If a client-based mapping between Identifier and Locator is required (i.e. executed on a user terminal) translation would be the recommended approach. For network-centric deployment a LISP-like mapping function on gateways or the session terminating servers and data centers can be deployed. How such a control plane could look like on L2/L3 to support LISP has recently been described in [I-D.portoles-lisp-eid-mobility]. In mobile network, IP packets are tunneled using GTP data plane protocol called GTP-U. First eNodeB or the base station tunnels UE's IP packets to the Serving Gateway, in S1 GTP tunnel and then the serving gateway tunnels to the Packet Gateway, called S5 tunnel. Both of them are UDP tunnels which adds 8 octet header and GTP protocol header is 12 octets, so a total of 20 octets are used. In addition also an IPSec header should be accounted for between eNodeB and SGW. On the other hand in an end-to-end path between UEs or towards the Application Function the network has either to keep a lot of status information (meta data) for finding and maintaining the optimum path - or apply encapsulation with specific headers between eNB and SGW/ PGW - as tunneling. As exemplarily shown above, however, tunneling adds a lot of overhead to the user IP packets and therefore inefficiencies arise including reducing the MTU size. von Hugo & Sarikaya Expires September 14, 2017 [Page 8] Internet-Draft 5G IP Issues March 2017 If tunneling can be avoided, i.e. if edge networks can be designed with no tunneling, a corollary of this would be no gateways would be needed, leading to edge networks with no tunneling or no gateway. The means to avoid gateways and tunneling a direct end-to-end routing has to be established in the edge network. With routing support edge networks can direct the user traffic to the correct destinations, rather than tunneling to the gateways. In order to deal with user mobility, ID-oriented networking protocol would be needed. So it needs to be evaluated if using ID-oriented networking protocol with routing will lead to more efficient delivery of user IP packets in the edge network compared with 4G edge network techniques of tunneling with gateways. As we deal with carrier-grade networks here also the aspects of AAA and charging have to be considered. The main reason why tunneling is used in 4G edge networks and broadband network is to direct the user traffic so that the operator can identify and handle the traffic according to underlying service class specific demands. Another issue is charging and accounting the user properly and both requires the traffic to be routed via specific gateway nodes using the tunnel endpoint identifiers (TEID) carried in GTP header. Edge networks with no gateways should enable enough control to the operators so that charging and other functions on the user traffic is properly conducted. Optimum use of available resources may also require a common control framework including e.g. user plane communication between devices directly or via relays / access nodes only. How such an efficient, scalable, and performant solution in case of mobility has to be designed - preferably without much effort due to complex state handling - is one of the challenging questions. 7. Logical Network Isolation (Slicing) Concepts Within the framework of 5G a network slice is seen as an independent logical end-to-end network, defined by a set of specific network functions providing service-specific network characteristic (performance). The basic Network Functions can be both physical and virtual in nature, and comprise C-plane and D-plane tasks (maybe supplemented by Management), and should be independently instantiated and operated. Network functions are adapted and configured according to service demands which includes as well parameter settings as their logical and spatial location within the network topology (e.g. at central or remote processing clouds, i.e. data centers, to achieve e.g. a low transmission delay towards the end user). von Hugo & Sarikaya Expires September 14, 2017 [Page 9] Internet-Draft 5G IP Issues March 2017 A major issue in isolation between different network slices beside the security and reliability is a minimum interference in between them in terms of trade-off with respect to joint usage of shared resources (e.g. radio spectrum for wireless access or processing capacity for network function execution). Here again, the more limited the resources are, the more important it is to achieve a highly effient usage creating the need for proper mechanisms (e.g., algorithms and protocols) to orchestrate and coordinate resource assignment (and to monitor the actual network slice performance). 8. Towards Converged Access-Agnostic Core Network Currently network infrastructure is being transformed into two-layer data center or cloud as Core Network (CN) and the Access Network which mainly accommodates 5G radio access network on the wireless side and central office on the wireline network closer to the user. This new architecture enables us to flexibly deploy 5G Virtual Network Functions (VNFs) based on the service scenarios. The division of work in this case is to deploy 5G control plane VNFs in the core cloud and 5G user/data plane VNFs and related applications in the edge cloud. The new architecture also leads us to a converged access independent core network with a common access network - core network interface which integrates 5G network with the fixed network leading us to 5G Fixed Mobile Convergence (FMC). 5G architecture minimizes dependencies between Access Network (AN) and Core Network (CN), the architecture is defined with a converged access-agnostic core network with a common AN - CN interface which integrates different 3GPP and non-3GPP access types. Proposed 5G architecture is shown in Figure 1. The rectangles are the network functions and the lines are their interconnections or reference points from N1 to N15. Network Function names are given on the right hand side. The reference points usually carry a specific protocol such as GTP (GTP-C for control plane, e.g. over N2 or GTP-U for data plane, e.g. over N3) or Non-Access Stratum (NAS) of 3GPP. Access and Mobility Management Function (AMF) is the Network Function (NF) that terminates N1 and N2. User Plane Function (UPF) is the NF that terminates N3. We explain a few important network functions here. Access and Mobility Management Function (AMF) is in charge of registration management, connection management, reachability management, mobility Management, it is transparent proxy for routing session management messages. It does access authentication and access authorization. von Hugo & Sarikaya Expires September 14, 2017 [Page 10] Internet-Draft 5G IP Issues March 2017 Session Management Function (SMF) is in charge of session establishment, modify and release, including tunnel maintainance between UPF and the access network (AN) node. UE IP address allocation and management (incl. optional Authorization), selection and control of the user plane (UP), i.e. data plane function. SMF configures traffic steering at UPF to route traffic to proper destination (i.e the corresponding Data Network, DN); termination of interfaces towards policy control functions (PCF); control part of policy enforcement and QoS termination of session management (SM) parts of non-access stratum (NAS) messages, downlink Data Notification; initiator of AN specific SM information, sent via AMF over N2 to AN; support for interaction with external DN for transport of signalling for PDU session authorization/authentication by external DN. User Plane Function (UPF) is anchor point for mobility (when applicable); external PDU session point of interconnect to Data Network; packet routing and forwarding Packet inspection and User plane part of Policy rule enforcement; uplink classifier to support routing traffic flows to a data network; branching point to support multi-homed PDU session; transport level packet marking in the uplink and downlink; downlink packet buffering and downlink data notification triggering. According to 5G architecture, 5G UE is expected to use Non-Access Stratum (as opposed to Access-Stratum (AS) which is used between radio network and UE) signaling for establishment of communication sessions and for maintaining continuous communications with the user equipment as it moves with 5G core network even when UE is connected to 5G core network via a non-3GPP access network, e.g. over Wi-Fi, oftentimes simultaneously to the wireless radio access network (RAN). Key principles and concepts in 5G architecture include separation of User Plane (UP) functions from the Control Plane (CP) functions, allowing independent scalability, evolution and a flexible deployment e.g. centralised location or distributed (remote) location; definition of the the network functions, e.g. to enable flexible and efficient network slicing. Network slicing (see Section 7) with slices that may include components served by fixed networks is another innovation in 3GPP 5G architecture work as well as the definition of a common core network which is access agnostic. Wherever applicable, procedures (i.e. the set of interactions between network functions) are defined as services, so that their re-use is possible. Each Network Function can interact with the other NF directly if required. The architecture does not preclude the use of an intermediate function to help route control plane messages. von Hugo & Sarikaya Expires September 14, 2017 [Page 11] Internet-Draft 5G IP Issues March 2017 +----+ +---+ Authentication |AUSF|---N13---|UDM| Server Function +----+ +---+ (AUSF) \ /\ Core Access and \ / \ Mobility Management N12 N8 N10 Function (AMF) \ / \ Data network (DN) +---+ +---+ +---+ +--+ ________|AMF|-N11-|SMF|-N7-|PCF|--N5-|AF| / +---+ +---+ +---+ +--+ / / N14|_______/__N15_____| / / / Policy Control N1 N2 / Function (PCF) / / N4 Session Management / / / Function (SMF) / / / Unified Data / / / Management (UDM) +--+ +---+ +---+ /---\ User Equipment(UE) |UE|-------|RAN|---N3---|UPF|---N6- -|DN | (Radio)Access Network ((R)AN) +--+ +---+ +---+ \---/ User Plane Function (UPF) |-N9-| Figure 1: 5G Architecture One of the challenges in 5G FMC is how to provide seamless mobility when 5G UE while in a 5G radio access network later moves to an area of Wi-Fi access point connected to a central office while both access networks are served by a converged common core. Another challenge is to enable flexible and seamless management of the user sessions while accessing sometimes simultaneously over UE's multiple interfaces, e.g. 5G and Wi-Fi. 9. Session Management Architecture Session management responsible for the setup of the connectivity for the UE as well as managing the user plane for that connectivity is identified as one of the key issues in 5G system architecture in [TR23.799]. It is one of the network functions, the Session Management Function (SMF) in 5G Architecture described in Section 8. Session management design issues include managing multiple access, multiple connectivity, multiple transport paths, e.g. to RAN and to non-3GPP access network (AN), sometimes simultaneously and how to efficiently transmit and receive infrequent small amounts of data and short data bursts, e.g. for Narrow Band Internet of Things (NB-IoT). In this section, we take a look at how SMF can be structured. Using control plane data plane separation principle, SMF is a control plane function as such it corresponds to Network Connection Manager von Hugo & Sarikaya Expires September 14, 2017 [Page 12] Internet-Draft 5G IP Issues March 2017 (NCM). There is a data plane component for user data traffic forwarding called Network Multi-Access Data Proxy (MADP) which is part of the User Plane Function (UPF) in Figure 1. It can be argued that we also need corresponding client side NCM, called CCM and MADP hosted on the UE [I-D.kanugovi-intarea-mams-protocol]. Network Multi-Access Data Proxy (MADP) in the core network handles the user data traffic forwarding across multiple network paths, as well as other user-plane functionalities, e.g. encapsulation, fragmentation, concatenation, reordering, retransmission, etc. N-MADP is the distribution node for uplink and downlink data with visibility of packets at the IP layer. Network Connection Manager (NCM) in the core network configures identification and distribution rules for different user data traffic type at the N-MADP. The NCM configures the routing in the MADP based on signaling exchanged with the CCM in UE. In the uplink, NCM specifies the core network path to be used by MADP to route uplink user data at the MADP. In the downlink, NCM specifies the access links to be used for delivery of data to the client at the MADP. At the UE, MADP handles encapsulation, fragmentation, concatenation, reordering, retransmissions, etc. C-MADP is configured by CCM based on signaling exchange with NCM and local policies at the UE. At the UE, CCM manages the multiple network connections. CCM is responsible for exchange of MAMS signaling messages with the NCM for supporting functions like configuring uplink and downlink user network paths for transporting user data packets, link sounding and reporting to support adaptive network path selection by NCM. In the downlink, for the user data received by UE, it configures IP layer forwarding for application data packets received over any of the accesses to reach the appropriate application module on the client. In the uplink, for the data transmitted by UE, it configures the routing table to determine the best access to be used for uplink data based on a combination of local policy and network policy delivered by the NCM. The challenges of this kind of session management design include if such a design can be simplified so that NB-IoT type of very simple sessions can also be handled. Regarding SMF and AMF, identifying the correlation between session management and mobility management, identifying the interactions between session management and the mobility framework required to enable the various mobility scenarios while minimizing any negative impact on the user experience investigating solutions to coordinate the relocation of user-plane flows with the relocation of applications (hosted close to the point von Hugo & Sarikaya Expires September 14, 2017 [Page 13] Internet-Draft 5G IP Issues March 2017 of attachment of the UE) due to the mobility of users can be considered as the challenges of 5G architecture. 10. Investigations in 5G IP Protocols With both physical and logical mobility of (an extremely high number of) entities and virtualization of network functions the traditional usage of IP addresses for denoting both IDentifier and Address or logical entity and location as source or destination of data packets becomes cumbersome. New approaches to solve the issues are proposed in LISP WG in terms of [RFC6830] and ICN RG (see [RFC7476]) but also ILNP [RFC6740] and ILA [I-D.herbert-nvo3-ila] address this challenge. By separating a Routing LOCator (RLOC) from a unique Identity (EID) LISP keeps a single address to each session endpoint even in multi- homing but requires a dedicated mapping mechanism for compatibility with the (LISP-unaware) Internet. ILNP (and ILNP-based ILA) avoid encapsulation and require no changes in higher layers (except the transport layer) re-using part of an (IPv6) Address as Identifier and Locator. ILA does not require any changes in transport layer but it is IPv6 only. In LISP the EID/RLOC split can be collocated in the same entity: EID mobile, RLOC static or dynamic. Predictive RLOCs [I-D.farinacci-lisp-predictive-rlocs] can be used if LISP entity knows where the user going so that the system can mitigate mobility impacts. LISP can be used between the Serving and Packet data Gateways. Best solution is to keep LISP close to the moving entity with the functions as close to the edge as possible. ILNP defines minimal changes on IPv4 and IPv6, it requires changes on the domain name system and the transport layer [RFC6740]. Both ILNP and ILNP-based ILA rely on the routing system or LTE core network to route to the translated address. LISP requires routing system changes, it is implemented on the routers, possibly on the edge routers. That means LISP requires changes on LTE core network. ILNP does not use encapsulation so it is light weight. LISP is UDP encapsulated so in IPv6, LISP messages incur 52 bytes of overhead. ILNP nodes send Locator Update messages which are ICMPv4/v6 messages to its correspondent nodes when its Locator value changes during an active session. Correspondent node could be a fixed node such as Google server which means ILNP has to be implemented by the fixed nodes as well. von Hugo & Sarikaya Expires September 14, 2017 [Page 14] Internet-Draft 5G IP Issues March 2017 ILA is a major update to ILNP [I-D.herbert-nvo3-ila]. It is originally designed for network virtualization to be used in cloud networks. ILA can encode a virtual network identifier (VNID) and virtual address as an ILNP identifier. ILA adaptation for 3G network mobility is investigated in [I-D.mueller-ila-mobility]. Further investigations are needed for anchor-less mobility in a 5G fixed mobile convergence network with a converged core network. The prospective approach is to overcome tunneling and encapsulation overhead by simplified routing according to identifiers not bound to locations and thus allowing for relocation within underlying infrastructure. Such an approach should also incorporate session management in support of session and service continuity in the 5G architecture with a common core enabling mobility in multiple access networks. Anchor points perform important duties such as policy, accounting etc. as well as mapping that cannot be ignored. In anchor-less mobility, the absolute best place to perform these functions (if it is not at an anchor point in the network) is actually in the terminal/UE itself. When anchors are removed then it becomes a challenge to provide functions like security and trust and use the UE as the only remaining single anchor point to perform its own accounting and policy and other functions. There are secure execution environments/processors in UE's these days, where all the finger print recognition, password encryption etc. is done and perhaps it is possible to extend these to run secure network functions on behalf of the slices. This way, the NFV cloud extends into the terminal's secure execution engine. As none of the mentioned existing proposals fully covers the 5G requirements consistently, in this document, the authors propose the following steps for investigations on further enhancements that have to be performed. Problem statement on the need for a next generation or 5G mobility protocol with session management, exploiting previous standardization efforts. Requirements on a new 5G FMC network mobility protocol in view of 5G execution environments such as in Section 8, and issues such as in Section 6. An architecture document that uses all the relevant Network Functions identified in 5G architecture and possibly their subdivisions or components when deploying 5G FMC network mobility and session management protocol and their interconnections. von Hugo & Sarikaya Expires September 14, 2017 [Page 15] Internet-Draft 5G IP Issues March 2017 A document on possible solution space investigations including adaptations into specific architectures such as 5G architecture. 11. IANA Considerations None. 12. 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. 13. 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 (details have to be added). Especially as Identifiers and mapping of locators to them are addressed the discussion on identifier and privacy should consider existing solutions such as 3GPP Globally Unique Temporary UE Identity (GUTI) which is a temporary identity obfuscating the permanent identity in the mobile network and specified in [TS23.003]. 14. 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 and careful review by the 5GangIP mailing list (Dino Farinacci, Tom Herbert, Julius Mueller, Robert Moskowitz, Peter Ashwood, to name just a few) are gratefully acknowledged. von Hugo & Sarikaya Expires September 14, 2017 [Page 16] Internet-Draft 5G IP Issues March 2017 15. References 15.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . 15.2. Informative References [I-D.arkko-ietf-trends-and-observations] Arkko, J., Atlas, A., Doria, A., Gondrom, T., Kolkman, O., olshansky@isoc.org, o., Schliesser, B., Sparks, R., and R. White, "IETF Trends and Observations", draft-arkko-ietf- trends-and-observations-00 (work in progress), February 2016. [I-D.farinacci-lisp-predictive-rlocs] Farinacci, D. and P. Pillay-Esnault, "LISP Predictive RLOCs", draft-farinacci-lisp-predictive-rlocs-01 (work in progress), November 2016. [I-D.herbert-nvo3-ila] Herbert, T., "Identifier-locator addressing for IPv6", draft-herbert-nvo3-ila-03 (work in progress), October 2016. [I-D.ietf-dmm-4283mnids] Perkins, C. and V. Devarapalli, "MN Identifier Types for RFC 4283 Mobile Node Identifier Option", draft-ietf-dmm- 4283mnids-04 (work in progress), January 2017. [I-D.kanugovi-intarea-mams-protocol] Kanugovi, S., Vasudevan, S., Baboescu, F., Zhu, J., Peng, S., and J. Mueller, "Multiple Access Management Services", draft-kanugovi-intarea-mams-protocol-03 (work in progress), March 2017. [I-D.mueller-ila-mobility] Mueller, J. and T. Herbert, "Mobility Management Using Identifier Locator Addressing", draft-mueller-ila- mobility-03 (work in progress), February 2017. von Hugo & Sarikaya Expires September 14, 2017 [Page 17] Internet-Draft 5G IP Issues March 2017 [I-D.portoles-lisp-eid-mobility] Portoles-Comeras, M., Ashtaputre, V., Moreno, V., Maino, F., and D. Farinacci, "LISP L2/L3 EID Mobility Using a Unified Control Plane", draft-portoles-lisp-eid- mobility-01 (work in progress), October 2016. [M.2083] ITU-R, "Rec. ITU-R M.2083-0, IMT Vision-Framework and overall objectives of the future development of IMT for 2020 and beyond", September 2015. [METIS] Elayoubi, S. and et al., "5G Service Requirements and Operational Use Cases: Analysis and METIS II Vision", Proc. euCNC, 2016. [NGMN] NGMN Alliance, "NGMN White Paper", February 2015. [RFC2516] Mamakos, L., Lidl, K., Evarts, J., Carrel, D., Simone, D., and R. Wheeler, "A Method for Transmitting PPP Over Ethernet (PPPoE)", RFC 2516, DOI 10.17487/RFC2516, February 1999, . [RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008, . [RFC6740] Atkinson, RJ. and SN. Bhatti, "Identifier-Locator Network Protocol (ILNP) Architectural Description", RFC 6740, DOI 10.17487/RFC6740, November 2012, . [RFC6830] Farinacci, D., Fuller, V., Meyer, D., and D. Lewis, "The Locator/ID Separation Protocol (LISP)", RFC 6830, DOI 10.17487/RFC6830, January 2013, . [RFC7476] Pentikousis, K., Ed., Ohlman, B., Corujo, D., Boggia, G., Tyson, G., Davies, E., Molinaro, A., and S. Eum, "Information-Centric Networking: Baseline Scenarios", RFC 7476, DOI 10.17487/RFC7476, March 2015, . [TR23.799] "3GPP TR23.799, Study on Architecture for Next Generation System (Release 14)", December 2016. [TS23.003] "3GPP TS23.003, Numbering, addressing and identification (Release 14)", September 2016. von Hugo & Sarikaya Expires September 14, 2017 [Page 18] Internet-Draft 5G IP Issues March 2017 Authors' Addresses Dirk von Hugo Telekom Innovation Laboratories Deutsche-Telekom-Allee 7 D-64295 Darmstadt Germany Email: Dirk.von-Hugo@telekom.de Behcet Sarikaya Huawei 5340 Legacy Dr. Plano, TX 75024 Email: sarikaya@ieee.org von Hugo & Sarikaya Expires September 14, 2017 [Page 19]