Network Working Group D. von Hugo Internet-Draft Deutsche Telekom AG Intended status: Standards Track B. Sarikaya Expires: August 1, 2018 January 28, 2018 IP Issues and Associated Gaps in Fifth Generation Wireless Networks draft-hspab-5gangip-atticps-00.txt Abstract This document attempts to make the case for new work that need to be developed to be used among various virtualized functions and the end user which may be moving. First a set of use cases on tunneling, charging, mobility anchors are developed and then the steps of proposed new work is described next. 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 August 1, 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 von Hugo, et al. Expires August 1, 2018 [Page 1] Internet-Draft nextgenprot January 2018 (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. 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. Conventions and Terminology . . . . . . . . . . . . . . . . . 2 3. Issues in Fifth Generation Wireless Networks . . . . . . . . 2 4. Identifier Locator Separation Systems . . . . . . . . . . . . 4 5. Work Plan . . . . . . . . . . . . . . . . . . . . . . . . . . 5 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 7. Security Considerations . . . . . . . . . . . . . . . . . . . 6 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 9. Normative References . . . . . . . . . . . . . . . . . . . . 6 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 1. Introduction Virtualized network functions enable operators to remove single points of failure and distribute network state in a more efficient way. These functions are divided into control plane and data plane functions. Control plane and data plane protocols are used when these functions interact with each other over well defined interfaces between the functions. 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 [RFC2119]. 3. Issues in Fifth Generation Wireless Networks Means for enabling to set up and manage connectivity among end user terminals or between an end user terminal and an application function in the network are provided by systems for mobile communication such as cellular access and core networks as defined by 3GPP (e.g., LTE and EPC for 4G). Architecture and protocols in such systems have been developped previously in a rather independent manner from evolution of IP protocols as done in IETF although many protocols are used for e.g. authentication, address assignment, and provision of applications to the end user terminal. von Hugo, et al. Expires August 1, 2018 [Page 2] Internet-Draft nextgenprot January 2018 With expected change in the future regarding services and service demands as well as in the dynamicity of network features to be supported, the traditional approaches may turn out to be not flexible enough to efficiently and effectively provide the services. Some issues as also partly mentioned elsewhere are described in the following. [ETSI NGP] describes requirements for how to better provide mobile Internet access addressing as key points: Efficiency: Smaller Headers, Scalable protocol structures Security: Native, Scalable, Association and Stakeholder based Addressing: Location, Network Address separation and ID separation Transmission: Flexible, Efficient, Context Aware and Profile based Mobility: Native, Scalable, Context Aware Documentation missing on GTP-U User plane GTP protocol called GTP-U has been selected to be used on interfaces N3 and N9. GTP is UDP based tunneling protocol used to carry general packet radio service (GPRS) within wireless core network. GTP-U header contains 12 octets 4 octets of it are used to carry Tunnel Endpoint Identifier or TEID. TEID indicates which tunnel this packet belongs and TEID values are negotiated on the control plane. We can say that GTP-U is a means that multiplexes and de-multiplexes packets between a given pair of tunnel endpoints. GTP which is heavily used in 4G networks and now to be used in 5G networks is not known in IETF. There is no documentation on GTP. Also there are concerns that GTP is used more to carry IPv4 packets and operators possibly due to lack of expertise are not using it for IPv6. Tunneling blues As explained above delivery of user or UE packets is based on tunneling. That means to every IPv6 packet at least 52 octets of overhead is added. Also since over the air delivery is not involved possibly no header compression is involved. Tunneling is suitable for point-to-point communication and introduces complexities to point-to-multipoint communication, i.e. IP multicast. von Hugo, et al. Expires August 1, 2018 [Page 3] Internet-Draft nextgenprot January 2018 Another issue with tunneling is it introduces gateways in the core network such as packet data network gateway or PGW. Gateways are prominent places for single-point failure for security attacks like DOS or DDOS. Charging etc. It seems like a major reason for the use of tunneling is charging. Tunneling user packets to certain gateways certainly enables very effectively to account for and subsequently charge user traffic. Other features to be supported by tunneling are policy and security enforcement, providing a point for traffic monitoring and legal interception etc. Mobility anchors Some gateways are used as mobility anchors as enabled by tunneling. In 4G LTE networks PGW is a fixed mobility anchor which means that UE packets are always anchored from the PGW that serves that specific UE. In 5G networks the use of mobility anchor continues but it is not a fixed anchor. Based on user mobility, the anchor, i.e. UPF assigned to the UE may be changed and another UPF takes over. Dynamic anchoring used in 5G is expected to enable much faster communication. Ideally no anchoring is better and dynamic anchoring ranks next. The issue with anchoring is continued use of gateways or anchor points and exposure to single-point failure. Also roaming policies of the operator are enforced at the mobility anchors. So the operators are almost encouraged to setup such anchors and it is not clear how much the user benefits from it. 4. Identifier Locator Separation Systems Identifier locator separation systems like ILNP, LISP and ILA may present themselves as an effective solution to packet delivery data plane protocol without tunneling. They can also handle mobility as well as correspondent node mobility updates with already standardized control plane extensions, e.g. ILNP. It should be noted that open source systems have recently started to pay attention to the identifier locator addressing systems. Fast Data open source initiative is a good example [FD.io]. FD.io has recently included identifier locator addressing as one of the network services in its Vector Packet Processor (VPP) features as of version 17.1. von Hugo, et al. Expires August 1, 2018 [Page 4] Internet-Draft nextgenprot January 2018 We will attempt to cover the issues with using Id-Loc systems in 5G. Identifier space Most systems use 64-bit identifiers because of the commonly used 64-bit division of 128 bit IPv6 address. However it can be argued that it is difficult to derive globally unique identifiers only using 64 bits. So it is better to use longer identifiers, e.g. 80 bits or longer. Charging of User Data Packet delivery without tunneling removes the need for gateways and anchor points but also raises the issue of user data charging. How to achieve user data charging without tunneling to a specific charging gateway becomes an issue. We should mention that unlimited user data plans are becoming more and more popular and this helps solve the problem. Privacy Issues The use of identifiers unique for each user brings privacy issues. If the identifier is stolen then your traffic can be unlawfully tracked, there could be serious implications of it. Privacy of identifiers is especially an issue for a UE communication with a server like Google, Facebook, LinkedIn, etc. Privacy issue can be mitigated only if Id-Loc system has proxy mode of operation. In proxy mode, user traffic is intercepted by a proxy. Proxy node which could be placed at the subnet router or site border router. The router tunnels the traffic to the server. In the process UE identifier becomes hidden and this hopefully removes privacy issues. 5G specific identifiers can also used to deal with privacy issues. IMSI is known to be 64 bit and unique for each UE. IMSI should not be exposed to any entities. It is like 64-identifier. Instead identifiers like 5G-GUTI can be used. 5. Work Plan Work plan will include development of the following documents: GTP documentation. GTP-U will be documented emphasizing IETF relevant aspects. GTP-U lends itself to better explain the issues in the fifth generation wireless networks. von Hugo, et al. Expires August 1, 2018 [Page 5] Internet-Draft nextgenprot January 2018 Deployment/application of ILA/ILNP to fifth generation wireless network architecture. The aim will be to show the flexibility and delay minimization that can be achieved only if ILA/ILNP can be used in the data plane, because every packet from/to a UE in fifth generation wireless networks needs to traverse the virtual network function called UPF which is the IP anchor point and this will create unnecessary delay. Slicing will considered. The feature may enable faster deployment since slices can be instantiated with ILA/ILNP support. Performance in case of UE mobility can be compared in slices with and without identifier locator addressing support. 6. IANA Considerations TBD. 7. Security Considerations TBD. 8. Acknowledgements The authors would like to express their thanks for contributing and interesting discussions to Alex Petrescu, Arashmid Akhavain, Saleem Bhatti, and Tom Herbert. 9. References 9.1. 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, . 9.2. Informative References [ETSI NGP] ETSI White Paper No. 17, "Next Generation Protocols - Market Drivers and Key Scenarios", May 2016 [FD.io] White paper "FD.io - Vector Packet Processing", July 2017, available at https://fd.io/wp-content/uploads/sites/34/ 2017/07/FDioVPPwhitepaperJuly2017.pdf von Hugo, et al. Expires August 1, 2018 [Page 6] Internet-Draft nextgenprot January 2018 Authors' Addresses Dirk von Hugo Deutsche Telekom AG Deutsche-Telekom-Allee 7 D-64295 Darmstadt Germany Email: Dirk.von-Hugo@telekom.de Behcet Sarikaya Email: sarikaya@ieee.org von Hugo, et al. Expires August 1, 2018 [Page 7]