6man WG F. Garneij Internet-Draft Ericsson Intended status: Informational February 14, 2014 Expires: August 18, 2014 IPv6 Periodic RA Cellular Impact Investigation draft-garneij-ipv6-nd-m2m-issues-00.txt Abstract The use of IPv6 in 3GPP cellular broadband for accessing the Internet and other data services like VoLTE via smartphones has increased as a result of EPS network deployments worldwide and new IPv6 capable smartphones tablets, and netbook computers. The upcoming rise of IoT/M2M is anticipated to bring billions of new devices into these networks and the majority of these devices will be using only IPv6. This document discusses the EPS network impact of IoT/M2M IPv6 connectivity specifically targeting the IPv6 Stateless Address Auto Configuration (SLAAC), as specified in [RFC4861] and [RFC4862], which currently is the only supported IPv6 address configuration mechanism in 3GPP standards. 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 August 18, 2014. Copyright Notice Copyright (c) 2014 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 Garneij Expires August 18, 2014 [Page 1] Internet-Draft IPv6 ND and Cellular networks impact February 2014 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. Background . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. The M2M Scenario and Neighbor Discovery Impact . . . . . . . . 4 3. Definition Of Terms . . . . . . . . . . . . . . . . . . . . . . 4 4. Analysis of Results . . . . . . . . . . . . . . . . . . . . . . 5 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 5 6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5 6.1. Normative References . . . . . . . . . . . . . . . . . . . 5 6.2. Informative References . . . . . . . . . . . . . . . . . . 6 Appendix A. . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 6 Garneij Expires August 18, 2014 [Page 2] Internet-Draft IPv6 ND and Cellular networks impact February 2014 1. Background Conceptually, IPv6 multicast messages are supposed to avoid broadcast messages, but in practice, the multicast operation at many link layers the mutlicast message is a broadcast. 3GPP links are cellular links consuming expensive radio spectrum. Thus such radio networks like to limit unnecessary signals in the network. IPv6 neighbor discovery being the heart of IPv6 protocol, the document shows how it can affect the cellular networks for M2M. M2M networks are usually low bandwidth radio networks. In 3GPP networks, mobility and connectivity is generated by the arrangement of allocated radio resources and EPC node resources into a PDN connection. The following list gives the logical functions performed within the Evolved Packet System (EPS): o Network Access Control Functions. o Packet Routing and Transfer Functions o Mobility Management Functions. o Security Functions o Radio Resource management functions o Network Management Functions For a User Equipment (UE) attached to a 3GPP network there are procedures defined related to device mobility, EPS Mobility Management (EMM) states and connectivity session, EPS Connectivity Management (ECM) states as described in [TS.23401] Section 4.6. The purpose of this document is to analyze the EPS resources impacted by the procedures of the IPv6 Stateless Address Auto Configuration (SLAAC), as specified in [RFC4861] and [RFC4862], as it is utilized in 3GPP standards. Special attention is put on EPS control signaling load and UE targeting packets generated by IPv6 periodic Router Advertisements (unsolicited multicast Router Advertisements). In an effort to adapt initial and periodic Router Advertisements in order to preserve radio resources and UE power consumption while still allowing for appropriate robustness and fast user-plane set-up time even in bad radio conditions to the radio, 3GPP has defined specific values and behavior for Router Advertisement in 3GPP TS 29.061 Section 11.2.1.3.4 IPv6 Router Configuration Variables. Since in EPS, radio and network resources are not permanently assigned to a specific UE there is a cost associated with the allocation and release of resources and associated changes of states in EPS nodes. It is desirable to reduce or avoid any additional periodic packets that are not of any use to the application using the 3GPP derived UE connectivity. 2G and 3G radio resource allocation have their own mechanisms with similar functionality but these are not described or considered in this document. Garneij Expires August 18, 2014 [Page 3] Internet-Draft IPv6 ND and Cellular networks impact February 2014 2. The M2M Scenario and Neighbor Discovery Impact The analysis considers an IoT/M2M UE deployment scenario with less frequent packet communications occurrences than would normally be seen in a smartphone. Given an infrequent communication pattern the current ECM state before a downlink packet is to be sent, UE ECM state is with high probability going to be found in state IDLE. Sending a packet to the UE while in ECM_IDLE state triggers UE Paging followed by a UE Service Request and radio resource allocation. These procedures are considered as among the heavier procedures in EPS with regards to control signaling load and node state changes. They are energy consuming in radio and in node processing power utilized by the procedures. It is also likely that other devices with different communications usage patterns like smartphones may compete over network resources causing the procedure to be repeated on order to complete. It should be noted that in addition to establishing connectivity, security functions create node state that are used in the UE Service Request procedure to provide authentication, ciphering and integrity protection. The use case to be analyzed considers the following network dimensioning for a single P-GW node based on estimations and derived from real world network deployment best practices: o There are 10,000,000 simultaneous IPv6 PDN connections to IoT/M2M devices. No dedicated bearers. Communication direction for IoT/ M2M service is from network to UE infrequent (e.g. twice a day or less). GTP-U is used between P-GW and S-GW as described in TS.23401 of 3GPP specification o EPS Connectivity Management (ECM) state is ECM_IDLE, paging will be done o Tracking Area (TA) contains 100 base stations (eNodeB) o MME UE Tracking Area Identifier (TAI) list containing 10 TA which gives 10 * 100 eNodeB = 1000 eNodeB for a UE TAI list o Calculation: periodic Router Advertisement interval is 18900 s (5,25h) The analysis focus on the connectivity state changes and resource allocation are related to 1) Packet Routing and Transfer Functions 2) Mobility Management Functions 3) Radio Resource Management Functions 3. Definition Of Terms 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 [RFC2119]. Garneij Expires August 18, 2014 [Page 4] Internet-Draft IPv6 ND and Cellular networks impact February 2014 3GPP Third Generation Partnership Project. Throughout the document, the term "3GPP networks" refers to architectures standardized by 3GPP, in Second, Third, and Fourth Generation releases: 99, 4, and 5, as well as future releases. EPS Evolved packet System eNodeB The eNodeB is a base station entity that supports the Long-Term Evolution (LTE) air interface. MME Mobility Management Entity UE User Equipment or host terminal M2M Machine to Machine Communication networks and related standards. M2M includes industrial networks and communication. 4. Analysis of Results If the periodic router advertisements are allowed in the network, the measurement result shows that approximately 529 PPS(RA) can be sent to the eNodeB from the Edge Router/Gateway device(PDN GW). And there is ~100 to ~1000 state changes per second for MME, eNodeB, UE in the network. It has been shown that a single downlink packet consumes energy and bandwidth and ties up resources in the EPS network and UE. It is desirable to free up the 3GPP networks from periodic signaling traffic (in this case IPv6 ND) so that the bandwith can be used for packets that have business values. 5. Acknowledgements 6. References 6.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 2434, October 1998. Garneij Expires August 18, 2014 [Page 5] Internet-Draft IPv6 ND and Cellular networks impact February 2014 [6LOWPAN-ND] Shelby, Z., Chakrabarti, S., Nordmark, E., and C. Bormann, "ND Optimizations for 6LoWPAN", RFC 6775, November 2012. [ND] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, "Neighbor Discovery for IP version 6", RFC 4861, September 2007. 6.2. Informative References [IPV6] Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6), Specification", RFC 2460, December 1998. [AUTOCONF] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless Autoconfiguration", RFC 4862, September 2007. [3GPP] Korhonen, J., "IPv6 in 3rd Generation Partnership Project (3GPP) Evolved Packet System (EPS)", RFC 6459, January 2012. Appendix A. Author's Address Fredrik Garneij Ericsson Sweden Email: fredrik.garneij@ericsson.com Garneij Expires August 18, 2014 [Page 6]