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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group D. Liu 3 Internet-Draft H. Deng 4 Intended status: Informational China Mobile 5 Expires: January 09, 2014 July 08, 2013 7 Mobility Support in Software Defined Networking 8 draft-liu-sdn-mobility-00 10 Abstract 12 This document discusses the SDN mobility problem and potential 13 solutions. 15 Status of This Memo 17 This Internet-Draft is submitted in full conformance with the 18 provisions of BCP 78 and BCP 79. 20 Internet-Drafts are working documents of the Internet Engineering 21 Task Force (IETF). Note that other groups may also distribute 22 working documents as Internet-Drafts. The list of current Internet- 23 Drafts is at http://datatracker.ietf.org/drafts/current/. 25 Internet-Drafts are draft documents valid for a maximum of six months 26 and may be updated, replaced, or obsoleted by other documents at any 27 time. It is inappropriate to use Internet-Drafts as reference 28 material or to cite them other than as "work in progress." 30 This Internet-Draft will expire on January 09, 2014. 32 Copyright Notice 34 Copyright (c) 2013 IETF Trust and the persons identified as the 35 document authors. All rights reserved. 37 This document is subject to BCP 78 and the IETF Trust's Legal 38 Provisions Relating to IETF Documents 39 (http://trustee.ietf.org/license-info) in effect on the date of 40 publication of this document. Please review these documents 41 carefully, as they describe your rights and restrictions with respect 42 to this document. Code Components extracted from this document must 43 include Simplified BSD License text as described in Section 4.e of 44 the Trust Legal Provisions and are provided without warranty as 45 described in the Simplified BSD License. 47 Table of Contents 49 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 50 2. Conventions and Terminologies . . . . . . . . . . . . . . . . 2 51 2.1. Conventions used in this document . . . . . . . . . . . . 2 52 2.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 2 53 3. Motivation of SDN mobility . . . . . . . . . . . . . . . . . 2 54 4. SDN mobility problem analysis and potential solutions . . . . 3 55 4.1. Enhance SDN to support mobility tunnel handling. . . . . 3 56 4.2. Routing based SDN mobility support . . . . . . . . . . . 4 57 5. Security Considerations . . . . . . . . . . . . . . . . . . . 5 58 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 59 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 60 7.1. Normative References . . . . . . . . . . . . . . . . . . 5 61 7.2. Informative References . . . . . . . . . . . . . . . . . 5 62 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 64 1. Introduction 66 Software defined networking provides a very flexible way to process 67 IP packets and flows. It decouples the control and forwarding 68 function of traditional IP appliance. IP mobility support has been 69 specified by IETF. There is currently not much discussion regarding 70 the mobility support in SDN network. This document discusses the 71 motivation, problem and potential solution of the mobility support in 72 SDN network. 74 2. Conventions and Terminologies 76 2.1. Conventions used in this document 78 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL","SHALL NOT", 79 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 80 document are to be interpreted as described in [RFC2119]. 82 2.2. Terminology 84 SDN: Software Defined Networking 86 3. Motivation of SDN mobility 88 IP mobility support has been specified in IETF for years. Both 89 [RFC2002], [RFC3775], [RFC5555],[RFC5213] share the similar idea that 90 it introduce an anchoring point to maintain the mapping of the home 91 address and routing address of the mobile node. It uses tunnel to 92 encapsulate the user traffic so that the application layer is not 93 aware of the mobility event. 95 IP protocol has been used intensively in current cellular network 96 architecture. For example, in LTE network architecture, IP support 97 is enabled in the data plane. Also In the control plane and mobility 98 supprot, IP moblitliy protocol is used. Both S2a/S2b/S2c interface 99 is specified that can based on IP mobility protocol. 101 There is ongoing research work and discussions of using SDN in 102 cellular network. SDN can provide the IP packets processing ability 103 for the cellular core network. Mobility support is critical for the 104 cellular core network. If mobility can be supported by SDN, the 105 cellular core network can be significantly simplified. The data 106 plane traffic routing can also be optimized. The following figure 107 shows an architecture of the cellular core network that build upon 108 SDN concept. 110 +--------------------+ +--------------+ +----------+ 111 |mobility management | | Charging | | Policy | 112 +--------------------+ +--------------+ +----------+ 113 +----------|----------------------|----------------------|-------------+ 114 | controller | 115 +----------------------------------------------------------------------+ 116 +---------------------------------|------------------------------------+ 117 | forwarding and packet swithching function | 118 +----------------------------------------------------------------------+ 119 +---------------------------------|------------------------------------+ 120 | wireless access network | 121 +----------------------------------------------------------------------+ 123 Figure 1. SDN based Mobile core network 125 4. SDN mobility problem analysis and potential solutions 127 The purpose of mobility management is to maintain the session 128 continuity from the application's perspective. Normally, when a 129 mobile node change its attachment point, its IP address will be 130 changed accordingly. If there is no mobility support, the 131 application layer session will be broken. For example, TCP session 132 can not survive when the source IP address changes. 134 There are several potential ways for SDN network to support mobility. 135 The following sections will discuss the potential solution in detail. 137 4.1. Enhance SDN to support mobility tunnel handling. 139 Current mobility protocol mainly follows the concept of mobility 140 anchor. Mobility anchor point maintain the mapping of home address 141 and routing address. For example, in Mobile IP, the home agent 142 maintain the mapping of home address and care of address. When the 143 care of address changes due to mobile node's movement, the foreign 144 agent or the mobile node will send binding update request to the home 145 agent to update the binding cache entry. The foreign agent or the 146 mobile node will set up bi-directional tunnel towards the home agent. 147 All the user traffic will be encapsulated in the bi-directional 148 tunnel. 150 To enable SDN to support mobility, one potential solution is to 151 enable the SDN controller and SDN forwarding function to support IP 152 mobility protocol related tunnelling processing. 154 +-------------------+ 155 |mobility management| 156 +-------------------+ 157 | API 158 +-----------------+ 159 +-----------| controller |------------+ 160 | +-----------------+ | 161 | | | 162 | | | 163 | | | 164 | | | 165 | | | 166 | +--------------------------------------+ | 167 | | | | | 168 +---------+ +---------+ +----------+ 169 | FA/MAG | | FA/MAG | | LMA/HA | 170 +---------+ +---------+ +----------+ 172 Figure 2. Enhance SDN to support mobility tunnel processing 174 The mobility management function could run on top of the controller. 175 The controller controlls the forwarding function. To support 176 mobility, the mobility management function monitors the mobile node's 177 movement event. When the FA/MAG detects the mobile node's movement, 178 it needs to update the binding cache entry that maybe maintained in 179 the mobility management function. The mobility management function 180 then control the forwarding function(FA/MAG) to do the mobility 181 tunnel processing. When the packets arrives at the LMA/HA, the 182 mobility management function will controll the forwarding function to 183 decapsulate the packets and forward the packets to the Internet. 185 4.2. Routing based SDN mobility support 186 SDN provides a very flexiable way of packet and flow processing. It 187 is in nature can react quickly on the routing changes of the network. 188 When the mobile node changes its point of attachment, the forwarding 189 function will notify the mobility management function running on top 190 of the controller, the controller then calculate the forwarding rules 191 based on the destination IP address of the IP packet. The controller 192 then push the forwarding rules to the forwarding function and the IP 193 packet will be forwarded accordingly. When the user session 194 terminated, the mobility management function will delete the 195 forwarding rules. In this manner, the application lalyer session 196 continuity will be guaranteed since the mobile node's IP address is 197 not changed during the movement. 199 There are lots of interesting problems need to be solved to make SDN 200 support mobility. For example, the forwarding function needs to 201 detect the movement event of the mobile node and notify the 202 controller and mobility management function in a timely manner. A 203 routing path needs to be set up from the MAG/FA to the Internet 204 access point in a timely manner. To achieve this, new protocol and 205 mechnism may need to be defined in IETF. 207 5. Security Considerations 209 TBD 211 6. IANA Considerations 213 None 215 7. References 217 7.1. Normative References 219 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 220 Requirement Levels", BCP 14, RFC 2119, March 1997. 222 7.2. Informative References 224 [RFC2002] Perkins, C., "IP Mobility Support", RFC 2002, October 225 1996. 227 [RFC3775] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support 228 in IPv6", RFC 3775, June 2004. 230 [RFC5213] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K., 231 and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008. 233 [RFC5555] Soliman, H., "Mobile IPv6 Support for Dual Stack Hosts and 234 Routers", RFC 5555, June 2009. 236 [RFC6275] Perkins, C., Johnson, D., and J. Arkko, "Mobility Support 237 in IPv6", RFC 6275, July 2011. 239 Authors' Addresses 241 Dapeng Liu 242 China Mobile 243 Unit2, 28 Xuanwumenxi Ave, Xuanwu District, Beijing 100053, China 244 Email: liudapeng@chinamobile.com 246 Hui Deng 247 China Mobile 248 32 Xuanwumen West Street 249 Beijng, Xicheng District 100053 250 China 252 Email: denghui@chinamobile.com