Network Working Group D. Liu Internet-Draft H. Deng Intended status: Informational China Mobile Expires: January 09, 2014 July 08, 2013 Mobility Support in Software Defined Networking draft-liu-sdn-mobility-00 Abstract This document discusses the SDN mobility problem and potential solutions. 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 January 09, 2014. Copyright Notice Copyright (c) 2013 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. Liu & Deng Expires January 09, 2014 [Page 1] Internet-Draft sdn-mobility July 2013 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Conventions and Terminologies . . . . . . . . . . . . . . . . 2 2.1. Conventions used in this document . . . . . . . . . . . . 2 2.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 2 3. Motivation of SDN mobility . . . . . . . . . . . . . . . . . 2 4. SDN mobility problem analysis and potential solutions . . . . 3 4.1. Enhance SDN to support mobility tunnel handling. . . . . 3 4.2. Routing based SDN mobility support . . . . . . . . . . . 4 5. Security Considerations . . . . . . . . . . . . . . . . . . . 5 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 7.1. Normative References . . . . . . . . . . . . . . . . . . 5 7.2. Informative References . . . . . . . . . . . . . . . . . 5 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 1. Introduction Software defined networking provides a very flexible way to process IP packets and flows. It decouples the control and forwarding function of traditional IP appliance. IP mobility support has been specified by IETF. There is currently not much discussion regarding the mobility support in SDN network. This document discusses the motivation, problem and potential solution of the mobility support in SDN network. 2. Conventions and Terminologies 2.1. Conventions used in this document 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]. 2.2. Terminology SDN: Software Defined Networking 3. Motivation of SDN mobility IP mobility support has been specified in IETF for years. Both [RFC2002], [RFC3775], [RFC5555],[RFC5213] share the similar idea that it introduce an anchoring point to maintain the mapping of the home address and routing address of the mobile node. It uses tunnel to encapsulate the user traffic so that the application layer is not aware of the mobility event. Liu & Deng Expires January 09, 2014 [Page 2] Internet-Draft sdn-mobility July 2013 IP protocol has been used intensively in current cellular network architecture. For example, in LTE network architecture, IP support is enabled in the data plane. Also In the control plane and mobility supprot, IP moblitliy protocol is used. Both S2a/S2b/S2c interface is specified that can based on IP mobility protocol. There is ongoing research work and discussions of using SDN in cellular network. SDN can provide the IP packets processing ability for the cellular core network. Mobility support is critical for the cellular core network. If mobility can be supported by SDN, the cellular core network can be significantly simplified. The data plane traffic routing can also be optimized. The following figure shows an architecture of the cellular core network that build upon SDN concept. +--------------------+ +--------------+ +----------+ |mobility management | | Charging | | Policy | +--------------------+ +--------------+ +----------+ +----------|----------------------|----------------------|-------------+ | controller | +----------------------------------------------------------------------+ +---------------------------------|------------------------------------+ | forwarding and packet swithching function | +----------------------------------------------------------------------+ +---------------------------------|------------------------------------+ | wireless access network | +----------------------------------------------------------------------+ Figure 1. SDN based Mobile core network 4. SDN mobility problem analysis and potential solutions The purpose of mobility management is to maintain the session continuity from the application's perspective. Normally, when a mobile node change its attachment point, its IP address will be changed accordingly. If there is no mobility support, the application layer session will be broken. For example, TCP session can not survive when the source IP address changes. There are several potential ways for SDN network to support mobility. The following sections will discuss the potential solution in detail. 4.1. Enhance SDN to support mobility tunnel handling. Current mobility protocol mainly follows the concept of mobility anchor. Mobility anchor point maintain the mapping of home address Liu & Deng Expires January 09, 2014 [Page 3] Internet-Draft sdn-mobility July 2013 and routing address. For example, in Mobile IP, the home agent maintain the mapping of home address and care of address. When the care of address changes due to mobile node's movement, the foreign agent or the mobile node will send binding update request to the home agent to update the binding cache entry. The foreign agent or the mobile node will set up bi-directional tunnel towards the home agent. All the user traffic will be encapsulated in the bi-directional tunnel. To enable SDN to support mobility, one potential solution is to enable the SDN controller and SDN forwarding function to support IP mobility protocol related tunnelling processing. +-------------------+ |mobility management| +-------------------+ | API +-----------------+ +-----------| controller |------------+ | +-----------------+ | | | | | | | | | | | | | | | | | +--------------------------------------+ | | | | | | +---------+ +---------+ +----------+ | FA/MAG | | FA/MAG | | LMA/HA | +---------+ +---------+ +----------+ Figure 2. Enhance SDN to support mobility tunnel processing The mobility management function could run on top of the controller. The controller controlls the forwarding function. To support mobility, the mobility management function monitors the mobile node's movement event. When the FA/MAG detects the mobile node's movement, it needs to update the binding cache entry that maybe maintained in the mobility management function. The mobility management function then control the forwarding function(FA/MAG) to do the mobility tunnel processing. When the packets arrives at the LMA/HA, the mobility management function will controll the forwarding function to decapsulate the packets and forward the packets to the Internet. 4.2. Routing based SDN mobility support Liu & Deng Expires January 09, 2014 [Page 4] Internet-Draft sdn-mobility July 2013 SDN provides a very flexiable way of packet and flow processing. It is in nature can react quickly on the routing changes of the network. When the mobile node changes its point of attachment, the forwarding function will notify the mobility management function running on top of the controller, the controller then calculate the forwarding rules based on the destination IP address of the IP packet. The controller then push the forwarding rules to the forwarding function and the IP packet will be forwarded accordingly. When the user session terminated, the mobility management function will delete the forwarding rules. In this manner, the application lalyer session continuity will be guaranteed since the mobile node's IP address is not changed during the movement. There are lots of interesting problems need to be solved to make SDN support mobility. For example, the forwarding function needs to detect the movement event of the mobile node and notify the controller and mobility management function in a timely manner. A routing path needs to be set up from the MAG/FA to the Internet access point in a timely manner. To achieve this, new protocol and mechnism may need to be defined in IETF. 5. Security Considerations TBD 6. IANA Considerations None 7. References 7.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. 7.2. Informative References [RFC2002] Perkins, C., "IP Mobility Support", RFC 2002, October 1996. [RFC3775] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support in IPv6", RFC 3775, June 2004. [RFC5213] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K., and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008. Liu & Deng Expires January 09, 2014 [Page 5] Internet-Draft sdn-mobility July 2013 [RFC5555] Soliman, H., "Mobile IPv6 Support for Dual Stack Hosts and Routers", RFC 5555, June 2009. [RFC6275] Perkins, C., Johnson, D., and J. Arkko, "Mobility Support in IPv6", RFC 6275, July 2011. Authors' Addresses Dapeng Liu China Mobile Unit2, 28 Xuanwumenxi Ave, Xuanwu District, Beijing 100053, China Email: liudapeng@chinamobile.com Hui Deng China Mobile 32 Xuanwumen West Street Beijng, Xicheng District 100053 China Email: denghui@chinamobile.com Liu & Deng Expires January 09, 2014 [Page 6]