Mobility Extensions for IPv6 (MEXT) S. Koh, J. Kim Internet Draft Kyungpook National University Intended status: Informational H. Jung Expires: September 2011 ETRI March 7, 2011 Extension of Proxy Mobile IPv6 for Distributed Mobility Control draft-sjkoh-mext-pmip-dmc-00.txt Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. This document may not be modified, and derivative works of it may not be created, and it may not be published except as an Internet-Draft. This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. This document may not be modified, and derivative works of it may not be created, except to publish it as an RFC and to translate it into languages other than English. 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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." Koh, Kim & Jung Expires September 2011 [Page 1] Internet-Draft PMIP-DMC March 2011 The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html This Internet-Draft will expire on September 7, 2011. Copyright Notice Copyright (c) 2011 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. 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. Abstract Mobile cellular networks with hierarchical architecture are now changing to flat architecture due to ever-increasing mobile Internet traffics. Most of the existing mobility protocols are based on a centralized mobility anchor, by which all the control and data traffics are processed. In the flat network architecture, however, the centralized mobility scheme has some limitations, which include unwanted traffic flowing into core network, service degradation by a single point of failure, and increased operational costs, etc. This draft proposes some mobility schemes for distributed mobility control in the flat architecture of future network. Based on the well-known Proxy Mobile IPv6 (PMIP), we propose the three schemes of distributed mobility control: Signal-driven PMIP (S-PMIP), Data- driven Distributed PMIP (DD-PMIP), and Signal-driven Distributed PMIP (SD-PMIP). This draft proposes an extension of PMIP for distributed mobility control. Koh, Kim & Jung Expires September 2011 [Page 2] Internet-Draft PMIP-DMC March 2011 Table of Contents 1. Introduction ................................................ 3 2. Conventions used in this document ............................ 4 3. Overview of Distributed Mobility Control ..................... 5 4. Distributed Mobility Control Schemes in the PMIP Networks ..... 6 4.1. Overview ............................................... 6 4.2. Signal-driven PMIP (S-PMIP) ............................. 7 4.3. Data-driven Distributed PMIP (DD-PMIP) .................. 7 4.4. Signal-driven Distributed PMIP (SD-PMIP) ................ 8 5. Security Considerations ...................................... 8 6. IANA Considerations ......................................... 8 7. Conclusions ................................................. 8 8. References .................................................. 9 8.1. Normative References .................................... 9 8.2. Informative References .................................. 9 9. Acknowledgments ............................................ 10 1. Introduction With emergence of new types of wireless/mobile networks and wide popularity of smart phones, the number of mobile Internet users has been rapidly increasing. It is reported that the number of mobile Internet users will be 1.6 billion in around 2014 and thus exceed the number of desktop users. This mobile-oriented trend inevitably tends to introduce a large amount of traffics into mobile Internet infrastructure. The cellular system is a typical infrastructure for mobile Internet, as shown in the SAE of 3GPP. The cellular network was originally designed as hierarchical architecture to support circuit-based voice traffics. However, an ever-increasing demand of mobile Internet traffics has enforced non-hierarchical or flat structure on mobile networks, so as to provide data services more cost-effectively. Now, the flat architecture is regarded as a promising technology for future mobile networks. Most of existing protocols for Internet mobility are based on the centralized approach, in which all the control and data traffics will be processed by a centralized mobility anchor, such as Home Agent (HA) of Mobile IP (MIP) [4] or Local Mobility Anchor (LMA) of Proxy MIP (PMIP) [5]. The centralized mobility anchor allows a mobile host to be reachable, when it is not connected to its home domain, by ensuring the forwarding of packets destined to or sent from the mobile device. In the flat architecture, however, such a centralized mobility scheme is vulnerable to some problems. First, Koh, Kim & Jung Expires September 2011 [Page 3] Internet-Draft PMIP-DMC March 2011 the centralized anchor may induce unwanted traffic into the core network, which tends to give a big burden to mobile network operators in terms of operational costs. In addition, a single point of failure of the central anchor may affect overall data transmission and degradation of performance, which will increase the cost of network dimensioning and engineering. To overcome the limitations of centralized management, the IETF has recently discussed the distributed mobility management. The distributed mobility management can be divided into the partially distributed approach, in which only the data plane is distributed, and the fully distributed approach where both data plane and control plane are distributed. In the centralized management, the routing path through a centralized anchor tends to be longer, which results in non-optimal routes and performance degradation, whereas the route optimization will be intrinsically supported in the distributed management. Moreover, the distributed mobility management can reduce unnecessary traffics, if the two end hosts communicate directly each other, not relying on a centralized anchor. This will also be helpful to reduce the handover delay. Moreover, the centralized approach is vulnerable to a single point of failure, whereas the distributed approach will mitigate such problem to a local network. In this draft we discuss the distributed mobility control in the flat architecture of future network, which is a part of research on Mobile Oriented Future Internet (MOFI) supported by Korean government [8]. Based on the PMIP [5], we propose the three schemes of distributed mobility control: Signal-driven PMIP (S-PMIP), Data- driven Distributed PMIP (DD-PMIP), and Signal-driven Distributed PMIP (SD-PMIP). S-PMIP can be regarded as a partially distributed approach, whereas DD-PMIP and SD-PMIP correspond to the fully distributed schemes. 2. Conventions used in this document In examples, "C:" and "S:" indicate lines sent by the client and server respectively. 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]. In this document, these words will appear with that interpretation only when in ALL CAPS. Lower case uses of these words are not to be interpreted as carrying RFC-2119 significance. Koh, Kim & Jung Expires September 2011 [Page 4] Internet-Draft PMIP-DMC March 2011 In this document, the characters ">>" preceding an indented line(s) indicates a compliance requirement statement using the key words listed above. This convention aids reviewers in quickly identifying or finding the explicit compliance requirements of this RFC. 3. Overview of Distributed Mobility Control In centralized mobility control, the information of binding between Home address (HoA) and Care of Address (CoA) is kept at a central mobility anchor (e.g., HA or LMA), and the data packets destined to mobile nodes are routed via this anchor. In other words, such the mobility control systems are centralized in both data plane and control plane. Most of current mobile networks, such as UMTS, CDMA, and 3GPP SAE networks, are based on such the centralized approach. However, such the centralized approach has several limitations, which include degradation of mobility performance, worse scalability, costly maintenance and operations of the network, and vulnerability of a single point of failure or attack. Moreover, network operators tend to have a big concern due to a large amount of unwanted traffic flowing into their core network. To address these problems of centralized mobility management, the IETF recently began to discuss the distributed mobility control approaches. In the distributed mobility control, the mobility control functions are distributed to multiple locations in the network, so that a mobile node may be served by a nearby mobility agent. The distributed mobility control can be divided into the partially distributed approach, in which only data plane is distributed, and the fully distributed one where both data plane and control plane are distributed. In the partially distributed approach, the control plane is separated from the data plane, and only data plane will be distributed for route optimization. First, a mobile node (MN) is connected to a mobility agent (MA). Then, the MA binds the location of MN with the control function. If a correspondent node (CN) sends a data packet toward MN, the MA will find the location of MN by contacting with the control function, in which location query and query acknowledgement messages can be exchanged. Based on the obtained location information, the MA of CN can deliver the data packets directly to the MA of MN. Now, the data packet is forwarded to MN. In the fully distributed architecture, both control plane and data plane are distributed, which can further be classified into the data-driven multicast/broadcast scheme and the peer-to-peer search scheme. Koh, Kim & Jung Expires September 2011 [Page 5] Internet-Draft PMIP-DMC March 2011 In the data-driven multicast/broadcast scheme, when a MN is attached to MA, no binding operation is performed. For data packets transmitted by CN, the MA of CN will deliver them all of the MAs by using multicast or broadcast in the domain. Then, the MA of MN will forward them to MN. This scheme does not use any binding process and searching (or query) procedure to find the MN. However, unnecessary data packets may be excessively generated in the domain, since the data packets will be delivered to all of MAs. In the peer-to-peer search scheme, just before transmission of data packets, a searching process will be activated among MAs in the domain to find the location of MN, which is described in Fig. 3. After network attachment, CN transmits a data packet to its MA. The MA of CN will find the location of MN by using an appropriate searching mechanism, such as the distributed hash table (DHT). Then, the MA of MN will respond to the MN of CN. Now, the MA of CN delivers the data packet to the MA of MN. The data packet will be forwarded to MN. 4. Distributed Mobility Control Schemes in the PMIP Networks It is noted that many of existing mobility protocols can be used to implement the distributed mobility control or a completely new protocol may be designed. In this draft, we will design the distributed mobility control schemes based on the PMIP, since it is the most promising protocol used in current mobile networks, as shown in the 3GPP/SAE and WiMAX specifications. 4.1. Overview In this section, we propose the three extensional schemes for distributed mobility control based on PMIP network: Signal-driven PMIPv6 (S-PMIP), Data-driven Distributed PMIPv6 (DD-PMIP), Signal- driven Distributed PMIPv6 (SD-PMIP). The existing PMIPv6 can be regarded as a centralized architecture, in which MAG performs the Proxy Binding Update (PBU) operation with LMA, and the data packets are first delivered to LMA and then forwarded to MN, without using any search (or query) mechanism. The proposed S-PMIPv6 is a partially distributed architecture in which the control plane is separated from the data plane. The PBU operation will be performed between MAG and LMA, as done in PMIP. In the packet delivery operation, however, the MAG of CN first finds the CoA of MN, just before data delivery, by contacting with LMA. To do this, the MAG of CN will transmit a newly defined Proxy Binding Query (PBQ) message to LMA, and the LMA will respond with a Proxy Koh, Kim & Jung Expires September 2011 [Page 6] Internet-Draft PMIP-DMC March 2011 Query ACK (PQA) message to the MAG. In this sense, this scheme is named 'signal-driven' scheme. After that, the MAG of CN will deliver the data packet directly to the MAG of MN, and further to MN. The proposed DD-PMIP scheme is a fully distributed architecture, which is similar to the data-driven multicast/broadcast scheme described in Section 2. In this scheme, LMA is not used and the PBU operation is not performed. The MAG of CN will send a data packet to all of the MAGs by multicast in the domain, without using the PBQ operation. In this sense, this scheme is named 'signal-driven' scheme. Finally, the proposed SD-PMIPv6 is also a fully distributed architecture, which is similar to the peer-to-peer search scheme described in Section 2. No binding update operation is performed. In the data packet delivery, the MAG of CN will find the MAG of MN by using sending a PBQ message to all of the MAGs by multicast. The MAG of MN will respond with a PBA message. After that, the MAG of CN will deliver the data packet directly to the MAG of MN, further to MN. For signaling operation for location query in the S-PMIP and SD-PMIP schemes, we define the PBQ and PQA messages by adding the 'Q' flag bit into the existing PBU and Proxy Binding ACK (PBA) packets, respectively. 4.2. Signal-driven PMIP (S-PMIP) First, the MN setups a connection with the MAG and obtains its HoA (step 1). The MAG sends a PBU message to LMA to bind HoA and CoA of MN (step 2). On receiving the PBU request, the LMA will create the associated database entry, and send the PBA to the MAG (step 3). Now, CN sends a data packet to MN (step 4). Then, the MAG sends a PBQ message to LMA to find the CoA of MN (step 5). On the reception of PBQ, the LMA responds with a PQA message including the CoA of MN to the MAG of CN, after lookup of its database (step 6). During this process, the MAG may buffer the data packets received from the CN to prevent the packet losses. After establish the tunnel, the MAG sends the data packets buffered in the MAG first. After that, the MAG of CN sends the data packet to MAG of MN (step 7). Finally, the data packet is forwarded to MN (step 8). 4.3. Data-driven Distributed PMIP (DD-PMIP) The MN setups a connection with the MAG (step 1). When CN sends a data packet to MN (step 2), the corresponding MAG sends the data packet to all the MAGs in the PMIPv6 domain by multicast (step 3). Koh, Kim & Jung Expires September 2011 [Page 7] Internet-Draft PMIP-DMC March 2011 On receiving the data packet from MAG of CN, the MAG of MN will respond with a PQA message to the MAG of CN (step 4), which ensures that the further subsequent data packets of CN can be delivered to MAG of MN by unicast, without relying on multicast transmission. Now, the MAG of MN will deliver the data packet to MN (step 5). 4.4. Signal-driven Distributed PMIP (SD-PMIP) The MN setups a connection with the MAG (step 1). When CN sends a data packet to MN (step 2), the MAG of CN sends a PBQ message all the MAGs in the domain (step 3). Then, only the MAG of MN will respond with a PQA message to MAGH of CN (step 4). Now, the data packet will be delivered to MAG of MN (step 5), and further to MN (step 6). 5. Security Considerations TBD 6. IANA Considerations TBD 7. Conclusions In this draft, we present the distributed mobility control architecture that has recently been discussed in the IETF, and propose the three extensional schemes for distributed mobility control in the PMIP-based mobile networks: S-PMIP, DD-PMIP, and SD- PMIP. The S-PMIP is a partially distributed approach, whereas the other schemes, DD-PMIP and SD-PMIP, are regarded as fully distributed schemes. In S-PMIP, the control plane for location query is separated from the data plane. In DD-PMIP, no binding and query mechanisms are used, and a data packet will be delivered to all the MAGs by multicast. In SD-PMIP, the binding operation is not used. Instead, the location query message is multicast to all the MAGs to find the CoA of MN. For future works, the proposed distributed mobility schemes need to be further elaborated by reflecting more realistic network environments and also verified by simulations and testbed experimentations. Koh, Kim & Jung Expires September 2011 [Page 8] Internet-Draft PMIP-DMC March 2011 8. References 8.1. Normative References [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [2] Crocker, D. and Overell, P.(Editors), "Augmented BNF for Syntax Specifications: ABNF", RFC 2234, Internet Mail Consortium and Demon Internet Ltd., November 1997. [3] Johnson, D. and et al., "Mobility Support in IPv6", RFC 3775, June 2004. [4] Gundavelli, S. and et al., "Proxy Mobile IPv6", RFC 5213, August 2008. [5] Chan, H. and et al., "Problem Statement for Distributed and Dynamic Mobility Management", IETF Internet-Draft, draft-chan- distributed-mobility-ps-00, October 2010. [6] Yokota, H. and et al., "Use case Scenarios for Distributed Mobility Management, IETF Internet-Draft, draft-yokota-dmm- scenario-00, October 2010. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2234] Crocker, D. and Overell, P.(Editors), "Augmented BNF for Syntax Specifications: ABNF", RFC 2234, Internet Mail Consortium and Demon Internet Ltd., November 1997. [RFC3775] D. Johnson, C. Perkins, and K. Arkko, "Mobility support in IPv6", RFC 3775, June 2004. [RFC5213] S. Gundavelli, K. Leung, V. Decarapalli, K. Chowdhury, and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008. 8.2. Informative References [7] Bosch, P., "Flat cellular (UMTS) networks", Conference of WCNC 2007, Hong Kong, March 2007. [8] Daoud, K. and Herbelin, P. and Crespi, N. "UFA: Ultra Flat Architecture for high bit rate services in mobile networks", Conference of PIMRC 2008, September 2008. Koh, Kim & Jung Expires September 2011 [Page 9] Internet-Draft PMIP-DMC March 2011 [9] Zoltan Faigle, et al., "Evaluation and Comparison of Signalling Protocol Alternatives for the Ultra Flat Architecture", Conference of ICSNC 2010, August 2010. [10] Homepage of Mobile Optimized Future Internet, http://www.mofi.re.kr [11] 3GPP TS 23.402, "Architecture enhancements for non-3GPP accesses (Release 10)", V10.1.0, September 2010-09. [12] Wimax Forum. "WiMAX Forum Network Architecture (Stage 2: Architecture Tenets, Reference Model and Reference Points)", Release 1.0 Version 4, February 2009. 9. Acknowledgments This document was prepared using 2-Word-v2.0.template.dot. Koh, Kim & Jung Expires September 2011 [Page 10] Internet-Draft PMIP-DMC March 2011 Authors' Addresses Seok Joo Koh Kyungpook National University, KOREA Email: sjkoh@knu.ac.kr Ji In Kim Kyungpook National University, KOREA Email: jiin16@gmail.com Hee Young Jung Electronics and Telecommunications Research Institute, KOREA Email: hyjung@etri.re.kr Koh, Kim & Jung Expires September 2011 [Page 11]