INTERNET-DRAFT H. Jiang Intended Status: Proposed Standard Huawei Technologies Expires: December 31, 2012 June 29, 2012 Problem statement for distributed mobility management draft-jiang-dmm-ps-00 Abstract Due to the limitation of sub-optimal routing, reliability and scalability problems in the centralized mobility management approach, distributed mobility management approaches are developed to resolve those problems. However, the proposed distributed mobility management approaches also bring some new problems. This document mainly introduces two kinds of approaches classified by the control plane management mode and proposes the new problems should be resolved in the future. Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/1id-abstracts.html The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html Copyright and License Notice Copyright (c) 2012 IETF Trust and the persons identified as the document authors. All rights reserved. H. Jiang Expires January 1, 2013 [Page 1] INTERNET DRAFT Problem State for DMM June 30, 2012 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. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Requirements and Terminology . . . . . . . . . . . . . . . . . 3 2.1 Requirements . . . . . . . . . . . . . . . . . . . . . . . . 3 2.2 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 4 3. DMM overview . . . . . . . . . . . . . . . . . . . . . . . . . 4 3.1 F-DMM solution . . . . . . . . . . . . . . . . . . . . . . . 4 3.2 P-DMM solution . . . . . . . . . . . . . . . . . . . . . . . 4 4 Problem statement . . . . . . . . . . . . . . . . . . . . . . . 5 4.1 Signaling costs . . . . . . . . . . . . . . . . . . . . . . 5 4.2 Resource utilization . . . . . . . . . . . . . . . . . . . . 5 4.3 Deployment problem . . . . . . . . . . . . . . . . . . . . . 6 4.4 Multihoming support . . . . . . . . . . . . . . . . . . . . 6 5 Security Considerations . . . . . . . . . . . . . . . . . . . . 6 5 IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6 6 References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 6.1 Normative References . . . . . . . . . . . . . . . . . . . 6 6.2 Informative References . . . . . . . . . . . . . . . . . . 6 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7 H. Jiang Expires January 1, 2013 [Page 2] INTERNET DRAFT Problem State for DMM June 30, 2012 1. Introduction With the development of the mobile communication technologies, the number of mobile subscribers is growing year by year with the result that the amount of data traffic generated by them is experiencing a huge growth, and the future traffic amount is unpredictable. More and more users prefer to user mobile phones and tablet to obtain data information through wireless technologies. In the meanwhile more and more mobile Internet applications designed for handheld mobile terminals have already attracted the attention of most mobile users. In order to supply the perfect user experiences for those mobile subscribers to increase the acceptance, the mobile operators SHOULD adopt the suitable protocols or architecture to management those huge number of mobile terminals. Thus IETF have proposed some standards to deal with the mobility management problems for mobile nodes. Typical protocols include Mobile IPv6 (MIPv6) and Proxy Mobile IPv6 (PMIPv6). These protocols generally utilize the mobility anchor to handle the management operations. Thus the key point for those approaches is based on the centralized theory. However, the centralized approach has several drawbacks such as sub-optimal routing, scalability problem, reliability problem and so on. For overcoming the drawbacks of the centralized mobility management approaches, the new approach SHOULD be distributed and never utilizes a central management point to deliver the control and data packets. Thus the IETF researchers begin to discuss the requirements and propose the solutions. Then the proposed solutions can be divided into two kinds: fully distributed and partially distributed. The main difference is whether the control plane is distributed or centralized. However, as other already deployed mobility management protocols, whether the fully distributed mobility management protocols or the partially distributed mobility management protocols are not perfect and with some limitations had to be considered and resolved. So this document analyzes the model of distributed mobility management and proposes some problems in the deployment situation. 2. Requirements and Terminology 2.1 Requirements 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]. H. Jiang Expires January 1, 2013 [Page 3] INTERNET DRAFT Problem State for DMM June 30, 2012 2.2 Terminology In addition to the terminology defined in [RFC5213], the following terminology is also used: DMM: Distributed Mobility Management F-DMM: Fully Distributed Mobility Management P-DMM: Partially Distributed Mobility Management NME: Network Management Entity is an access router and allocates the prefix for MN which attaching to it. It can be used to exchange messages for MN to complete the mobility management. CCE: Central Control Entity is a central control unit used to manage the location and other information for MN in P-DMM. 3. DMM overview As mentioned above, Distributed Mobility Management (DMM) can be divided as follows: 3.1 F-DMM solution In F-DMM solution, Network Management Entity (NME) which achieves the mobility management is an access router with the function of anchor. It takes the role of LMA and MAG as in PMIPv6. So when MN attaches the NME1, NME1 advertises the prefix for MN to configure the IP address. When MN moves to attach NEM2, NEM2 will advertise the new prefix to MN and sends a PBU message to NME1. After receiving the reply PBA message, NME1 will create a tunnel with NME2. So the traffic transmitted by NME1 will be forwarded to NME2 so as to reach MN. And so on, the tunnels will be created with the MN's moving situation. 3.2 P-DMM solution In P-DMM solution, the Central Control Entity (CCE) is used to execute the control signaling interaction and manage the statement of the MN. CCE achieves the control functions as LMA in PMIPv6. When MN connects to NME1, NME1 advertises the prefix for MN to configure the IP address. NME1 sends a PBU message to CCE. Then CCE replies a PBA message to confirm the new registration. When MN moves to NME2, it gets a new prefix. NME2 sends a PBU to CCE for registration. By H. Jiang Expires January 1, 2013 [Page 4] INTERNET DRAFT Problem State for DMM June 30, 2012 searching the BCE table, CCE gets former location information of MN and sends PBU messages to those NMEs. After receiving PBU message, NME1 will send a PBA message to CCE to confirm and another PBA to NME2. Then the tunnel will be created between NME1 and NME2. So the traffic transmitted by NME1 will be forwarded to NME2 so as to reach MN. And so on, the tunnels will be created with the MN's moving situation. 4 Problem statement Although DMM approaches solve some problems caused by centralized mobility management approaches, it also brings some new challenges which SHOULD be resolved for the real large scale business deployment. 4.1 Signaling costs Signaling cost is measurement criteria to evaluate the mobility management approach. In F-DMM solution, because the control plane is also distributed, the way NME to verify if the attachment of MN is fresh is to send PBU messages to other NMEs. Apparently, in a large scale network with lots of NMEs, it will cost too much signaling to get this information. Otherwise, the new solution SHOULD be proposed to alleviate the signaling cost. In P-DMM solution, When NME sends a PBU message to CCE after a MN attachment, CCE will sends PBA messages to all NMEs in the local area to obtain the PBA reply. This cost is very large if the network domain is large and with many NEMs. For example, if the MN is moving in a city to get service, then the PBA messages costs are expensive. 4.2 Resource utilization In both of two DMM approaches, how to manage the network resource is also important. Each time when MN attaches to a new NME, it will create a new tunnel between the new NME and previous NME after the registration. So when MN keeps on moving in the large network area and frequently attaching to different NME, then there are many tunnels between those NEMs. The problem is that most of those tunnels will be idle after the moving, so it is unnecessary to keep the mobility session for those cases. Moreover, the number of NMEs involves the mobility session will increase and become very large. So Removing some NMEs which MAY not be used such as having long distance with the latest location of MN. H. Jiang Expires January 1, 2013 [Page 5] INTERNET DRAFT Problem State for DMM June 30, 2012 4.3 Deployment problem Whether F-DMM or P-DMM, how to deploy the network architecture is a head-scratching puzzlement. For F-DMM, the deployment of NMEs depends on the network area that MN locating. For P-DMM, the location of CCE is also troublesome. Moreover, CCE also will cause the single point failure problem. So it only can be used in small area or localized moving cases. In large area network, mobile operators SLOULD deploy many CCEs to keep synchronization so as to manage the mobility of MN conveniently and save the long distance network cost. 4.4 Multihoming support Up to now, the proposed DMM solutions in IETF have not talking about the multihoming support for MN. All solutions are just assuming that MN connects to the network by one interface. So when MN moving, the mobility handover and session maintaining is very clearly and easy to achieve. However, in multihoming scenario, how to keep the mobility session well when one interface of MN moving while other interfaces remain unchanged is also unclear. 5 Security Considerations None 5 IANA Considerations None 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. 6.2 Informative References [RFC5213] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K., and B. Patil, "Proxy Mobile IPv6", RFC5213, August 2008. [RFC6275] Perkins, C., Johnson, D., and J. Arkko, "Mobility Support in IPv6", RFC6275, July 2011. H. Jiang Expires January 1, 2013 [Page 6] INTERNET DRAFT Problem State for DMM June 30, 2012 [I-D.yokota-dmm-scenario] Yokota, H., Seite, P., Demaria, E., and Z. Cao, "Use case scenarios for Distributed Mobility Management",draft-yokota-dmm-scenario-00 (expired), October 2010. [Paper-Distributed.Centralized.Mobility] Fabio, G., Antonio, O., Carlos J. Bernardos and Rui, Costa. ,"A Network-based Localized Mobility Solution for Distributed Mobility Management", Proceedings of International Workshop on Mobility Management for Flat Networks (MMFN 2011). Authors' Addresses Haisheng Jiang Huawei Building, No.156 Beiqing Rd. Z-park ,Shi-Chuang-Ke-Ji-Shi-Fan-Yuan,Hai-Dian District, Beijing 100095 P.R. China EMail: haisheng.jiang@huawei.com H. Jiang Expires January 1, 2013 [Page 7]