Network Working Group H. Chan (Ed.) Internet-Draft Huawei Technologies Intended status: Informational March 3, 2012 Expires: September 4, 2012 Requirements of distributed mobility management draft-chan-dmm-requirements-00 Abstract The traditional hierarchical structure of cellular networks has led to deployment models which are heavily centralized. Mobility management with centralized mobility anchoring in existing hierarchical mobile networks is quite prone to suboptimal routing and issues related to scalability. Centralized functions present a single point of failure, and inevitably introduce longer delays and higher signaling loads for network operations related to mobility management. To make matters worse, there are numerous variants of Mobile IP in addition to other protocols standardized outside the IETF, making it much more difficult to create economical and interoperable solutions. In this document we examine the problems of centralized mobility management and identify requirements for distributed and dynamic mobility management. 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 September 4, 2012. Copyright Notice Copyright (c) 2012 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 Chan (Ed.) Expires September 4, 2012 [Page 1] Internet-Draft DMM-Reqs March 2012 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. Conventions used in this document . . . . . . . . . . . . . . 5 3. Centralized versus distributed mobility management . . . . . . 5 3.1. Centralized mobility management . . . . . . . . . . . . . 6 3.2. Distributed mobility management . . . . . . . . . . . . . 6 4. Problem statement . . . . . . . . . . . . . . . . . . . . . . 8 4.1. Non-optimal routes . . . . . . . . . . . . . . . . . . . . 8 4.2. Non-optimality in Evolved Network Architecture . . . . . . 10 4.3. Lack of user-centricity . . . . . . . . . . . . . . . . . 11 4.4. Low scalability of centralized route and mobility context maintenance . . . . . . . . . . . . . . . . . . . 11 4.5. Wasting resources to support mobile nodes not needing mobility support . . . . . . . . . . . . . . . . . . . . . 12 4.6. Complicated deployment with too many variants and extensions of MIP . . . . . . . . . . . . . . . . . . . . 12 4.7. Mobility signaling overhead with peer-to-peer communication . . . . . . . . . . . . . . . . . . . . . . 13 4.8. Single point of failure and attack . . . . . . . . . . . . 14 5. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 14 6. Security Considerations . . . . . . . . . . . . . . . . . . . 15 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15 8. Co-authors and Contributors . . . . . . . . . . . . . . . . . 15 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 16 9.1. Normative References . . . . . . . . . . . . . . . . . . . 16 9.2. Informative References . . . . . . . . . . . . . . . . . . 16 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 18 Chan (Ed.) Expires September 4, 2012 [Page 2] Internet-Draft DMM-Reqs March 2012 1. Introduction In the past decade a fair number of mobility protocols have been standardized. Although the protocols differ in terms of functions and associated message format, we can identify a few key common features: presence of a centralized mobility anchor providing global reachability and an always-on experience; extensions to optimize handover performance while users roam across wireless cells; extensions to enable the use of heterogeneous wireless interfaces for multi-mode terminals (e.g. cellular phones). The presence of the centralized mobility anchor allows a mobile device to be reachable when it is not connected to its home domain. The anchor point, among other tasks, ensures reachability of forwarding of packets destined to or sent from the mobile device. Most of the deployed architectures today have a small number of centralized anchors managing the traffic of millions of mobile subscribers. Compared with a distributed approach, a centralized approach is likely to have several issues or limitations affecting performance and scalability, which require costly network dimensioning and engineering to resolve. To optimize handovers from the perspective of mobile nodes, the base protocols have been extended to efficiently handle packet forwarding between the previous and new points of attachment. These extensions are necessary when applications impose stringent requirements in terms of delay. Notions of localization and distribution of local agents have been introduced to reduce signaling overhead. Unfortunately today we witness difficulties in getting such protocols deployed, often leading to sub-optimal choices. Moreover, the availability of multi-mode devices and the possibility of using several network interfaces simultaneously have motivated the development of more new protocol extensions. Deployment is further complicated with so many extensions. Mobile users are, more than ever, consuming Internet content; such traffic imposes new requirements on mobile core networks for data traffic delivery. When the traffic demand exceeds available capacity, service providers need to implement new strategies such as selective traffic offload (e.g. 3GPP work items LIPA/SIPTO) through alternative access networks (e.g. WLAN). Moreover, the localization of content providers closer to the Mobile/Fixed Internet Service Providers network requires taking into account local Content Delivery Chan (Ed.) Expires September 4, 2012 [Page 3] Internet-Draft DMM-Reqs March 2012 Networks (CDNs) while providing mobility services. When demand exceeds capacity, both offloading and CDN techniques could benefit from the development of mobile architectures with fewer levels of routing hierarchy introduced into the data path by the mobility management system. This trend in network flattening is reinforced by a shift in users traffic behavior, aimed at increasing direct communications among peers in the same geographical area. Distributed mobility management in a truly flat mobile architecture would anchor the traffic closer to the point of attachment of the user and overcome the suboptimal routing issues of a centralized mobility scheme. While deploying [Paper-Locating.User] today's mobile networks, service providers face new challenges. More often than not, mobile devices remain attached to the same point of attachment. Specific IP mobility management support is not required for applications that launch and complete while the mobile device is connected to the same point of attachment. However, the mobility support has been designed to be always on and to maintain the context for each mobile subscriber as long as they are connected to the network. This can result in a waste of resources and ever-increasing costs for the service provider. Infrequent mobility and intelligence of many applications suggest that mobility can be provided dynamically, thus simplifying the context maintained in the different nodes of the mobile network. The proposed charter will address two complementary aspects of mobility management procedures: the distribution of mobility anchors to achieve a more flat design and the dynamic activation/deactivation of mobility protocol support as an enabler to distributed mobility management. The former has the goal of positioning mobility anchors (HA, LMA) closer to the user; ideally, these mobility agents could be collocated with the first hop router. The latter, facilitated by the distribution of mobility anchors, aims at identifying when mobility must be activated and identifying sessions that do not impose mobility management -- thus reducing the amount of state information to be maintained in the various mobility agents of the mobile network. The key idea is that dynamic mobility management relaxes some constraints while also repositioning mobility anchors; it avoids the establishment of non optimal tunnels between two topologically distant anchors. Considering the above, the distributed mobility management working group will: Define the problem statement and associated requirements for distributed mobility management. This work aims at defining the problem space and identifies the key functional requirements. Chan (Ed.) Expires September 4, 2012 [Page 4] Internet-Draft DMM-Reqs March 2012 Produce a gap analysis mapping the above requirements against existing solutions. Give best practices for the deployment of existing mobility protocols in a distributed mobility management and describe limitations of each such approach. Describe extensions, if needed, to current mobility protocols for their applications in distributed mobility architectures. This document describes the motivations of distributed mobility management and the proposed work in Section 1.1. Section 1.2 summarizes the problems with centralized IP mobility management compared with distributed and dynamic mobility management, which is elaborated in Section 4. The requirements to address these problems are given in Section 5. A companion document [dmm-scenario] discusses the use case scenarios. Much of the contents this document together with those in [dmm- scenario] have been merged and elaborated into the following review paper: [Paper-Distributed.Mobility.Review]. 2. 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]. 3. Centralized versus distributed mobility management Mobility management functions may be implemented at different layers of the network protocol stack. At the IP (network) layer, they may reside in the network or in the mobile node. In particular, a network-based solution resides in the network only. It therefore enables mobility for existing hosts and network applications which are already in deployment but lack mobility support. At the IP layer, a mobility management protocol to achieve session continuity is typically based on the principle of distinguishing between identifier and routing address and maintaining a mapping between them. With Mobile IP, the home address serves as an identifier of the device whereas the care-of-address takes the role of routing address, and the binding between them is maintained at the mobility anchor, i.e., the home agent. If packets can be continuously delivered to a mobile device at its home address, then Chan (Ed.) Expires September 4, 2012 [Page 5] Internet-Draft DMM-Reqs March 2012 all sessions using that home address can be preserved even though the routing or care-of address changes. The next two subsections explain centralized and distributed mobility management functions in the network. 3.1. Centralized mobility management With centralized mobility management, the mapping information between the stable node identifier and the changing IP address of an MN is kept at a centralized mobility anchor. Packets destined to an MN are routed via this anchor. In other words, such mobility management systems are centralized in both the control plane and the data plane. Many existing mobility management deployments make use of centralized mobility anchoring in a hierarchical network architecture, as shown in Figure 1. Examples of such centralized mobility anchors are the home agent (HA) and local mobility anchor (LMA) in Mobile IP [RFC3775] and Proxy Mobile IP [RFC5213], respectively. Current mobile networks such as the Third Generation Partnership Project (3GPP) UMTS networks, CDMA networks, and 3GPP Evolved Packet System (EPS) networks also employ centralized mobility management, with Gateway GPRS Support Node (GGSN) and Serving GPRS Support Node (SGSN) in the 3GPP UMTS hierarchical network and with Packet data network Gateway (P-GW) and Serving Gateway (S-GW) in the 3GPP EPS network. UMTS 3GPP SAE MIP/PMIP +------+ +------+ +------+ | GGSN | | P-GW | |HA/LMA| +------+ +------+ +------+ /\ /\ /\ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ +------+ +------+ +------+ +------+ +------+ +------+ | SGSN | | SGSN | | S-GW | | S-GW | |FA/MAG| |FA/MAG| +------+ +------+ +------+ +------+ +------+ +------+ Figure 1. Centralized mobility management. 3.2. Distributed mobility management Mobility management functions may also be distributed to multiple locations in different networks as shown in Figure 2, so that a mobile node in any of these networks may be served by a closeby mobility function (MF). Chan (Ed.) Expires September 4, 2012 [Page 6] Internet-Draft DMM-Reqs March 2012 +------+ +------+ +------+ +------+ | MF | | MF | | MF | | MF | +------+ +------+ +------+ +------+ | ---- | MN | ---- Figure 2. Distributed mobility management. Mobility management may be partially distributed, i.e., only the data plane is distributed, or fully distributed where both the data plane and control plane are distributed. These different approaches are described in detail in [I-D.dmm-scenario]. [Paper-New.Perspective] discusses some initial steps towards a clear definition of what mobility management may be, to assist in better developing distributed architecture. [Paper- Characterization.Mobility.Management] analyses current mobility solutions and propses an initial decoupling of mobility management into well-defined functional blocks, identifying their interactions, as well as a potential grouping, which later can assist in deriving more flexible mobility management architectures. According to the split functional blocks, this paper proposes three ways into which mobility management functional blocks can be groups, as an initial way to consider a better distribution: location and handover management, control and data plane, user and access perspective. A distributed mobility management scheme is proposed in [Paper- Distributed.Dynamic.Mobility] for future flat IP architecture consisting of access nodes. The benefits of this design over centralized mobility management are also verified through simulations in [Paper-Distributed.Centralized.Mobility]. Before designing new mobility management protocols for a future flat IP architecture, one should first ask whether the existing mobility management protocols that have already been deployed for the hierarchical mobile networks can be extended to serve the flat IP architecture. MIPv4 has already been deployed in 3GPP2 networks, and PMIPv6 has already been adopted in WiMAX Forum and in 3GPP standards. Using MIP or PMIP for both centralized and distributed architectures would ease the migration of the current mobile networks towards a flat architecture. It has therefore been proposed to adapt MIP or PMIPv6 to achieve distributed mobility management by using a distributed mobility anchor architecture. In [Paper-Migrating.Home.Agents], the HA functionality is copied to many locations. The HoA of all MNs are anycast addresses, so that a Chan (Ed.) Expires September 4, 2012 [Page 7] Internet-Draft DMM-Reqs March 2012 packet destined to a HoA from any CN from any network can be routed via the nearest copy of the HA. In addition, distributing the function of HA using a distributed hash table structure is proposed in [Paper-Distributed.Mobility.SAE]. A lookup query to the hash table will retrieve the location information of an MN is stored. In [Paper-Distributed.Mobility.PMIP], only the mobility routing (MR) function is duplicated and distributed in many locations. The location information for any MN that has moved to a visited network is still centralized and kept at a location management (LM) function in the home network of the MN. The LM function at different networks constitutes a distributed database system of all the MNs that belong to any of these networks and have moved to a visited network. The location information is maintained in the form of a hierarchy: the LM at the home network, the CoA of the MR of the visited network, and then the CoA to reach the MN in the visited network. The LM in the home network keeps a binding of the HoA of the MN to the CoA of the MR of the visited network. The MR keeps the binding of the HoA of the MN to the CoA of the MN in the case of MIP, or the proxy-CoA of the Mobile Access Gateway (MAG) serving the MN in the case of PMIP. [I-D.PMIP-DMC] discusses two distributed mobility control schemes using the PMIP protocol: Signal-driven PMIP (S-PMIP) and Signal- driven Distributed PMIP (SD-PMIP). S-PMIP is a partially distributed scheme, in which the control plane (using a Proxy Binding Query to get the Proxy-CoA of the MN) is separate from the data plane, and the optimized data path is directly between the CN and the MN. SD-PMIP is a fully distributed scheme, in which the Proxy Binding Update is not performed, and instead each MAG will multicast a Proxy Binding Query message to all of the MAGs in its local PMIP domain to retrieve the Proxy-CoA of the MN. 4. Problem statement This section identifies problems and limitations of centralized mobility approaches, and compares against possible distributed approaches. 4.1. Non-optimal routes Routing via a centralized anchor often results in a longer route. Figure 3 shows two cases of non-optimized routes. Chan (Ed.) Expires September 4, 2012 [Page 8] Internet-Draft DMM-Reqs March 2012 MIP/PMIP +------+ |HA/LMA| +------+ /\ \ \ +---+ / \ \ \ |CDN| / \ \ \ +---+ / \ \ \ | / \ \ \ | +------+ +------+ +------+ +------+ |FA/MAG| |FA/MAG| |FA/MAG| |FA/MAG| +------+ +------+ +------+ +------+ | | ---- ---- | CN | | MN | ---- ---- Figure 3. Non-optimized route when communicating with CN and when accessing local content. In the first case, the mobile node and the correspondent node are close to each other but are both far from the mobility anchor. Packets destined to the mobile node need to be routed via the mobility anchor, which is not on the shortest path. The second case involves a content delivery network (CDN). A user may obtain content from a server, such as when watching a video. As such usage becomes more popular, resulting in an increase in the core network traffic, service providers may relieve the core network traffic by placing these contents closer to the users in the access network in the form of cache or local CDN servers. Yet as the MN is getting content from a local or cache server of a CDN, even though the server is close to the MN, packets still need to go through the core network to route via the mobility anchor in the home network of the MN, if the MN uses the HoA as its identifier. In a distributed mobility management design, one possibility is to have mobility anchors distributed in different access networks so that packets may be routed via a nearby mobility anchor function, as shown in Figure 4. Chan (Ed.) Expires September 4, 2012 [Page 9] Internet-Draft DMM-Reqs March 2012 +---+ |CDN| +---+ | | +------+ +------+ +------+ +------+ | MF | | MF | | MF | | MF | +------+ +------+ +------+ +------+ | | ---- ---- | CN | | MN | ---- ---- Figure 4. Mobile node in any network is served by a close by mobility function. Due to the above limitation, with the centralized mobility anchor design, route optimization extensions to mobility protocols are therefore needed. Whereas the location privacy of each MN may be compromised when the CoA of an MN is given to the CN, those mobility protocol deployments that lack such optimization extensions will encounter non-optimal routes, which affect the performance. In contrast, route optimization may be naturally an integral part of a distributed mobility management design. With the help of such intrinsic route optimization, the data transmission delay will be reduced, by which the data transmission throughputs can be enhanced. Furthermore, the data traffic overhead at the mobility agents such as the HA and the LMA in the core network can be alleviated significantly. 4.2. Non-optimality in Evolved Network Architecture Centralized mobility management is currently deployed to support the existing hierarchical mobile data networks. It leverages on the hierarchical architecture. However, the volume of wireless data traffic continues to increase exponentially. The data traffic increase would require costly capacity upgrade of centralized architectures. It is thus predictable that the data traffic increase will soon overload the centralized data anchor point, e.g., the P-GW in 3GPP EPS. In order to address this issue, a trend in the evolution of mobile networks is to distribute network functions close to access networks. These network functions can be the content servers in a CDN, and also the data anchor point. Mobile networks have been evolving from a hierarchical architecture to a more flattened architecture. In the 3GPP standards, the GPRS network has the hierarchy GGSN "C SGSN "C RNC "C NB (Node B). In Chan (Ed.) Expires September 4, 2012 [Page 10] Internet-Draft DMM-Reqs March 2012 3GPP EPS networks, the hierarchy is reduced to P-GW "C S-GW "C eNB (Evolved NB). In some deployments, the P-GW and the S-GW are collocated to further reduce the hierarchy. Reducing the hierarchy this way reduces the number of different physical network elements in the network, contributing to easier system maintenance and lower cost. As mobile networks become more flattened, the centralized mobility management can become non-optimal. Mobility management deployment with distributed architecture is then needed to support the more flattened network and the CDN networks. 4.3. Lack of user-centricity The mobility anchor point, as the main element of a mobility management system, has been object of intensive studies in order to create more distributed and decentralized systems. Accordingly, its role, its functionalities, and the location it should take in the network (e.g. router, server, etc) are not a consensus. Depending on the architecture, on the network characteristics, and on the functionalities we have in the mobility anchor element, its location may vary, and its function in the whole system may change. Considering that user-centric networks present particular characteristics (e.g. there is no clear splitting between network elements and end-devices), the current centralized standards may not be suitable. Thus, a novel mobility management approach should be designed for such networks, considering all its particularities and following this trend of rethinking the mobility anchor point element. These aspects reinforce the need for distributed and dynamic mobility mechanisms. Positioning the anchor-point in network elements closer to the end user provides the capability to have a more flexible mobility management service, with (potentially) more control in terms of users expectations; it also assists the access operation by lowering the operation complexity. For instance, traffic locality can be more easily achieved by having mobility management functionality deployed in elements that are closer to customer premises, or on the edges of the access network. 4.4. Low scalability of centralized route and mobility context maintenance Special routes are set up to enable session continuity when a handover occurs. Packets sent from the CN need to be tunneled between the HA and FA in MIP and between the LMA and MAG in PMIP. However, these network elements at the ends of the tunnel are also routers performing the regular routing tasks for ordinary packets not involving a mobile node. These ordinary packets need to be directly routed according to the routing table in the routers without tunneling. Therefore, the network must be able to distinguish those Chan (Ed.) Expires September 4, 2012 [Page 11] Internet-Draft DMM-Reqs March 2012 packets requiring tunneling from the regular packets. For each packet that requires tunneling owing to mobility, the network will encapsulate it with a proper outer IP header with the proper source and destination IP addresses. The network therefore needs to maintain and manage the mobility context of each MN, which is the relevant information needed to characterize the mobility situation of that MN to allow the network to distinguish their packets from other packets and to perform the required tunneling. Setting up such special routes and maintaining the mobility context for each MN is more difficult to scale in a centralized design with a large number of MNs. Distributing the route maintenance function and the mobility context maintenance function among different networks can be more scalable. 4.5. Wasting resources to support mobile nodes not needing mobility support The problem of centralized route and mobility context maintenance is aggravated when the via routes are set up for many more MNs that are not requiring IP mobility support. On the one hand, the network needs to provide mobility support for the increasing number of mobile devices because the existing mobility management has been designed to always provide such support as long as a mobile device is attached to the network. On the other hand, many nomadic users connected to a network in an office or meeting room. Such users will not move for the entire network session. It has been measured that over two- thirds of a user mobility is local [Paper-Locating.User]. In addition, it is possible to have the intelligence for applications to manage mobility without needing help from the network. Network resources are therefore wasted to provide mobility support for the devices that do not really need it at the moment. It is necessary to dynamically set up the via routes only for MNs that actually undergo handovers and lack higher-layer mobility support. With distributed mobility anchors, such dynamic mobility management mechanism may then also be distributed. Therefore, dynamic mobility and distributed mobility may complement each other and may be integrated. 4.6. Complicated deployment with too many variants and extensions of MIP Mobile IP, which has primarily been deployed in a centralized manner for the hierarchical mobile networks, already has numerous variants and extensions including PMIP, Fast MIP (FMIP) [RFC4068] [RFC4988] , Proxy-based FMIP (PFMIP) [RFC5949] , hierarchical MIP (HMIP) [RFC5380] , Dual-Stack Mobile IP (DSMIP) [RFC5454] [RFC5555] and Chan (Ed.) Expires September 4, 2012 [Page 12] Internet-Draft DMM-Reqs March 2012 there may be more to come. These different modifications or extensions of MIP have been developed over the years owing to the different needs that are found afterwards. Deployment can then become complicated, especially if interoperability with different deployments is an issue. A desirable feature of mobility management is to be able to work with network architectures of both hierarchical networks and flattened networks, so that the mobility management protocol possesses enough flexibility to support different networks. In addition, one goal of dynamic mobility management is the capability to selectively turn on and off mobility support and certain different mobility signaling. Such flexibility in the design is compatible with the goal to integrate different mobility variants as options. Some additional extensions to the base protocols may then be needed to improve the integration. 4.7. Mobility signaling overhead with peer-to-peer communication In peer-to-peer communications, end users communicate by sending packets directly addressed to each other's IP address. However, they need to find each other's IP address first through signaling in the network. While different schemes for this purpose may be used, MIP already has a mechanism to locate an MN and may be used in this way. In particular, MIPv6 Route Optimization (RO) mode enables a more efficient data packets exchange than the bidirectional tunneling (BT) mode, as shown in Figure 5. MIP/PMIP +------+ |HA/LMA| +------+ /\ \ \ / \ \ \ / \ \ \ / \ \ \ / \ \ \ +------+ +------+ +------+ +------+ |FA/MAG| |FA/MAG| |FA/MAG| |FA/MAG| +------+ +------+ +------+ +------+ | | ---- ---- | MN |<--->| CN | ---- ---- Figure 5. Non-optimized route when communicating with CN and when accessing local content. Chan (Ed.) Expires September 4, 2012 [Page 13] Internet-Draft DMM-Reqs March 2012 This RO mode is expected to be used whenever possible unless the MN is not interested in disclosing its topological location, i.e., the CoA, to the CN (e.g., for privacy reasons) or some other network constraints are put in place. However, MIPv6 RO mode requires exchanging a significant amount of signaling messages in order to establish and periodically refresh a bidirectional security association (BSA) between an MN and its CN. While the mobility signaling exchange impacts the overall handover latency, the BSA is needed to authenticate the binding update and acknowledgment messages (note that the latter is not mandatory). In addition, the amount of mobility signaling messages increases further when both endpoints are mobile. A dynamic mobility management capability to turn off these signaling when they are not needed will enable the RO mode between two mobile endpoints at minimum or no cost. It will also reduce the handover latency owing to the removal of the extra signaling. These benefits for peer-to-peer communications will encourage the adoption and large-scale deployment of dynamic mobility management. 4.8. Single point of failure and attack A centralized anchoring architecture is generally more vulnerable to a single point of failure or attack, requiring duplication and backups of the support functions. On the other hand, a distributed mobility management architecture has intrinsically mitigated the problem to a local network which is then of a smaller scope. In addition, the availability of such functions in neighboring networks has already provided the needed architecture to support protection. 5. Requirements After reviewing the problems and limitations of centralized deployment in Section 4, this section states the requirements as follows: 1. Distributed mobility requirement: The mobility management functions in interconnecting networks be available in multiple locations and therefore are always close to any node so that the node may perform handover with session continuity without routing the data-plane traffic via a centralized anchor. It is noted that centralized functions in the control plane are not excluded and should still be possible. This requirement enables mobility management deployment in a Chan (Ed.) Expires September 4, 2012 [Page 14] Internet-Draft DMM-Reqs March 2012 distributed architure to avoid the non-optimal routes described in Section 4.1. It enables placing the mobility anchor closer to the access network to which the mobile node is attached, thereby supporting the more flattened network and the CDN networks described in Section 4.2. Such a distributed architecture is more scalable than a centralized one as described in Section 4.4, and avoids the single point of failure and attack as described in Section 4.8. 2. Dynamic mobility requirement: A network supporting a mix of mobile nodes some of which may be stationary for extended time while others may be actively mobile may minimize traffic overhead and avoid unnecessary mobility support. This requirement addresses the problems of unnecessary mobility support described in Section 4.5 and of the mobility signaling overhead with peer-to-peer communication described in Section 4.7. 3. To further ease the deployment it is desirable that the mobility management can be deployed in a mix of hierarchical architecture and distributed architecture and the different variants and extensions of MIP are compatible and integrated. 6. Security Considerations TBD 7. IANA Considerations None 8. Co-authors and Contributors This problem statement document is a joint effort among the following participants. Each individual has made significant contributions to this work. Dapeng Liu: liudapeng@chinamobile.com Pierrick Seite: pierrick.seite@orange-ftgroup.com Hidetoshi Yokota: yokota@kddilabs.jp Charles E. Perkins: charliep@computer.org Chan (Ed.) Expires September 4, 2012 [Page 15] Internet-Draft DMM-Reqs March 2012 Melia Telemaco: telemaco.melia@alcatel-lucent.com Elena Demaria: elena.demaria@telecomitalia.it Wassim Michel Haddad: Wassam.Haddad@ericsson.com Hui Deng: denghui@chinamobile.com Seok Joo Koh: sjkoh@knu.ac.kr Rute Sofia (in collaboration with Tiago Condeixa, Andrea Nascimento, and Susana Sargento): rute.sofia@ulusofona.pt 9. References 9.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. 9.2. Informative References [I-D.PMIP-dmc] Koh, S., Kim, J., Jung, H., and Y. Han, "Use of Proxy Mobile IPv6 for Distributed Mobility Control", draft-sjkoh-mext-pmip-dmc-01 (work in progress), March 2011. [I-D.dmm-scenario] Yokota, H., Seite, P., Demaria, E., and Z. Cao, "Use case scenarios for Distributed Mobility Management", draft-yokota-dmm-scenario-00 (work in progress), October 2010. [Paper-Characterization.Mobility.Management] Nascimento, A., Sofia, R., Condeixa, T., and S. Sargento, "A Characterization of Mobility Management in User-centric Networks", Proceeding of NEW2AN 2011 in Lecture Notes in Computer Science, 2011, Volume 6869/2011, 314-325, DOI: 10.1007/978-3-642-22875-9_29, August 2011. [Paper-Distributed.Centralized.Mobility] Bertin, P., Bonjour, S., and J-M. Bonnin, "A Distributed or Centralized Mobility", Proceedings of Global Communications Conference (GlobeCom), December 2009. [Paper-Distributed.Dynamic.Mobility] Chan (Ed.) Expires September 4, 2012 [Page 16] Internet-Draft DMM-Reqs March 2012 Bertin, P., Bonjour, S., and J-M. Bonnin, "A Distributed Dynamic Mobility Management Scheme Designed for Flat IP Architectures", Proceedings of 3rd International Conference on New Technologies, Mobility and Security (NTMS), 2008. [Paper-Distributed.Mobility.PMIP] Chan, H., "Proxy Mobile IP with Distributed Mobility Anchors", Proceedings of GlobeCom Workshop on Seamless Wireless Mobility, December 2010. [Paper-Distributed.Mobility.Review] Chan, H., Yokota, H., Xie, J., Seite, P., and D. Liu, "Distributed and Dynamic Mobility Management in Mobile Internet: Current Approaches and Issues, Journal of Communications, vol. 6, no. 1, pp. 4-15, Feb 2011.", Proceedings of GlobeCom Workshop on Seamless Wireless Mobility, February 2011. [Paper-Distributed.Mobility.SAE] Fisher, M., Anderson, F., Kopsel, A., Schafer, G., and M. Schlager, "A Distributed IP Mobility Approach for 3G SAE", Proceedings of the 19th International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC), 2008. [Paper-Locating.User] Kirby, G., "Locating the User", Communication International, 1995. [Paper-Migrating.Home.Agents] Wakikawa, R., Valadon, G., and J. Murai, "Migrating Home Agents Towards Internet-scale Mobility Deployments", Proceedings of the ACM 2nd CoNEXT Conference on Future Networking Technologies, December 2006. [Paper-New.Perspective] Condeixa, T., Matos, R., Matos, A., Sargento, S., and R. Sofia, "A New Perspective on Mobility Management: Scenarios and Approaches", Proceeding of 2nd International ICST Conference on Mobile Networks and Management (NONAMI) 2010, pp 340-353., September 2010. [RFC3775] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support in IPv6", RFC 3775, June 2004. [RFC4068] Koodli, R., "Fast Handovers for Mobile IPv6", RFC 4068, July 2005. Chan (Ed.) Expires September 4, 2012 [Page 17] Internet-Draft DMM-Reqs March 2012 [RFC4988] Koodli, R. and C. Perkins, "Mobile IPv4 Fast Handovers", RFC 4988, October 2007. [RFC5213] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K., and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008. [RFC5380] Soliman, H., Castelluccia, C., ElMalki, K., and L. Bellier, "Hierarchical Mobile IPv6 (HMIPv6) Mobility Management", RFC 5380, October 2008. [RFC5454] Tsirtsis, G., Park, V., and H. Soliman, "Dual-Stack Mobile IPv4", RFC 5454, March 2009. [RFC5555] Soliman, H., "Mobile IPv6 Support for Dual Stack Hosts and Routers", RFC 5555, June 2009. [RFC5949] Yokota, H., Chowdhury, K., Koodli, R., Patil, B., and F. Xia, "Fast Handovers for Proxy Mobile IPv6", RFC 5949, September 2010. Author's Address H Anthony Chan (editor) Huawei Technologies 5340 Legacy Dr. Building 3, Plano, TX 75024, USA Email: h.a.chan@ieee.org - Dapeng Liu China Mobile Unit2, 28 Xuanwumenxi Ave, Xuanwu District, Beijing 100053, China Email: liudapeng@chinamobile.com - Pierrick Seite France Telecom - Orange 4, rue du Clos Courtel, BP 91226, Cesson-Sevigne 35512, France Email: pierrick.seite@orange-ftgroup.com - Hidetoshi Yokota KDDI Lab 2-1-15 Ohara, Fujimino, Saitama, 356-8502 Japan Email: yokota@kddilabs.jp - Charles E. Perkins Tellabs Inc. 4555 Great America Parkway, #S5-130 Email: charliep@computer.org - Chan (Ed.) Expires September 4, 2012 [Page 18] Internet-Draft DMM-Reqs March 2012 Melia Telemaco Alcatel-Lucent Bell Labs Email: telemaco.melia@alcatel-lucent.com - Wassim Michel Haddad Ericsson 300 Holger Dr, San Jose, CA 95134, USA Email: Wassam.Haddad@ericsson.com - Elena Demaria Telecom Italia via G. Reiss Romoli, 274, TORINO, 10148, Italy Email: elena.demaria@telecomitalia.it - Seok Joo Koh Kyungpook National University, Korea Email: sjkoh@knu.ac.kr - Rute Sofia University Lusofona, Portugal Email: rute.sofia@ulusofona.pt - Chan (Ed.) Expires September 4, 2012 [Page 19]