DMM WG JC. Zuniga Internet-Draft InterDigital Intended status: Informational CJ. Bernardos Expires: April 26, 2013 UC3M T. Melia Alcatel-Lucent C. Perkins Futurewei October 23, 2012 Mobility Practices and DMM Gap Analysis draft-zuniga-dmm-gap-analysis-02 Abstract This document describes practices for the deployment of existing mobility protocols in a distributed mobility management environment, and identifies the limitations in the current practices with respect to providing the expected functionality. The practices description and gap analysis are performed for IP-based mobility protocols, dividing them into two main solution families: client- and network-based. 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 April 26, 2013. 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 Zuniga, et al. Expires April 26, 2013 [Page 1] Internet-Draft DMM Gap Analysis October 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. Zuniga, et al. Expires April 26, 2013 [Page 2] Internet-Draft DMM Gap Analysis October 2012 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Practices: deployment of existing solutions in a DMM fashion . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.1. Client-based mobility . . . . . . . . . . . . . . . . . . 4 2.1.1. Mobile IPv6 / NEMO . . . . . . . . . . . . . . . . . . 5 2.1.2. Mobile IPv6 Route Optimization . . . . . . . . . . . . 5 2.1.3. Hierarchical Mobile IPv6 . . . . . . . . . . . . . . . 7 2.1.4. Home Agent switch . . . . . . . . . . . . . . . . . . 8 2.1.5. Flow Mobility . . . . . . . . . . . . . . . . . . . . 8 2.1.6. Source Address Selection . . . . . . . . . . . . . . . 8 2.2. Network-based mobility . . . . . . . . . . . . . . . . . . 9 2.2.1. Proxy Mobile IPv6 . . . . . . . . . . . . . . . . . . 9 2.2.2. Local Routing . . . . . . . . . . . . . . . . . . . . 10 2.2.3. LMA runtime assignment . . . . . . . . . . . . . . . . 10 2.2.4. Source Address Selection . . . . . . . . . . . . . . . 11 2.2.5. Multihoming in PMIPv6 . . . . . . . . . . . . . . . . 11 3. Gap Analysis: limitations in current practices . . . . . . . . 12 3.1. Client-based mobility . . . . . . . . . . . . . . . . . . 12 3.1.1. REQ1: Distributed deployment . . . . . . . . . . . . . 12 3.1.2. REQ2: Transparency to Upper Layers when needed . . . . 13 3.1.3. REQ3: IPv6 deployment . . . . . . . . . . . . . . . . 14 3.1.4. REQ4: Existing mobility protocols . . . . . . . . . . 14 3.1.5. REQ5: Compatibility . . . . . . . . . . . . . . . . . 15 3.1.6. REQ6: Security considerations . . . . . . . . . . . . 15 3.2. Network-based mobility . . . . . . . . . . . . . . . . . . 15 3.2.1. REQ1: Distributed deployment . . . . . . . . . . . . . 15 3.2.2. REQ2: Transparency to Upper Layers when needed . . . . 17 3.2.3. REQ3: IPv6 deployment . . . . . . . . . . . . . . . . 17 3.2.4. REQ4: Existing mobility protocols . . . . . . . . . . 18 3.2.5. REQ5: Compatibility . . . . . . . . . . . . . . . . . 18 3.2.6. REQ6: Security considerations . . . . . . . . . . . . 18 4. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19 6. Security Considerations . . . . . . . . . . . . . . . . . . . 19 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 20 7.1. Normative References . . . . . . . . . . . . . . . . . . . 20 7.2. Informative References . . . . . . . . . . . . . . . . . . 21 Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . . 22 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 22 Zuniga, et al. Expires April 26, 2013 [Page 3] Internet-Draft DMM Gap Analysis October 2012 1. Introduction The Distributed Mobility Management (DMM) approach aims at setting up IP networks so that traffic is distributed in an optimal way and does not rely on centrally deployed anchors to manage IP mobility sessions. A first step towards the definition of DMM solutions is the definition of the problem of distributed mobility management and the identification of the main requirements for a distributed mobility management solution [I-D.ietf-dmm-requirements]. We first analyze existing practices of deployment of IP mobility solutions from a DMM perspective [I-D.perkins-dmm-matrix], [I-D.patil-dmm-issues-and-approaches2dmm]. After that, a gap analysis is carried out, identifying what can be achieved with existing solutions and what is missing in order to meet the DMM requirements identified in [I-D.ietf-dmm-requirements]. 2. Practices: deployment of existing solutions in a DMM fashion This section documents practices for the deployment of existing mobility protocols in a distributed mobility management (DMM) fashion. The scope is limited to existing IPv6-based mobility protocols, such as Mobile IPv6 [RFC6275], NEMO Basic Support Protocol [RFC3963], Proxy Mobile IPv6 [RFC5213], and their extensions, such as Hierarchical Mobile IPv6 [RFC5380], Mobile IPv6 Fast Handovers [RFC5568] or Localized Routing for Proxy Mobile IPv6 [RFC6705], among others [RFC6301]. The section is divided in two parts: client-based and network-based mobility solutions. 2.1. Client-based mobility Mobile IPv6 (MIPv6) [RFC6275] and its extension to support mobile networks, the NEMO Basic Support protocol (hereafter, simply NEMO) [RFC3963] are well-known client-based IP mobility protocols. They heavily rely on the function of the Home Agent (HA), a centralized anchor, to provide mobile nodes (hosts and routers) with mobility support. We next describe how Mobile IPv6/NEMO and several additional protocol extensions can be deployed to meet some of the DMM requirements [I-D.ietf-dmm-requirements]. Zuniga, et al. Expires April 26, 2013 [Page 4] Internet-Draft DMM Gap Analysis October 2012 2.1.1. Mobile IPv6 / NEMO <- INTERNET -> <- HOME NETWORK -> <---- ACCESS NETWORK ----> ------- ------- | CN1 | ------- | AR1 |-(o) zzzz (o) ------- | HA1 | ------- | ------- (MN1 anchored at HA1) ------- ------- | MN1 | | AR2 |-(o) ------- ------- ------- | HA2 | ------- ------- | AR3 |-(o) zzzz (o) ------- | ------- (MN2 anchored at HA2) ------- | CN2 | ------- | MN2 | ------- | AR4 |-(o) ------- ------- CN1 CN2 HA1 HA2 AR1 MN1 AR3 MN2 | | | | | | | | |<------------>|<=================+=====>| | | BT mode | | | | | | | | | |<----------------------------------------+----->| RO mode | | | | | | | | Figure 1: Distributed operation of Mobile IPv6 (BT and RO) / NEMO Due to the heavy dependence on the home agent role, the base Mobile IPv6 and NEMO protocols (i.e., without additional extensions) cannot be easily deployed in a distributed fashion. One approach would be to deploy several HAs (as shown in Figure 1), and assign to each MN the one closest to its topological location [RFC4640], [RFC5026], [RFC6611]. In the example shown in Figure 1, MN1 is assigned HA1 (and a home address anchored by HA1), while MN2 is assigned HA2. Note that current Mobile IPv6 / NEMO specifications do not allow the use of multiple home agents by a mobile node simultaneously, and therefore the benefits of this deployment model shown here are limited. For example, if MN1 moves and attaches to AR3, the path followed by data packets would be suboptimal, as they have to traverse HA1, which is no longer close to the topological attachment point of MN1. 2.1.2. Mobile IPv6 Route Optimization One of the main goals of DMM is to avoid the suboptimal routing caused by centralized anchoring. By default, Mobile IPv6 and NEMO use the so-called Bidirectional Tunnel (BT) mode, in which data Zuniga, et al. Expires April 26, 2013 [Page 5] Internet-Draft DMM Gap Analysis October 2012 traffic is always encapsulated between the MN and its HA. Mobile IPv6 also specifies the Route Optimization (RO) mode, which allows the MN to update its current location on the CNs, and then use the direct path between them. Using the example shown in Figure 1, MN1 is using BT mode with CN2 and MN2 is in RO mode with CN1. Note that this RO mode has several drawbacks: o The RO mode is only supported by Mobile IPv6. There is no route optimization support standardized for the NEMO protocol, although many different solutions have been proposed. o The RO mode requires additional signaling, which adds some protocol overhead. o The signaling required to enable RO involves the home agent, and it is repeated periodically because of security reasons [RFC4225]. This basically means that the HA remains as single point of failure, because the Mobile IPv6 RO mode does not mean HA-less operation. o The RO mode requires additional support on the correspondent node (CN). Notwithstanding these considerations, RO mode does offer the possibility of substantially reducing traffic through the Home Agent, when it can be supported on the relevant network nodes. Zuniga, et al. Expires April 26, 2013 [Page 6] Internet-Draft DMM Gap Analysis October 2012 2.1.3. Hierarchical Mobile IPv6 <- INTERNET -> <- HOME NETWORK -> <------- ACCESS NETWORK -------> ----- /|AR1|-(o) zz (o) -------- / ----- | | MAP1 |< ------- -------- \ ----- | MN1 | ------- \|AR2| ------- | CN1 | ----- HoA anchored ------- ----- at HA1 ------- /|AR3| RCoA anchored | HA1 | -------- / ----- at MAP1 ------- | MAP2 |< LCoA anchored -------- \ ----- at AR1 \|AR4| ------- ----- | CN2 | ----- ------- /|AR5| -------- / ----- | MAP3 |< -------- \ ----- \|AR6| ----- CN1 CN2 HA1 MAP1 AR1 MN1 | | | | ________|__________ | |<------------------>|<==============>|<________+__________>| HoA | | | | | | | |<-------------------------->|<===================>| RCoA | | | | | | Figure 2: Hierarchical Mobile IPv6 Hierarchical Mobile IPv6 (HMIPv6) [RFC5380] allows reducing the amount of mobility signaling as well as improving the overall handover performance of Mobile IPv6 by introducing a new hierarchy level to handle local mobility. The Mobility Anchor Point (MAP) entity is introduced as a local mobility handling node deployed closer to the mobile node. When HMIPv6 is used, the MN has two different temporal addresses: the Regional Care-of Address (RCoA) and the Local Care-of Address (LCoA). The RCoA is anchored at one MAP, that plays the role of local home agent, while the LCoA is anchored at the access router level. The mobile node uses the RCoA as the CoA signaled to its home agent. Therefore, while roaming within a local domain handled by the same MAP, the mobile node does not need to update its home agent (i.e., Zuniga, et al. Expires April 26, 2013 [Page 7] Internet-Draft DMM Gap Analysis October 2012 the mobile node does not change RCoA). The use of HMIPv6 allows some route optimization, as a mobile node may decide to directly use the RCoA as source address for a communication with a given correspondent node, notably if the MN does not expect to move outside the local domain during the lifetime of the communication. This can be seen as a potential DMM mode of operation. In the example shown in Figure 2, MN1 is using its global HoA to communicate with CN1, while it is using its RCoA to communicate with CN2. Additionally, a local domain might have several MAPs deployed, enabling hence different kind of HMIPv6 deployments (e.g., flat and distributed). The HMIPv6 specification supports a flexible selection of the MAP (e.g., based on the distance between the MN and the MAP, taking into consideration the expected mobility pattern of the MN, etc.). 2.1.4. Home Agent switch The Home Agent switch specification [RFC5142] defines a new mobility header for signaling a mobile node that it should acquire a new home agent. Although the purposes of this specification do not include the case of changing the mobile node's home address, as that might imply loss of connectivity for ongoing connections, it could be used to force the change of home agent in those situations where there are no active data sessions running that cannot cope themselves with a change of home address. 2.1.5. Flow Mobility There exist different protocols meant to support flow mobility with Mobile IPv6, namely the multiple care-of address registration [RFC5648], the flow bindings in Mobile IPv6 and NEMO [RFC6089] and the traffic selectors for flow bindings [RFC6088]. The use of these extensions allows a mobile node to associate different flows with different care-of addresses that the mobile owns at a given time. This could also be used, combined with the route optimization support, to improve the paths followed by data packets. 2.1.6. Source Address Selection The IPv6 socket API for source address selection [RFC5014], [RFC6724] can be used by an application running on a mobile node to express its preference of using a home address or a care-of address in a given connection. This allows, for example, an application which can survive an IP address change to always prefer the use of a care-of address. Similarly, and as mentioned in [RFC6275], a mobile node can Zuniga, et al. Expires April 26, 2013 [Page 8] Internet-Draft DMM Gap Analysis October 2012 also prefer the use of a care-of address for sessions that are going to finish before the mobile node hands off to a different attachment point (e.g., short-lived connections like DNS dialogs). This could be based on user or operator policies, and it is typically performed by a connection manager (e.g., [I-D.seite-mif-cm]). 2.2. Network-based mobility Proxy Mobile IPv6 (PMIPv6) [RFC5213] and GPRS Tunneling Protocol (GTP) [3GPP.29.060] are the main network-based IP mobility protocols specified for IPv6. Architecturally, both solutions are similar, as they rely on the function of the Local Mobility Anchor (LMA) or Packet Data Gateway (PDG) to provide mobile nodes with mobility support, without requiring the involvement of the mobile nodes, and providing the required functionality by the Mobile Access Gateway (MAG), Service Data Gateway (SGW), or Evolved Packet Data Gateway (ePDG). We next describe how network-based mobility protocols and several additional protocol extensions can be deployed to meet some of the DMM requirements [I-D.ietf-dmm-requirements]. 2.2.1. Proxy Mobile IPv6 <- INTERNET -><- HOME NET -><----------- ACCESS NETWORK ------------> ------- | CN1 | -------- -------- -------- ------- -------- | MAG1 | | MAG2 | | MAG3 | | LMA1 | ---+---- ---+---- ---+---- ------- -------- | | | | CN2 | (o) (o) (o) ------- -------- x x | LMA2 | x x ------- -------- (o) (o) | CN3 | | | ------- ---+--- ---+--- Anchored | MN1 | Anchored | MN2 | at LMA1 -> ------- at LMA2 -> ------- CN1 CN2 LMA1 LMA2 MAG1 MN1 MAG3 MN2 | | | | | | | | |<------------>|<================>|<---->| | | | | | | | | | | | |<------------>|<========================>|<----->| | | | | | | | | Figure 3: Distributed operation of Proxy Mobile IPv6 As with Mobile IPv6, plain Proxy Mobile IPv6 operation cannot be easily decentralized. One simple, but still suboptimal, approach Zuniga, et al. Expires April 26, 2013 [Page 9] Internet-Draft DMM Gap Analysis October 2012 would be to deploy several local mobility anchors and use a topological position-based assignment to attach mobile nodes (an example of this type of assignment is shown in Figure 3. This assignment can be static or dynamic (as described in Section 2.2.3). The main advantage of this simple approach is that the IP address anchor (i.e., the LMA) is placed close to the mobile node, and therefore resulting paths are close-to-optimal. On the other hand, as soon as the mobile node moves, the resulting path starts to deviate from the optimal one. 2.2.2. Local Routing [RFC6705] enables optimal routing in Proxy Mobile IPv6 in three cases: i) when two communicating MNs are attached to the same MAG and LMA, ii) when two communicating MNs are attached to different MAGs but to the same LMA, and iii) when two communicating MNs are attached to the same MAG but have different LMAs. In these three cases, data traffic between the two mobile nodes does not traverse the LMA(s), thus providing some form of distribution, since the traffic is locally routed at the edge. The main disadvantage of this approach is that it only tackles the MN-to-MN communication scenario, and only under certain circumstances. In the context of 3GPP, the closest analogy is the use of the X2 interface between two eNBs to directly exchange data traffic during handover procedures. 3GPP does not foresee the use of local routing at any other point of the network given the structure of the EPS bearer model. 2.2.3. LMA runtime assignment [RFC6463] specifies a runtime local mobility anchor assignment functionality and corresponding mobility options for Proxy Mobile IPv6. This runtime local mobility anchor assignment takes place during the Proxy Binding Update / Proxy Binding Acknowledgment message exchange between a mobile access gateway and a local mobility anchor. While this mechanism is mainly aimed for load-balancing purposes, it can also be used to select an optimal LMA from the routing point of view. A runtime LMA assignment can be used to change the assigned LMA of an MN, for example in case when the mobile node does not have any session active, or when running sessions can survive an IP address change. In the context of 3GPP networks, similar considerations have been discussed with respect to Selective IP Traffic Offload (SIPTO) above the RAN or at the macro. When an MN is allowed to get some SIPTO Zuniga, et al. Expires April 26, 2013 [Page 10] Internet-Draft DMM Gap Analysis October 2012 service, a geographically close PGW is selected. That is, upon establishment of the Packet Data Network (PDN) connection, the MN is configured with an IP address belonging to an optimal P-GW from a routing point of view. The drawback is that if the MN moves out of the region covered by that PGW, the mobile node will have to disconnect from the network and reconnect again, since no seamless session continuity is provided. In this sense, applications that cannot not survive an IP address change will present an unpredictable behavior. 2.2.4. Source Address Selection Also in the context of network-based mobility, the use of a source address selection API can be considered as means to achieve better routing (by using different anchors). For instance, an MN connected to a PMIPv6 domain could attach two different wireless network interfaces to two different MAGs, hence configuring a different set of HNPs on both interfaces (potentially combining both IPv4 and IPv6). Based on application requirements or operator's policies the connection manager logic could instruct the IP stack on the MN to route selected traffic on a specific wireless interface [I-D.seite-mif-cm]. It should be noted that source address selection mostly provides for better routing but not session continuity. In the context of 3GPP networks, two ongoing study items are currently addressing the issue of selecting a wireless interface or an IP address for a specific application. The study item DIDA (Data IDentification in ANDSF) is addressing the need to map an application ID to a specific wireless interface, while the study item Operator Policies for IP Interface Selection (OPIIS) is addressing the need of selecting the right APN for a given application. Taking into account that there is a one to one link between APN and PDN connection (IP address) the second study item clearly addresses from a 3GPP perspective the same problem space as [RFC6724]. 2.2.5. Multihoming in PMIPv6 PMIPv6 provides some multihoming support. RFC 5213 specifies that the LMA can maintain one mobility session per attached interface and that upon handover the full set of HNPs can be moved to another interface in case of inter-technology handover (MAGs providing different wireless access technology) or maintained on the same interface in case of intra-technology handover (MAGs providing the same wireless access technology). An MN can also attach two different interfaces to the PMIPv6 domain (as described in Section 2.2.4) two different interfaces to the PMIPv6 domain, hence resulting in a multihomed device being able to send/receive traffic sequentially or simultaneously from both network interfaces. Zuniga, et al. Expires April 26, 2013 [Page 11] Internet-Draft DMM Gap Analysis October 2012 [I-D.ietf-netext-pmipv6-flowmob] extends the base RFC5213 capabilities so that a mobility session can be shared across two different access networks. It derives that a selected flow could be routed through different paths, hence achieving some sort of better routing. Yet all the traffic is anchored at centralized anchor points. In the context of 3GPP networks the Multi-Access PDN Connectivity (MAPCON) feature addresses the use of multiple PDN connections, hence the use of multiple wireless interfaces either sequentially or simultaneously. 3. Gap Analysis: limitations in current practices This section identifies the limitations in the current practices (documented in Section 2) with respect to the requirements listed in [I-D.ietf-dmm-requirements]. The section is also divided in two parts: client-based and network- based mobility. Each part analyzes how well the requirements listed in [I-D.ietf-dmm-requirements] are covered/met by the current practices, highlighting existing limitations and gaps. 3.1. Client-based mobility 3.1.1. REQ1: Distributed deployment MIPv6 / NEMO A careful home agent deployment and policy configuration of the Mobile IPv6 / NEMO protocols can achieve some distribution. However, as soon as the mobile node moves and changes its initial attachment point, the anchors are no longer placed optimally, incurring in sub-optimal routes. If the mobile node is not expected to move within a limited area, this configuration might be considered sufficient. Otherwise, additional mechanisms to support dynamic anchoring would be needed. Mobile IPv6 RO The use of route optimization support enables a close-to anchor-less operation, which effectively can be considered as a fully distributed configuration. However, as explained before in this document, the home agent is still used for the signaling and therefore remains as a critical centralized component. Additionally, there is no standardized RO support for network mobility. Zuniga, et al. Expires April 26, 2013 [Page 12] Internet-Draft DMM Gap Analysis October 2012 HMIPv6 The use of hierarchical mobile IPv6 can be seen as a step forward compared to a careful deployment of multiple home agents and its proper configuration, as it allows a mobile node to roam within a local domain, reducing the handover latency as well as the signaling overhead. If used together with mobile IPv6, traffic still has to traverse the centralized home agent, and therefore no distributed operation is achieved. HA switch The home agent switch specification can be used to enable obtaining more benefits from a multiple-HA deployment, as the mobile node could be instructed to switch to a closer home agent. To avoid packet loss, this switch must be performed at periods of time in which the mobile node does not have any active connection running. Even if some packet loss were acceptable for active sessions, the change of home address would also require the mobile node to re-establish those sessions. Flow mobility Considerations made for previous scenarios (e.g. for Route Optimization) could also apply here, extending those scenarios by the use of multiple attached interfaces. SA selection API The use of proper source address selection decisions, enabled by smart connection managers [I-D.seite-mif-cm], or mobility aware applications using a selection API [RFC5014], [RFC6724], would allow the mobile node to realize substantial benefits from deployments providing multiple anchors. 3.1.2. REQ2: Transparency to Upper Layers when needed MIPv6 / NEMO As a mobility protocol, the solution is transparent to the upper layers. However, as described before, this transparency comes with the cost of suboptimal routes if the MN moves away from its initial attachment point. Mobile IPv6 RO The use of the route optimization support is transparent to the upper layers. HMIPv6 The use of HMIPv6 is transparent to the upper layers. HA switch The use of the home agent switch functionality is not transparent to the upper layers, as a change of home agent normally implies a change of home address. Therefore, it is only recommended to switch home agent when there is no active session running on the mobile node. Zuniga, et al. Expires April 26, 2013 [Page 13] Internet-Draft DMM Gap Analysis October 2012 Flow mobility The use of flow mobility mechanisms is transparent to the upper layers. SA selection API The use of an intelligent source address mechanisms is transparent to the upper layers if performed by the connection manager. However if the selection is performed by the applications themselves, via the use of the API, then applications have to be mobility-aware. 3.1.3. REQ3: IPv6 deployment MIPv6 / NEMO Mobile IPv6 / NEMO protocols primarily support IPv6, although there are some extensions defined to also offer some IPv4 support [RFC5555]. Mobile IPv6 RO Route optimization only supports IPv6. HMIPv6 HMIPv6 is only defined for IPv6. HA switch The home agent switch specification supports only IPv6, although the use of the defined mechanisms to support dual stack IPv4/IPv6 mobile nodes would also enable some IPv4 support. Flow mobility Flow mobility is only defined for IPv6. SA selection API The use of source address selection mechanisms supports both IPv6 and IPv4. 3.1.4. REQ4: Existing mobility protocols MIPv6 / NEMO These approaches are ones of the base IETF-standardized mobility protocols: [RFC6275] and [RFC3963]. Mobile IPv6 RO This approach is based on an existing protocol [RFC6275]. HMIPv6 This approach is based on an existing protocol [RFC5380]. HA switch This approach is based on an existing protocol [RFC5142]. Flow mobility This approach is based on existing protocols [RFC5648], [RFC6089] and [RFC6088]. SA selection API This approach is based on existing protocols [RFC6724] and [RFC5014]. Zuniga, et al. Expires April 26, 2013 [Page 14] Internet-Draft DMM Gap Analysis October 2012 3.1.5. REQ5: Compatibility MIPv6 / NEMO This approach would be compatible with other protocols and work between trusted administrative domains, although as described before its operation would not provide the benefits of a fully distributed mechanism. The combination of different IP mobility protocols might have a performance/complexity cost associated, as described in [A. de la Oliva, et al.]. Mobile IPv6 RO This approach would be compatible with other protocols and work between trusted administrative domains, as long as mobile IPv6 is allowed. However, as highlighted before, mobile IPv6 route optimization requires specific support at the correspondent nodes. HMIPv6 HMIPv6 is compatible with other protocols. HA switch This approach would be compatible with other protocols and work between trusted administrative domains. Flow mobility This approach would be compatible with other protocols and work between trusted administrative domains. SA selection API This approach has no impact in terms of compatibility or use between trusted administrative domains. 3.1.6. REQ6: Security considerations MIPv6 / NEMO This approach includes security considerations. Mobile IPv6 RO This approach includes security considerations. HMIPv6 This approach includes security considerations. HA switch This approach includes security considerations. Flow mobility This approach includes security considerations. SA selection API This approach does not have security issues. 3.2. Network-based mobility 3.2.1. REQ1: Distributed deployment Zuniga, et al. Expires April 26, 2013 [Page 15] Internet-Draft DMM Gap Analysis October 2012 PMIPv6 As for the case of MIPv6, a careful deployment of the local mobility anchors and policy configuration of the Proxy Mobile IPv6 protocol can achieve some distribution. However, as soon as the mobile node moves and changes its initial attachment point, the anchor is no longer placed optimally, incurring in sub-optimal routes, which might be quite noticeable in case of medium to large PMIPv6 domains. If the mobile node movement is restricted to a well known limited area and/or the PMIPv6 domain is not large, this configuration might be considered sufficient. Otherwise, additional mechanisms to support dynamic anchoring would be needed. Local Routing As mentioned before, it enables optimal routing in three cases: the LMA manages the traffic of two mobile nodes connected to the same MAG, the LMA manages the traffic of two mobile nodes connected to different MAGs, the MAG manages the traffic of two mobile nodes connected to different LMAs. LR does not consider the case where the traffic should be optimized considering different MAGs and different LMAs. Inter LMA communication is not in scope. LR only enables better routing and does not consider the distribution of mobility anchors as such. LMA Runtime Assignment The LMA runtime assignment is used to allocate an optimal LMA mostly for load balancing purposes, for instance in scenarios where LMAs run in a datacenter-like infrastructure. It can be used to allocate a different LMA based on other policies such as routing although is not clear how the technology can be used to achieve distributed mobility management, especially considering scalability issues. Source Address Selection It can help in selecting a given IP source address although the current specifications have many limitations (for instance prefer IPv6 over IPv4, prefer HoA instead of CoA) and the socket extensions [RFC5014] require changes in the node. This solution alone is not sufficient to achieve anchors distribution in case of session continuity requirements, as some control logic (e.g., from a connection manager [I-D.seite-mif-cm]) is needed to intelligently perform source address selection. Multihoming in PMIPv6 As summarized in the previous section a single mobility session belongs to a single LMA (at the most the same mobility session is shared across two access networks). As of today there is no possibility to distribute anchors and to move the session between different LMAs. Zuniga, et al. Expires April 26, 2013 [Page 16] Internet-Draft DMM Gap Analysis October 2012 3.2.2. REQ2: Transparency to Upper Layers when needed PMIPv6 As a mobility protocol, the solution provides transparent mobility support for a mobile node while roaming within the PMIPv6 domain (e.g., if a mobile node moves outside the domain, established sessions cannot be maintained, unless the MN implements Mobile IPv6). However, as for the MIPv6 case, this transparent mobility support comes with the cost of suboptimal routes if the MN moves away from its initial attachment point, especially in large PMIPv6 domains. Local Routing During HO the standard mechanisms are used. In this sense if there is a MAG change while LR is enabled signaling is exchanged to inform the target MAG that upon handover LR should be re-established. The inter LMA case is not supported. For this solution the mobility context is always up, all the traffic receive seamless service. LMA Runtime Assignment Seamless support is provided as per RFC 5213. For this solution the mobility context is always up, all the traffic receive seamless service. Source Address Selection No seamless support is currently provided, since it requires solutions such as IP flow mobility for PMIPv6 [I-D.ietf-netext-pmipv6-flowmob]. Multihoming in PMIPv6 Seamless support falls back to standard PMIPv6 operations extended for IP flow mobility support. For this solution the mobility context is always up, all the traffic receive seamless service. 3.2.3. REQ3: IPv6 deployment PMIPv6 Although Proxy Mobile IPv6 primarily support IPv6, there are also extensions defined to also offer some limited IPv4 support [RFC5844]. Local Routing It supports both IPv4 (limited to the support provided by [RFC5844]) and IPv6. LMA Runtime Assignment It supports both IPv4 (limited to the support provided by [RFC5844]) and IPv6. Source Address Selection It supports both IPv4 and IPv6. Zuniga, et al. Expires April 26, 2013 [Page 17] Internet-Draft DMM Gap Analysis October 2012 Multihoming in PMIPv6 It supports both IPv4 (limited to the support provided by [RFC5844]) and IPv6. 3.2.4. REQ4: Existing mobility protocols PMIPv6 This approach is one of the base IETF-standardized mobility protocols: [RFC5213]. Local Routing It reuses [RFC5213]. LMA Runtime Assignment It reuses [RFC5213]. Source Address Selection This approach is based on local support on the terminal only. Multihoming in PMIPv6 It reuses [RFC5213]. 3.2.5. REQ5: Compatibility PMIPv6 This protocol is compatible with other protocols and can operate between trusted administrative domains, although there may be an associated penalty in terms of performance and/or complexity [A. de la Oliva, et al.]. Local Routing Since it extends [RFC5213], compatibility with existing network deployments and end hostsis provided. LMA Runtime Assignment Since it extends [RFC5213], compatibility with existing network deployments and end hostsis provided. Source Address Selection To enable the full set of use cases mentioned above extensions are required thus impacting the landscape of mobile devices. The extensions should not impact the network. Multihoming in PMIPv6 Since it extends [RFC5213], compatibility is provided. 3.2.6. REQ6: Security considerations PMIPv6 This approach includes security considerations. Local Routing It reuses [RFC5213]. As such, the same security considerations apply. Zuniga, et al. Expires April 26, 2013 [Page 18] Internet-Draft DMM Gap Analysis October 2012 LMA Runtime Assignment It reuses [RFC5213]. As such, the same security considerations apply. Source Address Selection There is not signaling involved to perform this action. Multihoming in PMIPv6 It reuses [RFC5213]. As such, the same security considerations apply. 4. Summary This section summarizes the identified IP-mobility protocols and their mappings (YES, NO, LIMITED) to the different dynamic mobility management requirements listed in [I-D.ietf-dmm-requirements]. +-------------+------+------+-----------+------+------+------+ | | REQ1 | REQ2 | REQ3 | REQ4 | REQ5 | REQ6 | +-------------+------+------+-----------+------+------+------+ | MIPv6/NEMO | NO | LIM | v6/v4 | YES | LIM | YES | | MIPv6 RO | NO | YES | v6 | YES | LIM | YES | | HMIPv6 | NO | YES | v6 | YES | LIM | YES | | HA switch | NO | NO | v6 | YES | YES | YES | | FlowMob | NO | YES | v6/LIM v4 | YES | YES | YES | | SAS w/ CB | NO | YES | v6/v4 | YES | YES | YES | | PMIPv6 | NO | LIM | v6/LIM v4 | YES | LIM | YES | | LR | NO | LIM | v6/LIM v4 | YES | YES | YES | | LMA RA | LIM | LIM | v6/LIM v4 | YES | YES | YES | | SAS w/ NB | NO | NO | v6/v4 | YES | YES | YES | | MuHo PMIPv6 | NO | LIM | v6/LIM v4 | YES | YES | YES | +-------------+------+------+-----------+------+------+------+ 5. IANA Considerations No IANA considerations. 6. Security Considerations This is an informational document that analyzes practices for the deployment of existing mobility protocols in a distributed mobility management environment, and identifies the limitations in the current practices. One of the requirements that these practices has to meet is to take into account security aspects, including confidentiality and integrity. This is briefly analyzed for each of the considered practices, and will be extended in future versions of this document. Zuniga, et al. Expires April 26, 2013 [Page 19] Internet-Draft DMM Gap Analysis October 2012 7. References 7.1. Normative References [RFC3963] Devarapalli, V., Wakikawa, R., Petrescu, A., and P. Thubert, "Network Mobility (NEMO) Basic Support Protocol", RFC 3963, January 2005. [RFC5026] Giaretta, G., Kempf, J., and V. Devarapalli, "Mobile IPv6 Bootstrapping in Split Scenario", RFC 5026, October 2007. [RFC5142] Haley, B., Devarapalli, V., Deng, H., and J. Kempf, "Mobility Header Home Agent Switch Message", RFC 5142, January 2008. [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. [RFC5555] Soliman, H., "Mobile IPv6 Support for Dual Stack Hosts and Routers", RFC 5555, June 2009. [RFC5568] Koodli, R., "Mobile IPv6 Fast Handovers", RFC 5568, July 2009. [RFC5648] Wakikawa, R., Devarapalli, V., Tsirtsis, G., Ernst, T., and K. Nagami, "Multiple Care-of Addresses Registration", RFC 5648, October 2009. [RFC5844] Wakikawa, R. and S. Gundavelli, "IPv4 Support for Proxy Mobile IPv6", RFC 5844, May 2010. [RFC6088] Tsirtsis, G., Giarreta, G., Soliman, H., and N. Montavont, "Traffic Selectors for Flow Bindings", RFC 6088, January 2011. [RFC6089] Tsirtsis, G., Soliman, H., Montavont, N., Giaretta, G., and K. Kuladinithi, "Flow Bindings in Mobile IPv6 and Network Mobility (NEMO) Basic Support", RFC 6089, January 2011. [RFC6275] Perkins, C., Johnson, D., and J. Arkko, "Mobility Support in IPv6", RFC 6275, July 2011. [RFC6463] Korhonen, J., Gundavelli, S., Yokota, H., and X. Cui, Zuniga, et al. Expires April 26, 2013 [Page 20] Internet-Draft DMM Gap Analysis October 2012 "Runtime Local Mobility Anchor (LMA) Assignment Support for Proxy Mobile IPv6", RFC 6463, February 2012. [RFC6611] Chowdhury, K. and A. Yegin, "Mobile IPv6 (MIPv6) Bootstrapping for the Integrated Scenario", RFC 6611, May 2012. [RFC6705] Krishnan, S., Koodli, R., Loureiro, P., Wu, Q., and A. Dutta, "Localized Routing for Proxy Mobile IPv6", RFC 6705, September 2012. [RFC6724] Thaler, D., Draves, R., Matsumoto, A., and T. Chown, "Default Address Selection for Internet Protocol Version 6 (IPv6)", RFC 6724, September 2012. 7.2. Informative References [3GPP.29.060] 3GPP, "General Packet Radio Service (GPRS); GPRS Tunnelling Protocol (GTP) across the Gn and Gp interface", 3GPP TS 29.060 3.19.0, March 2004. [A. de la Oliva, et al.] de la Oliva, A., Soto, I., Calderon, M., Bernardos, C., and M. Sanchez, "The costs and benefits of combining different IP mobility standards", Computer Standards & Interfaces, accepted for publication, doi:10.1016/ j.csi.2012.08.003 , 2012. [I-D.ietf-dmm-requirements] Chan, A., "Requirements for Distributed Mobility Management", draft-ietf-dmm-requirements-02 (work in progress), September 2012. [I-D.ietf-netext-pmipv6-flowmob] Bernardos, C., "Proxy Mobile IPv6 Extensions to Support Flow Mobility", draft-ietf-netext-pmipv6-flowmob-05 (work in progress), October 2012. [I-D.patil-dmm-issues-and-approaches2dmm] Patil, B., Williams, C., and J. Korhonen, "Approaches to Distributed mobility management using Mobile IPv6 and its extensions", draft-patil-dmm-issues-and-approaches2dmm-00 (work in progress), March 2012. [I-D.perkins-dmm-matrix] Perkins, C., Liu, D., and W. Luo, "DMM Comparison Matrix", draft-perkins-dmm-matrix-04 (work in progress), July 2012. Zuniga, et al. Expires April 26, 2013 [Page 21] Internet-Draft DMM Gap Analysis October 2012 [I-D.seite-mif-cm] Seite, P. and J. Zuniga, "MIF API Conn Mngr Considerations", draft-seite-mif-cm-00 (work in progress), September 2012. [RFC4225] Nikander, P., Arkko, J., Aura, T., Montenegro, G., and E. Nordmark, "Mobile IP Version 6 Route Optimization Security Design Background", RFC 4225, December 2005. [RFC4640] Patel, A. and G. Giaretta, "Problem Statement for bootstrapping Mobile IPv6 (MIPv6)", RFC 4640, September 2006. [RFC5014] Nordmark, E., Chakrabarti, S., and J. Laganier, "IPv6 Socket API for Source Address Selection", RFC 5014, September 2007. [RFC6301] Zhu, Z., Wakikawa, R., and L. Zhang, "A Survey of Mobility Support in the Internet", RFC 6301, July 2011. Appendix A. Acknowledgments The work of Carlos J. Bernardos and Telemaco Melia has been partially supported by the European Community's Seventh Framework Programme (FP7-ICT-2009-5) under grant agreement n. 258053 (MEDIEVAL project). The work of Carlos J. Bernardos has also been partially supported by the Ministry of Science and Innovation of Spain under the QUARTET project (TIN2009-13992-C02-01). The authors would like to thank Konstantinos Pentikousis, Georgios Karagian, Jouni Korhonen and Jong- Hyouk Lee for their valuable comments. Authors' Addresses Juan Carlos Zuniga InterDigital Communications, LLC 1000 Sherbrooke Street West, 10th floor Montreal, Quebec H3A 3G4 Canada Email: JuanCarlos.Zuniga@InterDigital.com URI: http://www.InterDigital.com/ Zuniga, et al. Expires April 26, 2013 [Page 22] Internet-Draft DMM Gap Analysis October 2012 Carlos J. Bernardos Universidad Carlos III de Madrid Av. Universidad, 30 Leganes, Madrid 28911 Spain Phone: +34 91624 6236 Email: cjbc@it.uc3m.es URI: http://www.it.uc3m.es/cjbc/ Telemaco Melia Alcatel-Lucent Bell Labs Route de Villejust Nozay, Ile de France 91620 France Email: telemaco.melia@alcatel-lucent.com Charles E. Perkins Futurewei USA Email: charliep@computer.org Zuniga, et al. Expires April 26, 2013 [Page 23]