NETEXT WG T. Melia, Ed. Internet-Draft Alcatel-Lucent Intended status: Informational S. Gundavelli, Ed. Expires: March 8, 2012 Cisco September 5, 2011 Logical Interface Support for multi-mode IP Hosts draft-ietf-netext-logical-interface-support-03.txt Abstract A Logical Interface is a software semantic internal to the host operating system. This semantic is available in all popular operating systems and is used in various protocol implementations. The Logical Interface support is required on the mobile node operating in a Proxy Mobile IPv6 domain, for leveraging various network-based mobility management features such as inter-technology handoffs, multihoming and flow mobility support. This document explains the operational details of Logical Interface construct and the specifics on how the link-layer implementations hide the physical interfaces from the IP stack and from the network nodes on the attached access networks. Furthermore, this document identifies the applicability of this approach to various link-layer technologies and analyzes the issues around it when used in context with various mobility management features. 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 March 8, 2012. Copyright Notice Copyright (c) 2011 IETF Trust and the persons identified as the document authors. All rights reserved. Melia & Gundavelli Expires March 8, 2012 [Page 1] Internet-Draft Logical Interface Support September 2011 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 . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Requirements Language . . . . . . . . . . . . . . . . . . . . 5 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 6 4. Hiding Link-layer Technologies - Approaches and Applicability . . . . . . . . . . . . . . . . . . . . . . . . 7 4.1. Link-layer Abstraction - Approaches . . . . . . . . . . . 7 4.2. Applicability Statement . . . . . . . . . . . . . . . . . 8 4.2.1. Link layer support . . . . . . . . . . . . . . . . . . 9 4.2.2. Logical Interface . . . . . . . . . . . . . . . . . . 9 5. Technology Use cases . . . . . . . . . . . . . . . . . . . . . 11 6. Logical Interface Functional Details . . . . . . . . . . . . . 12 6.1. Configuration of a Logical Interface . . . . . . . . . . . 13 6.2. MTU considerations . . . . . . . . . . . . . . . . . . . . 14 6.3. Supported Link models for a logical interface . . . . . . 14 6.4. Link-layer Identifier of a Logical Interface . . . . . . . 15 6.5. ND Considerations for Logical Interface . . . . . . . . . 15 6.6. Logical Interface Forwarding Conceptual Data Structures . 16 7. Logical Interface Use-cases in Proxy Mobile IPv6 . . . . . . . 18 7.1. Multihoming Support . . . . . . . . . . . . . . . . . . . 18 7.2. Inter-Technology Handoff Support . . . . . . . . . . . . . 19 7.3. Flow Mobility Support . . . . . . . . . . . . . . . . . . 21 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 22 9. Security Considerations . . . . . . . . . . . . . . . . . . . 23 10. Authors . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 24 Melia & Gundavelli Expires March 8, 2012 [Page 2] Internet-Draft Logical Interface Support September 2011 12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 24 12.1. Normative References . . . . . . . . . . . . . . . . . . . 24 12.2. Informative References . . . . . . . . . . . . . . . . . . 25 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 25 Melia & Gundavelli Expires March 8, 2012 [Page 3] Internet-Draft Logical Interface Support September 2011 1. Introduction Proxy Mobile IPv6 [RFC5213] is a network-based mobility protocol. Some of the key goals of the protocol include support for multihoming, inter-technology handoffs and flow mobility support. The base protocol features specified in [RFC5213] allow the mobile node to attach to the network using multiple interfaces (simultaneously or sequentially), or to perform handoff between different interfaces of the mobile node. However, for supporting these features, the mobile node is required to be activated with specific software configuration that allows the mobile node to either perform inter-technology handoffs between different interfaces, attach to the network using multiple interfaces, or perform flow movement from one access technology to another. This document analyzes from the mobile node's perspective a specific approach that allows the mobile node to leverage these mobility features. Specifically, it explores the use of the Logical Interface support, a semantic available on most operating systems. A Logical Interface is a construct internal to the operating system. It is an approach where the link-layer implementations hide the physical interfaces from the IP stack and from the network nodes on the attached access networks. This semantic is widely available in all popular operating systems. Many applications such as Mobile IP client [RFC3775] and IPsec VPN client [RFC4301] rely on this semantic for their protocol implementation and the same semantic can also be useful in this context. Specifically, the mobile node can use the logical interface configuration for leveraging various network-based mobility management features provided by the Proxy Mobile IPv6 domain [RFC5213]. The rest of the document provides the operational details of a Logical Interface on the mobile node and the inter-working between a mobile node using logical interface and network elements in the Proxy Mobile IPv6 domain when supporting some of the mobility management features. It also analyzes the issues involved with this approach and characterizes the contexts in which such usage is appropriate. Melia & Gundavelli Expires March 8, 2012 [Page 4] Internet-Draft Logical Interface Support September 2011 2. Requirements Language In this document, the key words "MAY", "MUST, "MUST NOT", "OPTIONAL", "RECOMMENDED", "SHOULD", and "SHOULD NOT", are to be interpreted as described in [RFC2119]. Melia & Gundavelli Expires March 8, 2012 [Page 5] Internet-Draft Logical Interface Support September 2011 3. Terminology All the mobility related terms used in this document are to be interpreted as defined in Proxy Mobile IPv6 specifications, [RFC5213] and [RFC5844]. In addition, this document introduces the following terms: PIF (Physical Interface) - a network interface card attached to an an host providing network connectivity (e.g. an Ethernet card, a WLAN card, an LTE interface). LIF (Logical Interface) - It is a virtual interface in the IP stack. It appears just as any other physical interface, provides similar semantics with respect to packet transmit and receieve functions to the upper layers in the IP stack. However, it is only logical construct and is not a representation of an instance of any physical hardware. VLL-ID (Virtual Link-layer ID) - a virtual link-layer address configured on the logical interface. This identifier can be randomly generated, or configured based on the link-layer address of one of the physical interface. Sub-If (Sub Interface) - a physical interface that is part of a logical interface construct. For example, a logical interface may have been created abstracting two physical interfaces, LTE and WLAN. These physical interfaces, LTE and WLAN are referred to as sub-interfaces of that logical interface. In some cases, a sub- interface can also be another logical interface, such as an IPsec tunnel interface. Melia & Gundavelli Expires March 8, 2012 [Page 6] Internet-Draft Logical Interface Support September 2011 4. Hiding Link-layer Technologies - Approaches and Applicability There are several techniques/mechanisms that allow hiding access technology changes or movement from host IP layer. This section classifies these existing techniques into a set of generic approaches, according to their most representative characteristics. Later sections of this document analyze the applicability of these solution approaches for supporting features such as, inter-technology handovers and IP flow mobility support for a mobile node in a Proxy Mobile IPv6 domain [RFC5213]. 4.1. Link-layer Abstraction - Approaches The following generic mechanisms can hide access technology changes from host IP layer: o Link-layer Support - Certain link-layer technologies are able to hide physical media changes from the upper layers (see Figure 1). For example, IEEE 802.11 is able to seamlessly change between IEEE 802.11a/b/g physical layers. Also, an 802.11 STA can move between different Access Points (APs) within the same domain without the IP stack being aware of the movement. In this case, the IEEE 802.11 MAC layer takes care of the mobility, making the media change invisible to the upper layers. Another example is IEEE 802.3, that supports changing the rate from 10Mbps to 100Mbps and to 1000Mbps. Mobile Node +-----------------------+ | TCP/UDP | AR1 AR2 +-----------------------+ +-----+ +-----+ | IP | | IP | | IP | +-----------------------+ +-----+ +-----+ | Link Layer (L2) | | L2 | | L2 | +-----+-----+-----+-----+ +-----+ +-----+ | L1a | L1b | L1c | L1d |<---------->| L1d | | L1b | +-----+-----+-----+-----+ +-----+ +-----+ ^ ^ |_________________________________________| Figure 1: Link layer support solution architecture There are also other examples with more complicated architectures, like for instance, 3GPP EPC [TS23401]. In this case, a UE can move (inter-RA handover) between GERAN/UTRAN/E-UTRAN, being this movement invisible to the IP layer at the UE, and also to the LMA logical component at the PGW. The link layer stack at the UE (i.e. PDCP and RLC layers), and the GTP between the RAN and the SGW (which plays the role of inter-3GPP AN mobility anchor) hide Melia & Gundavelli Expires March 8, 2012 [Page 7] Internet-Draft Logical Interface Support September 2011 this kind of mobility, which is not visible to the IP layer of the UE (see Figure 2). --------- | Appl. |<-----------------------------------------------------> --------- ---------- | |<+ - - - - - - - - - - - - - - - - - - - - +>| | | IP | . ----------------- . ------------------- . | IP | | |<+>| relay |<+>| relay | . | | --------- . ----------------- . ------------------- . ---------- | PDCP |<+>| PDCP | GTP-U |<+>| GTP-U | GTP-U |<+>| GTP-U | --------- . ----------------- . ------------------- . ---------- | RLC |<+>| RLC | UDP/IP |<+>| UDP/IP | UDP/IP |<+>| UDP/IP | --------- . ----------------- . ------------------- . ---------- | MAC |<+>| MAC | L2 |<+>| L2 | L2 |<+>| L2 | --------- . ----------------- . ------------------- . ---------- | L1 |<+>| L1 | L1 |<+>| L1 | L1 |<+>| L1 | --------- . ----------------- . ------------------- . ---------- UE Uu E-UTRAN S1-U SGW S5/S8a PGW Figure 2: 3GPP LTE/EPC data plane architecture (GTP option) o Logical interface: this refers to solutions (see Figure 3) that logically group/bond several physical interfaces so they appear to the upper layers (i.e. IP) as one single interface (where application sockets bind). Depending on the OS support, it might be possible to use more than one physical interface at a time -- so the node is simultaneously attached to different media -- or just to provide a fail-over mode. Controlling the way the different media is used (simultaneous, sequential attachment, etc) is not trivial and requires additional intelligence and/or configuration at the logical interface device driver. An example of this type of solution is the Logical interface, which is defined in this document, or the bonding driver (a Linux implementation). 4.2. Applicability Statement We now focus on the applicability of the above solutions against the following requirements: o multi technology support o sequential vs. simultaneous access Melia & Gundavelli Expires March 8, 2012 [Page 8] Internet-Draft Logical Interface Support September 2011 4.2.1. Link layer support Link layer mobility support applies to cases when the same link layer technology is used and mobility can be fully handled at these layers. One example is the case where several 802.11 APs are deployed in the same subnet and all of them share higher layer resources such as DHCP server, IP gateway, etc. In this case the APs can autonomously (or with the help of a central box) communicate and control the STA association changes from one AP to another, without the STA being aware of the movement. This type of scenario is applicable to cases when the different points of attachment (i.e. APs) belong to the same network domain, e.g. Enterprise, hotspots from same operator, etc. This type of solution does not typically allow for simultaneous attachment to different access networks, and therefore can only be considered for inter-access technology handovers, but not for flow mobility. Existing RFC 5213 handover hint mechanisms could benefit from link layer information (e.g. triggers) to detect and identify MN handovers. Link layer support is not applicable when two different access technologies are involved (e.g. 802.11 WLAN and 802.16 WiMAX) and the same is true when the same access technology expands over multiple network domains. This solution does not impose any change at the IP layer since changes in the access technology occur at layer two. 4.2.2. Logical Interface The use of a logical interface allows the mobile node to provide a single interface view to the layers above IP (thus not changing the IP layer itself). Upper layers can bind to this interface, which hides inner inter-access technology handovers or data flow transfers among different physical interfaces. This type of solution may support simultaneous attachment, in addition to sequential attachment. It requires additional support at the node and the network in order to benefit from simultaneous attachment. For example special mechanisms are required to enable addressing a particular interface from the network (e.g. for flow mobility). In particular extensions to PMIPv6 are required in order to enable the network (i.e., the MAG and LMA) to deal with logicql interfqce, instead to IP interfaces as current RFC5213 does. RFC5213 assumes that each physical interface capable of attaching to a MAG is an IP interface, while the logical interface solution groups several physical interfaces under the same IP logical interface. It is therefore clear that the Logical Interface approach satisfies Melia & Gundavelli Expires March 8, 2012 [Page 9] Internet-Draft Logical Interface Support September 2011 the multi technology and the sequential vs: simultaneous access support. Melia & Gundavelli Expires March 8, 2012 [Page 10] Internet-Draft Logical Interface Support September 2011 5. Technology Use cases The 3GPP has defined the Evolved Packet Core (EPC) for heterogeneous wireless access. A mobile device equipped with 3GPP and non-3GPP wireless technologies can simultaneously or senquentialy connect any of the available devices and receive IP services through any of them. This document focuses on the simultaneous/sequential use of these technologies and on the use cases that derive. As mentioned in the previous sections the Logical Interface construct is required to hide the specifities of each technology in the context of network based mobility (e.g. in PMIPv6 deployments). The LIF concept can be used with at least the following technologies: 3GPP access technologies (3G, LTE), WIMAX access technology and IEEE 802.11 access technology. 3GPP In most OS implementations the connection setup establishes a PPP interface through the IPCP and IPv6CP protocol [RFC5072]. In this case the PPP interface does not have any L2 address assigned and does not generate any ARP or ND message for layer two address resolution. Conversely recent implementations configure an ethernet alike interface at OS level hiding to the upper layers the PPP nature of the connection. It has been verified (Android platform) that in these cases the ethernet alike interface configures a random L2 MAC address and uses this address as source link layer address in ND messages. ARP is also run between the mobile device and the remote peer (the network is a /30 address space). WIMAX In WiMAX system also, the connection between the mobile station (MS) and the access router (AR) is a point-to-point link. The MS autoconfigures an address based on the prefix advertised by the AR or is assigned an address via DHCPv6. The stateless address auto-configuration is performed as per [RFC4861] and the IPv6 address is formed by adding an IID to the prefix learnt from Router Advertisement. IPv6 packets sent or received by the MS are identified by specific IDs, by which the AR can map them to the corresponding tunnel in the network. WIFI TBD IPsec TBD Melia & Gundavelli Expires March 8, 2012 [Page 11] Internet-Draft Logical Interface Support September 2011 6. Logical Interface Functional Details On most operating systems, a network interface is associated with a physical device that offers the services for transmitting and receiving IP packets to the applications on the host. In some configurations, a network interface can also be implemented as a logical interface which does not have the inherent capability to transmit, or receive packets on a physical medium, but relies on other physical interfaces for such services. Example of such configuration is an IP tunnel interface. General overview of a logical interface is shown in Figure 3. This section identifies the functional details of a logical interface and provides some implementation considerations. The logical interface allows heterogeneous attachment while leaving the change in the media transparent to the IP stack. Simultaneous and sequential network attachment procedures are possible enabling inter-technology and flow mobility scenarios. +----------------------------+ | TCP/UDP | Session to IP +---->| | Address binding | +----------------------------+ +---->| IP | IP Address +---->| | binding | +----------------------------+ +---->| Logical Interface | Logical to +---->| (MN-HoA) | Physical | +----------------------------+ Interface +---->| L2 | L2 | | L2 | binding |(IF#1)|(IF#2)| ..... |(IF#n)| +------+------+ +------+ | L1 | L1 | | L1 | | | | | | +------+------+ +------+ Figure 3: General overview of logical interface From the perspective of the IP stack and the applications, a Logical interface is just another interface. In fact, the Logical interface is the only one visible to the IP and upper layers when enabled. A host does not see any operational difference between a Logical and a physical interface. As with physical interfaces, a Logical interface is represented as a software object to which IP address configuration is bound. However, the Logical interface has some special properties which are essential for enabling inter-technology handover and flow- mobility features. Following are those properties: Melia & Gundavelli Expires March 8, 2012 [Page 12] Internet-Draft Logical Interface Support September 2011 o P1: The logical interface has a relation to a set of physical interfaces (sub-interfaces) on the host that it is abstracting. These sub-interfaces can be attached or detached from the Logical Interface at any time. The sub-interfaces attached to a Logical interface are not visible to the IP and upper layers. o P2: The logical Interface may either use a virtual interface identfier idependent of the interface identfiers of its sub- interfaces, or it may use the link-layer identifier from one of its sub-interfaces. o P3: Logical Interface has the path awareness with respect to the attached IP networks. For example, the logical interface may be bound to two IP networks, CAFE::/64 and BABA::/64, each of these prefixes may have been hosted on access networks attached through different sub-interfaces, WLAN and LTE. The logical interface has the path awareness with respect to IP network to sub-interface mapping. o P4: Logical Interface may be attached to multiple access technologies with different link MTU values. The adopted MTU value for the logical interface must be lowest MTU value across those access technologies. o P5: The Send/Receive functions of the Logical interface are mapped to the services exposed by the sub-interfaces. This mapping is dynamic and any change is not visible to the upper layers of the IP stack. o P6:Logical interface adapts to the link model underneath where the packet is being transmitted. When transmitting a packet on a sub- interface which is attached to a p2p link, the transmission conforms to the p2p link model and when transmitting on a sub- interface attached to a shared link, the transmission conforms to the shared link model. o P7: The Logical interface maintains IP flow information for each of its sub-interfaces. A conceptual data structure can be maintained for this purpose. The host may populate this information based on tracking each of the sub-interface for the active flows. 6.1. Configuration of a Logical Interface A host may be statically configured with the logical interface configuration, or an application such as a connection manager on the host may dynamically create it. Furthermore, the set of sub- interfaces that are part of a logical interface construct may be a Melia & Gundavelli Expires March 8, 2012 [Page 13] Internet-Draft Logical Interface Support September 2011 fixed set, or may be kept dynamic, with the sub-interfaces getting added or deleted as needed. The specifics on how a host creates a logical interface, or how it decides to add or delete a sub-interface to a logical interface is out side the scope of this document. 6.2. MTU considerations The link MTU (maximum transmission unit) value configured on a logical interface should be the lowest of the MTU values supported across any of the physical interfaces that are part of that logical interface construct. The MTU value should be configured as part of the logical interface creation on the host. Furthermore, this value must be updated any time there is a change to the logical interface construct, such as when interfaces are added or deleted from the logical interface setup. Any time there is an inter-technology handover between two access technologies, the applications on the host bound to the IP address configuration on the logical interface will not detect the change and will continue to use the MTU value of the logical interface for the outbound packets, which is never greater than the MTU value on that supported access network. However, the access network may continue to deliver the packets conforming to the MTU value supported on that access technology and the logical interface should be able to receive those packets from the physical interface attached to that network. 6.3. Supported Link models for a logical interface The sub-interfaces of a logical interface can be bound to a point-to- point or a shared link (Example: LTE and WLAN). The logical interface appears as a shared-link to the applications, and adapts to the link model of the sub-interface for packet communication. For example, when transmitting a packet on a sub-interface which is attached to a p2p link, the transmission conforms to the p2p link model and when transmitting on a sub-interface attached to a shared link, the transmission conforms to the shared link model. Based on the link to which the sub-interface is attached to, the layer-2 resolutions may or may not be needed. If the interface is bound to a P2P link with PPP running, there will not be any link- layer resolutions in the form of ARP/ND messages. However, if the interface is bound to a shared link such as Ethernet, there will be ND resolutions. The logical interface implementation has to maintain the required link model and the associated state for each sub- interface. Melia & Gundavelli Expires March 8, 2012 [Page 14] Internet-Draft Logical Interface Support September 2011 6.4. Link-layer Identifier of a Logical Interface The logical Interface may or may not use the link-layer identifier from one of its sub-interfaces. Following are the considerations. o In access architectures where it is possible to adopt a virtual link-layer identfier and use it for layer-2 communications in any of the access networks, a virtual identifier (VLL-Id) may be used. The specifics on how that identifier is chosen is out side the scope of this document. This identifier may be used for all link- layer communications. This identifier may also be used for generating IPv6 global or link-local addresses on that interface. o In access architectures, where the link-layer identifier is associated with a specific access technology, it will not be possible for the logical interface to adopt a virtual identifier and it use it across different access networks. In such networks, the logical interface must adopt the identifier of the respective sub-interface through which a packet is being transmitted. 6.5. ND Considerations for Logical Interface The following are the Neighbor Discovery related considerations for the logical interface. o Any Neighbor Discovery messages, such as Router Solicitation, Neighbor Solicitation messages that the host sends to a multicast destination address of link-local scope such as, all-nodes, all- routers, solicited-node multicast group addresses, using either an unspecified (::) source address, or a link-local address configured on the logical interface will be replicated and forwarded on each of the sub-interfaces under that logical interface. However, if the destination address is a unicast address and if that target is known to exist on a specific sub- interface, the message will be forwarded only on that specific sub-interface. o Any Neighbor Discovery messages, such as Router Advertisement, that the host receives from any of its sub-interfaces, will be associated with the logical interface, i.e., in some implementations the message will appear on the input interface of the logical interface. o When using Stateless Address Autoconfiguraion [RFC4862] for generating IPv6 address configuration on the logical interface, the host may use any of the IPv6 prefixes receieved from the Router Advertisement messages that it received from any of its sub-interfaces. Melia & Gundavelli Expires March 8, 2012 [Page 15] Internet-Draft Logical Interface Support September 2011 o The response to a Neighbor Discovery message received for a unicast, link-specific multicast group address, will be sent on the same sub-interface path where the packet was received. o When using DHCPv4 for obtaining address configuration for the logical interface, the value in the chaddr field in the DHCP messages will be based on the link-layer identfier scheme chosen by the logical interface. . 6.6. Logical Interface Forwarding Conceptual Data Structures The LIF should maintain the LIF and FLOW table data structures depicted in Figure 4 LIF TABLE FLOW table +===============================+ +===============================+ | PIF_ID | FLOW RoutingPolicies | | FLOW ID | PIF_ID | | | Home Network Prefix | +-------------------------------+ | | Link Layer Address | | FLOW_ID | PIF_ID | | | Status | +===============================+ +-------------------------------| | PIF_ID | FLOW RoutingPolicies | | | Home Network Prefix | | | Link Layer Address | | | Status | +-------------------------------+ | .... | .... | +===============================+ Figure 4 The LIF table maintains the mapping between the LIF and each PIF associated to the LIF (see P3). For each PIF entry the table should store the associated Routing Policies, the Home Network Prefix received during the SLAAC procedure, the configured Link Layer Address (as described above) and the Status of the PIF (e.g. active, not active). The method by which the Routing Policies are configured in the UE is out of scope of this document. It is however assumed that this method is in place and that these policies are configured in the LIF TABLE. The FLOW table allows a LIF to properly route each IP flow to the right interface (see P6). The LIF can identify flows arriving on its Melia & Gundavelli Expires March 8, 2012 [Page 16] Internet-Draft Logical Interface Support September 2011 PIFs and can map them accordingly for transmitting the corresponding packets. For locally generated traffic (e.g. unidirectional outgoing flows, mobile initiated traffic, etc.), the LIF should perform interface selection based on the Flow Routing Policies. In case traffic of an existing flow is suddenly received from the network on a different PIF than the one locally stored, the LIF should interpret the event as an explicit flow mobility trigger from the network and it should update the PIF_ID parameter in the FLOW table. Similarly, locally generated events from the PIFs or configuration updates to the local policy rules can cause updates to the table and hence trigger flow mobility. Melia & Gundavelli Expires March 8, 2012 [Page 17] Internet-Draft Logical Interface Support September 2011 7. Logical Interface Use-cases in Proxy Mobile IPv6 This section explains how the Logical interface support on the mobile node can be used for enabling some of the Proxy Mobile IPv6 protocol features. 7.1. Multihoming Support A mobile node with multiple interfaces can attach simultaneously to the Proxy Mobile IPv6 domain. Each of the attachment links are assigned a unique set of IPv6 prefixes. If the host is configured to use Logical interface over the physical interface through which it is attached, following are the related considerations. LMA's Binding Table +================================+ +----+ | HNP MN-ID CoA ATT LL-ID | |LMA | +================================+ +----+ | HNP-1 MN-1 PCoA-1 5 ZZZ | //\\ | HNP-2 MN-1 PCoA-2 4 ZZZ | +---------//--\\-----------+ ( // \\ ) ( // \\ ) +------//--------\\--------+ // \\ PCoA-1 // \\ PCoA-2 +----+ +----+ (WLAN) |MAG1| |MAG2| (WiMAX) +----+ +----+ \ / \ / HNP-1 \ / HNP-2 \ / \ / +-------+ +-------+ | if_1 | | if_2 | |(WLAN) | |(WiMAX)| +-------+-+-------+ | Logical | (LL-ID: ZZZ) | Interface | HNP-1::zzz/128 +-----------------| HNP-2::zzz/128 | MN | +-----------------+ Figure 5: Multihoming Support Melia & Gundavelli Expires March 8, 2012 [Page 18] Internet-Draft Logical Interface Support September 2011 o The mobile node detects the advertised prefixes from the MAG1 and MAG2 as the on link prefixes on the link to which the Logical interface is attached. o The mobile node can generate address configuration using stateless auto configuration mode from any of those prefixes. o The applications can be bound to any of the addresses bound to the Logical interface and that is determined based on the source address selection rules. o The host has path awareness for the hosted prefixes based on the received Router Advertisement messages. Any packets with source address generated using HNP_1 will be routed through the interface if_1 and for packets using source address from HNP_2 will be routed through the interface if_2. 7.2. Inter-Technology Handoff Support The Proxy Mobile IPv6 protocol enables a mobile node with multiple network interfaces to move between access technologies, but still retaining the same address configuration on its attached interface. The protocol enables a mobile node to achieve address continuity during handoffs. If the host is configured to use Logical interface over the physical interface through which it is attached, following are the related considerations. Melia & Gundavelli Expires March 8, 2012 [Page 19] Internet-Draft Logical Interface Support September 2011 LMA's Binding Table +================================+ +----+ | HNP MN-ID CoA ATT LL-ID | |LMA | +================================+ +----+ | HNP-1 MN-1 PCoA-1 5 ZZZ | //\\ (pCoA-2)(4) <-change +---------//--\\-----------+ ( // \\ ) ( // \\ ) +------//--------\\--------+ // \\ PCoA-1 // \\ PCoA-2 +----+ +----+ (WLAN) |MAG1| |MAG2| (WiMAX) +----+ +----+ \ / \ Handoff / \ ----> / HNP-1 \ / \ / +-------+ +-------+ | if_1 | | if_2 | |(WLAN) | |(WiMAX)| +-------+-+-------+ | Logical | (LL-ID: ZZZ) | Interface | HNP-1::zzz/128 +-----------------| | MN | +-----------------+ Figure 6: Inter-Technology Handoff Support o When the mobile node performs an handoff between if_1 and if_2, the change will not be visible to the applications of the mobile node. It will continue to receive Router Advertisements from the network, but from a different sub-interface path. o The protocol signaling between the network elements will ensure the local mobility anchor will switch the forwarding for the advertised prefix set from MAG1 to MAG2. o The MAG2 will host the prefix on the attached link and will include the home network prefixes in the Router Advertisements that it sends on the link. Melia & Gundavelli Expires March 8, 2012 [Page 20] Internet-Draft Logical Interface Support September 2011 7.3. Flow Mobility Support For supporting flow mobility support, there is a need to support vertical handoff scenarios such as transferring a subset of prefix(es) (hence the flows associated to it/them) from one interface to another. The mobile node can support this scenario by using the Logical interface support. This scenario is similar to the Inter- technology handoff scenario defined in Section 7.2, only a subset of the prefixes are moved between interfaces. Additionally, IP flow mobility in general initiates when the LMA decides to move a particular flow from its default path to a different one. The LMA can decide on which is the best MAG that should be used to forward a particular flow when the flow is initiated e.g. based on application policy profiles) and/or during the lifetime of the flow upon receiving a network-based or a mobile- based trigger. As an example of mobile-based triggers, the LMA could receive input (e.g.by means of a layer 2.5 function via L3 signaling [RFC5677]) from the MN detecting changes in the mobile wireless environment (e.g. weak radio signal, new network detected, etc.). Upon receiving these triggers, the LMA can initiate the flow mobility procedures. For instance, when the mobile node only supports single-radio operation (i.e. one radio transmitting at a time), only sequential (i.e. not simultaneous) attachment to different MAGs over different media is possible. In this case layer 2.5 signaling can be used to perform the inter-access technology handover and communicate to the LMA the desired target access technology, MN-ID, Flow-ID and prefix. Melia & Gundavelli Expires March 8, 2012 [Page 21] Internet-Draft Logical Interface Support September 2011 8. IANA Considerations This specification does not require any IANA Actions. Melia & Gundavelli Expires March 8, 2012 [Page 22] Internet-Draft Logical Interface Support September 2011 9. Security Considerations This specification explains the operational details of Logical interface on an IP host. The Logical Interface implementation on the host is not visible to the network and does not require any special security considerations. Melia & Gundavelli Expires March 8, 2012 [Page 23] Internet-Draft Logical Interface Support September 2011 10. Authors This document reflects contributions from the following authors (listed in alphabetical order): Carlos Jesus Bernardos Cano cjbc@it.uc3m.es Antonio De la Oliva aoliva@it.uc3m.es Yong-Geun Hong yonggeun.hong@gmail.com Kent Leung kleung@cisco.com Tran Minh Trung trungtm2909@gmail.com Hidetoshi Yokota yokota@kddilabs.jp Juan Carlos Zuniga JuanCarlos.Zuniga@InterDigital.com 11. Acknowledgements The authors would like to acknowledge prior discussions on this topic in NETLMM and NETEXT working groups. The authors would also like to thank Joo-Sang Youn, Pierrick Seite, Rajeev Koodli, Basavaraj Patil, Julien Laganier for all the discussions on this topic. 12. References 12.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. Melia & Gundavelli Expires March 8, 2012 [Page 24] Internet-Draft Logical Interface Support September 2011 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, September 2007. [RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless Address Autoconfiguration", September 2007. [RFC5213] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K., and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008. [RFC5844] Wakikawa, R. and S. Gundavelli, "IPv4 Support for Proxy Mobile IPv6", RFC 5844, May 2010. 12.2. Informative References [RFC3775] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support in IPv6", RFC 3775, June 2004. [RFC4301] Kent, S. and K. Seo, "Security Architecture for the Internet Protocol", RFC 4301, December 2005. [RFC5072] Varada, S., "IP Version 6 over PPP", September 2007. [RFC5677] Melia, T., Bajko, G., Das, S., Golmie, N., and JC. Zuniga, "IEEE 802.21 Mobility Services Framework Design (MSFD)", RFC 5677, December 2009. [RFC6085] Gundavelli, S., Townsley, M., Troan, O., and W. Dec, "Address Mapping of IPv6 Multicast Packets on Ethernet", RFC 6085, January 2011. [TS23401] "3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access.", 2009. Authors' Addresses Telemaco Melia (editor) Alcatel-Lucent Route de Villejust Nozay 91620 France Email: telemaco.melia@alcatel-lucent.com Melia & Gundavelli Expires March 8, 2012 [Page 25] Internet-Draft Logical Interface Support September 2011 Sri Gundavelli (editor) Cisco 170 West Tasman Drive San Jose, CA 95134 USA Email: sgundave@cisco.com Melia & Gundavelli Expires March 8, 2012 [Page 26]