MIF                                                       Hongke Zhang
Internet Draft                                               Fei Song
Intended status: Informational                               Boxin Du
Expires: November 29,2016                                    Mi Zhang
                                           Beijing Jiaotong University
                                                          May 29, 2016



                MIF API extension for combining IEEE 802.21
                draft-zhang-mif-api-extension-802-21-04.txt


Abstract

   The Application Program Interface (API) of MIF, specified in the MIF
   API consideration, must rely on lower layer functionalities when
   handover between homogeneous or heterogeneous networks is necessary.
   To improve the connectivity performance, the existing MIF API needs
   to be extended. IEEE is also aimed at the similar issue from
   different way. A kind of logical entities over the link layer
   protocol for handling the seamless handover has been defined in IEEE
   802.21. This document proposes a mechanism via integrating MIF API
   and IEEE 802.21 to support application service better.

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 November 28, 2016.









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Copyright Notice

   Copyright (c) 2016 IETF Trust and the persons identified as the
   document authors. All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
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   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.


































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Table of Contents


   1. Introduction ................................................ 4
   2. Terminology ................................................. 4
   3. The Relationship between IEEE MIHF and MIF API .............. 4
   4. The Extension of MIF API for Handover: A Case Study ......... 8
      4.1. The MN-initiated Handover .............................. 8
         4.1.1. Get Information ................................... 8
         4.1.2. Information Post .................................. 9
         4.1.3. Parameter Report .................................. 9
         4.1.4. Check Resources MN ................................ 9
         4.1.5. Resource Availability ............................. 9
         4.1.6. Connect to Interface .............................. 9
         4.1.7. Resource Preparation Messages .................... 10
         4.1.8. Establish Link Messages .......................... 10
         4.1.9. Link Up .......................................... 10
         4.1.10. Handover Completed .............................. 10
         4.1.11. Handover Completion Confirmation ................ 10
      4.2. The Network-initiated Handover ........................ 10
         4.2.1. Candidate Query Notification ..................... 11
         4.2.2. Candidate Query Result ........................... 11
         4.2.3. Check Resources Net .............................. 12
         4.2.4. Confirm Chosen Target ............................ 12
         4.2.5. Establish Link Messages .......................... 12
         4.2.6. Link Up .......................................... 12
         4.2.7. Handover Completed ............................... 12
         4.2.8. Handover Completion Confirmation ................. 12
   5. Discussions for New Messages from MIF Perspective .......... 12
      5.1. Get Information........................................ 13
      5.2. Release the Ongoing Connection ........................ 13
      5.3. Establish New L2 Connection ........................... 13
   6. Discussions for New Messages from IEEE Perspective ......... 13
   7. Security Considerations .................................... 16
   8. IANA Considerations ........................................ 16
   9. References ................................................. 16
      9.1. Normative References .................................. 16
      9.2. Informative References ................................ 16
   10. Acknowledgments ........................................... 17









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1. Introduction

   In MIF context, improved connectivity experiences SHOULD be created.
   Enhancing the performance of horizontal and vertical switches
   between networks is the main target. Such situation is quite similar
   with Media Independent Handover (MIH) described in [IEEE 802.21].
   The MIF Application Program Interface (API) specified in the MIF API
   consideration [I-D.ietf-mif-api-extension] describes a set of
   message calls to implement higher level APIs that solve the problems
   in multiple interface scenarios. However, this draft only provides a
   minimal set of message calls REQUIRED to implement the API. New
   functions could be added.

   According to [IEEE 802.21], the Media Independent Handover Function
   (MIHF) is a logical entity that facilitates MIH decision making
   based on inputs from the MIHF. It can provide abstracted services
   for higher layers. Communications with the lower layer of the
   mobility-management protocol stack can be achieved through
   technology-specific interfaces in MIHF.

   Although two mechanisms, MIF API and MIHF, are working in different
   layers and defined by different organizations, the requirements of
   compatibility are obvious. Some of the functions of MIF API SHOULD
   be supported by a connection manager (i.e. the MIHF), and vice
   versa. Owing to the advantages of both MIHF and its Service Access
   Points (SAPs), the functions of MIHF could be utilized in MIF API in
   order to handover issues. This document extends message calls of MIF
   API to support the MIH. Like [I-D.ietf-mif-api-extension], no
   bindings for programming languages are provided because they are
   left up to the implementation. This document only describes the
   messages sent and received, which can be read as a checklist for
   operating system vendors.

2. Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC-2119 [RFC2119].

3. The Relationship between IEEE MIHF and MIF API

   The purpose of IEEE 802.21 is to improve the user experience of
   mobile devices by facilitating handover among all IEEE 802 networks
   regardless of whether they are of different media types or not,
   including both wired and wireless. It also aims at making it
   possible for mobile devices to perform seamless handover between
   IEEE 802 and non IEEE networks. This standard defines:


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   1) A framework that enables service continuity while a Mobile Node
      (MN) transitions between heterogeneous link-layer technologies.

   2) MIHF.

   3) MIH_SAP and associated primitives for users to get services of
      MIHF.

   4) The definitions of new link-layer SAPs and associated primitives
      for each link-layer technology. They help MIHF to collect link
      information and control link behaviors during handovers.

   The concept of MIHF is a functional entity to fulfill the high-
   performance handovers. The primary advantage of MIHF is that it
   provides media-independent services to higher layers no matter which
   media-specific technology of lower layer is being used, such as IEEE
   Std.802.3, IEEE Std.802.11, IEEE Std.802.16, 3GPP and 3GPP2. It also
   defines three kinds of SAPs (will be detailed later) of MIHF and
   their primitives that interact between different layers. The MIHF
   can also act as a filter: the messages received from link layer
   SHOULD be processed and submitted to higher layer for meeting the
   subscribers' need. Therefore, MIHF should work under MIF API. In
   fact, MIF API SHOULD be served as a user of MIHF, as shown in Figure
   1. The subscribers can then only interact with the MIHF via one kind
   of SAPs (i.e. MIH_SAP) without knowing the lower things. The MIH
   protocol is not in the scope of this document.

   Three kinds of MIHF services are defined in the standard:  Media
   Independent Event Service (MIES), Media Independent Command Service
   (MICS) and Media Independent Information Service (MIIS).

   MIES provides event classification, event filtering and event
   reporting corresponding to dynamic changes in link characteristics,
   link status and link quality. It originates from lower layers and
   can be passed to MIHF or upper layers for the detection of handover
   requirement. MICS enables MIH users to manage and control link
   behavior relevant to handover and mobility. It is invoked by users
   or MIHF and makes effect on MIHF or lower layers.

   For example, in MN-initiated handover scenario, MICS is adopted for
   MN switching between different links. MIIS allows MN and network
   entities to discover information which has influence on the
   selection of appropriate networks during handovers. Figure 2 [IEEE
   802.21] shows MIH services and their initiation.





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                +-------------------------------------+
                |             Application             |
                +-------------------------------------+
                   /\     ||     /\   ||    /\   ||
                   ||     \/     ||   ||    ||   ||
                +--------------+ ||   ||    ||   ||
                |High Level API| ||   ||    ||   ||
                +--------------+ ||   ||    ||   ||
                   /\     ||     ||   ||    ||   ||
                   ||     \/     ||   \/    ||   ||
                +------------------------+  ||   ||
                |        MIF API         |  ||   ||
                +------------------------+  ||   ||
                    /\      ||              ||   \/
                    ||      ||   +--------------------+
                    ||      ||   | Communication API  |
                    ||      ||   +--------------------+
                    ||      ||         /\  /\
                    ||      ||         ||  ||
                    ||      \/         \/  \/
                +-------------------------------------+
                |                   MIHF              |
                +-------------------------------------+
                         /\              ||
                         ||              \/
                +-------------------------------------+
                |         Network Link API            |
                +-------------------------------------+
                    /\    ||              /\    ||
                    ||    \/              ||    \/
                +---------------+     +---------------+
                |    Network    |     |    Network    |
                |  Interface 1  |     |  Interface 2  |
                +---------------+     +---------------+

                Figure 1 The relationship of MIHF & MIF API

   The letters a, b, c in Figure 2 respectively represent:

   a. MIH_SAP

   b. MIH_LINK_SAP

   c. LLC_SAP

   The SAPs are divided into two categories:



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   1) Media dependent SAP (including MIH_LINK_SAP and LLC_SAP).

   2) Media independent SAP (MIH_SAP).

   +-------------+     Command      +-----------------------------+
   |             +     Service      |                             |
   |            / \ <---------------+                             |
   |           +   +                |       MIH User              |
   |           |   |    Event       |                             |
   | MIHF      |   |   Service      |    Layer 3 or Higher        |
   |           | a |--------------->|    Mobility Protocol        |
   | Event     |   |                |                             |
   | Service   |   |  Information   |                             |
   |           +   +   Service      |                             |
   | Command    \ /<--------------->|  +-------+        +-------+ |
   | Service     +                  +--+   c   +-+---+--+   c   +-+
   |             |     Command      +  +-------+ |   +  +-------+ |
   | Information |     Service     / \           |  / \           |
   | Service     |--------------->+   +          | +   +          |
   |             |                |   | Network1 | |   | Network2 |
   |             |      Event     |   | (e.g.IEEE| |   | (e.g.IEEE|
   |             |     Service    | b |  802.16) | | b |  802.11) |
   |             |<---------------|   |          | |   |          |
   |             |                |   |          | |   |          |
   |             |   Information  |   |          | |   |          |
   |             |     Service    +   +          | +   +          |
   |             |<--------------->\ /           |  \ /           |
   |             |                  +            |   +            |
   |             |                  |            |   |            |
   +-------------+                  +------------+   +------------+

                Figure 2 MIH services and their initiation

   SAP of the MIHF (i.e. MIH_SAP) is media independent. The MIH_SAP
   defines the interface between the MIHF and MIH users such as an
   upper layer mobility protocol or a handover function (e.g., MIF API)
   that might reside at higher layer transport entity as well. MIH_SAP
   allows the MIHF to provide services to the upper layers, the network
   management plane and the data bearer plane. Upper layers need to
   subscribe with the MIHF as users to receive MIHF events. In MIF
   case, the MIF API can directly send commands to the local MIHF via
   messages which use the service primitives of the MIH_SAP.

   All the messages REQUIRED for communicating successfully in MIF
   environment that described in the [I-D.ietf-mif-api-extension] MUST
   also be used here. These messages define the way that MIF API
   interacts with the higher layers or applications andneed to be added


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   into this set for handover process. These new messages SHOULD be
   exchanged between MIHF and MIF API. Some of them may use the
   services of MIHF.

4. The Extension of MIF API for Handover: A Case Study

   This section introduces the extension of message calls of MIF API in
   two parts based on the classification of handovers (MN-initiated
   handover and the network-initiated handover). In order to handle
   these two kinds of handovers successfully, MIF API SHOULD be
   extended respectively based on the characteristics of process.

4.1. The MN-initiated Handover

   The handover initated by MN includes the following seven steps:

   1) Information query. The MN collects network information from the
   MIIS server which the MN is connected to.

   2) Resource availability check. The MIF API sends request to find
   candidates and then receives a list of candidate networks in
   response message.

   3) Resource preparation. The MN SHOULD determine which target
   network is suitable and request it for resource preparation.

   4) Establish new L2 connection. The MIF API initiates a new link
   connection.

   5) Link up indication. The MIHF of MN notifies the MIF API that the
   link is up.

   6) Higher layer handover execution.

   7) Resource release. The original serving network resources must be
   released in the end.

   The following messages need to be added, which describe interactions
   between a MIHF and MIF APIs

4.1.1. Get Information

   This message is sent by the MIF API for the inquiry of the
   neighboring networks information. In MIH, we can use the
   MIH_Get_Information. request for the same purpose. After receiving
   this message, the MIHF inquires the MIIS server for the information,
   which will return a list of network information for MIF API.


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4.1.2. Information Post

   This message is sent to the MIF API by the MIIS server as a response
   to the Get Information message. MIH_Get_Information. confirm can be
   used to convey such information.

4.1.3. Parameter Report

   When attaching to a specific network, the MIF API needs to receive
   the lower layers link status to better control the whole connection.
   The MIHF can receive reports from the link layers and submit them to
   the higher layers. If the link is going down, the MIF API must
   notify its subscribers using "Interface is going away" message. The
   application or higher API could try to establish new connections by
   sending "Wants to connect" to MIHF and the connection process will
   restart from step 2 (i.e. Resource availability check).

   Another situation is when the MIF API receives a "Wants to connect"
   message from its subscriber, the MIF API SHOULD accordingly trigger
   a whole connection process to a new network accordingly. This can
   also begin from step 2.

4.1.4. Check Resources MN

   In the connection starts period, the MN SHOULD check the resource
   availability at the candidate networks. This message is sent to the
   MIHF by the MIF API. The serving network SHOULD request each
   candidate. The final result SHOULD be returned to the higher layer.
   The MIH_MN_HO_Candidate_Query. request can be used in the MIH case.

4.1.5. Resource Availability

   When receiving the resource availability of the candidates from the
   serving network, the MIHF SHOULD submit these messages to the MIF
   API. The MIH_MN_HO_Candidate_Query. confirm can be used in the MIH
   case.

4.1.6. Connect to Interface

   This message is sent to the MIF API by the upper applications. When
   the MIF API receives the Resource Availability, it could post the
   message to the higher layer. The upper application can use "Connect
   to Interface" to choose a better network interface. More about the
   choosing methods need further discussion.





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4.1.7. Resource Preparation Messages

   The MIF API can use the MIH_MN_HO_Commit. request, which includes
   the target network information, to request the network chose for
   resource preparation. When the preparation is done, the MIHF
   receives the response from the target network. It sends a
   MIH_MN_HO_Commit. confirm message to the MIF API in order to inform
   the status of the previously issued target notification request.

4.1.8. Establish Link Messages

   MIF API can solve the connection establishment problem using the
   MIH_Link_Action. request. This message primitively defined by the
   [IEEE 802.21] is to control the local or remote lower link layers.
   It includes a MIHF ID and a Link Actions List, which can realize
   many controlling functions. After the action has been executed, the
   MIF API should receive a MIH_Link_Action. confirm to indicate the
   result.

4.1.9. Link Up

   After the new link is established, the MAC layers MUST deliver a
   Link_Up. indication to the MIHF. The MIHF then passes the
   MIH_Link_Up. indication message to the MIF API. The MIF API can
   notify the upper applications using the "Link is going up" message.
   Then the higher layer handover execution might be triggered and the
   traffic flow can be re-established.

4.1.10. Handover Completed

   This message is sent to the local MIHF by the MIH API to release the
   resources of the previous serving network which was originally
   allocated to the MN. After identifying that the release is done, the
   target network Point of Service (PoS) sends the confirm message to
   the MIHF and the MIHF SHOULD also reply the MIF API with the same
   information.

4.1.11. Handover Completion Confirmation

   This message is sent to the MIF API by the MIHF indicating that the
   resource of the previous network is successfully released.

4.2. The Network-initiated Handover

   There are also seven steps in an intact network-initiated handover,
   like the MN-initiated handover:



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   1) Information query.

   2) Resource availability check.

   3) Resource preparation.

   4) Establish a L2 connection using MIH_Link_Action. request.

   5) Sent link indications to the MIF API.

   6) Higher layer handover execution.

   7) Resource release.

   The differences between Network-initiated case and MN-initiated case
   are in step 1 and step 2. The Get Information request and
   Information Query are respectively initiated by the MIH user of the
   serving network. When such MIH user obtains the information from the
   MIIS server, it sends requests to the MN for a response message
   containing the MN's handover acknowledgement, MN's preferred link
   and PoS lists.

   In step 3, the commitment of target network is also initiated by the
   MIH user of a serving network. After the resource is prepared, the
   PoS of serving network SHOULD notify the MN for the establishment of
   L2 connection in step 4.

   The following messages should be added in MIF API.

4.2.1. Candidate Query Notification

   This message is sent to MN's MIHF from the PoS of the serving
   network with a list of PoAs of each candidate network link. Such
   message suggests the MN SHOULD consider new access network. This
   message can use the MIH_Net_HO_Candidate_Query. indication.

4.2.2. Candidate Query Result

   This message is sent to the local serving network's MIHF from MN's
   MIF API, specifying whether the request of handover is permitted or
   not. MIH_Net_HO_Candidate_Query. response can be used here. When the
   handover is permitted, a new access network SHOULD be considered at
   the handover initiation stage.






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4.2.3. Check Resources Net

   This message is sent to the MN's MIF API by the PoS of serving
   network with a list of target network information and a set of
   resource parameters assigned to the MN for handover.
   MIH_Net_HO_Commit. indication can be used. Then the MIF API can
   trigger the establishment of L2 connection by using Link_Action.
   request. After the link connection is done, MIF API needs to inform
   the serving network. Link_Action. request might also have a list of
   actions for handover control during the link connection period.

4.2.4. Confirm Chosen Target

   This message is sent by the MN's MIF API as a response to the
   MIH_HO_Commit.indication, revealing that the indication is received.
   MIH_Net_HO_Commit. response can be used. Also such message might
   include a list of the results of previous actions.

4.2.5. Establish Link Messages

   This message is exactly the same as that of the MN-initiated
   process, for establishing a new L2 link connection.

4.2.6.  Link Up

   This message is exactly the same as that of the MN-initiated
   process, for informing the MIF API that the L2 link is completed.

4.2.7. Handover Completed

   This message is exactly the same as that of the MN-initiated
   process, for releasing the resources that have already attained by
   the MN.

4.2.8. Handover Completion Confirmation

   This message is exactly the same as that of the MN-initiated
   process, for confirming that the resources of the previous network
   are successfully released.

5. Discussions for New Messages from MIF Perspective

   New messages described in this document are critical for information
   exchanging and function achievement between MIHF and MIF API. Since
   both "upper layer requirements gathering" and "lower layer command
   delivering" (or reverse) can be achieved via messages, the logical



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   relationship should be discussed in-depth. The messages below are
   only the examples. Further updating is needed.

5.1. Get Information

   According to [IEEE 802.21], this information query is related to a
   specific interface. It has the flexibility to query either a
   specific data within a network interface or an extended schema of a
   given network. As an advanced application or upper APIs send
   "Announce Interface", "Announce PVD" and "Announce IE (Information
   Elements)", the MIF API could obtain the information via the
   Get_information. request in MIH.

5.2. Release the Ongoing Connection

   The [I-D.ietf-mif-api-extension] defines a message "Connection can
   be broken", which means that the MN can tolerate the connection
   being broken, e.g. for power conservation. When the subscribers of
   MIF API delivers this message, the MIF API SHOULD send "Release the
   ongoing connection" to the MIHF so that directly releasing the
   current resources of network to cut off this connection. This action
   will not weaken the application function.

5.3. Establish New L2 Connection

   According to [IEEE 802.21], the MIH_Link_Actions can trigger a L2
   link connection. When MN wants to build a TCP connection with an IP
   host, the MIF API will receive "Connect to Address" or "Connect to
   Address from Address" messages. Then the MIF API can use the
   MIH_Link_Actions. request to ask MIHF for new L2 link connection.

6. Discussions for New Messages from IEEE Perspective

   The following tables, table1, 2, 3 and 4, are from the [IEEE
   802.21]. These messages might be used in the MIF API because they
   are exchanged between the MIHF and its MIH users. Some of them have
   been discussed above, but the specific usage of the rest is not
   represented. This section presents only a direct list of their
   category and brief descriptions. Further discussion is needed.









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   +---------------------+--------------------------------------------+
   | Messages            | Description                                |
   | (Information)       |                                            |
   +---------------------+--------------------------------------------+
   | MIH_Get_Information | Request to get information from repository |
   +---------------------+--------------------------------------------+
   | MIH_Push_Information| Notify the MN of operator policies or      |
   |                     | other information                          |
   +---------------------+--------------------------------------------+
                   Figure 1 Information Messages of MIHF

   +---------------------+--------------------------------------------+
   | Messages (Event)    | Description                                |
   +---------------------+--------------------------------------------+
   | MIH_Link_Detected   | Link of a new access network has been      |
   |                     | detected. This event is typically on the   |
   |                     | MN when the first PoA of an access network |
   |                     | is detected                                |
   +---------------------+--------------------------------------------+
   | Track_timeout       | This event is not generated when           |
   |                     | subsequent PoAs of the same access network |
   |                     | are discovered                             |
   +---------------------+--------------------------------------------+
   | MIH_Link_Up         | L2 connection is established and link is   |
   |                     | available for use                          |
   +---------------------+--------------------------------------------+
   | MIH_Link_Down       | L2 connection is broken and link is not    |
   |                     | available for use                          |
   +---------------------+--------------------------------------------+
   | MIH_Link_Paremeters | Link parameters have crossed a specified   |
   | _Report             | threshold and need to be reported          |
   +---------------------+--------------------------------------------+
   | MIH_Link_Going_Down | Link conditions are degrading and          |
   |                     | connection loss is imminent                |
   +---------------------+--------------------------------------------+
   | MIH_Link_Handover   | L2 handover is imminent based on either    |
   | _Imminent           | the changes in the link conditions or      |
   |                     | additional information available in the    |
   |                     | network                                    |
   +---------------------+--------------------------------------------+
   | MIH_Link_Handover   | L2 handover to a new PoA has been          |
   | _Complete           | completed                                  |
   +---------------------+--------------------------------------------+
   | MIH_Link_PDU        | Indicate transmission status of a PDU      |
   | _Transmit_Status    |                                            |
   +---------------------+--------------------------------------------+
                      Figure 2 Event Messages of MIHF


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   +--------------------+---------------------------------------------+
   | Messages (Command) | Description                                 |
   +--------------------+---------------------------------------------+
   | MIH_Link_Get       | Get the status of a link                    |
   | _Parameters        |                                             |
   +--------------------+---------------------------------------------+
   | MIH_Net_HO         | Network initiates handover and sends a list |
   | _Candidate _Query  | of suggested networks and associated points |
   |                    | of attachment                               |
   +--------------------+---------------------------------------------+
   | MIH_Link_Configure | Configure link parameter thresholds         |
   | Thresholds         |                                             |
   +--------------------+---------------------------------------------+
   | MIH_Link_Actions   | Control the behavior of a set of links      |
   +--------------------+---------------------------------------------+
   | MIH_MN_HO_Candidate| Command used by MN to query and obtain      |
   | _Query             | handover related information about possible |
   |                    | candidate networks                          |
   +--------------------+---------------------------------------------+
   | MIH_N2N_HO_Query   | command sent by the serving MIHF entity to  |
   | _Resources         | the target MIHF entity for resource query   |
   +--------------------+---------------------------------------------+
   | MIH_MN_HO_Commit   | Command used by MN to notify the serving    |
   |                    | network of the decided target network       |
   |                    | information                                 |
   +--------------------+---------------------------------------------+
   | MIH_Net_HO_Commit  | Command used by the network to notify the   |
   |                    | MN of the decided target network information|
   +--------------------+---------------------------------------------+
   | MIH_N2N_HO_Commit  | Command used by a serving network to inform |
   |                    | a target network that an MN is about to     |
   |                    | move toward that network, initiate context  |
   |                    | transfer and perform handover preparation   |
   +--------------------+---------------------------------------------+
   | MIH_MN_HO_Complete | Notification from MIHF of the MN to the     |
   |                    | target or source MIHF indicating the        |
   |                    | status of handover completion               |
   +--------------------+---------------------------------------------+
   | MIH_N2N_HO_Complete| Notification from MIHF of the MN to the     |
   |                    | target or source MIHF indicating the        |
   |                    | status of handover completion               |
   +--------------------+---------------------------------------------+
   | MIH_N2N_HO_Complete| Notification from either source or target   |
   |                    | MIHF to the peer MIHF indicating the status |
   |                    | of the handover completion                  |
   +--------------------+---------------------------------------------+
                     Figure 3 Command Messages of MIHF


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   +---------------------+--------------------------------------------+
   | Messages            | Description                                |
   | (Service management)|                                            |
   +---------------------+--------------------------------------------+
   | MIH_Capability      | Discover list of Events and Commands       |
   | _Discover           | supported by MIHF                          |
   +---------------------+--------------------------------------------+
   | MIH_Register        | Register with a remote MIHF                |
   +---------------------+--------------------------------------------+
   | MIH_DeRegister      | Deregister with a remote MIHF              |
   +---------------------+--------------------------------------------+
   | MIH_Event_Subscribe | Subscribe for MIH event notification       |
   +---------------------+--------------------------------------------+
   | MIH_Event_Unsubscibe| Unsubscribe from MIH event notification    |
   +---------------------+--------------------------------------------+

                    Figure 4 Service Management of MIHF

7. Security Considerations

   This document does not contain any security considerations.

8. IANA Considerations

   There are presently no IANA considerations with this document.

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

   [IEEE 802.21] IEEE, "IEEE Standard for Local and Metropolitan Area
             Networks Part 21: Media Independent Handover Services",
             IEEE LAN/MAN Std 802.21-2008, January 2009.
             <http://www.ieee802.org/21/private/Published%20Spec/802.21
             -2008.pdf>.

   [I-D.ietf-mif-api-extension] Liu, D., Lemon, T., Ismailov, Y., and
             Z.Cao, "MIF API consideration", draft-ietf-mif-api-
             extension-05 (work in progress), Feb. 2014.





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10. Acknowledgments

   This document was prepared using 2-Word-v2.0.template.dot.

Authors' Addresses

   Hongke Zhang
   Beijing Jiaotong University (BJTU)
   Beijing, 100044, P.R.China

   Email: hkzhang@bjtu.edu.cn


   Fei Song
   Beijing Jiaotong University (BJTU)
   Beijing, 100044, P.R.China

   Email: fsong@bjtu.edu.cn


   Boxin Du
   Beijing Jiaotong University (BJTU)
   Beijing, 100044, P.R.China

   Email: 10291070@bjtu.edu.cn


   Mi Zhang
   Beijing Jiaotong University (BJTU)
   Beijing, 100044, P.R.China

   Email: 13120174@bjtu.edu.cn
















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