MIF Hongke Zhang
Internet Draft Fei Song
Intended status: Informational Boxin Du
Expires: November 18 2018 Mi Zhang
Beijing Jiaotong University
May 17, 2017
MIF API extension for combining IEEE 802.2
draft-zhang-mif-api-extension-802-21-06.txt
Abstract
The Application Program Interface (API) of MIF, specified in the
MIFAPI 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
IEEE802.21. 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 18, 2018.
Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved.
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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
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Table of Contents
1. Introduction ................................................. 3
2. Terminology .................................................. 3
3. The Relationship between IEEE MIHF and MIF API ............... 3
4. The Extension of MIF API for Handover: A Case Study........... 7
4.1. The MN-initiated Handover ............................... 7
4.1.1. Get Information .................................... 7
4.1.2. Information Post ................................... 8
4.1.3. Parameter Report ................................... 8
4.1.4. Check Resources MN ................................. 8
4.1.5. Resource Availability .............................. 8
4.1.6. Connect to Interface ............................... 8
4.1.7. Resource Preparation Messages ...................... 9
4.1.8. Establish Link Messages ............................ 9
4.1.9. Link Up ............................................ 9
4.1.10. Handover Completed ................................ 9
4.1.11. Handover Completion Confirmation .................. 9
4.2. The Network-initiated Handover .......................... 9
4.2.1. Candidate Query Notification ...................... 10
4.2.2. Candidate Query Result ............................ 10
4.2.3. Check Resources Net ............................... 10
4.2.4. Confirm Chosen Target ............................. 11
4.2.5. Establish Link Messages ........................... 11
4.2.6. Link Up ........................................... 11
4.2.7. Handover Completed ................................ 11
4.2.8. Handover Completion Confirmation .................. 11
5. Discussions for New Messages from MIF Perspective ........... 11
5.1. Get Information......................................... 11
5.2. Release the Ongoing Connection ......................... 12
5.3. Establish New L2 Connection ............................ 12
6. Discussions for New Messages from IEEE Perspective............12
7. Security Considerations ..................................... 15
8. IANA Considerations ......................................... 15
9. References .................................................. 15
9.1. Normative References ................................... 15
9.2. Informative References ................................. 15
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10. Acknowledgments ........................................... 15
1. Introduction
In MIF context, improved connectivity experiences SHOULD be created.
The main target is to enhance the performance of horizontal and
vertical switches between networks. 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 accomplish higher level APIs which 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 sending and
receiving, 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
Through facilitating handover among all IEEE 802 networks regardless
of whether they are of different media types or not, including both
wired and wireless, the purpose of IEEE 802.21 is to improve the user
experience of mobile devices. It also aims at making it possible for
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mobile devices to perform seamless handover between IEEE 802 and non
IEEE networks. This standard defines:
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 content 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 |
+---------------+ +---------------+
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:
1) Media dependent SAP (including MIH_LINK_SAP and LLC_SAP).
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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 + + | + + |
| |<--------------->\ / | \ / |
| | + | + |
| | | | | |
+-------------+ +------------+ +------------+
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
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.
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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 MIF API by the MIHF indicating that the
resource of the previous network is successfully released.
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:
1) Information query.
2) Resource availability check.
3) Resource preparation.
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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.
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
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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
successful.
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
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)",
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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.
+---------------------+--------------------------------------------+
| Messages | Description |
| (Information) | |
+---------------------+--------------------------------------------+
| MIH_Get_Information | Request to get information from repository |
+---------------------+--------------------------------------------+
| MIH_Push_Information| Notify the MN of operator policies or |
| | other information |
+---------------------+--------------------------------------------+
Table 1 Information Messages of MIHF
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+---------------------+--------------------------------------------+
| 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 | |
+---------------------+--------------------------------------------+
Table 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 |
+--------------------+---------------------------------------------+
Table 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 |
+---------------------+--------------------------------------------+
Table 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 Indicat
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.
10. Acknowledgments
This document was prepared using 2-Word-v2.0.template.dot.
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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
Zhang, et al. Expires November 17,2018 [Page 16]