Working Group Name Moneeb Gohar
Internet Draft Kyungpook National University
Intended status: Informational Seok Joo Koh
Expires: February 2010 Kyungpook National University
August 25, 2009
Fast Tree Join for Seamless Multicast Handover in Wireless/Mobile
Networks
draft-gohar-fmipv6-ftj-00.txt
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Abstract
This draft describes a fast handover mechanism to provide seamless
multicast services in the wireless/mobile networks based on the Fast
Mobile IPv6 (FMIPv6). When a mobile node (MN) moves from one access
router to another, it may encounter data loss. In the tree joining
case of the existing scheme, there is a problem of buffer overflow
during the packet forwarding from Previous Access Router (PAR) to New
Access Router (NAR), in which many packet losses may occur due to the
buffer overflow. In order to reduce this buffer overflow and the
concerned packet losses, we propose a new scheme of a fast tree join
for seamless multicast handover, which allows the NAR to join the
multicast tree before the FMIPv6 handover is completed. In the
proposed scheme, we consider the two specific cases: 1) the short
tree joining time, in which no packet forwarding will be required and
thus NAR can receive the multicast data from an upstream multicast
router before the FMIPv6 handover is completed, 2) the long tree
joining time, in which the packet forwarding will be required and
thus NAR will receive the multicast data after the FMIPv6 handover.
Table of Contents
1.Introduction.................................................. 2
2.Conventions used in this document............................. 6
3.Fast Tree Join for FMIPv6 Multicast Handover...................6
4.Conclusions....................................................8
5.References.....................................................9
5.1.Normative References......................................9
5.2.Informative References....................................9
Author's Addresses...............................................10
1. Introduction
The wireless data communication technologies are rapidly growing in
the communication industry [1]. Therefore, the movement or handover
in the wireless networks becomes one of the crucial issues to be
addressed [2]. The movement in the wireless/mobile networks can be
managed by using the Mobile IP (MIPv6) [3]. The MIPv6 was designed to
manage the movement of MN from one access router to another. To
improve the handover performance of MIPv6, the Fast Mobile IP
(FMIPv6) was proposed [4].
In the modern era of data communication technology, the users have
demanded the multicast services in the wireless mobile networks, such
as Internet broadcasting and multiple video/audio conferencing. Some
schemes are needed to support the mobile multicasting such as
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construction of a multicast tree, the delivery of multicast data, and
joining and leaving the multicast group [5].
This internet draft, describes a fast join to multicast tree for
seamless multicast handover to reduce handover latency with packet
losses and the signaling costs required for multicast handover.
The FMIPv6 is an extension of MIPv6 [4]. FMIPv6 can support the fast
handover, and reduce the handover latency and data loss. FMIPv6 can
also be used for fast handover of multicast sessions. Some works for
multicast fast handover have been proposed. One of these schemes the
work in [6] proposed to use the multicast group information option in
the fast binding update message (FBU) and in the handover initiation
message (HI). In the scheme, the PAR transmits the multicast group
information to the NAR through FBU, which may has taken a long join
delay. Recently, another scheme has been proposed for efficient
multicast [1], which introduced the new multicast options in the
mobility header to record the multicast group information. This
scheme also establishes a tunnel between PAR and NAR.
We note that a scheme of FMIPv6-based multicast handover that was
proposed in [7], where the ''Fast handover based on Mobile IP for
Multicasting'' (denoted by FMIP-M) scheme, as presented in Fig. 1
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MN PAR NAR HA RP
| | | | |
|--RtSolPr->| | | |
|<-PrRtAdv--| | | |
|---FBU---->| | | |
| |----HI-------------> | | |
| |<---HACK------------ | | |
| <--FBACK--|---FBACK---> | | |
Disconnect | | | |
| |=Path Extension=====>| | |
| |=Packet Forwarding==>| | |
| | |--------PIM JOIN------->|
| | |<-------PIM JOIN ACK----|
| | |<===Multicast Tree Data=|
| |<--HO COMPLETE------ | | |
Connect | | | |
|----------UNA------------------> | | |
| | |----BU------>| |
| | |<----BU ACK--| |
| | |<=Tunneling==| |
| |<---HO COMPLETE----- | | |
|<====Multicast Data Delivery=====| | |
Figure 1. Existing FMIP-M scheme
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In the FMIP-M scheme, MN receives an L2 trigger and sends a Router
Solicitation for Proxy (RtSolPr) to the PAR. The PAR replies to MN
with a Proxy Router Advertisement (PrRtAdv). MN then obtains a new
care of address (nCoA). The fast handover procedure actually starts
by sending a Fast Binding Update (FBU) message towards PAR that
contains a multicast group address. Given the information contained
in the FBU message, PAR sends a Handover Initiation (HI) message to
NAR. The HI message contains the information about Multicast Status
(M-Status), Hop Count (HC) from the multicast tree, and multicast
group address. The NAR will check the validity and uniqueness of the
nCoA. After that, NAR can reply to the PAR with a Handover
acknowledgement (HACK) message. It contains the M-Dec field, which
indicates a specific method used by NAR for multicast handover. In
addition, the HACK message may also contain the information of the
sequence number of data packets that will be maintained in the new
access router's buffer (denoted by SEQNARBuff in [7]), which is used
only when the M-Dec is set to 3. This SEQNARBuff represents the
sequence number of the first packet that will be stored in the NAR
buffer. The PAR then sends the Fast Binding Acknowledge (F-BACK)
message to MN and NAR both.
After sending the F-BACK message, the PAR begins to forward the
multicast data packets to NAR, in which the four specific cases can
be considered, as described in [7], which will be indicated by using
the M-Dec field of the HACK message. These four schemes can be
summarized as follows:
. Case 1 (Path Extension), in which the multicast service path is
extended from PAR to NAR. In this case, after the PAR received this
decision from the HACK message, the PAR started to forward the
multicast packets to NAR. This packet forwarding is performed until
NAR requests PAR to terminate the path extension;
. Case 2 (Bi-directional tunneling from Home Agent (HA)), in which in
this case, the PAR starts to forward the multicast packets (received
via the bi-directional tunneling) from the HA to NAR. This packet
forwarding will be continued until PAR receives the HO COMPLETE
message from NAR.
. Case 3 (Remote Subscription), in which NAR sends a tree join message
(PIM JOIN) to the upstream multicast source, which is indicated as
Rendezvous Point (RP) in Fig. 1. For the join message, the RP will
respond to NAR with a Join Ack (PIM JOIN-ACK) message, and then the
multicast data packets are now delivered to the NAR by using the
newly configured multicast tree. In this case, the PAR will also
forward the multicast packets, if any, to NAR.
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. Case 4, in which it is assumed that one of the users in the NAR
region has already joined the same multicast group and thus the NAR
is receiving the corresponding group data packets. So, in this case,
the PAR had only to forward the previously buffered multicast packets
to NAR.
On the other hand, when MN moves to the new network, it will send an
Unsolicitated Neighbor Advertisement (UNA) message to the NAR to
indicate that the handover has been completed, as done in the FMIPv6.
It is noted that the existing scheme may incur the 'buffer
overflow problem' in the buffer of PAR during the tree join process.
That is, if the tree join by NAR to RP takes a long time, the buffer
of PAR for packet forwarding may overflow and thus a significant
amount of data packets could be lost. In addition, the existing
scheme also tends to give have the large signaling and packet
forwarding costs.
In this draft, we propose a fast tree join scheme for seamless
multicast handover, in which the NAR will try to join the multicast
tree as soon as the handover event is detected (i.e., when NAR
receives the HI message from the PAR). The proposed scheme can also
reduce the signaling costs associated with the multicast handover.
2. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC-2119 Error!
Reference source not found..
3. Fast Tree Join for FMIPv6 Multicast Handover
In this draft, we describe a fast tree join (FTJ) scheme for seamless
multicast handover based on the FMIPv6 protocol, which is denoted by
FTJ-FMIP in this paper. The proposed scheme focuses on how to combine
the multicast service with the existing fast handover procedure for a
fast and reliable multicast packet delivery. In the proposed scheme, we
consider the following three cases: Path Extension method, Bi-
Directional Tunneling, and Remote Subscription. The fourth case, in
which NAR has already joined the tree, is not considered, since it is
too much trivial.
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In the tree joining case, we consider the following two scenarios: (a)
short tree join, in which the tree join process is completed before NAR
receive the FBACK message from PAR, and (b) long tree join, in which the
tree join is completed after NAR receives the FBACK message. In the
first case (short tree join), the PAR does not need to forward the data
packets to NAR, and instead NAR will receive the multicast data packets
directly from the multicast tree, and then send the HO COMPLETE message
to PAR On the other hand, in the second case, the NAR will receive some
of multicast data packets from PAR, until the tree join process is
completed.
Figure 2 shows the basic operation of the proposed FMIPv6-FTJ
scheme.
Upon receiving an indication from a wireless link-layer trigger, MN
initiates the handover by sending a message RtSolPr that contains both
the FBU option and the multicast address. After receiving the RtSolPr
message, PAR sends the PrRtAdv message to MN. At the same time, PAR will
send the HI message to the NAR.
When receiving the HI message, the NAR will immediately respond
with the HACK message to PAR, and then begin the tree join to the RP by
sending the PIM JOIN message. (FMIPv6-FTJ with Remote Subscription): in
which the tree join is completed earlier (i.e., before the NAR receives
the FBACK message from PAR). In this case, the NAR will receive the PIM
JOIN-ACK message from the upstream RP, and then send the HO-COMPLETE
message to the PAR. Accordingly, the PAR will not perform the packet
forwarding to NAR.
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MN PAR NAR RP
| | | |
|-RtSolPr[FBU] ->| | |
|<-PrRtAdv------ |----HI-------------> |--------PIM JOIN-------->|
| |<---HACK------------ | |
| | | |
| | |<-------PIM JOIN ACK-----|
| | |<===Multicast Tree Data==|
| |<---HO COMPLETE----- | |
| <--FBACK--|---FBACK---> | |
Disconnect | | |
| | | |
| | | |
| | | |
Connect | | |
|----------UNA------------------------>| |
|<======Multicast Data Delivery========| |
Figure 2. Proposed FMIPv6-FTJ scheme
To support the proposed FMIPv6-FTJ scheme, we suggest to use the three
modified messages. The existing RtSolPr and FBU messages are merged into
a single RtSolPr message that contains the FBU option and multicast
address. Note that the other two messages, HI and HACK, are changed to
include the MN ID (Home Address of MN) and the multicast address.
4. Conclusions
This internet draft describes a fast tree join for seamless multicast
handover in the FMIPv6-based wireless/mobile networks. In the
existing scheme, there may be a buffer overflow problem during the
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tree join process. Due to this buffer overflow problem, many packets
may be lost. TO overcome this drawback, the proposed scheme will
begin to join the multicast tree, as soon as the handover is detected.
5. References
5.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2234] Crocker, D. and Overell, P.(Editors), "Augmented BNF for
Syntax Specifications: ABNF", RFC 2234, Internet Mail
Consortium and Demon Internet Ltd., November 1997.
5.2. Informative References
[1] D. H. Kwon, et al., Design and implementation of an efficient
multicast support scheme for FMIPv6, INFOCOMM2006, pp. 1- -12, 2006.
[2] Nicolas Montavont and Thomas noel, ''Handover Management for
Mobile Nodes in IPv6 Networks,'' IEEE Communication Magazine, August
2002.
[3] D. Johnson, et al., ''Mobility Support in IPv6'', IETF RFC 3775,
2004.
[4] R. Koodli, ''Mobile IPv6 Fast Handovers'', IETF RFC 5268, 2008.
[5] Y. Min-hau, et al., ''The Implementation of Multicast in Mobile
IP'', IEEE Wireless Communications and Networking Conference, pp.
1796- -1800, 2003.
[6] F. Xia, and B. Sarikaya, FMIPv6 extension for multicast Handover,
draft-xia-mipshop-fmip-multicast-01, work in progress, March 2007.
[7] SANG-JO YOO and SEAK-JAE SHIN, ''Fast Handover Mechanism for
Seamless Multicasting Services in Mobile IPv6Wireless Networks,''
Wireless Personal Communications 42:509- -526, 2007.
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Author's Addresses
Moneeb Gohar
Kyungpook National University, KOREA
Email: moneebgohar@gmail.com
Seok Joo Koh
Kyungpook National University, KOREA
Email: sjkoh@knu.ac.kr
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