One document matched: draft-asaeda-multimob-pmip6-extension-02.txt
Differences from draft-asaeda-multimob-pmip6-extension-01.txt
MULTIMOB Group H. Asaeda
Internet-Draft Keio University
Intended status: Standards Track P. Seite
Expires: January 14, 2010 France Telecom
J. Xia
Huawei
July 13, 2009
PMIPv6 Extensions for Multicast
draft-asaeda-multimob-pmip6-extension-02
Status of this Memo
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document authors. All rights reserved.
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Abstract
This document describes Proxy Mobile IPv6 (PMIPv6) extensions to
support IP multicast. The Mobile Access Gateway (MAG) and the Local
Mobility Anchor (LMA) are the mobility entities defined in the PMIPv6
protocol. The proposed protocol extension provides; 1) a dedicated
multicast tunnel (M-Tunnel) between LMA and MAG, and 2) local routing
to deliver IP multicast packets for mobile nodes. This document
defines the roles of LMA and MAG to support IP multicast for the
mobile nodes.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Conventions and Terminology . . . . . . . . . . . . . . . . . 6
2.1. Conventions Used in This Document . . . . . . . . . . . . 6
2.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 6
3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.1. Multicast Communication in PMIPv6 . . . . . . . . . . . . 7
3.2. Multicast Tunnel (M-Tunnel) . . . . . . . . . . . . . . . 8
3.3. Protocol Sequence for Multicast Channel Subscription . . . 9
4. Local Mobility Anchor Operation . . . . . . . . . . . . . . . 12
4.1. LMA Operating As PIM-SM Router . . . . . . . . . . . . . . 12
4.2. LMA Operating As MLD Proxy . . . . . . . . . . . . . . . . 12
5. Mobile Access Gateway Operation . . . . . . . . . . . . . . . 13
5.1. MAG Operating As MLD Proxy . . . . . . . . . . . . . . . . 13
5.2. MAG Operating As PIM-SM Router . . . . . . . . . . . . . . 13
6. Mobile Node Operation . . . . . . . . . . . . . . . . . . . . 15
7. Dual-Mode Implementation . . . . . . . . . . . . . . . . . . . 16
8. Handover Process . . . . . . . . . . . . . . . . . . . . . . . 17
8.1. MAG Operating As MLD Proxy . . . . . . . . . . . . . . . . 17
8.2. MAG Operating As Multicast Router . . . . . . . . . . . . 20
8.3. Multicast Context Transfer Data Format . . . . . . . . . . 23
8.4. Proxy Binding Update with Multicast Extension . . . . . . 24
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 28
10. Security Considerations . . . . . . . . . . . . . . . . . . . 29
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 30
12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 31
12.1. Normative References . . . . . . . . . . . . . . . . . . . 31
12.2. Informative References . . . . . . . . . . . . . . . . . . 31
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 33
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1. Introduction
Proxy Mobile IPv6 (PMIPv6) [2] enables network-based mobility for
IPv6 mobile nodes (MNs) that do not implement any mobility protocols.
The Local Mobility Anchor (LMA) is the topological anchor point to
manages the mobile node's binding state. The Mobile Access Gateway
(MAG) is an access router or gateway that manages the mobility-
related signaling for an MN. An MN is attached to the Proxy Mobile
IPv6 Domain (PMIPv6-Domain) that includes LMA and MAG(s), and is able
to receive data coming from outside of the PMIPv6-Domain through LMA
and MAG.
Network-based mobility support for unicast is addressed in [2], while
multicast support in PMIPv6 is not discussed in it. LMA and MAG set
up a bi-directional tunnel for each MN and forwards MN's traffic. It
is possible to deliver multicast packets destined to an MN over the
subscriber's bi-directional tunnel. However, it highly wastes
network resources when a number of MNs join the same multicast
sessions/channels, because independent data copies of each multicast
packet is delivered in a unicast manner to MAG (as shown in
Figure 1). It also gives the overhead for the data encapsulation and
decapsulation at LMA and MAG respectively to forward the same
multicast packets.
MC1
\ =====MC1 for MN1======>
\--> =====MC1 for MN2======>
MC2---->LMA===MC1,MC2 for MN3====>MAG
=====MC1 for MN4======>
=====MC2 for MN5======>
:
:
MC: Multicast packets, ==>: Bi-directional tunnel
Figure 1: Multicast channel subscription through subscriber's bi-
directional tunnel
This document describes PMIPv6 extensions to support IP multicast
communication for mobile nodes in PMIPv6-Domain. The proposed
protocol extension provides; 1) a dedicated multicast tunnel
(M-Tunnel) between LMA and MAG, and 2) local routing to deliver IP
multicast packets for mobile nodes. In this document, multicast
listener mobility is considered, while multicast source mobility is
out of scope of this draft.
This document assumes that LMA must be capable of forwarding
multicast packets through MAG toward the corresponding mobile nodes.
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This condition requires LMA to attach multicast networks by
supporting multicast routing protocols such as Protocol-Independent
Multicast - Sparse Mode (PIM-SM) [3] or other methods, and make
traffic and QoS control if needed. And MAG must maintain multicast
membership status for the attached mobile nodes at the edge and
forwards the multicast data from LMA to the member nodes. This
condition requires MAG to support MLD [4]. Each mobile node will
connect MAG with a point-to-point access link.
Seamless handover must also be considered. When a mobile node
receiving multicast data moves from an access link to another access
link, the node continuously receives the multicast data through newly
attached MAG. The handover procedure should guarantee multicast
session continuity and avoid extra packet loss and session
disruption. Context transfer will be the required function to
support seamless handover, while its effective procedure should be
taken into account interaction with multicast communication
protocols.
The PMIPv6 extension proposed in this document does not require to
change unicast communication methods or protocols defined in [2], and
therefore both unicast and multicast communications for mobile nodes
in PMIPv6-Domain are enabled after all.
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2. Conventions and Terminology
2.1. 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 [1].
2.2. Terminology
The following terms used in this document are to be interpreted as
defined in the Proxy Mobile IPv6 specification [2]; Mobile Access
Gateway (MAG), Local Mobility Anchor (LMA), Mobile Node (MN), Proxy
Mobile IPv6 Domain (PMIPv6-Domain), LMA Address (LMAA), Proxy Care-of
Address (Proxy-CoA), Mobile Node's Home Network Prefix (MN-HNP),
Mobile Node Identifier (MN-Identifier), Proxy Binding Update (PBU),
and Proxy Binding Acknowledgement (PBA).
As defined in [8], "upstream interface" or "host interface" is an MLD
proxy device's interface in the direction of the root of the tree.
Each of an MLD proxy device's interfaces that is not in the direction
of the root of the tree is called "downstream interface" or "router
interface".
The Context Transfer Protocol (CXTP) specification [11] describes the
mechanism that allows better support for minimizes service disruption
during handover. In this document, CXTP is adopted for the multicast
context transfer protocol in PMIPv6, and "Multicast-Context Transfer
Data (M-CTD)" is defined as the new terminology for transferring MLD
state from previously attached MAG (p-MAG) to newly attached MAG
(n-MAG).
Mobile Node's Policy Profile includes "multicast channel
information", whose contents are the same one M-CTD contains, and the
mandatory fields of the policy profile specified in [2]. MN's Policy
Profile is provided by "policy store" whose definition is the same as
of [2], or by CXTP.
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3. Overview
3.1. Multicast Communication in PMIPv6
Required components to enable IP multicast are multicast routing
protocols and host-and-router communication protocols. This document
assumes PIM-SM [3] as the multicast routing protocol and MLDv2 [4] or
LW-MLDv2 [5] as the host-and-router communication protocol.
The architecture of a Proxy Mobile IPv6 domain is shown in Figure 2.
LMA and MAG are the core functional entities in PMIPv6-Domain. The
entire PMIPv6-Domain appears as a single link from the perspective of
each mobile node.
+---------+
| Content |
| Source |
+---------+
|
*** *** *** *** ***
* ** ** ** ** *
* *
* Fixed Internet *
* *
* ** ** ** ** *
*** *** *** *** ***
/ \
+----+ +----+
|LMA1| |LMA2|
+----+ +----+
LMAA1 -> | | <-- LMAA2
| |
\\ //\\
\\ // \\
\\ // \\
\\ // \\
\\ // \\
\\ // \\
Proxy-CoA1--> | | <-- Proxy-CoA2
+----+ +----+
|MAG1|---{MN2} |MAG2|
+----+ | +----+
| | |
MN-HNP1 --> | MN-HNP2 | <-- MN-HNP3, MN-HNP4
{MN1} {MN3}
Figure 2: Proxy Mobile IPv6 Domain
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When a mobile node wants to subscribe/unsubscribe a multicast
channel, the MN sends MLD Report messages with specifying sender and
multicast addresses to the access link. The attached MAG detects
this membership information and transfers the information to the
corresponding LMA over a multicast tunnel (M-Tunnel described in the
next section) when needed, or transfers the information to the
adjacent multicast router.
When an LMA receives the membership information with MLD Report
messages or with PIM Join/Prune messages, it coordinates the
corresponding multicast routing tree if necessary. This operation
requires multicast routing protocols or proxy functions for LMA.
When a MAG detects mobile node's handover, it can proceed the
seamless handover procedures. Since both PMIPv6 and multicast
protocols (i.e., MLD and PIM-SM) do not have the functions for
handover in the original protocol specifications, external functions
or protocols such as CXTP [11] can be additionally used with PMIPv6
Proxy Binding Update (PBU).
3.2. Multicast Tunnel (M-Tunnel)
MC1
\
\-->
MC2---->LMA===MC1,MC2 for MNs====>MAG
MC: Multicast packets, ==>: M-Tunnel
Figure 3: Multicast channel subscription through M-Tunnel
M-Tunnel is a bi-directional tunnel dedicated for MLD message and IP
multicast data transmissions between LMA and MAG. It aggregates the
same MLD and multicast packets and transmits different multicast
channel data as shown in Figure 3.
The format of the tunneled multicast packet forwarded from LMA is
shown below. "S" and "G" are the same notation used for (S,G)
multicast channel.
IPv6 header (src= LMAA, dst= Proxy-CoA) /* Tunnel Header */
IPv6 header (src= S, dst= G) /* Packet Header */
Upper layer protocols /* Packet Content*/
Figure 4: Tunneled multicast packet from LMA to MAG
When an MLD message is sent from MAG to LMA, the src and dst
addresses of tunnel header will be replaced to Proxy-CoA and LMAA,
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respectively. To convey an MLD message, the src address of the
packet header is changed to either LMA's or MAG's link-local address
and the dst address of the packet header is assigned based on the
MLD's condition. (See Section 5.1.15 and 5.2.14 of [4].)
M-Tunnel may be created dynamically when needed and removed when not
needed, or implementations MAY choose to use static pre-established
M-Tunnel instead of dynamically creating and tearing it down on a
need basis. The manner of M-Tunnel creation is similar to the manner
of a subscriber's bi-directional tunnel creation as described in
Section 5.6.1 of [2]. However, M-Tunnel is not per MN basis, but per
MAG basis. The M-Tunnel is shared with all MNs attached to the MAG.
3.3. Protocol Sequence for Multicast Channel Subscription
Upon multicast data reception, a mobile node sends MLD Report
messages including source and multicast addresses. Although MLDv2
specification [4] permits to use the unspecified address (::) for a
host whose interface has not acquired a valid link-local address yet,
MLDv2 Report messages MUST be sent with a valid IPv6 link-local
source address in PMIPv6 as defined in [9]. As well, MLDv2 Report
messages MAY be sent with an IP destination address of FF02:0:0:0:0:
0:0:16, to which all MLDv2-capable multicast routers listen, but the
IP unicast address of the attached MAG SHALL be used in many cases as
explained in [9].
An MLD proxy [8] can simplify the implementation of multicast data
forwarding. By not supporting complicated multicast routing
protocols, it reduces the implementation cost and the operational
overhead. Reducing the operational overhead will also contribute to
faster routing convergence. Another advantage is that an MLD proxy
can be independent of the multicast routing protocol used by the core
network routers.
When a MAG operates as an MLD proxy and receives MLD Report messages
from attached mobile nodes, it sends MLD messages on behalf of the
mobile nodes. MLD messages are always transferred over the M-Tunnel
as seen in Figure 5. MAG operating as an MLD proxy always registers
"downstream interface (or router interface)" upon MLD message
reception, but does not send MLD Report when the received source and
multicast addresses have been already reported to the same LMA
through the same "upstream interface (or host interface)".
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MN1 MN2 MAG LMA
| | | |
|------MLD Report--------->| |
| (S1,G1) join | MLD Report |
| | |===== M-Tunnel ===>|
| | | |---> PIM (S1,G1) join
| | | |
| |--MLD Report-->| |
| | (S2,G2) join | MLD Report |
| | |===== M-Tunnel ===>|
| | | |---> PIM (S2,G2) join
| | | |
| |--MLD Report-->| |
| | (S1,G1) join | |
| | | |
Figure 5: MLD Report Messages Transmission
When a MAG operates as a PIM-SM router and receives MLD report
messages from attached mobile nodes, it joins the multicast delivery
tree by sending PIM join messages to its neighboring routers. At the
same time, the MAG sends MLD report messages with the Hold extension
[9] with the corresponding multicast channel information to the LMA
(Figure 6). When receiving the MLD Hold, the LMA joins the multicast
delivery tree but does not forward multicast data to the MAG. The
idea is to make the LMA ready to forward data. When an MN changes
the network, it will be able to continuously receive multicast data
from the LMA, until a new MAG completes the handover routing update
(detailed in Section 8).
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MN1 MN2 MAG LMA
| | | |
|------MLD Report--------->| |
| (S1,G1) join |---> PIM (S1,G1) join
| | | |
| | | MLD Hold |
| | |===== M-Tunnel ===>|
| | | |---> PIM (S1,G1) join
| | | | (No data forwarding)
| |--MLD Report-->| |
| | (S2,G2) join |---> PIM (S2,G2) join
| | | |
| | | MLD Hold |
| | |===== M-Tunnel ===>|
| | | |---> PIM (S2,G2) join
| | | | (No data forwarding)
| |--MLD Report-->| |
| | (S1,G1) join | |
| | | |
Figure 6: MLD Report Messages Transmission when MAG acts as a router
Whether a MAG works as an MLD proxy or a PIM-SM router, it MAY store
multicast channel information reported by attached mobile nodes in
the MN's policy profile (as defined in [2]). This information may be
used by the new MAG during the handover process (see Section 8).
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4. Local Mobility Anchor Operation
4.1. LMA Operating As PIM-SM Router
An LMA is responsible for maintaining the mobile node's reachability
state and is the topological anchor point for the mobile node's home
network prefix(es). When an LMA acts as a PIM-SM [3] multicast
router, it serves MAGs as listener nodes when the MAGs act as MLD
proxies, or as downstream routers when the MAGs act as PIM-SM
routers. Each MAG is connected through an M-Tunnel for multicast
communication.
An LMA sets up the multicast state and joins the group. Multicast
packets are tunneled to a MAG that requested to receive the
corresponding multicast session after being received by the LMA. The
MAG forwards these packets to the MN according to the multicast
listener state in the MAG.
4.2. LMA Operating As MLD Proxy
An LMA may act as an MLD proxy [8]. When LMA acts as an MLD proxy,
multicast data is forwarded from outside to mobile nodes through an
M-Tunnel to MAG.
When LMA acts as an MLD proxy, the attached MAGs must also act as an
MLD proxy.
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5. Mobile Access Gateway Operation
The mobile access gateway (MAG) is the entity that performs the
mobility management on behalf of a mobile node. MAG is responsible
for detecting the mobile node's movements to and from the access
link.
5.1. MAG Operating As MLD Proxy
[2] supports only point-to-point access link types for MAG and MN
connection; hence an MN and a MAG are the only two nodes on an access
link, where the link is assumed to be multicast capable. Since a MAG
will deal with mobile nodes' membership states reported by a large
number of the downstream mobile nodes with MLD Report messages, the
protocol scalability must be taken into account.
A MAG acting as an MLD proxy sends MLD Query messages to all or some
of attached mobile nodes. After MAG receives MLD Report messages
from the mobile nodes, it forwards the MLD Report messages on behalf
of these mobile nodes to LMA. Mobile nodes send MLD messages with
their link-local address to MAG, and MAG forwards the MLD messages
through the M-Tunnel to LMA with the MAG's link-local address.
An MLD proxy requires that the upstream and downstream interfaces
MUST be statistically configured. As well, MAG MUST configure an
upstream interface that is the interface MLD Report messages are sent
to LMA and downstream interfaces that are the interfaces MLD Report
messages are received from mobile nodes. This upstream interface is
the M-Tunnel end-point at the MAG.
5.2. MAG Operating As PIM-SM Router
The optimal multicast routing path does not always include LMA,
especially in local routing as described in Section 6.10.3 of [2].
The local routing option is designed to support node-to-node
communication within PMIPv6-Domain where a local content source
exists.
To enable local routing, MAG MUST run multicast routing protocols to
attach the optimal multicast routing path. This document assume use
of PIM-SM [3] as the supported multicast routing protocol.
Because of its implementation or operational costs, operators may not
want to support PIM-SM on MAG. However, an MLD proxy requires to
statically configure its upstream interface, which is an M-Tunnel as
specified in Section 5.1, to receive all multicast data. Therefore,
if operators take into account the case that an upstream interface
for the optimized multicast path is NOT an M-Tunnel to LMA but other
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interface, and want MAG to "dynamically select" optimized routing
path, MAG MUST act as a PIM-SM router.
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6. Mobile Node Operation
Mobile nodes attached to MAG can behave as the regular receiver
hosts. A mobile node sends MLD messages to MAG when it wants to
subscribe and unsubscribe IP multicast channels. And mobile nodes do
not change their behaviors whether MAG is acting as an MLD proxy or a
PIM-SM router. All MLD related considerations are described in [9],
which will give some advantage for its resource saving and seamless
handover for PMIPv6 multicast.
[2] allows a mobile node is a router. However, to avoid the
complexity, in this document, MN may behave as an MLD proxy [8] but
should not act as a PIM-SM router, when MN needs to forward multicast
data to its downstream nodes.
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7. Dual-Mode Implementation
Operators may want to make LMA or MAG act as both an MLD proxy and a
PIM-SM multicast router to support different customers. This
document proposes a "dual-mode" implementation that enables LMA or
MAG to support both an MLD proxy function and a multicast routing
function simultaneously.
To simplify mobile node's handover procedure among dual-mode MAGs,
p-MAG and n-MAG should not change the behaviors for the same mobile
node. For instance, in dual-mode, if p-MAG that a mobile node
attaches is working as an MLD proxy, n-MAG that the mobile node will
attach must also work as an MLD proxy. It is same as of PIM-SM.
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8. Handover Process
MAG is responsible for detecting the mobile node's movements to and
from the access link and for initiating binding registrations to the
mobile node's LMA. MAG tracks the mobile node's movements to and
from the access link and for signaling the mobile node's LMA. In
PMIPv6, it SHOULD NOT require for mobile nodes to initiate to re-
subscribe multicast channels, and MAG SHOULD keep multicast channel
subscription status for mobile nodes even if they attach a different
MAG in PMIPv6-Domain. In this section, mobility handover procedures
are described.
8.1. MAG Operating As MLD Proxy
When MAG operates as an MLD proxy, there are two possible ways to
proceed MLD listener handover; MLD listener handover with CXTP and
MLD listener handover with MN's Policy Profile. A Proxy Binding
Update with multicast extension (PBU-M) (defined in Section 8.4) is
always used to request the LMA to forward multicast data.
The MLD listener handover with CXTP shown in Figure 7 is defined as
follows.
1. Whenever MN attaches to n-MAG, the n-MAG requests multicast
context transfer to p-MAG.
2. p-MAG provides the multicast states corresponding to the moving
MN-Identifier to n-MAG. p-MAG utilizes a context transfer
protocol to deliver MN's profile to n-MAG, and sends Multicast
Context Transfer Data (M-CTD) (defined in Section 8.3) to n-MAG.
3. n-MAG records MN's profile including multicast channel
information.
4. n-MAG subscribes multicast channel on behalf of MN. PBU-M is
transmitted to LMA. If the received PBA message has the Status
field value set to 0 (Proxy Binding Update accepted), the MAG
MUST establish an M-Tunnel for forwarding corresponding
multicast data if there is no existing M-Tunnel to that LMA.
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MN p-MAG n-MAG LMA
| | | |
|-MLD Report->| MLD Report |
| |============= M-Tunnel ===========>|
| | | |---> PIM join
| | Multicast data |
|<------------|<============ M-Tunnel ============|
| | | |
Detach | | |
| | | |
Attach | | |
| | | |
|------------RS-------------->| |
| |<---CT-Req-----| |
| | | |
| |-----CXTP----->| |
| | M-CTD | MLD Report |
| | |-------PBU-M------>|
| | | |
| | |<-------PBA--------|
| | | |
|<-----------RA---------------| |
| | | |
| | | Multicast data |
|<----------------------------|<==== M-Tunnel ====|
| | | |
|<---------MLD Query----------| MLD Report |
|----------MLD Report-------->|===== M-Tunnel ===>|
| | | |
Figure 7: MLD listener handover with CXTP
After MN attaches to n-MAG, the multicast data will be delivered to
the MN immediately. MN's multicast membership state is maintained
with MLD Query and Report messages exchanged by MN and n-MAG.
Mobile node's multicast state is kept in MN's profile. If MN's
policy profile is stored in a policy store [2], it is not necessary
to use a context transfer protocol between p-MAG and n-MAG. In such
a case, n-MAG obtains MN's multicast state by the same mechanism used
to acquire MN-ID and profile during MN's attachment process [2].
The procedure for MLD listener handover with MN's Policy Profile
(Figure 8) is shown as follows.
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1. n-MAG obtains the MN-Identifier and learns multicast channel
information described in Mobile Node's Policy Profile associated
to this MN-Identifier.
2. n-MAG prepares the PBU-M that includes multicast channel
information the MN has subscribed.
3. n-MAG transmits PBU-M to LMA. If the received PBA message has
the Status field value set to 0 (Proxy Binding Update accepted),
the MAG MUST establish an M-Tunnel for forwarding corresponding
multicast data if there is no existing M-Tunnel to that LMA.
4. LMA forwards requested multicast data through an M-Tunnel
between the LMA and n-MAG.
MN p-MAG n-MAG LMA
| | | |
|-MLD Report->| MLD Report |
| |============= M-Tunnel ===========>|
| | | |---> PIM join
| | Multicast data |
|<------------|<============ M-Tunnel ============|
| | | |
Detach | | |
| | | |
Attach | MN attachment event |
| | (Acquire MN-Id and Profile) |
| | | |
|------------RS-------------->| |
| | | MLD Report |
| | |-------PBU-M------>|
| | | |
| | |<-------PBA--------|
| | | |
|<-----------RA---------------| |
| | | |
| | | Multicast data |
|<----------------------------|<==== M-Tunnel ====|
| | | |
|<---------MLD Query----------| MLD Report |
|----------MLD Report-------->|===== M-Tunnel ===>|
| | | |
Figure 8: MLD listener handover with MN's Policy Profile
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8.2. MAG Operating As Multicast Router
MAG operating PIM-SM multicast routing protocol joins the multicast
delivery tree when an attached mobile node subscribes a multicast
channel. In order to reduce handover latency, LMA forwards multicast
data to n-MAG until n-MAG has completed to join the multicast
delivery tree. A Proxy Binding Update with multicast extension
(PBU-M) is always used to request the LMA to forward multicast data.
When MAG operates PIM-SM routing protocol, leveraging CXTP is the
possible handover scenario with the following procedure.
1. Whenever MN attaches to n-MAG, the n-MAG requests multicast
context transfer to p-MAG.
2. p-MAG provides the multicast states corresponding to the moving
MN-Identifier to n-MAG. p-MAG utilizes a context transfer
protocol to deliver MN's profile to n-MAG, and sends M-CTD to
n-MAG.
3. n-MAG initiates the process to subscribe the multicast channels.
4. n-MAG requests LMA to forward multicast data in the meantime.
n-MAG prepares the PBU-M that includes multicast channel
information the MN has subscribed and has not yet received at
n-MAG.
5. LMA forwards requested multicast data through an M-Tunnel
between the LMA and n-MAG.
6. Whenever n-MAG joins the multicast delivery tree, it notifies
the LMA to stop forwarding the data and switches to the optimal
multicast routing path.
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MN p-MAG n-MAG LMA
| | | |
|--MLD Report->| MLD Hold |
| |=========== M-Tunnel =============>|
| |---> PIM join | |---> PIM join
| | | |
|<--Multicast--| | |
| data | | |
Detach | | |
| | | |
Attach | | |
| | | |
|-------------RS-------------->| |
| | | |
| |<---CT-Req-----| |
| | | |
| |-----CXTP----->| |
| | M-CTD |---> PIM join |
| | | |
| | | MLD Report (join) |
| | |-------PBU-M------>|
| | | |
| | |<-------PBA--------|
| | | |
|<------------RA---------------| |
| | | |
| | | Multicast data |
| | |<==== M-Tunnel ====|
|<-------Multicast data--------| |
| | | |
| | Join process completed |
| | | |
| | | MLD Hold |
| | |-------PBU-M------>|
| | | |
|<-------Multicast data--------| |
| | | |
Figure 9: PIM-SM handover with CXTP
The following procedure is for PIM-SM handover using MN's Policy
Profile.
1. When n-MAG detects a mobile node movement, it obtains the MN-
Identifier and learns multicast channel information described in
Mobile Node's Policy Profile associated to this MN-Identifier.
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2. n-MAG prepares the PBU-M that includes multicast channel
information the MN has subscribed and has not yet received at
n-MAG.
3. n-MAG transmits PBU-M to LMA. If the received PBA message has
the Status field value set to 0, the MAG MUST establish an
M-Tunnel for forwarding corresponding multicast data if there is
no existing M-Tunnel to that LMA.
4. LMA subscribes requested multicast channels and forwards the
data through an M-Tunnel between the LMA and n-MAG.
5. Whenever n-MAG joins the multicast delivery tree, it notifies
the LMA to stop forwarding the data and switches to the optimal
multicast routing path.
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MN p-MAG n-MAG LMA
| | | |
|--MLD Report->| | |
| | MLD Hold |
| |=========== M-Tunnel =============>|
| |---> PIM join | |---> PIM join
| | | |
|<--Multicast--| | |
| data | | |
| | | |
Detach | | |
| | | |
Attach | MN attachment event |
| | (Acquire MN-Id and Profile) |
|-------------RS-------------->| |
| | |---> PIM join |
| | | |
| | | MLD Report (join) |
| | |-------PBU-M------>|
| | | |
| | |<-------PBA--------|
| | | |
|<------------RA---------------| |
| | | |
| | | Multicast data |
| | |<==== M-Tunnel ====|
|<-------Multicast data--------| |
| | | |
| | Join process completed |
| | | |
| | | MLD Hold |
| | |-------PBU-M------>|
| | | |
|<-------Multicast data--------| |
| | | |
Figure 10: PIM-SM handover with MN's Policy Profile
8.3. Multicast Context Transfer Data Format
The following information is necessary to keep mobile node's
membership status, and hence M-CTD includes the information.
1. Receiver address - indicates an address of a receiver host
sending the Current-State Report.
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2. Last membership report - indicates the time that the router
receives the last Current-State Report.
3. Filter mode - indicates either INCLUDE or EXCLUDE as defined in
[4].
4. Source addresses and multicast address - indicates the address
pair that the receiver has joined.
8.4. Proxy Binding Update with Multicast Extension
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence # |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|A|H|L|K|M|R|P|C| Reserved | Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. .
. Mobility options .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 11: Proxy Binding Update Message with Multicast Extension
A Binding Update message that is sent by MAG to LMA is referred to as
the "Proxy Binding Update" message. A new flag (C) is included in
the Binding Update message with multicast extension. The rest of the
Binding Update message format remains the same as defined in [10] and
with the additional (R), (M), and (P) flags, as specified in [12],
[13], and [2], respectively.
Multicast Channel Subscription Flag
A new flag (C) is included in the Binding Update message to
indicate to LMA that the Binding Update message is a multicast
channel subscription.
When (C) flag is specified in PBU-M message, the mobility options
field includes the same information of MLDv2 Report message [4]:
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 143 | Reserved | Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved |Nr of Mcast Address Records (M)|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. .
. Multicast Address Record [1] .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. .
. Multicast Address Record [2] .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| . |
. . .
| . |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. .
. Multicast Address Record [M] .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 12
Each Multicast Address Record has the following internal format:
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Record Type | Aux Data Len | Number of Sources (N) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
* *
| |
* Multicast Address *
| |
* *
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
* *
| |
* Source Address [1] *
| |
* *
| |
+- -+
| |
* *
| |
* Source Address [2] *
| |
* *
| |
+- -+
. . .
. . .
. . .
+- -+
| |
* *
| |
* Source Address [N] *
| |
* *
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. .
. Auxiliary Data .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 13
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All the above fields contain data with the same definitions in [4].
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9. IANA Considerations
This document creates a new registry for the flags in the Binding
Update message called the "Binding Update Flags".
The following flags are reserved:
(A) 0x8000 [RFC3775]
(H) 0x4000 [RFC3775]
(L) 0x2000 [RFC3775]
(K) 0x1000 [RFC3775]
(M) 0x0800 [RFC4140]
(R) 0x0400 [RFC3963]
(P) 0x0200 [RFC5213]
This document reserves a new flag (C) for "Proxy Binding Update with
Multicast Extension" as described in Section 8.4 as follows:
(C) 0x0100
The rest of the values in the 16-bit field are reserved. New values
can be assigned by Standards Action or IESG approval.
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10. Security Considerations
TBD.
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11. Acknowledgements
Many of the specifications described in this document are discussed
and provided by the multimob mailing-list.
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12. References
12.1. Normative References
[1] Bradner, S., "Key words for use in RFCs to indicate requirement
levels", RFC 2119, March 1997.
[2] Gundavelli, S, Ed., Leung, K., Devarapalli, V., Chowdhury, K.,
and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008.
[3] Fenner, B., Handley, M., Holbrook, H., and I. Kouvelas,
"Protocol Independent Multicast - Sparse Mode (PIM-SM):
Protocol Specification (Revised)", RFC 4601, August 2006.
[4] Vida, R. and L. Costa, "Multicast Listener Discovery Version 2
(MLDv2) for IPv6", RFC 3810, June 2004.
[5] Liu, H., Cao, W., and H. Asaeda, "Lightweight IGMPv3 and MLDv2
Protocols",
draft-ietf-mboned-lightweight-igmpv3-mldv2-05.txt (work in
progress), May 2009.
[6] Deering, S., Fenner, W., and B. Haberman, "Multicast Listener
Discovery (MLD) for IPv6", RFC 2710, October 1999.
[7] Holbrook, H. and B. Cain, "Source-Specific Multicast for IP",
RFC 4607, August 2006.
[8] Fenner, B., He, H., Haberman, B., and H. Sandick, "Internet
Group Management Protocol (IGMP) / Multicast Listener Discovery
(MLD)-Based Multicast Forwarding ("IGMP/MLD Proxying")",
RFC 4605, August 2006.
[9] Asaeda, H. and T. Schmidt, "IGMP and MLD Extensions for Mobile
Hosts and Routers",
draft-asaeda-multimob-igmp-mld-mobility-extensions-03.txt (work
in progress), July 2009.
[10] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support in
IPv6", RFC 3775, June 2004.
[11] Loughney, Ed., J., Nakhjiri, M., Perkins, C., and R. Koodli,
"Context Transfer Protocol (CXTP)", RFC 4067, July 2005.
12.2. Informative References
[12] Devarapalli, V., Wakikawa, R., Petrescu, A., and P. Thubert,
"Network Mobility (NEMO) Basic Support Protocol", RFC 3963,
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January 2005.
[13] Soliman, H., Castelluccia, C., El Malki, K., and L. Bellier,
"Hierarchical Mobile IPv6 Mobility Management (HMIPv6)",
RFC 4140, August 2005.
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Authors' Addresses
Hitoshi Asaeda
Keio University
Graduate School of Media and Governance
5322 Endo
Fujisawa, Kanagawa 252-8520
Japan
Email: asaeda@wide.ad.jp
URI: http://www.sfc.wide.ad.jp/~asaeda/
Pierrick Seite
France Telecom
4, rue du Clos Courtel
BP 91226, Cesson-Sevigne 35512
France
Email: pierrick.seite@orange-ftgroup.com
Jinwei Xia
Huawei Technologies Co., Ltd.
Huihong Mansion, No.91 Baixia Rd.
Nanjing, Jiangsu 21001
China
Email: xiajinwei@huawei.com
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