MULTIMOB Group H. Asaeda
Internet-Draft Keio University
Intended status: Standards Track P. Seite
Expires: August 28, 2011 France Telecom
J. Xia
Huawei
February 24, 2011
PMIPv6 Extensions for Multicast
draft-asaeda-multimob-pmip6-extension-05
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.
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 August 28, 2011.
Copyright Notice
Copyright (c) 2011 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
Asaeda, et al. Expires August 28, 2011 [Page 1]
Internet-Draft PMIPv6 Extensions for Multicast February 2011
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
This document may contain material from IETF Documents or IETF
Contributions published or made publicly available before November
10, 2008. The person(s) controlling the copyright in some of this
material may not have granted the IETF Trust the right to allow
modifications of such material outside the IETF Standards Process.
Without obtaining an adequate license from the person(s) controlling
the copyright in such materials, this document may not be modified
outside the IETF Standards Process, and derivative works of it may
not be created outside the IETF Standards Process, except to format
it for publication as an RFC or to translate it into languages other
than English.
Asaeda, et al. Expires August 28, 2011 [Page 2]
Internet-Draft PMIPv6 Extensions for Multicast February 2011
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Conventions and 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. Handover Process . . . . . . . . . . . . . . . . . . . . . . . 16
7.1. MAG Operating As MLD Proxy . . . . . . . . . . . . . . . . 16
7.2. MAG Operating As PIM-SM Router . . . . . . . . . . . . . . 19
7.3. Multicast Context Transfer Data Format . . . . . . . . . . 22
7.4. Proxy Binding Update with Multicast Extension . . . . . . 23
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 27
9. Security Considerations . . . . . . . . . . . . . . . . . . . 28
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 29
11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 30
11.1. Normative References . . . . . . . . . . . . . . . . . . . 30
11.2. Informative References . . . . . . . . . . . . . . . . . . 31
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 32
Asaeda, et al. Expires August 28, 2011 [Page 3]
Internet-Draft PMIPv6 Extensions for Multicast February 2011
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. Since LMA and
MAG set up a bi-directional tunnel for each mobile node and forwards
all mobile node's traffic according to [2], it highly wastes network
resources when a large number of mobile nodes join/subscribe the same
multicast sessions/channels, because independent data copies of the
same multicast packet are delivered to the subscriber nodes in a
unicast manner through MAG.
The base solution described in [14] provides options for deploying
multicast listener functions in PMIPv6-Domains without modifying
mobility and multicast protocol standards. However, in this
specification, MAG MUST act as an MLD proxy and hence MUST dedicate a
tunnel link between LMA and MAG to an incoming interface for all
multicast traffic. This limitation does not allow to use PIM-SM
native routing on MAG, does not enable local routing, and does not
support source mobility. Furthermore, although it would be able to
minimize the join latency for mobile nodes attached to a new network
by tuning the Startup Query Interval value for the new MAG as
proposed in [17], the base solution does not provide any seamless
handover mechanism with a context transfer function.
This document describes PMIPv6 extensions to support IP multicast
communication for mobile nodes in PMIPv6-Domain. The proposed
protocol extension provides; 1) a dedicated bi-directional multicast
tunnel (M-Tunnel) between LMA and MAG, 2) seamless handover, and 3)
local routing to deliver IP multicast packets for mobile nodes when
MAG acts as a router. When MAG acts as a router (see Section 5.2),
multicast source mobility can be enabled in PMIPv6-Domain. However,
multicast listener mobility is mainly focused on in this document;
therefore the detail description of source mobility is out of scope
of this document.
This document assumes that LMA must be capable of forwarding
multicast packets through MAG toward the corresponding mobile nodes.
This condition requires LMA to attach multicast networks and enable
Asaeda, et al. Expires August 28, 2011 [Page 4]
Internet-Draft PMIPv6 Extensions for Multicast February 2011
either the Protocol-Independent Multicast - Sparse Mode (PIM-SM)
multicast routing protocol [3] or MLD proxy [8] function. 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], whether it
acts as a PIM-SM router or MLD proxy. Each mobile node will connect
MAG with a point-to-point access link.
On the other hands, this document does not cover the scenario in
which a single LMA or MAG enables both a PIM-SM routing protocol and
MLD proxy function simultaneously. Therefore, handover for mobile
nodes between a PIM-SM capable MAG to MLD proxy MAG is out of scope
of this document. It is assumed that all MAGs in the PMIPv6-Domain
behave in the same way, either acting as a PIM-SM router or MLD
proxy.
Seamless handover is also considered in this document. When a mobile
node receiving multicast data detaches from the current MAG and
attaches to a new MAG, the node should be able to continuously
receive the multicast data through the new MAG. The handover
procedure guarantees multicast session continuity and avoids 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.
Asaeda, et al. Expires August 28, 2011 [Page 5]
Internet-Draft PMIPv6 Extensions for Multicast February 2011
2. Conventions and 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 [1].
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). A Proxy Binding Update with multicast extension (PBU-M)
newly defined in this document is also used to request the LMA to
forward multicast data.
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]. Mobile
node's Policy Profile is provided by "policy store" whose definition
is the same as of [2], or by CXTP.
Asaeda, et al. Expires August 28, 2011 [Page 6]
Internet-Draft PMIPv6 Extensions for Multicast February 2011
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 1.
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 1: Proxy Mobile IPv6 Domain
Asaeda, et al. Expires August 28, 2011 [Page 7]
Internet-Draft PMIPv6 Extensions for Multicast February 2011
When a mobile node wants to subscribe/unsubscribe a multicast
channel, it 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 2: 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 can transmit different multicast
channel data as shown in Figure 2.
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 3: 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,
Asaeda, et al. Expires August 28, 2011 [Page 8]
Internet-Draft PMIPv6 Extensions for Multicast February 2011
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 can be dynamically created along with the multicast
subscription state. The manner of this "dynamic M-Tunnel" creation
is similar to the manner of a subscriber's bi-directional tunnel
creation described in Section 5.6.1 of [2]. MAG initiates M-Tunnel
establishment when a mobile node, which is the first subscriber of
multicast channels, attaches to the PMIPv6-Domain, and maintains the
M-Tunnel as active until the last subscriber mobile node terminates
its multicast channel subscription.
On the other hand, instead of dynamically creating the M-Tunnel and
tearing it down on an "on-demand" basis, an M-Tunnel can be pre-
established without detecting a multicast channel subscription
request from a mobile node and kept while the MAG is running. This
"static M-Tunnel" creation is usually done in a bootstrap phase of
MAG.
Administrators or operators shall decide whether dynamic or static
M-Tunnel is chosen in their network by the configuration. Such
decision may be implementation dependent. Note that, in each case,
M-Tunnel is not per mobile node basis, but per MAG basis; it is
shared with all mobile nodes attached to 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.
Asaeda, et al. Expires August 28, 2011 [Page 9]
Internet-Draft PMIPv6 Extensions for Multicast February 2011
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 4. 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)".
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 4: 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 5). 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 a mobile node
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 7).
Asaeda, et al. Expires August 28, 2011 [Page 10]
Internet-Draft PMIPv6 Extensions for Multicast February 2011
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 5: 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 7).
Asaeda, et al. Expires August 28, 2011 [Page 11]
Internet-Draft PMIPv6 Extensions for Multicast February 2011
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 mobile node 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.
Asaeda, et al. Expires August 28, 2011 [Page 12]
Internet-Draft PMIPv6 Extensions for Multicast February 2011
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
Asaeda, et al. Expires August 28, 2011 [Page 13]
Internet-Draft PMIPv6 Extensions for Multicast February 2011
interface, and want MAG to "dynamically select" optimized routing
path, MAG MUST act as a PIM-SM router.
Asaeda, et al. Expires August 28, 2011 [Page 14]
Internet-Draft PMIPv6 Extensions for Multicast February 2011
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.
PMIPv6 [2] also covers network mobility where a mobile node is a
router. However, to avoid the complexity, in this document, the
mobile router should behave as an MLD proxy [8] but should not act as
a PIM-SM router, when the mobile router needs to forward multicast
data to its downstream nodes.
Asaeda, et al. Expires August 28, 2011 [Page 15]
Internet-Draft PMIPv6 Extensions for Multicast February 2011
7. 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.
7.1. 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 7.4) is
always used to request the LMA to forward multicast data.
The MLD listener handover with CXTP shown in Figure 6 is defined as
follows.
1. Whenever MN attaches to n-MAG, the n-MAG requests multicast
context transfer to p-MAG. The n-MAG identifies the p-MAG using
the same mechanism described in [12]: either the MN or the new
access network provides the AP-ID of the previous network to the
n-MAG. This information is used by the n-MAG to identify the
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 Policy Profile to n-MAG, and sends
Multicast Context Transfer Data (M-CTD) (defined in Section 7.3)
to n-MAG.
3. n-MAG records MN's Policy Profile including multicast channel
information.
4. If there are multicast channels the MN has subscribed but the
n-MAG has not yet subscribed, n-MAG prepares the PBU-M including
(C) flag (specified in Section 7.4) and multicast channel
information, and transmits the PBU-M to LMA.
5. If the received PBA message has the Status field value set to 0
(Proxy Binding Update accepted) and if there is no existing
M-Tunnel to that LMA, the n-MAG establishes an M-Tunnel for
forwarding corresponding multicast data.
Asaeda, et al. Expires August 28, 2011 [Page 16]
Internet-Draft PMIPv6 Extensions for Multicast February 2011
6. 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 | | |
| | | |
|------------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 6: 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 Policy 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 Policy Profile during MN's
attachment process [2].
The procedures for MLD listener handover with MN's Policy Profile
Asaeda, et al. Expires August 28, 2011 [Page 17]
Internet-Draft PMIPv6 Extensions for Multicast February 2011
(Figure 7) are shown as follows.
1. Whenever MN attaches to n-MAG, the n-MAG obtains the MN-
Identifier and learns multicast channel information described in
Mobile Node's Policy Profile associated to this MN-Identifier.
2. If there are multicast channels the MN has subscribed but the
n-MAG has not yet subscribed, n-MAG prepares the PBU-M including
(C) flag and multicast channel information, and transmits the
PBU-M to LMA.
3. If the received PBA message has the Status field value set to 0
and if there is no existing M-Tunnel to that LMA, the n-MAG
establishes an M-Tunnel for forwarding corresponding multicast
data.
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 ===>|
| | | |
Asaeda, et al. Expires August 28, 2011 [Page 18]
Internet-Draft PMIPv6 Extensions for Multicast February 2011
Figure 7: MLD listener handover with MN's Policy Profile
7.2. MAG Operating As PIM-SM 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 procedures.
1. Whenever MN attaches to n-MAG, the n-MAG requests multicast
context transfer to p-MAG. The n-MAG identifies p-MAG as
described in Section 7.1.
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 Policy Profile to n-MAG, and sends
M-CTD to n-MAG.
3. n-MAG records MN's Policy Profile including multicast channel
information.
4. If there are multicast channels the MN has subscribed but the
n-MAG has not yet subscribed, n-MAG joins the corresponding
multicast channels, prepares the PBU-M including (C) flag and
multicast channel information, and transmits the PBU-M to LMA.
5. If the received PBA message has the Status field value set to 0
and if there is no existing M-Tunnel to that LMA, the n-MAG
establishes an M-Tunnel for forwarding corresponding multicast
data.
6. LMA forwards requested multicast data through an M-Tunnel
between the LMA and n-MAG.
7. Whenever n-MAG joins the multicast delivery tree, it notifies
the LMA to stop forwarding the data, switches to the optimal
multicast routing path, and forwards the multicast data.
Asaeda, et al. Expires August 28, 2011 [Page 19]
Internet-Draft PMIPv6 Extensions for Multicast February 2011
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 8: PIM-SM handover with CXTP
The following procedures are for PIM-SM handover using MN's Policy
Profile.
1. Whenever MN attaches to n-MAG, the n-MAG obtains the MN-
Identifier and learns multicast channel information described in
Mobile Node's Policy Profile associated to this MN-Identifier.
Asaeda, et al. Expires August 28, 2011 [Page 20]
Internet-Draft PMIPv6 Extensions for Multicast February 2011
2. If there are multicast channels the MN has subscribed but the
n-MAG has not yet subscribed, n-MAG joins the corresponding
multicast channels, prepares the PBU-M including (C) flag and
multicast channel information, and transmits the PBU-M to LMA.
3. If the received PBA message has the Status field value set to 0
and if there is no existing M-Tunnel to that LMA, the n-MAG
establishes an M-Tunnel for forwarding corresponding multicast
data.
4. LMA forwards requested multicast 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, switches to the optimal
multicast routing path, and forwards the multicast data.
Asaeda, et al. Expires August 28, 2011 [Page 21]
Internet-Draft PMIPv6 Extensions for Multicast February 2011
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 9: PIM-SM handover with MN's Policy Profile
7.3. Multicast Context Transfer Data Format
The following information included in M-CTD is used to distinguish
mobile node's membership status.
1. Receiver address - indicates the address of the MN sending the
Current-State Report.
Asaeda, et al. Expires August 28, 2011 [Page 22]
Internet-Draft PMIPv6 Extensions for Multicast February 2011
2. Filter mode - indicates either INCLUDE or EXCLUDE as defined in
[4].
3. Source addresses and multicast address - indicates the address
pairs the MN has joined.
To cooperate with CXTP, an IGMP/MLD-based explicit membership
tracking function [13] MUST be enabled on MAG (whether the MAG
behaves as a router or proxy). The explicit tracking function
enables a router to keep track of downstream multicast membership
state created by downstream hosts attached on the router's link.
Since [13] does not maintain information of an (S,G) join request
with EXCLUDE filter mode, when the "Filter mode" is EXCLUDE, "Source
address" MUST be "Null".
7.4. 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 10: 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 Proxy Binding Update message with Multicast extension (PBU-M).
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 [15], [16], 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]:
Asaeda, et al. Expires August 28, 2011 [Page 23]
Internet-Draft PMIPv6 Extensions for Multicast February 2011
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 11
Each Multicast Address Record has the following internal format:
Asaeda, et al. Expires August 28, 2011 [Page 24]
Internet-Draft PMIPv6 Extensions for Multicast February 2011
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Record Type | Aux Data Len | Number of Sources (N) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
* *
| |
* Multicast Address *
| |
* *
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
* *
| |
* Source Address [1] *
| |
* *
| |
+- -+
| |
* *
| |
* Source Address [2] *
| |
* *
| |
+- -+
. . .
. . .
. . .
+- -+
| |
* *
| |
* Source Address [N] *
| |
* *
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. .
. Auxiliary Data .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 12
Asaeda, et al. Expires August 28, 2011 [Page 25]
Internet-Draft PMIPv6 Extensions for Multicast February 2011
All the above fields contain data with the same definitions in [4].
Asaeda, et al. Expires August 28, 2011 [Page 26]
Internet-Draft PMIPv6 Extensions for Multicast February 2011
8. 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 7.4 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.
Asaeda, et al. Expires August 28, 2011 [Page 27]
Internet-Draft PMIPv6 Extensions for Multicast February 2011
9. Security Considerations
TBD.
Asaeda, et al. Expires August 28, 2011 [Page 28]
Internet-Draft PMIPv6 Extensions for Multicast February 2011
10. Acknowledgements
Many of the specifications described in this document are discussed
and provided by the multimob mailing-list.
Asaeda, et al. Expires August 28, 2011 [Page 29]
Internet-Draft PMIPv6 Extensions for Multicast February 2011
11. References
11.1. 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] Yokota, H., Chowdhury, K., Koodli, R., Patil, B., and F. Xia,
"Fast Handovers for Proxy Mobile IPv6", RFC 5949,
September 2010.
Asaeda, et al. Expires August 28, 2011 [Page 30]
Internet-Draft PMIPv6 Extensions for Multicast February 2011
[13] Asaeda, H. and Y. Uchida, "IGMP/MLD-Based Explicit Membership
Tracking Function for Multicast Routers",
draft-asaeda-mboned-explicit-tracking-01.txt (work in
progress), October 2010.
[14] Schmidt, T., Waehlisch, M., and S. Krishnan, "Base Deployment
for Multicast Listener Support in PMIPv6 Domains",
draft-ietf-multimob-pmipv6-base-solution-07.txt (work in
progress), December 2010.
11.2. Informative References
[15] Devarapalli, V., Wakikawa, R., Petrescu, A., and P. Thubert,
"Network Mobility (NEMO) Basic Support Protocol", RFC 3963,
January 2005.
[16] Soliman, H., Castelluccia, C., El Malki, K., and L. Bellier,
"Hierarchical Mobile IPv6 Mobility Management (HMIPv6)",
RFC 4140, August 2005.
[17] Asaeda, H., Uchida, Y., Liu, H., and Q. Wu, "Tuning the
Behavior of IGMP and MLD for Mobile Hosts and Routers",
draft-asaeda-multimob-igmp-mld-optimization-05.txt (work in
progress), February 2011.
Asaeda, et al. Expires August 28, 2011 [Page 31]
Internet-Draft PMIPv6 Extensions for Multicast February 2011
Authors' Addresses
Hitoshi Asaeda
Keio University
Graduate School of Media and Governance
5322 Endo
Fujisawa, Kanagawa 252-0816
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
Asaeda, et al. Expires August 28, 2011 [Page 32]