PIM Working Group LM. Contreras
Internet-Draft Telefonica I+D
Intended status: Experimental CJ. Bernardos
Expires: January 4, 2014 UC3M
JC. Zuniga
InterDigital
July 3, 2013
Extension of the MLD proxy functionality to support multiple upstream
interfaces
draft-contreras-pim-multiple-upstreams-00
Abstract
This document presents different scenarios of applicability for an
MLD proxy running more than one upstream interface. Since those
scenarios impose different requirements on the MLD proxy with
multiple upstream interfaces, it is important to ensure that the
proxy functionality addresses all of them for compatibility.
The purpose of this document is to define the requirements in an MLD
proxy with multiple interfaces covering a variety of applicability
scenarios, and to specify the proxy functionality to satisfy all of
them.
Status of this Memo
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This Internet-Draft will expire on January 4, 2014.
Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Problem statement . . . . . . . . . . . . . . . . . . . . . . 4
4. Scenarios of applicability . . . . . . . . . . . . . . . . . . 7
4.1. Fixed network scenarios . . . . . . . . . . . . . . . . . 7
4.1.1. Multicast wholesale offer for residential services . . 8
4.1.1.1. Requirements . . . . . . . . . . . . . . . . . . . 8
4.1.2. Multicast resiliency . . . . . . . . . . . . . . . . . 8
4.1.2.1. Requirements . . . . . . . . . . . . . . . . . . . 8
4.1.3. Load balancing for multicast traffic in the metro
segment . . . . . . . . . . . . . . . . . . . . . . . 9
4.1.3.1. Requirements . . . . . . . . . . . . . . . . . . . 9
4.1.4. Summary of the requirements needed for mobile
network scenarios . . . . . . . . . . . . . . . . . . 9
4.2. Mobile network scenarios . . . . . . . . . . . . . . . . . 10
4.2.1. Applicability to multicast listener mobility . . . . . 10
4.2.1.1. Single MLD proxy instance on MAG . . . . . . . . . 11
4.2.1.1.1. Requirements . . . . . . . . . . . . . . . . . 11
4.2.1.2. Remote and local multicast subscription . . . . . 11
4.2.1.2.1. Requirements . . . . . . . . . . . . . . . . . 12
4.2.1.3. Dual subscription to multicast groups during
handover . . . . . . . . . . . . . . . . . . . . . 12
4.2.1.3.1. Requirements . . . . . . . . . . . . . . . . . 13
4.2.2. Applicability to multicast source mobility . . . . . . 13
4.2.2.1. Support of remote and direct subscription in
basic source mobility . . . . . . . . . . . . . . 13
4.2.2.1.1. Requirements . . . . . . . . . . . . . . . . . 14
4.2.2.2. Direct communication between source and
listener associated with distinct LMAs but on
the same MAG . . . . . . . . . . . . . . . . . . . 14
4.2.2.2.1. Requirements . . . . . . . . . . . . . . . . . 15
4.2.2.3. Route optimization support in source mobility
for remote subscribers . . . . . . . . . . . . . . 15
4.2.2.3.1. Requirements . . . . . . . . . . . . . . . . . 15
4.2.3. Summary of the requirements needed for mobile
network scenarios . . . . . . . . . . . . . . . . . . 16
5. Functional specification of an MLD proxy with multiple
interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . 18
6. Security Considerations . . . . . . . . . . . . . . . . . . . 18
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 18
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 18
9.1. Normative References . . . . . . . . . . . . . . . . . . . 18
9.2. Informative References . . . . . . . . . . . . . . . . . . 19
Appendix A. Basic support for multicast listener with PMIPv6 . . 19
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 21
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1. Introduction
The aim of this document is to define the functionality that an MLD
proxy with multiple upstream interfaces should have in order to
support different scenarios of applicability in both fixed and mobile
networks. This compatibility is needed in order to simplify node
functionality and to ensure an easier deployment of multicast
capabilities in all the use cases described in this document.
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC2119 [RFC2119].
This document uses the terminology defined in RFC4605 [RFC4605].
Specifically, the definition of Upstream and Downstream interfaces,
which are reproduced here for completeness.
Upstream interface: A proxy device's interface in the direction of
the root of the tree. Also called the "Host interface".
Downstream interface: Each of a proxy device's interfaces that is
not in the direction of the root of the tree. Also called the
"Router interfaces".
3. Problem statement
The concept of MLD proxy with several upstream interfaces has emerged
as a way of optimizing (and in some cases enabling) service delivery
scenarios where separate multicast service providers are reachable
through the same access network infrastructure. Figure 1 presents
the conceptual model under consideration.
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downstream upstream
interface interface A
| |
| | _______________
| +-------+ v / \
| | O-------( Multicast Set 1 )
+----------+ v | MLD | \_______________/
| Listener |------| | _______________
+----------+ | Proxy | / \
| O-------( Multicast Set 2 )
+-------+ ^ \_______________/
|
|
upstream
interface B
Figure 1: Concept of MLD proxy with multiple upstream interfaces
For illustrative purposes, two applications for fixed and mobile
networks are here introduced. They will be elaborated later on the
document.
In the case of fixed networks, multicast wholesale services in a
competitive residential market require an efficient distribution of
multicast traffic from different operators, i.e. the incumbent
operator and a number of alternative ones, on the network
infrastructure of the former. Existing proposals are based on the
use of PIM routing from the metro network, and multicast traffic
aggregation on the same tree. A different approach could be achieved
with the use of an MLD proxy with multiple upstream interfaces, each
of them pointing to a distinct multicast router in the metro border
which is part of separated multicast trees deep in the network.
Figure 2 graphically describes this scenario.
In the case of mobile networks, IP mobility services guarantee the
continuity of the IP session while a Mobile Node (MN) changes its
point of attachment. Proxy Mobile IPv6 (PMIPv6) RFC5213 [RFC5213]
standardized a protocol that allows the network to manage the MN
mobility without requiring specific support from the mobile terminal.
The traffic to the MN is tunneled from the Home Network making use of
two entities, one acting as mobility anchor, and the other as
Mobility Access Gateway (MAG). Multicast support in PMIPv6 RFC6224
[RFC6224] implies the delivery of all the multicast traffic from the
Home Network, via the mobility anchor. However, multicast routing
optimization [I-D.ietf-multimob-pmipv6-ropt] could take advantage of
an MLD proxy with multiple upstream interfaces by supporting the
decision of subscribing a multicast content from the Home Network or
from the local PMIPv6 domain if it is locally available. Figure 3
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presents this scenario.
Informational text is provided in Appendix A summarizing how the
basic solution for deploying multicast listener mobility with Proxy
Mobile IPv6 works.
downstream upstream
interface interface A
| |
| | _______________
| +--------+ v / \
| | O-------( Multicast Set 1 )
| | Aggr. | \_______________/
+----+ v | Switch | (e.g. from the Incumbent
| AN |-------| | Operator)
+----+ | (MLD | _______________
(e.g. | Proxy) | / \
DSLAM) | O-------( Multicast Set 2 )
+--------+ ^ \_______________/
| (e.g. from an Alternative
| Operator)
|
upstream
interface B
Figure 2: Example of usage of an MLD proxy with multiple upstream
interfaces in a fixed network scenario
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downstream upstream
interface interface A
| |
| | _______________
| +--------+ v / \
| | O-------( Multicast Set 1 )
| | | \_______________/
+----+ v | MAG | e.g. from the Home Network
| MN |-------| | via the mobility anchor)
+----+ | (MLD | _______________
| Proxy) | / \
| O-------( Multicast Set 2 )
+--------+ ^ \_______________/
| (e.g. from the local PMIPv6
| domain via direct routing)
|
upstream
interface B
Figure 3: Example of usage of an MLD proxy with multiple upstream
interfaces in a mobile network scenario
Since those scenarios can motivate distinct needs in terms of MLD
proxy functionality, it is necessary to consider a comprehensive
approach, looking at the possible scenarios, and establishing a
minimum set of requirements which can allow the operation of a
versatile MLD proxy with multiple upstream interfaces as a common
entity to all of them (i.e., no different kinds of proxies depending
on the scenario, but a common proxy applicable to all the potential
scenarios).
4. Scenarios of applicability
This section describes in detail a number of scenarios of
applicability of an MLD proxy with multiple upstream interfaces in
place. A number of requirements for the MLD proxy functionality are
identified from those scenarios.
4.1. Fixed network scenarios
Residential broadband users get access to multiple IP services
through fixed network infrastructures. End user's equipment is
connected to an access node, and the traffic of a number of access
nodes is collected in aggregation switches.
For the multicast service, the use of an MLD proxy with multiple
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upstream interfaces in those switches can provide service flexibility
in a lightweight and simpler manner if compared with PIM-routing
based alternatives.
4.1.1. Multicast wholesale offer for residential services
This scenario has been already introduced in the previous section,
and can be seen in Figure 2. There are two different operators, the
one operating the fixed network where the end user is connected
(e.g., typically an incumbent operator), and the one providing the
Internet service to the end user (e.g., an alternative Internet
service provider). Both can offer multicast streams that can be
subscribed by the end user, independently of which provider
contributes with the content.
Note that it is assumed that both providers offer distinct multicast
groups. However, more than one subscription to multicast channels of
different providers could take place simultaneously.
4.1.1.1. Requirements
o The MLD proxy should be able to deliver multicast control messages
sent by the end user to the corresponding provider's multicast
router.
o The MLD proxy should be able to deliver multicast control messages
sent by each of the providers to the corresponding end user.
4.1.2. Multicast resiliency
In current PIM-based solutions, the resiliency of the multicast
distribution relays on the routing capabilities provided by protocols
like PIM and VRRP. A simpler scheme could be achieved by
implementing different upstream interfaces on MLD proxies, providing
path diversity through the connection to distinct leaves of a given
multicast tree.
It is assumed that only one of the upstream interfaces is active in
receiving the multicast content, while the other is up and in standby
for fast switching.
4.1.2.1. Requirements
o The MLD proxy should be able to deliver multicast control messages
sent by the end user to the corresponding active upstream
interface.
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o The MLD proxy should be able to deliver multicast control messages
received in the active upstream to the end users, while ignoring
the control messages of the standby upstream interface.
o The MLD proxy should be able of rapidly switching from the active
to the standby upstream interface in case of network failure,
transparently to the end user.
4.1.3. Load balancing for multicast traffic in the metro segment
A single upstream interface in existing MLD proxy functionality
typically forces the distribution of all the channels on the same
path in the last segment of the network. Multiple upstream
interfaces could naturally split the demand, alleviating the
bandwidth requirements in the metro segment.
4.1.3.1. Requirements
o The MLD proxy should be able to deliver multicast control messages
sent by the end user to the corresponding multicast router which
provides the channel of interest.
o The MLD proxy should be able to deliver multicast control messages
sent by each of the multicast routers to the corresponding end
user.
o The MLD proxy should be able to decide which upstream interface is
selected for any new channel request according to defined criteria
(e.g., load balancing).
4.1.4. Summary of the requirements needed for mobile network scenarios
Following the analysis above, a number of different requirements can
be identified by the MLD proxy to support multiple upstream
interfaces in fixed network scenarios. The following table
summarizes these requirements.
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+-----------------------------------+
| Fixed Network Scenarios |
+---------+-----------+-----------+-----------+
|Functio- | Multicast | Multicast | Load |
|nality | Wholesale | Resiliency| Balancing |
+---------+-----------+-----------+-----------+
|Upstream | | | |
|Control | X | X | X |
|Delivery | | | |
+---------+-----------+-----------+-----------+
|Downstr. | | | |
|Control | X | X | X |
|Delivery | | | |
+---------+-----------+-----------+-----------+
|Active / | | | |
|Standby | | X | |
|Upstream | | | |
+---------+-----------+-----------+-----------+
|Upstr i/f| | | |
|selection| | | X |
|per group| | | |
+---------+-----------+-----------+-----------+
|Upstr i/f| | | |
|selection| | X | |
|all group| | | |
+---------+-----------+-----------+-----------+
Figure 4: Functionality needed on MLD proxy with multiple upstream
interfaces per application scenario in fixed networks
4.2. Mobile network scenarios
The mobile networks considered in this document are supposed to run
PMIPv6 protocol for IP mobility management. A brief description of
multicast provision in PMIPv6-based networks can be found in Appendix
A.
The use of an MLD proxy supporting multiple upstream interfaces can
improve the performance and the scalability of multicast-capable
PMIPv6 domains.
4.2.1. Applicability to multicast listener mobility
Three sub-cases can be identified for the multicast listener
mobility.
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4.2.1.1. Single MLD proxy instance on MAG
The base solution for multicast service in PMIPv6 RFC6224 [RFC6224]
assumes that any MN subscribed to multicast services receive the
multicast traffic through the associated LMA, as in the unicast case.
As standard MLD proxy functionality only supports one upstream
interface, the MAG should implement several separated MLD proxy
instances, one per LMA, in order to serve the multicast traffic to
the MNs, according to any particular LMA-MN association.
A way of avoiding the multiplicity of MLD proxy instance in a MAG is
to deploy a unique MLD proxy instance with multiple upstream
interfaces, one per LMA, without any change in the multicast traffic
distribution.
4.2.1.1.1. Requirements
o The MLD proxy should be able of delivering the multicast control
messages sent by the MNs to the associated LMA.
o The MLD proxy should be able of delivering the multicast control
messages sent by each of the connected LMAs to the corresponding
MN.
o The MLD proxy should be able of routing the multicast data coming
from different LMAs to the corresponding MNs according to the MN
to LMA association.
o The MLD proxy should be able of maintaining a 1:1 association
between an MN and LMA (or downstream to upstream).
4.2.1.2. Remote and local multicast subscription
This scenario has been already introduced in the previous section,
and can be seen in Figure 3. Standard MLD proxy definition, with a
unique upstream interface per proxy, does not allow the reception of
multicast traffic from distinct upstream multicast routers. In other
words, all the multicast traffic being sent to the MLD proxy in
downstream traverses a concrete, unique router before reaching the
MAG. There are, however, situations where different multicast
content could reach the MLD proxy through distinct next-hop routers.
For instance, the solution adopted to avoid the tunnel convergence
problem in basic multicast PMIPv6 deployments
[I-D.ietf-multimob-pmipv6-ropt] considers the possibility of
subscription to a multicast source local to the PMIPv6 domain. In
that situation, some multicast content will be accesses remotely,
through the home network via the multicast tree mobility anchor,
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while some other multicast content will reach the proxy directly, via
a local router in the domain.
4.2.1.2.1. Requirements
o The MLD proxy should be able of delivering the multicast control
messages sent by the MNs to the associated upstream interface
based on the location of the source, remote or local, for a
certain multicast group.
o The MLD proxy should be able of delivering the multicast control
messages sent either local or remotely to the corresponding MNs.
o The MLD proxy should be able of routing the multicast data coming
from different upstream interfaces to a certain MN according to
the MN subscription, either local or remote. Note that it is
assumed that a multicast group can be subscribed either locally or
remotely, but not simultaneously. However more than one
subscription could happen, being local or remote independently.
o The MLD proxy should be able of maintaining a 1:N association
between an MN and the remote and local multicast router (or
downstream to upstream).
o The MLD proxy should be able of switching between local or remote
subscription for per multicast group according to specific
configuration parameters (out of the scope of this document).
4.2.1.3. Dual subscription to multicast groups during handover
In the event of an MN handover, once an MN moves from a previous MAG
(pMAG) to a new MAG (nMAG), the nMAG needs to set up the multicast
status for the incoming MN, and subscribe the multicast channels it
was receiving before the handover event. The MN will then experience
a certain delay until it receives again the subscribed content.
A generic solution is being defined in
[I-D.ietf-multimob-handover-optimization] to speed up the knowledge
of the ongoing subscription by the nMAG. However, for the particular
case that the underlying radio access technology supports layer-2
triggers (thus requiring extra capabilities on the mobile node),
there could be inter-MAG cooperation for handover support if pMAG and
nMAG are known in advance.
This could be the case, for instance for those contents not already
arriving to the nMAG, where the nMAG temporally subscribes the
multicast groups of the ongoing MN's subscription via the pMAG, while
the multicast delivery tree among the nMAG and the mobility anchor is
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being established.
A similar approach is followed in
[I-D.schmidt-multimob-fmipv6-pfmipv6-multicast] despite the solution
proposed there differs from this approach (i.e., there is no
consideration of an MLD proxy with multiple interfaces).
4.2.1.3.1. Requirements
o The MLD proxy should be able of delivering the multicast control
messages sent by the MNs to the associated upstream interface
based on the handover specific moment, for a certain multicast
group.
o The MLD proxy should be able of delivering the multicast control
messages sent either from pMAG or the multicast anchor to the
corresponding MNs, based on the handover specific moment.
o The MLD proxy should be able of handle the incoming packet flows
from the two simultaneous upstream interfaces, in order to not
duplicate traffic delivered on the point-to-point link to the MN.
o The MLD proxy should be able of maintaining a 1:N association
between an MN and both the remote multicast router and the pMAG
(or downstream to upstream).
o The MLD proxy should be able of switching between local or remote
subscription for all the multicast groups (from pMAG to multicast
anchor) according to specific configuration parameters (out of the
scope of this document).
4.2.2. Applicability to multicast source mobility
A couple of sub-cases can be identified for the multicast source
mobility.
4.2.2.1. Support of remote and direct subscription in basic source
mobility
In the basic case of source mobility, the multicast source is
connected to one of the downstream interfaces of an MLD proxy.
According to the standard specification RFC4605 [RFC4605] every
packet sent by the multicast source will be forwarded towards the
root of the multicast tree.
However, linked to the mobility listener problem, there could be the
case of simultaneous remote subscribers, subscribing to the multicast
content through the home network, and local subscribers, requesting
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the contents directly via a multicast router residing on the same
PMIPv6 domain where the source is attached to.
Then, in order to provide the co-existence of both types of
subscribers, an MLD proxy with two upstream interfaces could
simultaneously serve all kind of multicast subscribers.
Basic source mobility is being defined in RFC4605 [RFC4605] but the
solution proposed there does not allow simultaneous co-existence of
remote and local subscribers (i.e., the content sent by the source is
either distributed locally to a multicast router in the PMIPv6
domain, or remotely by using the bi-directional tunnel towards the
mobility anchor, but not both simultaneously).
4.2.2.1.1. Requirements
o The MLD proxy should be able of forwarding (replicating) the
multicast content to both upstream interfaces, in case of
simultaneous remote and local distribution.
o The MLD proxy should be able of handling control information
incoming through any of the two upstream interfaces, providing the
expected behavior for each of the multicast trees.
o The MLD proxy should be able of routing the multicast data towards
different upstream interfaces for both remote and local
subscriptions that could happen simultaneously.
o The MLD proxy should be able of maintaining a 1:N association
between an MN and both the remote and local multicast router (or
downstream to upstream).
4.2.2.2. Direct communication between source and listener associated
with distinct LMAs but on the same MAG
In a certain PMIPv6 domain can be MNs associated to distinct LMAs
using the same MAG to get access to their corresponding home
networks. For multicast communication, according to the base
solution RFC6224 [RFC6224], each MN - LMA association implies a
distinct MLD proxy instance to be invoked in the MAG.
In these conditions, when a mobile source is serving multicast
content to a mobile listener, both attached to the same MAG but each
of them associated to different LMAs, the multicast flow must
traverse the PMIPv6 domain from the MAG to the LMA where the source
maintains an association, then from that LMA to the LMA where the
listener is associated to, and finally come back to the same MAG from
where the flow departed. This routing is extremely inefficient.
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An MLD proxy with multiple upstream interfaces avoids this behavior
since it allows to invoke a unique MLD proxy instance in the MAG. In
this case, the multicast source can directly communicate with the
multicast listener, without need for delivering the multicast traffic
to the LMAs.
4.2.2.2.1. Requirements
o The MLD proxy should be able of forwarding (replicating) the
multicast content to different upstream or downstream interfaces
where subscribers are present.
o The MLD proxy should be able of handling control information
incoming through any of the upstream or downstream interfaces
requesting a multicast flow being injected in another downstream
interface.
o The MLD proxy should be able of maintaining a 1:N association
between an MN and any of the upstream or downstream interfaces
demanding the multicast content.
4.2.2.3. Route optimization support in source mobility for remote
subscribers
Even in a scenario of remote subscription, there could be the case
where both the source and the listener are attached to the same
PMIPv6-Domain (for instance, no possibility of direct routing within
the PMIPv6, or source and listener pertaining to distinct home
networks). In this situation there is a possibility of route
optimization if inter-MAG communication is enabled, in such a way
that the listeners in the PMIPv6 domain are served through the
tunnels between MAGs, while the rest of remote listeners are served
through the mobility anchor.
A multi-upstream MLD proxy would allow the simultaneous delivery of
traffic to such kind of remote listeners.
A similar route optimization approach is proposed in
[I-D.liu-multimob-pmipv6-multicast-ro].
4.2.2.3.1. Requirements
o The MLD proxy should be able of forwarding (replicating) the
multicast content to both kinds of upstream interfaces, inter-MAG
tunnel interfaces and MAG to mobility anchor tunnel interface.
o The MLD proxy should be able of handling control information
incoming through any of the two types of upstream interfaces,
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providing the expected behavior for each of the multicast trees
(e.g., no forwarding traffic on one inter-MAG link once there are
not more listeners requesting the content).
o The MLD proxy should be able of routing the multicast data towards
different upstream interfaces for both remote and route optimized
subscriptions that could happen simultaneously.
o The MLD proxy should be able of maintaining a 1:N association
between an MN and both the remote and local MAGs (or downstream to
upstream).
4.2.3. Summary of the requirements needed for mobile network scenarios
After the previous analysis, a number of different requirements can
be identified by the MLD proxy to support multiple upstream
interfaces in mobile network scenarios. The following table
summarizes these requirements.
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+----------------------------------------------------+
| Mobile Network Scenarios |
+--------------------------+-------------------------+
| Mulicast Listener | Mulicast Source |
+---------+--------+--------+--------+--------+--------+-------+
| | Single| Remote | Dual | Direct |Listener| Route |
|Functio- | MLD |& local | subscr.|& remote|& source|optimi.|
|nality | Proxy | subscr.| in HO | subscr.| on MAG | |
+---------+--------+--------+--------+--------+--------+-------+
|Upstream | | | | | | |
|Control | X | X | X | X | X | X |
|Delivery | | | | | | |
+---------+--------+--------+--------+--------+--------+-------+
|Downstr. | | | | | | |
|Control | X | X | X | | X | |
|Delivery | | | | | | |
+---------+--------+--------+--------+--------+--------+-------+
|Upstream | | | | | | |
|Data | | | | X | | X |
|Delivery | | | | | | |
+---------+--------+--------+--------+--------+--------+-------+
|Downstr. | | | | | | |
|Data | X | X | X | | X | |
|Delivery | | | | | | |
+---------+--------+--------+--------+--------+--------+-------+
|1:1 MN to| | | | | | |
|upstream | X | | | | | |
|assoc. | | | | | | |
+---------+--------+--------+--------+--------+--------+-------+
|1:N MN to| | | | | | |
|upstream | | X | X | X | X | X |
|assoc. | | | | | | |
+---------+--------+--------+--------+--------+--------+-------+
|Upstr i/f| | | | | | |
|selection| | X | | | | |
|per group| | | | | | |
+---------+--------+--------+--------+--------+--------+-------+
|Upstr i/f| | | | | | |
|selection| | | X | | | |
|all group| | | | | | |
+---------+--------+--------+--------+--------+--------+-------+
|Upstream | | | | | | |
|traffic | | | | X | | X |
|replicat.| | | | | | |
+---------+--------+--------+--------+--------+--------+-------+
Figure 5: Functionality needed on MLD proxy with multiple upstream
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interfaces per application scenario in mobile networks
5. Functional specification of an MLD proxy with multiple interfaces
To be completed
6. Security Considerations
To be completed
7. IANA Considerations
To be completed
8. Acknowledgments
The authors thank Stig Venaas for his valuable comments and
suggestions.
The research of Carlos J. Bernardos leading to these results has
received funding from the European Community's Seventh Framework
Programme (FP7-ICT-2009-5) under grant agreement n. 258053 (MEDIEVAL
project), being also partially supported by the Ministry of Science
and Innovation (MICINN) of Spain under the QUARTET project (TIN2009-
13992-C02-01).
9. References
9.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4605] 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.
[RFC5213] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K.,
and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008.
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9.2. Informative References
[I-D.ietf-multimob-handover-optimization]
Contreras, L., Bernardos, C., and I. Soto, "PMIPv6
multicast handover optimization by the Subscription
Information Acquisition through the LMA (SIAL)",
draft-ietf-multimob-handover-optimization-02 (work in
progress), February 2013.
[I-D.ietf-multimob-pmipv6-ropt]
Zuniga, J., Contreras, L., Bernardos, C., Jeon, S., and Y.
Kim, "Multicast Mobility Routing Optimizations for Proxy
Mobile IPv6", draft-ietf-multimob-pmipv6-ropt-06 (work in
progress), June 2013.
[I-D.liu-multimob-pmipv6-multicast-ro]
Liu, J. and W. Luo, "Routes Optimization for Multicast
Sender in Proxy Mobile IPv6 Domain",
draft-liu-multimob-pmipv6-multicast-ro-02 (work in
progress), July 2012.
[I-D.schmidt-multimob-fmipv6-pfmipv6-multicast]
Schmidt, T., Waehlisch, M., Koodli, R., and G. Fairhurst,
"Multicast Listener Extensions for MIPv6 and PMIPv6 Fast
Handovers",
draft-schmidt-multimob-fmipv6-pfmipv6-multicast-07 (work
in progress), October 2012.
[RFC6224] Schmidt, T., Waehlisch, M., and S. Krishnan, "Base
Deployment for Multicast Listener Support in Proxy Mobile
IPv6 (PMIPv6) Domains", RFC 6224, April 2011.
Appendix A. Basic support for multicast listener with PMIPv6
This section briefly summarizes the operation of Proxy Mobile IPv6
RFC5213 [RFC5213] and how multicast listener support works with
PMIPv6 as specified in RFC6224 [RFC6224].
Proxy Mobile IPv6 (PMIPv6) RFC5213 [RFC5213] is a network-based
mobility management protocol which enables the network to provide
mobility support to standard IP terminals residing in the network.
These terminals enjoy this mobility service without being required to
implement any mobility-specific IP operations. Namely, PMIPv6 is one
of the mechanisms adopted by the 3GPP to support the mobility
management of non-3GPP terminals in future Evolved Packet System
(EPS) networks.
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PMIPv6 allows a Media Access Gateway (MAG) to establish a distinct
bi-directional tunnel with different Local Mobility Anchors (LMAs),
being each tunnel shared by the attached Mobile Nodes (MNs). Each
mobile node is associated with a corresponding LMA, which keeps track
of its current location, that is, the MAG where the mobile node is
attached. IP-in-IP encapsulation is used within the tunnel to
forward traffic between the LMA and the MAG. Figure 4 (taken from
RFC5213 [RFC5213]) shows the architecture of a PMIPv6 domain.
+----+ +----+
|LMA1| |LMA2|
+----+ +----+
LMAA1 -> | | <-- LMAA2
| |
\\ //\\
\\ // \\
\\ // \\
+---\\------------- //------\\----+
( \\ IPv4/IPv6 // \\ )
( \\ Network // \\ )
+------\\--------//------------\\-+
\\ // \\
\\ // \\
\\ // \\
Proxy-CoA1--> | | <-- Proxy-CoA2
+----+ +----+
|MAG1|-----{MN2} |MAG2|
+----+ | +----+
| | |
MN-HNP1 --> | MN-HNP2 | <-- MN-HNP3, MN-HNP4
{MN1} {MN3}
Figure 6: Proxy Mobile IPv6 Domain
The basic solution for the distribution of multicast traffic within a
PMIPv6 domain RFC6224 [RFC6224] makes use of the bi-directional LMA-
MAG tunnels. The base solution follows the so-called remote
subscription model, in which the subscribed multicast content is
delivered from the Home Network. By doing so, an individual copy of
every multicast flow is delivered through the tunnel connecting the
mobility anchor to any of the access gateways in the domain. In many
cases, these individual copies traverse the same routers in the path
towards the access gateways, incurring in an inefficient
distribution, equivalent to the unicast distribution of the multicast
content in the domain.
The reference scenario for multicast deployment in Proxy Mobile IPv6
domains is illustrated in Figure 5 (taken from RFC6224 [RFC6224]).
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This fact leads to distribution inefficiencies and higher per-bit
delivery costs, incurred by the PMIPv6 domain operator offering
transport capabilities to the Home Network operator for serving their
MNs when attached to the PMIPv6 domain. As long as the remotely
subscribed multicast service is not affected, it seems worthy to
explore more optimal ways of distributing such content within the
PIMPv6 domain.
+-------------+
| Content |
| Source |
+-------------+
|
*** *** *** ***
* ** ** ** *
* *
* Fixed Internet *
* *
* ** ** ** *
*** *** *** ***
/
+----+ +----+
|LMA1| |LMA2| Multicast Anchor
+----+ +----+
LMAA1 | | LMAA2
| |
\\ //\\
\\ // \\
\\ // \\ Unicast Tunnel
\\ // \\
\\ // \\
\\ // \\
Proxy-CoA1 || || Proxy-CoA2
+----+ +----+
|MAG1| |MAG2| MLD Proxy
+----+ +----+
| | |
MN-HNP1 | | MN-HNP2 | MN-HNP3
MN1 MN2 MN3
Figure 7: Reference Network for Multicast Deployment in PMIPv6
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Authors' Addresses
Luis M. Contreras
Telefonica I+D
Ronda de la Comunicacion, s/n
Sur-3 building, 3rd floor
Madrid 28050
Spain
Email: lmcm@tid.es
Carlos J. Bernardos
Universidad Carlos III de Madrid
Av. Universidad, 30
Leganes, Madrid 28911
Spain
Phone: +34 91624 6236
Email: cjbc@it.uc3m.es
URI: http://www.it.uc3m.es/cjbc/
Juan Carlos
InterDigital Communications, LLC
1000 Sherbrooke Street West, 10th floor
Montreal, Quebec H3A 3G4
Canada
Email: JuanCarlos.Zuniga@InterDigital.com
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