IP Multicast Use Case Analysis for PMIPv6-based Distributed Mobility Management
draft-sfigueiredo-multimob-use-case-dmm-00
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| Authors | Sergio Figueiredo , Rui L. Aguiar, Seil Jeon | ||
| Last updated | 2012-03-05 | ||
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draft-sfigueiredo-multimob-use-case-dmm-00
MULTIMOB Group S. Figueiredo
Internet Draft R. L. Aguiar
Intended status: Standards Track Universidade de Aveiro
Expires: August 4, 2012 S. Jeon
Instituto de Telecomunicacoes
March 5, 2012
IP Multicast Use Case Analysis for PMIPv6-based Distributed Mobility
Management
draft-sfigueiredo-multimob-use-case-dmm-00
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Abstract
As mobile networks are moving towards distributed mobility management,
the application of IP multicast is needed to provide efficient
content delivery on the network. This document describes use cases
when IP multicast is applied on PMIPv6-based DMM, and analyzes
problems focused on user plane issues.
Table of Contents
1. Introduction ................................................ 3
2. Conventions and Terminology.................................. 3
3. Use Cases Description........................................ 4
3.1. Multicast listener support.............................. 4
3.1.1. MLD-P in MAR....................................... 4
3.1.1.1. Duplicated Traffic............................ 5
3.1.1.2. Non-optimal routing........................... 6
3.1.2. Multicast Router in MAR............................ 7
3.2. Multicast sender support................................ 7
3.2.1. MLD-P in MAR....................................... 7
3.2.1.1. Triangular routing............................ 8
3.2.2. Multicast Router in MAR........................... 10
4. IANA Considerations ........................................ 11
5. Security Considerations..................................... 11
6. References ................................................. 11
6.1. Normative References................................... 11
6.2. Informative References................................. 11
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1. Introduction
As a consequence of forthcoming multimedia avalanche, several
optimization mechanisms are being considered towards efficient and
resilient mobile networks. As verified in [DDMM-MI], current IP
mobility management solutions have limitations in supporting
efficient management and deployment. Thus, several proposals aiming
at the distribution of the mobility management functions [DDMM-FP]
were presented. While the problems resulting from the application of
mobility solutions in multicast traffic are known, affecting its
efficiency and leading to non-negligible service disruption, among
others ([IPMM][RFC5757]). It is still not clear how the change from
centralized to distributed mobility solutions may affect IP multicast
support.
This document briefly describes use cases of IP multicast in a
PMIPv6-based DMM environment, and analyses consequent problems. Both
listener and sender perspective are studied, with MLD Proxy and
Multicast Router at the Mobility Access Router (MAR).
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 [RFC2119].
This document uses the terminology defined in [RFC5213], [RFC6275],
and [RFC3810], and [RFC4601]. Specifically, the definition of PMIPv6
domain is reused from [RFC5213] and reproduced here for completeness.
- Mobility Access Router (MAR): A router with the capability of
acting both as a mobility anchor and as an access router, in a per
flow basis.
- Previous Mobility Access Router (P-MAR): The MAR where the MN was
attached to previously to the network-layer mobility process, and
that may be acting as an anchor for one or multiple flows.
- New Mobile Access Gateway (N-MAR): The MAR to which the MN is
currently attached, providing the access functionality and thus
delivers all the flows destined to the MN.
- Multicast Listener Discovery Proxy (MLD-P): An entity following
[RFC4605].
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3. Use Cases Description
This draft focuses on describing problems that occur when deploying
IP multicast on a general PMIPv6-derived DMM architecture, as there
is not yet a fully specified unicast DMM protocol. So, the unicast
DMM concept used in this document is assumed as follows: MAG and an
LMA functionalities defined in [RFC5213] are equipped within a same
physical entity, called MAR, and a MAR provides tunnel-based
forwarding to provide a home network prefix (HNP)-based flow
necessary IP session continuity whenever the MN having assigned HNP
moves to another MAR.
3.1. Multicast listener support
3.1.1. MLD-P in MAR
Once a MN initially attaches to the P-MAR as shown in Figure 1), it
receives a home prefix address, which will be associated with
communications started at that MAR. The P-MAR transmits an MLD Query
message towards the MN and receives the MLD Report messages from the
MN. On receiving MLD Proxy message from the MN, the P-MAR tries to
join multicast network. When joining procedure ends, multicast data
is transmitted using IP multicasting scheme.
+----------------+
| Multicast |
| Infrastructure |
+----------------+
*
* (S,G)
*
+----------+ +----------+
| P-MAR |---------------| N-MAR |
| |***************| |
| (MLD-P) |---------------| (MLD-P) |
+----------+ +----------+
* *
* *
+------+ +------+
| MN | -----> | MN |
+------+ +------+
Figure 1 Multicasting architecture using distributed mobility
management
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When the MN moves to the N-MAR, the N-MAR is required to establish a
tunnel for IP session continuity of the packets towards the HNP
assigned from the P-MAR as soon as the N-MAR detects that the MN came
from the P-MAR. Following the operation of the MLD-P [RFC4605] on the
N-MAR, the MLD-P instance on the N-MAR configures the upstream
interface towards the P-MAR associated with the MN when Base Solution,
defined in [RFC6224], is applied to the DMM. This is simple and
applicable as a network-based multicast DMM approach. However, a
couple of relevant issues happen.
3.1.1.1. Duplicated Traffic
One problem is duplicated traffic, which is similar to the tunnel
convergence problem occurring in [RFC6224], as shown in Figure 2.
MN1 and MN3, which moved from MAR1 and MAR3, respectively, are
currently located at the MAR2. Through respective established tunnels
for MN1 and MN3, they receive multicast packets of the same channel
through different MARs. This causes duplicated traffic, converging to
the MAR2. The magnitude of replicated traffic will be much bigger
than that of PMIPv6 because it is expected that the number of MARs at
access level that will be deployed is much larger than that of LMAs
at core level within a PMIPv6 domain.
As referred, when a MN first subscribes multicast content, its
current MAR's MLD-P will forward its subscription to the multicast
infrastructure. As such, an extra duplication factor may occur, if
the subscription being done is already being received from one or
multiple tunnels due to other listeners (refer to MN2 from Figure 2
for an example).
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+----------------+
| Multicast Tree | *
+----------------+ *
* * *
* * *
* * *
(S,G) * (S,G) * * (S,G)
* * *
+----------+ (-->) +----------+ (<--) +----------+
| MAR1 |---------| MAR2 |---------| MAR3 |
| |*********| |*********| |
| (MLD-P) |---------| (MLD-P) |---------| (MLD-P) |
+----------+ Tun.1 +----------+ Tun.2 +----------+
* * *
* * *
* * *
+---+ move +---+ +---+ +---+ move +---+
|MN1| ---> |MN1| |MN2| |MN3| <--- |MN3|
+---+ +---+ +---+ +---+ +---+
(<--/-->) : direction of the multicast packet flow
Figure 2 Data replication
3.1.1.2. Non-optimal routing
Another issue is non-optimal routing (Figure 3). If we consider a
significantly large domain, there is the possibility that the
multicast packets need to traverse a long distance, depending on the
setup of the upstream interface of MLD-P instance, even through the
current MAR is connected to the multicast infrastructure. If an
operator wants to deploy the upstream interface of all the MARs
towards multicast source or multicast routing network, this issue
doesn't happen and such an approach is extremely simple and mobility-
agnostic way but there may occur media synchronization issue.
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+----------------+
| Multicast |
| Infrastructure |
+----------------+
*
* (S,G)
*
+----------+ +----------+
| P-MAR |------ ------| N-MAR |
| |****** ... ******| |
|(MLD-P) |------ ------| (MLD-P) |
+----------+ +----------+
* *
* *
+------+ +------+
| MN | -----> | MN |
+------+ +------+
Figure 3 Non-optimal routing problem
3.1.2. Multicast Router in MAR
TBD
3.2. Multicast sender support
To provide sender multicasting support, a MAR may be required to act
as MLD-P or multicast router. Depending on the equipped fuctions, we
describe issues for multicast sender support.
3.2.1. MLD-P in MAR
In order for the multicast content to reach the multicast tree, the
MLD-P SHOULD configure its upstream interface towards a MR [PM-HOME].
In the case of MR or MAR, it MAY act as the Rendezvous Point (RP) but
cause frequent multicast tree reconstruction and associated service
disruptions whenever the MN moves.
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+------+ +----------------+
| RP |---------| Multicast |
+------+ | Infrastructure |
* +----------------+
* (S,G) |
* |
+----------+ +----------+
| P-MAR |----------| N-MAR |
| |**********| |
| (MLD-P) |----------| (MLD-P) |
+----------+ +----------+
* *
* *
+------+ +------+
| S | ----> | S |
+------+ +------+
Figure 4 Multicast sender mobility
3.2.1.1. Triangular routing
When a listener attaches to a MAR where a source is transmitting, if
the multicast traffic may be anchored through not current MAR (not
MAR2 but MAR1 in Figure 5, and then multicast data would be reached
through the mobility tunnel between MAR2 to MAR1. An listener (L1),
subscribed to the source's channel, receives the multicast content
from multicast infrastructure, therefore a non-optimal route is made.
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+------+ +----------------+
| RP |*********| Multicast |
+------+ | Infrastructure |
* +----------------+
* (S,G) *
* *
+----------+ +----------+
| MAR1 |-------| MAR2 |
| |*******| |
| (MLD-P) |-------| (MLD-P) |
+----------+ +----------+
* * *
* * *
+------+ move +------+ +-----+
| S | ---> | S | | L1 |
+------+ +------+ +-----+
Figure 5 Triagular routing after source mobility
The same problem also occurs in the opposite process, i.e. if a
multicast source starts transmitting multicast content at a MAR, and
a listener moves to the same MAR while receiving the source's content
(Figure 6).
+------+ +----------------+
| RP |*********| Multicast |
+------+ | Infrastructure |
* +----------------+
* (S,G) *
* *
+----------+ +----------+
| MAR1 |-------| MAR2 |
| |*******| |
| (MLD-P) |-------| (MLD-P) |
+----------+ +----------+
* * *
* * *
+------+ +----+ move +----+
| S | | L1 | <--- | L1 |
+------+ +----+ +----+
Figure 6 Triangular routing after listener mobility
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When the source and the listener are within same MAR (MAR2) as their
anchor, if both the source/listener try to start the session and the
receive it, respectively at MAR2, the traffic will be optimally sent
to the listener. As the traffic reaches the MLD-P via the downstream
interface to which the source is attached, it will be sent through
the interface through which the listener sent the MLD Report. However,
if the source and the listener move to different MARs, the traffic
will traverse the following non-optimal path, even though they share
a common MAR2:
S -> Source's MAR1 -> MAR2 -> Multicast Tree -> MAR2 -> Listener's
MAR3
This problem is depicted in Figure 7.
+----------------+
| Multicast Tree |
+----------------+
* *
* *
* *
* *
* *
+----------+ (-->) +----------+ (-->) +----------+
| MAR1 |---------| MAR2 |---------| MAR3 |
| |*********| |*********| |
| (MLD-P) |---------| (MLD-P) |---------| (MLD-P) |
+----------+ Tun.1 +----------+ Tun.2 +----------+
* * * *
* * * *
* * * *
+---+ move +---+ +---+ move +---+
| S | <--- | S | | L | --> | L |
+---+ +---+ +---+ +---+
(<--/-->) : direction of the multicast packet flow
Figure 7 Non-optimal routing due to mobile sender
3.2.2. Multicast Router in MAR
TBD
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4. IANA Considerations
This document makes no request of IANA.
5. Security Considerations
TBD
6. References
6.1. Normative References
[RFC2119] S. Bradner, "Key words for use in RFCs to Indicate
Requirement Levels", RFC 2119, March 1997.
[RFC6275] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support
in IPv6", RFC 6275, July 2011.
[RFC3810] R. Vida, and L. Costa, "Multicast Listener Discovery
Version 2 (MLDv2) for IPv6," IETF RFC 3810, June 2004.
[RFC5213] S. Gundavelli, K. Leung, V. Devarapalli, K. Chowdhury, and
B. Patil, "Proxy Mobile IPv6", IETF RFC 5213, August 2008.
[RFC4605] B. Fenner, H. He, B. Haberman, and H. Sandick, "Internet
Group Management Protocol (IGMP) / Multicast Listener
Discovery (MLD) Based Multicast Forwarding ("IGMP/MLD
Proxying")", IETF RFC 4605, August 2006.
[RFC4601] B. Fenner, M. Handley, H. Holbrook, and I. Kouvelas,
"Protocol Independent Multicast - Sparse Mode (PIM-SM):
Protocol Specification (Revised)", RFC 4601, August 2006.
6.2. Informative References
[RFC5757] T. Schmidt, M. Waehlisch, and G. Fairhurst, "Multicast
Mobility in Mobile IP Version 6 (MIPv6): Problem Statement
and Brief Survey," RFC 5757, February 2010.
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[RFC6224] T. Schmidt, M. Waehlisch, S. Krishnan, "Base Deployment
for Multicast Listener Support in PMIPv6 Domain," RFC 6224,
April 2011.
[DDMM-FP] P. Bertin, S. Bonjour, and J.-M., Bonnin, "A Distributed
Dynamic Mobility Management Scheme Designed for Flat IP
Architectures," Proc. of NTMS 2008. , November 2008.
[DDMM-MI] H. A. Chan, H. Yokota, J. Xie, P. Seite, D. Liu,
"Distributed and Dynamic Mobility Management in Mobile
Internet: Current Approaches and Issues", Journal of
Communications, vol. 6, no. 1, pp. 4-15, February 2011.
[IPMM] I. Romdhani, M. Kellil, and H. Lach, "IP Mobile Multicast :
Challenges and Solutions," IEEE Communications Surveys &
Tutorials, vol. 6, no. 1, pp. 18-41, 2004.
[PM-HOME] S. Jeon, N. Kang, and Y. Kim, "Mobility Management based on
Proxy Mobile IPv6 for Multicasting Services in Home
Networks," IEEE Transactions on Consumer Electronics (TCE),
vol. 55, no. 3, pp. 1227-1232, August 2009.
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Authors' Addresses
Sergio Figueiredo
Instituto de Telecomunicacoes
Campus Universitario de Santiago
3810-193 Aveiro, Portugal
E-mail: sfigueiredo@av.it.pt
Seil Jeon
Instituto de Telecomunicacoes
Campus Universitario de Santiago
3810-193 Aveiro, Portugal
E-mail: seiljeon@av.it.pt
Rui L. Aguiar
Instituto de Telecomunicacoes
Campus Universitario de Santiago
3810-193 Aveiro, Portugal
E-mail: ruilaa@ua.pt
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