Internet DRAFT - draft-schmidt-multimob-pmipv6-base-source
draft-schmidt-multimob-pmipv6-base-source
MULTIMOB Group T C. Schmidt
Internet-Draft HAW Hamburg
Intended status: Informational M. Waehlisch
Expires: May 3, 2012 link-lab & FU Berlin
M. Farooq
HAW Hamburg
October 31, 2011
Mobile Multicast Sender Support in PMIPv6 Domains with Base Multicast
Deployment
draft-schmidt-multimob-pmipv6-base-source-01
Abstract
Multicast communication can be enabled in Proxy Mobile IPv6 domains
by deploying MLD Proxy functions at Mobile Access Gateways, and
multicast routing functions at Local Mobility Anchors. This document
describes the support of mobile multicast senders in Proxy Mobile
IPv6 domains that is provided by this base deployment scenario.
Mobile sources remain agnostic of multicast mobility operations.
Requirements Language
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].
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 May 3, 2012.
Copyright Notice
Copyright (c) 2011 IETF Trust and the persons identified as the
Schmidt, et al. Expires May 3, 2012 [Page 1]
Internet-Draft Multicast Senders in PMIPv6 October 2011
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
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.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Source Mobility Details . . . . . . . . . . . . . . . . . . . 7
4.1. Operations of the Mobile Node . . . . . . . . . . . . . . 7
4.2. Operations of the Mobile Access Gateway . . . . . . . . . 7
4.3. Operations of the Local Mobility Anchor . . . . . . . . . 7
4.3.1. Local Mobility Anchors Operating PIM . . . . . . . . . 7
4.4. IPv4 Support . . . . . . . . . . . . . . . . . . . . . . . 8
4.5. Efficiency of the Distribution System . . . . . . . . . . 9
4.6. Multicast Availability throughout the Access Network . . . 9
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
6. Security Considerations . . . . . . . . . . . . . . . . . . . 9
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 10
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10
8.1. Normative References . . . . . . . . . . . . . . . . . . . 10
8.2. Informative References . . . . . . . . . . . . . . . . . . 11
Appendix A. Evaluation of Traffic Flows . . . . . . . . . . . . . 11
Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12
Schmidt, et al. Expires May 3, 2012 [Page 2]
Internet-Draft Multicast Senders in PMIPv6 October 2011
1. Introduction
Proxy Mobile IPv6 (PMIPv6) [RFC5213] extends Mobile IPv6 (MIPv6)
[RFC3775] by network-based management functions that enable IP
mobility for a host without requiring its participation in any
mobility-related signaling. Additional network entities called the
Local Mobility Anchor (LMA), and Mobile Access Gateways (MAGs), are
responsible for managing IP mobility on behalf of the mobile node
(MN). An MN connected to a PMIPv6 domain, which only operates
according to the base specifications of [RFC5213], cannot participate
in multicast communication, as MAGs will discard group packets.
Multicast support for mobile listeners can be enabled within a PMIPv6
domain by deploying MLD Proxy functions at Mobile Access Gateways,
and multicast routing functions at Local Mobility Anchors [RFC6224].
This base deployment option is the simplest way to PMIPv6 multicast
extensions in the sense that it neither requires new protocol
operations nor additional infrastructure entities. Standard software
functions need to be activated on PMIPv6 entities, only, on the price
of possibly non-optimal multicast routing.
This document describes the support of mobile multicast senders in
Proxy Mobile IPv6 domains as it is provided by the base deployment
scenario [RFC6224]. Mobile Nodes in this setting remain agnostic of
multicast mobility operations. This document discusses implications
on multicast routing, but does not address specific optimizations and
efficiency improvements of multicast routing for network-based
mobility as discussed in [RFC5757].
2. Terminology
This document uses the terminology as defined for the mobility
protocols [RFC3775], [RFC5213] and [RFC5844], as well as the
multicast edge related protocols [RFC3376], [RFC3810] and [RFC4605].
3. Overview
The reference scenario for multicast deployment in Proxy Mobile IPv6
domains is illustrated in Figure 1.
Schmidt, et al. Expires May 3, 2012 [Page 3]
Internet-Draft Multicast Senders in PMIPv6 October 2011
+-------------+
| Multicast |
| Listeners |
+-------------+
|
*** *** *** ***
* ** ** ** *
* *
* 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
Multicast Sender + Listener(s)
Figure 1: Reference Network for Multicast Deployment in PMIPv6 with
Source Mobility
An MN in a PMIPv6 domain will decide on multicast data transmission
completely independent of its current mobility conditions. It will
send packets as initiated by applications, using its source address
with Home Network Prefix (HNP) and a multicast destination addresses
chosen by application needs. Multicast packets will arrive at the
currently active MAG via one of its downstream local (wireless)
links. A multicast unaware MAG would simply discard these packets in
the absence of a multicast forwarding information base (MFIB).
An MN can successfully distribute multicast data in PMIPv6, if MLD
proxy functions are deployed at the MAG as described in [RFC6224].
In this set-up, the MLD proxy instance serving a mobile multicast
Schmidt, et al. Expires May 3, 2012 [Page 4]
Internet-Draft Multicast Senders in PMIPv6 October 2011
source has configured its upstream interface at the tunnel towards
MN's corresponding LMA. For each LMA, there will be a separate
instance of an MLD proxy.
According to the specifications given in [RFC4605], multicast data
arriving from a downstream interface of an MLD proxy will be
forwarded to the upstream interface and to all but the incoming
downstream interfaces with appropriate forwarding states for this
group. Thus multicast streams originating from an MN will arrive at
the corresponding LMA and directly at all mobile receivers co-located
at the same MAG. Serving as the designated multicast router or an
additional MLD proxy, the LMA forwards data to the fixed Internet, if
forwarding states are maintained through multicast routing. If the
LMA is acting as another MLD proxy, it will forward the multicast
data to its upstream interface, and based upon the downstream
interfaces' subscriptions accordingly.
In case of a handover, the MN (unaware of IP mobility) can continue
to send multicast packets as soon as network connectivity is
reconfigured. At this time, the MAG has determined the corresponding
LMA, and IPv6 unicast address configuration with PMIPv6 bindings have
been performed. Multicast packets arriving at the MAG are discarded
until the MAG has completed the following steps.
1. The MAG SHOULD determine whether the MN is admissible to
multicast services, and stop here otherwise.
2. The MAG adds the new downstream link to the MLD proxy instance
with up-link to the corresponding LMA.
As soon as the MN's uplink is associated with the corresponding MLD
proxy instance, multicast packets are forwarded again to the LMA and
eventually to receivers within the PMIP domain (see the call flow in
Figure 2). In this way, multicast source mobility is transparently
enabled in PMIPv6 domains that deploy the base scenario for
multicast.
Schmidt, et al. Expires May 3, 2012 [Page 5]
Internet-Draft Multicast Senders in PMIPv6 October 2011
MN1 MAG1 MN2 MAG2 LMA
| | | | |
| | Mcast Data | | |
| |<---------------+ | |
| | Mcast Data | | |
| Join(G) +================================================>|
+--------------> | | | |
| Mcast Data | | | |
|<---------------+ | | |
| | | | |
| < Movement of MN 2 to MAG2 & PMIP Binding Update > |
| | | | |
| | |--- Rtr Sol -->| |
| | |<-- Rtr Adv ---| |
| | | | |
| | | < MLD Proxy Configuration > |
| | | | |
| | | MLD Query | |
| | |<--------------+ |
| | | Mcast Data | |
| | +-------------->| |
| | | | Mcast Data |
| | | +===============>|
| | | | |
| | Mcast Data | | |
| |<================================================+
| Mcast Data | | | |
|<---------------+ | | |
| | | | |
Figure 2: Call Flow for Group Communication in Multicast-enabled PMIP
These multicast deployment considerations likewise apply for mobile
nodes that operate with their IPv4 stack enabled in a PMIPv6 domain.
PMIPv6 can provide IPv4 home address mobility support [RFC5844].
IPv4 multicast is handled by an IGMP proxy function at the MAG in an
analogous way.
Following these deployment steps, multicast traffic distribution
transparently inter-operates with PMIPv6. It is worth noting that a
MN - while being attached to the same MAG as the mobile source, but
associated with a different LMA, cannot receive multicast traffic on
a shortest path. Instead, multicast streams flow up to the LMA of
the mobile source, are transferred to the LMA of the mobile listener
and tunneled downwards to the MAG again (see Appendix A for further
considerations).
Schmidt, et al. Expires May 3, 2012 [Page 6]
Internet-Draft Multicast Senders in PMIPv6 October 2011
4. Source Mobility Details
Incorporating multicast source mobility in PMIPv6 requires to deploy
general multicast functions at PMIPv6 routers and to define their
interaction with the PMIPv6 protocol in the following way.
4.1. Operations of the Mobile Node
A Mobile Node willing to send multicast data will proceed as if
attached to the fixed Internet. No specific mobility or other
multicast related functionalities are required at the MN.
4.2. Operations of the Mobile Access Gateway
A Mobile Access Gateway is required to have MLD proxy instances
deployed corresponding to each LMA, taking the corresponding tunnel
as its unique upstream link, cf., [RFC6224]. On the arrival of a MN,
the MAG decides on the mapping of downstream links to a proxy
instance and the upstream link to the LMA based on the regular
Binding Update List as maintained by PMIPv6 standard operations.
When multicast data is received from the MN, the MAG MUST identify
the corresponding proxy instance from the incoming interface and
forwards multicast data upstream according to [RFC4605].
The MAG MAY apply special admission control to enable multicast data
transition from a MN. It is advisable to take special care that MLD
proxy implementations do not redistribute multicast data to
downstream interfaces without appropriate subscriptions in place.
4.3. Operations of the Local Mobility Anchor
For any MN, the Local Mobility Anchor acts as the persistent Home
Agent and at the same time as the default multicast upstream for the
corresponding MAG. It will manage and maintain a multicast
forwarding information base for all group traffic arriving from its
mobile sources. It SHOULD participate in multicast routing functions
that enable traffic redistribution to all adjacent LMAs within the
PMIPv6 domain and thereby ensure a continuous receptivity while the
source is in motion.
4.3.1. Local Mobility Anchors Operating PIM
Local Mobility Anchors that operate the PIM routing protocol
[RFC4601] will require sources to be directly connected for sending
PIM registers to the RP. This does not hold in a PMIPv6 domain, as
MAGs are routers intermediate to MN and the LMA. In this sense, MNs
are multicast sources external to the PIM-SM domain.
Schmidt, et al. Expires May 3, 2012 [Page 7]
Internet-Draft Multicast Senders in PMIPv6 October 2011
To cure this defect common to all set-ups of subsidiary domains not
running PIM, the LMA should act as a PIM Border Router and activate
the Border-bit. In this case, the DirectlyConnected(S) is treated as
being TRUE for mobile sources and the PIM-SM forwarding rule "iif ==
RPF_interface(S)" is relaxed to be TRUE, as the incoming tunnel
interface from MAG to LMA is considered as not part of the PIM-SM
component of the LMA (see A.1 of [RFC4601] ).
4.4. IPv4 Support
An MN in a PMIPv6 domain may use an IPv4 address transparently for
communication as specified in [RFC5844]. For this purpose, LMAs can
register IPv4-Proxy-CoAs in its Binding Caches and MAGs can provide
IPv4 support in access networks. Correspondingly, multicast
membership management will be performed by the MN using IGMP. For
multicast support on the network side, an IGMP proxy function needs
to be deployed at MAGs in exactly the same way as for IPv6.
[RFC4605] defines IGMP proxy behaviour in full agreement with IPv6/
MLD. Thus IPv4 support can be transparently provided following the
obvious deployment analogy.
For a dual-stack IPv4/IPv6 access network, the MAG proxy instances
SHOULD choose multicast signaling according to address configurations
on the link, but MAY submit IGMP and MLD queries in parallel, if
needed. It should further be noted that the infrastructure cannot
identify two data streams as identical when distributed via an IPv4
and IPv6 multicast group. Thus duplicate data may be forwarded on a
heterogeneous network layer.
A particular note is worth giving the scenario of [RFC5845] in which
overlapping private address spaces of different operators can be
hosted in a PMIP domain by using GRE encapsulation with key
identification. This scenario implies that unicast communication in
the MAG-LMA tunnel can be individually identified per MN by the GRE
keys. This scenario still does not impose any special treatment of
multicast communication for the following reasons.
Multicast streams from and to MNs arrive at a MAG on point-to-point
links (identical to unicast). between the routers and independent of
any individual MN. So the MAG-proxy and the LMA SHOULD NOT use GRE
key identifiers, but plain GRE encapsulation in multicast
communication (including MLD queries and reports). Multicast traffic
sent upstream and downstream of MAG-to-LMA tunnels proceeds as
router-to-router forwarding according to the multicast forwarding
information base (MFIB) of the MAG or LMA and independent of MN's
unicast addresses, while the MAG proxy instance re-distributes
multicast data down the point-to-point links (interfaces) according
to its own MFIB, independent of MN's IP addresses.
Schmidt, et al. Expires May 3, 2012 [Page 8]
Internet-Draft Multicast Senders in PMIPv6 October 2011
4.5. Efficiency of the Distribution System
In the following efficiency-related issues are enumerated.
Multicast reception at LMA In the current deployment scenario, the
LMA will receive all multicast traffic originating from its
associated MNs. There is no mechanism to suppress upstream
forwarding in the absence of receivers.
MNs on the same MAG using different LMAs For a mobile receiver and a
source that use different LMAs, the traffic has to go up to one
LMA, cross over to the other LMA, and then be tunneled back to the
same MAG, causing redundant flows in the access network and at the
MAG.
4.6. Multicast Availability throughout the Access Network
There may be deployment scenarios, where multicast services are
available throughout the access network independent of the PMIPv6
infrastructure. Direct multicast access at MAGs may be supported
through native multicast routing within a flat access network that
includes a multicast router, via dedicated (tunnel or VPN) links
between MAGs and designated multicast routers.
Multicast traffic distribution can be simplified in these scenarios.
A single proxy instance at MAGs with up-link into the multicast cloud
will serve as a first hop gateway into the multicast routing domain
and avoid traffic duplication or detour routing. However, mobility
of the multicast source in this scenario will require some multicast
routing protocols to rebuild distribution trees. This can cause
significant service disruptions or delays (see [RFC5757] for further
details).
5. IANA Considerations
This document makes no request of IANA.
Note to RFC Editor: this section may be removed on publication as an
RFC.
6. Security Considerations
This draft does not introduce additional messages or novel protocol
operations. Consequently, no new threats are introduced by this
document in addition to those identified as security concerns of
[RFC3810], [RFC4605], [RFC5213], and [RFC5844].
Schmidt, et al. Expires May 3, 2012 [Page 9]
Internet-Draft Multicast Senders in PMIPv6 October 2011
However, particular attention should be paid to implications of
combining multicast and mobility management at network entities. As
this specification allows mobile nodes to initiate the creation of
multicast forwarding states at MAGs and LMAs while changing
attachments, threats of resource exhaustion at PMIP routers and
access networks arrive from rapid state changes, as well as from high
volume data streams routed into access networks of limited
capacities. In addition to proper authorization checks of MNs, rate
controls at replicators MAY be required to protect the agents and the
downstream networks. In particular, MLD proxy implementations at
MAGs SHOULD carefully procure for automatic multicast state
extinction on the departure of MNs, as mobile multicast listeners in
the PMIPv6 domain will not actively terminate group membership prior
to departure.
7. Acknowledgements
The authors would like to thank (in alphabetical order) Jouni
Korhonen and Stig Venaas for advice, help and reviews of the
document. Funding by the German Federal Ministry of Education and
Research within the G-LAB Initiative is gratefully acknowledged.
8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2710] Deering, S., Fenner, W., and B. Haberman, "Multicast
Listener Discovery (MLD) for IPv6", RFC 2710,
October 1999.
[RFC3376] Cain, B., Deering, S., Kouvelas, I., Fenner, B., and A.
Thyagarajan, "Internet Group Management Protocol, Version
3", RFC 3376, October 2002.
[RFC3775] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support
in IPv6", RFC 3775, June 2004.
[RFC3810] Vida, R. and L. Costa, "Multicast Listener Discovery
Version 2 (MLDv2) for IPv6", RFC 3810, June 2004.
[RFC4601] Fenner, B., Handley, M., Holbrook, H., and I. Kouvelas,
"Protocol Independent Multicast - Sparse Mode (PIM-SM):
Protocol Specification (Revised)", RFC 4601, August 2006.
Schmidt, et al. Expires May 3, 2012 [Page 10]
Internet-Draft Multicast Senders in PMIPv6 October 2011
[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.
[RFC5844] Wakikawa, R. and S. Gundavelli, "IPv4 Support for Proxy
Mobile IPv6", RFC 5844, May 2010.
[RFC6224] Schmidt, T., Waehlisch, M., and S. Krishnan, "Base
Deployment for Multicast Listener Support in Proxy Mobile
IPv6 (PMIPv6) Domains", RFC 6224, April 2011.
8.2. Informative References
[RFC2236] Fenner, W., "Internet Group Management Protocol, Version
2", RFC 2236, November 1997.
[RFC5757] Schmidt, T., Waehlisch, M., and G. Fairhurst, "Multicast
Mobility in Mobile IP Version 6 (MIPv6): Problem Statement
and Brief Survey", RFC 5757, February 2010.
[RFC5845] Muhanna, A., Khalil, M., Gundavelli, S., and K. Leung,
"Generic Routing Encapsulation (GRE) Key Option for Proxy
Mobile IPv6", RFC 5845, June 2010.
Appendix A. Evaluation of Traffic Flows
TODO
Appendix B. Change Log
The following changes have been made from version
draft-schmidt-multimob-pmipv6-base-source-00:
1. Added specifics of PIM directly connected neighbor requirements
for sources
2. Updated references
3. Editorial improvements
Schmidt, et al. Expires May 3, 2012 [Page 11]
Internet-Draft Multicast Senders in PMIPv6 October 2011
Authors' Addresses
Thomas C. Schmidt
HAW Hamburg
Berliner Tor 7
Hamburg 20099
Germany
Email: schmidt@informatik.haw-hamburg.de
URI: http://inet.cpt.haw-hamburg.de/members/schmidt
Matthias Waehlisch
link-lab & FU Berlin
Hoenower Str. 35
Berlin 10318
Germany
Email: mw@link-lab.net
Muhamma Omer Farooq
HAW Hamburg
Berliner Tor 7
Hamburg 20099
Germany
Email: omer.farooq@ymail.com
Schmidt, et al. Expires May 3, 2012 [Page 12]
