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Versions: (draft-chakrabarti-mip4-mcbc) 00 01

Network Working Group                                   A. Muhanna (Ed.)
Internet-Draft                                                  Ericsson
Intended status: Standards Track                                B. Patil
Expires: January 13, 2011                                          Nokia
                                                          S. Chakrabarti
                                                             IP Infusion
                                                           G. Montenegro
                                                   Microsoft Corporation
                                                                   Y. Wu
                                                                 ZTE USA
                                                           July 12, 2010


      IPv4 Mobility Extension for Multicast and Broadcast Packets
                      draft-ietf-mip4-mcbc-01.txt

Abstract

   This document specifies a new Mobile IPv4 extension which is used to
   negotiate the Multicast-Broadcast Encapsulation Delivery style in the
   case of Mobile IPv4 Foreign Agent Care-of Address mode registration.
   With this extension the mobile node is able to negotiate the type of
   traffic that needs to be encapsulated for delivery to the foreign
   agent while other types of traffic use the direct delivery style.
   This mechanism eliminates the tunnel overhead between the mobile node
   and the foreign agent.  Multicast and broadcast applications on a
   mobile IPv4 mobile node are better served with this extension.

Status of this Memo

   This Internet-Draft is submitted to IETF 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 January 13, 2011.

Copyright Notice

   Copyright (c) 2010 IETF Trust and the persons identified as the



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   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.  Conventions & Terminology  . . . . . . . . . . . . . . . . . .  5
     2.1.  Conventions used in this document  . . . . . . . . . . . .  5
     2.2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . .  5
   3.  Multicast-Broadcast Encapsulating Delivery Style . . . . . . .  5
     3.1.  Multicast-Broadcast Encapsulating Delivery Extension . . .  6
     3.2.  Packet Header Formats for Visited Network Traffic  . . . .  7
     3.3.  Packet Header Formats for Homebound Traffic  . . . . . . .  8
   4.  Multicast-Broadcast Encapsulating delivery Style Vs
       RFC3024 Encapsulating delivery . . . . . . . . . . . . . . . .  8
   5.  Link-layer Assisted Delivery Style (LLADS) . . . . . . . . . .  9
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . . 10
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 10
   8.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 10
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 10
     9.1.  Normative references . . . . . . . . . . . . . . . . . . . 10
     9.2.  Informative references . . . . . . . . . . . . . . . . . . 11
   Appendix A.  Appendix-A  . . . . . . . . . . . . . . . . . . . . . 11
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11

















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1.  Introduction

   The IP Mobility Protocol [RFC3344] describes multicast and broadcast
   packet transmission between the mobile node and the home network or
   visited network.  Reverse Tunneling for Mobile IP [RFC3024] includes
   support for reverse tunneling of multicast and broadcast packets to
   the home network using the encapsulating delivery style between the
   mobile nodes and the foreign agent.  However, [RFC3024] says that
   once the encapsulated delivery style is negotiated, all packets
   exchanged between the mobile node and the foreign agent must be
   delivered encapsulated.  The delivery (of packets between the MN and
   FA) methods specified in the base mobile IPv4 specification [RFC3344]
   prevents an MN from sending unicast packets to the FA.  Tunnelling
   overhead is an issue especially on wireless links with the current
   specification.  Multicast and broadcast applications for a MN running
   mobile IPv4 client software also are negatively impacted.  In
   particular, this imposition prevents direct delivery of unicast
   packets from the mobile node to the foreign agent.  This causes a
   huge tunnel overhead in the (typically) wireless medium between the
   mobile node and the foreign agent and indirectly makes it impossible
   for the mobile node to use any of the multicast and broadcast
   services.

   Additionally, [RFC3344] sections 4.3 and 4.4 discusses multicast and
   broadcast routing to and from the mobile node in the presence of
   triangular routing and with a co-located Care-of address.  Reverse
   tunneling for Mobile IP [RFC3024] uses the optimal direct delivery
   style from the mobile node via the foreign agent if only unicast
   traffic is being reverse tunneled.  If, however, multicast or
   broadcast packets are also meant to be reverse tunneled, it
   introduces the Encapsulating Delivery Style.  Unfortunately, once the
   encapsulating delivery style is negotiated, it applies to all reverse
   tunneling traffics, including unicast.  [RFC3344] also mandates, in
   the case of FA Care-of Address mode, that all multicast and broadcast
   packets be delivered encapsulated to mobile node.  This also imposes
   tunnel overhead for multicast and broadcast packets.  While tunneling
   overhead on wired links may be acceptable, it has a higher cost and
   throughput impact in wireless links.  Even though, Mobile IP has been
   deployed for 3G data services, there has not been much usage of
   multicast or broadcast data transfer to or from the mobile node.
   Services like PTT (Push-To-Talk) rely on multicast.  Other services
   such as IPTV also use multicast to distribute streaming video to
   mobile nodes.  Hence it is essential to ensure that the mobile IPv4
   clients support multicast and broadcast packet delivery in an optimal
   manner.

   Current mobile IPv4 specifications [RFC3344] and [RFC3024] do not
   clearly address multicast/broadcast packet delivery for a MN with FA



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   care-of-address. for example, for encapsulating delivery style, the
   source address of the outer and inner IP header is the home address
   of the mobile node as described in section 5.2.2 of [RFC3024].  In
   addition, section 5.4 talks about local delivery of multicast/
   broadcast packets in the visited network but some corner cases are
   not completely specified.  In particular, multicast messages from the
   mobile node to the visited network may be needed for retrieving
   service information.  A mobile node may use all-mobility-agent
   multicast as the destination address and its home-address as the
   source-address for local service discovery.  In this case, the
   foreign agents must consider all messages with the all-mobility-agent
   multicast as the destination address as special case and reply back
   directly to the mobile-node.  However, this scenario makes foreign
   agent processing a bit more complex when reverse-tunnel is setup and
   the mobile-node sends multicast messages towards the reverse tunnel
   using its home-address as the source address.  The all-mobility-
   agents multicast address is used for router solicitation by the
   mobile node, so foreign agent implementations must use it as a
   special address.  This leads to complexity if in the reverse tunnel
   the mobile node uses its home address as the source address for other
   multicast messages destined to the home and visited network.

   Currently different organizations [3GPP2] define their own mechanism
   to obtain local information such as DNS server IP address through
   AAA.  All Mobility-agent multicast is used for router solicitation by
   the mobile node and the implementation can treat this address
   specially at the foreign agent.  However, the implementation of
   foreign agent needs to apply multicast-address filtering and gets
   very complex if the mobile client uses the home address as source
   address for other multicast messages destined to the home and visited
   network, in the reverse tunnel mode.  Even if multicast packets are
   delivered locally, the return packet which has the destination
   address as the home address will be routed back all the way to the
   home agent of the mobile node to be tunneled back to the foreign
   agent and then to the mobile node.  [RFC3024] recommends selective
   reverse tunneling by delivering packets directly to the foreign
   agent, while encapsulating them for reverse tunnel delivery.  But the
   specification is not clear about the source addresses of the packets
   from the mobile node in case of selective direct delivery.  Although
   it clearly states that for the mobile node which uses co-located
   care-of address mode.

   This specification aims to clarify the delivery of multicast messages
   when reverse tunneling is used, adds the capability to selectively
   negotiates which type of traffic to be delivered using encapsulating
   delivery, e.g., only for multicast and broadcast packets from mobile
   node to foreign agent, while allowing direct delivery for other type
   of traffic, e.g., unicast, and explores direct delivery options of



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   multicast messages between the mobile node and the foreign agent by
   using link-layer capabilities.

   Section 3 describes the new delivery extension for multicast-
   broadcast packets in reverse tunnel mode.


2.  Conventions & Terminology

2.1.  Conventions used in this document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

2.2.  Terminology

   All the general mobility related terminology and abbreviations are to
   be interpreted as defined in IP Mobility Protocol [RFC3344] and
   Reverse tunneling for Mobile IP [RFC3024].  The following terms are
   used in this document.

   MN

      Mobile Node.

   FA

      Foreign Agent.

   FA-CoA

      Foreign Agent as the Mobile Node Care-of Address.


3.  Multicast-Broadcast Encapsulating Delivery Style

   The Mobile IP reverse tunneling [RFC3024] defines the Encapsulating
   delivery style for delivering multicast and broadcast packets from
   the mobile node to the foreign agent in the FA-CoA mode.  It also
   mandates Encapsulating delivery mode for sending multicast/broadcast
   packets to reverse-tunnel to home agent via the foreign agent.  But
   [RFC3024] section 2 says that all reverse-tunneled traffic is
   encapsulated when Encapsulating Delivery is negotiated.  The
   "Multicast-Broadcast Encapsulating Delivery Style" (MBEDS) extension
   defined in this specification applies encapsulation only to the
   reverse-tunneled multicast and broadcast packets, leaving direct
   delivery for reverse-tunneled unicast packets.  The main motivation



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   for adding this extension is to save the overhead of additional IP
   header for unicast packets which consequently will enable the use of
   Multicast and Broadcast packets when Mobile IPv4 is in use.  This
   procedure works for both shared media like ethernet, IEEE 802.11 and
   links of a point-to-point nature such as those defined by 3GPP, 3GPP2
   and IEEE 802.16.

3.1.  Multicast-Broadcast Encapsulating Delivery Extension

   The proposed extension is used in Mobile IPv4 signaling to negotiate
   the Multicast-Broadcast Encapsulation Delivery Style.  Foreign agents
   SHOULD support the Multicast-Broadcast Encapsulating Delivery Style
   Extension.  A registration request MAY include either a regular
   encapsulating delivery extension (see section 3.3 in [RFC3024]) or a
   Multicast-Broadcast Encapsulating Delivery extension, but not both.
   If both extensions are present, the foreign agent will consider that
   an error scenario and the FA MUST reject the registration request by
   sending a registration reply with the code field set to "Poorly
   Formed Request".

   If a foreign agent supports MBEDS, then the foreign agent SHOULD
   advertise the MBEDS extension in its router advertisement to inform
   the mobile node about the type of delivery style it supports.  This
   will avoid the possibility of multiple registration requests to
   figure out which encapsulating mode the foreign agent supports.

   If the MN includes an MBEDS extension, if MUST do so after the
   Mobile-Home Authentication Extension, and before the Mobile-Foreign
   Authentication Extension, if present.  The Encapsulating Delivery
   Style Extension MUST NOT be included if the 'T' bit is not set in the
   Registration Request.

   If no delivery style extension is present, Direct Delivery per RFC
   3024 is assumed.

   The Multicast-Broadcast Encapsulation Extension format is as in
   Figure 1 below.



      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      |     Length    |       Bit-field Value         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


           Figure 1: Multicast-Broadcast Encapsulating Extension



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   Type

      <IANA>

   Length

      8-bit unsigned integer indicating the length in octets of the Bit-
      Field .  It is set to 2.

   Bit-Field Value

      A 16-bit bit-field.  Value specifies what type of packets are
      encapsulated.  The following bits are defined (0 being the right-
      most bit, 15 the left-most bit):

      0:

         All packets are encapsulated between a mobile node and a
         foreign agent.  It is same as the Encapsulating Delivery Style
         in RFC3024.  NOTE: obsolete EDS in 3024?.

      1:

         Only multicast and broadcast packets are encapsulated (MBEDS).

      2:

         Link-layer Assisted Delivery Style (LLAS) for local network.


      All other bits values are reserved.


   NOTE: Only MBEDS packets are reverse tunneled after being
   decapsulated at the foreign agent, not those directly destined to the
   foreign-agent address or all mobility agent address.  These are
   processed locally by the foreign agent.

3.2.  Packet Header Formats for Visited Network Traffic

   Other than Mobile IP agent solicitation packets, there might be some
   multicast or broadcast packets meant for consumption at the visited
   network.  If the mobile node can acquire a local IP address, then it
   MUST direct deliver the multicast and broadcast traffic for local
   use.  If the mobile node can have only one IP address, (i.e. home
   address) then it MUST send all the multicast and broadcast packets
   encapsulated.  These packets will be sent to the home network through
   the reverse tunnel after being decapsulated at the foreign agent;



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   only exceptions are the multicast solicitation messages for the
   mobility agent.

   In some cases, the mobile node may want to send multicast or
   broadcast packets to visited network entities other than the foreign
   agent.  In those cases they should always be direct delivered by
   acquiring a local IP address or using link-layer mechanism if
   possible.  Please see the section 'Link-layer Assisted Delivery
   Style' below for details.

3.3.  Packet Header Formats for Homebound Traffic

   The packet format and processing for encapsulated multicast and
   broadcast traffic is the same as defined in section 5.2 of Reverse
   Tunneling for Mobile IP [RFC3024].  Additionally, the packet format
   and processing for unicast traffic is the same as defined in section
   5.1 of the same specification.


4.  Multicast-Broadcast Encapsulating delivery Style Vs RFC3024
    Encapsulating delivery

   RFC3024 encapsulating delivery style does not require the foreign-
   agent to advertise an extension as well for the mobile node
   efficiency.  MBEDS provides an option for foreign agent to advertise
   the extension with supported extension types, so that a mobile node
   can request a delivery style that the foreign agent supports.

   RFC3024 encapsulating delivery style requires all multicast,
   broadcast and unicast traffic to be encapsulated in order to be
   reverse tunneled.  In MBEDS unicast packets are always direct
   delivered to the foreign agent.  Most of the the cases a node sends
   unicast packets for communication with a correspondent node and
   occasionally it may send broadcast or multicast packets to the home
   network.  Thus this new style of delivery relieves the overhead of
   encapsulation for most traffic.

   MBEDS introduces TLV style extension for delivery style.  Therefore,
   this extension can be used to negotiate different delivery styles in
   the future.  Currently, it can be backward compatible with RFC3024
   encapsulating delivery style when the value field is zero.  NOTE: We
   should make this a bit field to allow for easier advertisement and
   other extensions.

   A mobile node SHOULD use either RFC3024 style encapsulating delivery
   extension or the MBEDS extension (defined in this document), but not
   both at the same time.  If both extensions are received at the
   foreign-agent, the foreign agent MUST reject the registration request



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   by sending a registration reply with error (70) "Poorly Formed
   Request".


5.  Link-layer Assisted Delivery Style (LLADS)

   This section discusses direct-delivery of multicast and broadcast
   packets between the mobile node and the foreign agent by taking
   advantage of link-layer mechanisms.  Certain link-layers allow for
   direct delivery from the MN to the FA (and vice-versa) without the
   need for encapsulation.  In effect, this is assumed by RFC 3024 for
   Direct Delivery Style.  In this mode, a unicast packet at the IP
   layer is carried over a unicast link-layer delivery mechanism.  For
   example, the FA's MAC address is the link-layer destination address,
   or the packet is sent on a link of a point-to-point nature as in 3G
   networks.  Broadcast and multicast packets, however are typically
   sent using a link-layer broadcast or multicast mechanism: a broadcast
   or multicast MAC address for IEEE 802.11 networks.  If, however,
   these packets had the FA unicast MAC address while carrying an IP
   layer broadcast or multicast destination, then there would be no need
   for encapsulation to remove the ambiguity.  The packet would be
   unequivocally directed at, and consumed by the FA.  Notice that in
   links of a point-to-point nature, there is no ambiguity even for
   multicast and broadcast packets: these are unequivocally delivered to
   the FA.  The Link-layer Assisted Delivery Style allows for direct
   delivery of unicast, multicast and broadcast packets over link-layers
   that can support it.  In particular, it requires that regardless of
   whether the IP layer packet is unicast, broadcast or multicast, (1)
   when sending from MN to FA, the FA unicast address always be used,
   and (2) when sending from FA to MN, the MN unicast address always be
   used.  The FA advertises such capability per the extension defined
   above, and the MN requests it in its registration request.

   The LLADS imposes the least amount of tunneling overhead of the
   delivery styles as it effectively uses the equivalent of direct
   delivery for unicast, broadcast and multicast.  It enables the MN to
   deliver packets to the FA for the foreign agent to reverse tunnel
   them back to the MN's home network.

   However LLADS does not by itself allow the MN to deliver packets such
   that the FA know whether or not it should reverse tunnel them, or
   process them as local packets (e.g., perhaps forwarding them to local
   services).  Certain networks have the capability of enabling
   additional context at the link-layer to effect different
   classification and treatment of packets otherwise indistinguishable
   at the IP layer, e.g., by establishing additional PDP contexts in
   3GPP or additional service flows (and the corresponding CIDs) in
   WiMAX networks.  In such networks, it is possible for the MN and the



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   FA to establish additional context such that packets sent by the MN
   to the FA are classified correctly upon arrival into either packets
   meant for local consumption, or packets meant to be reverse tunneled.
   In the absence of any IP layer differentiation (i.e., by sending
   packets meant for local consumption with the MN's local care-of
   address as source address), such link-layer mechanisms can provide
   the necessary means for the FA to select the correct processing for
   packets received from the MN.  Such link-layer mechanisms, however,
   are out of scope of this document.


6.  Security Considerations

   This draft does not introduce any security threats on the top of what
   is defined in IP Mobility Protocol [RFC3344].  If included, the
   Multicast-Broadcast Encapsulating Delivery Style extension MUST be
   added after the MN-HA authentication extension and before the MN-FA
   authentication extension, if present.


7.  IANA Considerations

   This document defines a new IP Mobility extension, as described in
   Section 3.1 and uses a type <IANA-TBD>.  The Multicast-Broadcast
   Encapsulation Delivery Extension type is assigned from the range of
   values associated with the skippable IP Mobility extensions.


8.  Acknowledgments

   The authors like to thank Charlie Perkins, Alex Bachmutsky, De Juan
   Huarte Federico, Parviz Yegani, Jayshree Bharatia for their comments
   and contribution in shaping up this document.  We also thank the
   WiMAX Forum NWG members for their valuable input and suggestions
   during the initial discussion of the problem.


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.

   [RFC3024]  Montenegro, G., "Reverse Tunneling for Mobile IP,
              revised", RFC 3024, January 2001.

   [RFC3344]  Perkins, C., "IP Mobility Support for IPv4", RFC 3344,



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              August 2002.

9.2.  Informative references

   [3GPP2]    "3GPP2 - Third Generation Partnership Project 2: X.P0028-
              200", Online web site http://www.3gpp2.org.

   [NWG]      "NWG - WiMAX Network Architecture Group", Online web
              site http://www.wimaxforum.org.


Appendix A.  Appendix-A

   TBD.


Authors' Addresses

   Ahmad Muhanna (Editor)
   Ericsson Inc.
   2201 Lakeside Blvd.
   Richardson, TX  75082
   USA

   Email: ahmad.muhanna@ericsson.com


   Basavaraj Patil
   Nokia
   6021 Connection Drive
   Irving, TX  75039
   USA

   Email: basavaraj.patil@nokia.com


   Samita Chakrabarti
   IP Infusion
   1188 Arquest Street
   Sunnyvale, CA
   USA

   Email: samitac@ipinfusion.com








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   Gabriel Montenegro
   Microsoft Corporation
   One Microsoft Way
   Redmond, WA  98052
   USA

   Email: gabriel.montenegro@microsoft.com


   Yingzhe Wu
   ZTE USA
   10105 Pacific Heights Blvd, Suite 250
   San Diego, CA  92121
   USA

   Email: yingzhe.wu@zteusa.com



































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