Network Working Group                                             W. Luo
Internet-Draft                                                     Y. Tu
Intended status: Standards Track                                     ZTE
Expires: January 31, 2014                                  July 30, 2013


 Distributed Mobility Management Approaches with IPv6 Prefix Properties
                draft-luo-dmm-ipv6-prefix-properties-00

Abstract

   This document proposes a potential distributed mobility management
   solution by taking advantage of the feature with IPv6 Prefix Mobility
   Management.  Solutions for extending properties to IPv6 prefixes are
   introduced by defining an extension to the IPv6 Neighbor Discovery
   protocol and its Prefix Information Option (PIO).  In the case of
   Distributed Mobility Management, this idea can also be leveraged to
   describe the mobility management properties associated to the IPv6
   prefix.

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
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on January 31, 2014.









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Copyright Notice

   Copyright (c) 2013 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Solution Overview . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Detailed Scenarios and Approaches . . . . . . . . . . . . . .   5
     3.1.  Initial Attachment  . . . . . . . . . . . . . . . . . . .   5
     3.2.  Data forwarding . . . . . . . . . . . . . . . . . . . . .   6
     3.3.  Handoff Scenario  . . . . . . . . . . . . . . . . . . . .   7
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
   5.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  10
     5.1.  Normative References  . . . . . . . . . . . . . . . . . .  10
     5.2.  Informative References  . . . . . . . . . . . . . . . . .  10
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

   Centralized mobility anchoring imposes some limitations to the system
   such as single point of failure, non optimal routing and etc. which
   are discussed in [I-D.ietf-dmm-requirements] [I-D.liu-mext-
   distributed-mobile-ip].  Given the exponential grow of smart-phone
   devices (e.g. iPhone) with mobile service applications, and the
   uprising social media trend driving the peer-to-peer communications,
   centralized mobility anchoring magnifies these issues and is no long
   a good fit to handle the new traffic pattern that is happening in the
   internet and in private networks.  The design intent of Distributed
   Mobility Management is to mitigate those drawbacks, various solutions
   are introduced in current DMM working group.

   Solutions for extending properties to IPv6 prefixes are introduced
   in[I-D.korhonen-6man-prefix-properties] by defining an extension to
   the IPv6 Neighbor Discovery protocol and its Prefix Information
   Option (PIO).  For a specific use case, this idea can also be
   leveraged to describe the mobility management properties associated



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   to the IPv6 prefix.  This document proposes a potential distributed
   mobility management solution by taking advantage of the feature with
   IPv6 Prefix Mobility Management.

2.  Solution Overview

   The proposed solution in this draft introduces two new logic
   functions for the distributed mobility management which is quite
   similar with [I-D.luo-dmm-pmip-based-dmm-approach] :

   1.  Location Management Function (LMF), maintaining the mappings
       between IP addresses and location of terminals

   2.  Distributed Anchoring Function (DAF), which is composed of
       Distributed Routing sub-Function (DRF) and Distributed Mobility
       sub-Function (DMF).  The DRF operates as the distributed tunnel
       end-point at the first hop router of the mobile node or the
       corresponding node to support the optimized routing between two
       end-points, whereas the DMF supports the mobile node's mobility
       handover operation with minimal packet loss during the optimized
       route establishment

   The distributed anchor is referred as enhanced LMA (eLAM) which is a
   RFC[5213] specified LMA integrated with the DAF function and is
   supposed to be the mobile node's first router as described in
   [I-D.luo-dmm-pmip-based-dmm-approach] section 7.

   The[I-D.korhonen-6man-prefix-properties] specifies a mechanism for
   delivering property of IPv6 prefixes to terminal nodes (i.e. the 'C'
   flag in Prefix Information Option).  As one specific use case, the
   mechanism can be re-used for delivering mobility management property
   of IPv6 prefix by the distributed anchor to mobile node for
   distributed mobility management.

   When distributed anchor detects an initial attachment of a mobile
   node, it will send a RA message to that mobile node.  The RA includes
   IPv6 prefixes, and each prefix is tagged with its properties which
   includes its mobility management property.  According to the mobility
   management property, the IPv6 prefix can be distinguished by the
   mobile node into two categories, i.e. global prefix vs. local prefix
   defined as following:

   o  Global Prefix: if an IPv6 address derived from a global prefix is
      used as source address for a session, this session will be
      provided with fully mobility support by using the mobility
      management mechanism specified in this draft.  That means, the
      address always remains valid even the point of attachment is
      changed.



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   o  Local Prefix: if an IPv6 address derived from a local prefix is
      used as source address for a session, no or limited mobility
      support will be provided for this session.  The address may not be
      valid when the point of attachment is changed.

   Based on the acquired mobility management property, mobile node can
   distinguish the two categories.  If application on mobile requires
   mobility support, the mobile will derive an IPv6 address from the
   global prefix by having the application to invoke an appropriate
   socket API extension.  Otherwise, the application on the mobile that
   requires no or limited mobility support will derive IPv6 address from
   local prefix by invoking another appropriate socket API extension.

   The network doesn't provide mobility for those local IPv6 prefixes,
   which means IPv6 address which is derived from local prefixes is
   treated as a plain IPv6 address and generic IPv6 routing mechanism is
   applied.  When mobile node changes its point of attachment, e.g. from
   previous distributed anchor to next distributed anchor, the local
   prefix assigned by previous distributed anchor will be
   deprecated\invalidated, and the applications which are based on those
   prefixes will suffer an IPv6 addresses change.  When attaching to
   next distributed anchor, the mobile node can be advertised with new
   local prefix by the next distributed anchor.

   Mechanisms used for maintaining mobility for those global IPv6
   prefixes are quite similar with the mechanisms specified in
   [I-D.luo-dmm-pmip-based-dmm-approach] which mainly includes three
   aspects as following:

   a.  Initial Attachment: as described above, during the initial
       attachment, the distributed anchor sends RA message with one or
       more local and global prefixes which can be distinguished by the
       mobile node according to their mobility management property.
       Distributed anchor only updates the location information to the
       LMF for those global prefixes.  Section 3.1 provides more
       detailed description.

   b.  Data Forwarding: if the application on the mobile node requires
       mobility support (such as VOIP), it will ask an IPv6 address
       which is derived from a global prefix and establish a session
       based on this global address as its source address with its
       correspondent node.  When distributed anchor of the correspondent
       node receives traffic send to that global address, it will query
       the LMF for the location information of that global address and
       forward the traffic based on the location information (e.g. IP in
       IP tunnel).  Section 3.2 provides more detailed description.





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   c.  Handoff: when mobile node changes its point of attachment from
       previous distributed anchor to next distributed anchor, the next
       distributed anchor will advertise the same global prefix to the
       mobile node on the new link and update new location information
       for that global prefix to the LMF for the purpose of maintaining
       the reachability of mobile node's global prefix.  Section 3.3
       provides more detailed description.

3.  Detailed Scenarios and Approaches

   As described above, the distributed anchor in this draft is referred
   as eLMA as shown in figures below.  Note that, although the MAG as
   defined in RFC[5213] is not shown in the figures below, one should
   aware that, the MAG could be co-located with the eLMA.

3.1.  Initial Attachment

      Internet
         |           +-----+
         |           | LMF |
   Border Router     +-----+
         |
         +-----------------+---------
                           |
                       +---+---+
                       | eLMA1 |
                       | (DAF) |
                       +--+----+
            Global Prefix |  |Local Prefix
                (PreB)    |  |  (PreA)
                          V  V
                         +----+
                         | MN |
                         +----+
         IP1: From PreA (Local, without mobility)
         IP2: From PreB (Global, with mobility)


   Figure 1.  Initial Attach

   When eLMA1 detects an initial attachment of a mobile node, it sends a
   RA message to that mobile.  The RA includes two categories of
   prefixes, local prefix (PreA) and global prefix (PreB).  The eLMA
   should set PreA (i.e. local prefix) with high priority and PreB (i.e.
   global prefix) with low priority as according to
   [I-D.korhonen-6man-prefix-properties].





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   The mobile node will derive its IPv6 addresses based on these two
   categories of IPv6 prefixes provided by the RA message.  The derived
   IPv6 addresses include local IPv6 address (IP1 in figure 1) and
   global IPv6 address (IP2 in figure 1).  Applications on the mobile
   node could select an appropriate IPv6 address as its source address
   as described in section 4 in [I-D.korhonen-6man-prefix-properties].

   Furthermore, the eLMA1 needs to perform the location update for the
   MN based on the MN's global prefix-to-location mapping info, i.e.
   {MN's global prefix, eLMA's IPv6 address}, for this particular mobile
   node to the LMF based on the mechanism introduced in section 7.2
   of[I-D.luo-dmm-pmip-based-dmm-approach].  Note that, the distributed
   anchor performs the location update only for the MN's global prefix.

3.2.  Data forwarding

                                IP1 as destination:
                                common routing
                          |             +-------+       +----+
                          |             | eLMA3 |_______| CN |
       +-----+            +-------------+ (DAF) |       +----+
       | LMF |            |             +-------+
       +-----+            |     IP2 as destination:
                          |     Routing based on location
       --------------+----+     (e.g. IP in IP tunnel)
                     |
                 +---+---+
                 | eLMA1 |
                 | (DAF) |
                 +--+----+
      Global Prefix |  |Local Prefix
          (PreB)    |  |  (PreA)
                    V  V
                   +----+
                   | MN |
                   +----+
   IP1: From PreA (Local, without mobility)
   IP2: From PreB (Global, with mobility)


   Figure 2.1 Data forwarding mechanism

   When correspondent node (CN) sends traffic to the mobile node, the
   traffic arrives at CN's distributed anchor first (i.e. eLMA3 in
   figure 2.1).  Depending on the category of the destination IPv6
   address, eLMA3 should operate accordingly:





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   a.  If the destination IPv6 address with local IPv6 prefix (IP1 in
       figure 2.1), eLMA3 will route the IP packet by using the generic
       IPv6 routing mechanism.

   b.  Otherwise, if the destination IPv6 address with global IPv6
       prefix (IP2 in figure 2.1), then eLMA3 will route this IP packet
       using routing mechanism as specified in section 7.2 of
       [I-D.luo-dmm-pmip-based-dmm-approach].

                +-------+               +----+
                | eLMA3 |<--------------+ CN |
                | (DAF) |               +----+
                +-------+   Destination IP (IP2)is
   Tunneled        ||       global IPv6 address
   forwarding      ||       configured on MN
   based on MN's   ||
   location        ||
                   VV
                +-------+               +----+
                | eLMA1 +-------------->| MN |
                | (DAF) |               +----+
                +-------+


   Figure 2.2 traffic between CN and MN, when destination is global IPv6
   address of MN, routing is optimized.

   As shown in figure 2.2, if the traffic from CN is sent to the mobile
   node's global IPv6 address (i.e. IP2), the routing will be:
   CN-->eLMA3==>eLMA1-->MN which is based on optimized route.

   Note that, the tunnel between eLMA1 and eLMA3 is not per MN-CN pair,
   rather, it is a single tunnel between two distributed anchor peers.
   Any traffic between the MNs which are attached to these two peers
   will be routed over the same tunnel of which the tunnel is over an
   optimal routing path between the peers.

3.3.  Handoff Scenario

                                              IP1 as destination:
                                              can not be reachable
                                              after handoff
        Internet                              IP3 as destination:
            |                                 common routing
            |                                     +-------+       +----+
            |                              |      | eLMA3 |_______| CN |
            |          +-----+             +------+ (DAF) |       +----+
      Border Router    | LMF |             |      +-------+



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            |          +-----+             |  IP2 as destination:
            |                              |  Routing based on location
            +-----+---------------------+--+
                  |                     |
              +---+---+             +---+---+
              | eLMA2 |             | eLMA1 |
              | (DAF) |             | (DAF) |
              +-------+             +--+----+
   Local Prefix |  |   Global Prefix   |  |Local Prefix
     (PreC)     |  |       (PreB)      |  |  (PreA)
                V  V                   V  V
               +----+                 +----+
               | MN |   <------------ | MN |
               +----+                 +----+
    IP3: From PreC                IP1: From PreA
    (Local, without mobility)     (Local, without mobility)
    IP2:Keep unchanged            IP2: From PreB
    (Global, with mobility)       (Global, with mobility)


   Figure 3.1 Handover Scenario.

   The handover between distributed anchors happens when the mobile node
   switches to a new distributed anchor, i.e. switching its anchor from
   eLMA1 to eLMA2 as shown in figure 3.1.  Once eLMA2 detects the
   attachment from the MN, it will send a RA which includes local
   prefix(es) and global prefix(es) to the mobile node and the handover
   operation is described as follows:

   a.  MN's local prefix assigned by the previous distributed anchor
       (PreA in figure 3.1) will be deprecated\invalidated.  In this
       case, the traffic which is sent to IP1 (configured from PreA)
       from CN will be discarded by the IPv6 routing system
       automatically; unless, a temporary tunnel between the previous
       and the next distributed anchors is setup to maintain the
       reachability to the previous local prefix.  Applications which
       rely on those local prefixes may suffer a change of source IP
       address.

   b.  New local prefix(es) (i.e. PreC in figure 3.1) carried in the RA
       message and is assigned by eLMA2 is now have high priority.  The
       MN will derive a new IPv6 local address (IP3 in figure 3.1) for
       the PreC.

   c.  The global prefix(es) (i.e.PreB in figure 3.1) in the RA message
       remain the same global prefix(es) as assigned by eLMA1 which is
       the distributed anchor of this MN during its initial attachment.
       The eLMA2 shall perform the location update for the global



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       prefixes of this MN based on the IPv6 address of eLMA2 to LMF to
       maintain the reachability of those global prefix(es).  The
       details for the handover can be reviewed in section 7.2 of
       [I-D.luo-dmm-pmip-based-dmm-approach].

   Thus, after the handover, the mobile node can be reached either via
   its new local IPv6 address (i.e. IP3) or via its global IPv6 address
   (i.e. IP2); and if a temporary tunnel is present between eLMA1 and
   eLMA2, also be researchable via its previous local IPv6 address
   (i.e.IP1).

   It is the network policy to decide to maintain the reachability to
   the previous local prefix via a temporary tunnel between the previous
   distributed anchor and the next distributed anchor as described in
   section 4.4.2 of Korhonen-draft[I-D.korhonen-6man-prefix-properties]
   (Note that the distributed anchor refers to MAG in Korhonen-draft and
   eLMA in this draft).  Never-the-less, the purpose for such temporary
   tunnel to support service continuity when employing the local prefix
   is similar to the tunnel used by the global prefix for the mobility
   management purpose.

                +-------+               +----+
                | eLMA3 |<--------------+ CN |
                | (DAF) |               +----+
                +-------+   Destination IP (IP2) is
   Tunneled        ||       global IPv6 address
   forwarding      ||       configured on MN
   based on MN's   ||
   new location    ||
                   VV
                +-------+               +----+
                | eLMA2 +-------------->| MN |
                | (DAF) |               +----+
                +-------+
   (New Distributed anchor after handoff)


   Figure 3.2 traffic between CN and MN after the handover, when
   destination is global IPv6 address of MN, routing is also optimized..

   As shown in figure 3.2, if the traffic from CN is sent to the mobile
   node's global IPv6 address (i.e. IP2) after the handover, the routing
   will be: CN-->eLMA3==>eLMA2-->MN.  The routing is still optimized.

4.  IANA Considerations

   This document makes no request of IANA.




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5.  References

5.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC5213]  Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K.,
              and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008.

5.2.  Informative References

   [I-D.ietf-dmm-requirements]
              Chan, H., "Requirements for Distributed Mobility
              Management", June 2013.

   [I-D.korhonen-6man-prefix-properties]
              Korhonen, J., Patil, B., and S. Gundavelli, "IPv6 Prefix
              Mobility Management Properties", July 2013.

   [I-D.korhonen-dmm-local-prefix]
              Korhonen, J. and T. Savolainen, "Local Prefix Lifetime
              Management for Proxy Mobile IPv6", July 2013.

   [I-D.luo-dmm-pmip-based-dmm-approach]
              Luo, W. and J. Liu, "PMIP Based DMM Approaches", .

Authors' Addresses

   Wen Luo
   ZTE
   No.68, Zijinhua RD,Yuhuatai District
   Nanjing, Jiangsu  210012
   China

   Email: luo.wen@zte.com.cn


   Yangwei Tu
   ZTE
   No.68, Zijinhua RD,Yuhuatai District
   Nanjing, Jiangsu  210012
   China

   Email: tu.yangwei@zte.com.cn






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