Internet DRAFT - draft-wei-dmm-ro-consideration

draft-wei-dmm-ro-consideration






Distributed Mobility Management (DMM)                             X. Wei
Internet-Draft                                       Huawei Technologies
Intended status: Informational                         February 13, 2014
Expires: August 17, 2014


         Consideration of Routing Optimization for DMM network
                   draft-wei-dmm-ro-consideration-00

Abstract

   Distributed Mobility Management (DMM) is designed to be a distributed
   and scalable mobility management solution, and providing optimal
   route for traffics is one of DMM's aims.  There have been several
   proposals on DMM framework, and this document provides discussion on
   how to optimize traffic routes, and aims to provide suggestioins on
   how to avoid long route in DMM network.

Status of this Memo

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   This Internet-Draft will expire on August 17, 2014.

Copyright Notice

   Copyright (c) 2014 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
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   the Trust Legal Provisions and are provided without warranty as



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   described in the Simplified BSD License.


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Terminology and Abbreviation . . . . . . . . . . . . . . . . .  4
     2.1.  Conventions Used in This Document  . . . . . . . . . . . .  4
   3.  Impacts of routing optimization  . . . . . . . . . . . . . . .  5
     3.1.  Tunneling  . . . . . . . . . . . . . . . . . . . . . . . .  5
     3.2.  IP changing  . . . . . . . . . . . . . . . . . . . . . . .  6
     3.3.  Local Routing  . . . . . . . . . . . . . . . . . . . . . .  7
   4.  Conclusions  . . . . . . . . . . . . . . . . . . . . . . . . .  9
   5.  Security Considerations  . . . . . . . . . . . . . . . . . . . 10
   6.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 11
   7.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
     7.1.  Normative References . . . . . . . . . . . . . . . . . . . 12
     7.2.  Informative References . . . . . . . . . . . . . . . . . . 12
   Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 13
































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1.  Introduction

   The new network service scenarios such as network traffic offloading
   and mobility service in local Content Delivery Networks (CDNs) impose
   new requirements on network mobility management, and a more flat
   mobility management system with fewer levels of routing hierarchy
   introduced into the data path is more preferred.  So Distributed
   Mobility Management (DMM) is proposed to satisfy these new network
   mobility management requirements, and DMM aims to solve the problems
   such as non-optimal routes, poor network scalability, and single
   point of failure and attack which are widely faced by existing
   centralized mobility management protocols [4].

   Currently several solutions on DMM framework are being discussed,
   some of the solutions are based on existing IP mobility management
   protocols [5] [6], and others provide new solutions [7] [8].  These
   solutions provide their own DMM frameworks, and in order to transport
   traffic through an optimal path the basic idea of these solutions is
   placing mobility anchors in a distributed way.

   Routing redundancy is a common problem in mobile IP network.  In
   mobile IP network, Mobility Anchor (MA) acts as topological anchor of
   IP address, and due to the existing of mobility anchors, the packets
   sent from MN's Correspondent Node (CN) are always firstly routed to
   MN's mobility anchor and then forwarded to MN.  In order to reduce
   routing redundancy problem existing in mobile IP network, some
   routing optimization methods could be implemented.  Because mobility
   anchor will be existed in DMM network, so routing optimization
   method(s) would also be taken into consideration in the design of DMM
   network.

   This document provides some considerations of routing optimization
   related issues for the design of DMM network, several routing
   optimization methods and their impacts on traffic will be discussed.

















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2.  Terminology and Abbreviation

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
   thisdocument are to be interpreted as described in [1].












































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3.  Impacts of routing optimization

   This section analyzes the impacts of routing optimization on network
   traffic.  Several routing optimization methods, including tunneling,
   changing the IP address and local routing, are discussed here.

3.1.  Tunneling

   In IP network, tunnel could be used to hide the network topology, and
   it is a method of changing the route of traffic.  Because tunnel can
   let traffic travel in network without constrain of network topology,
   so it is often used as a tool for changing the route of network
   traffics.

   In DMM network, MAs are distributed deployed and towards to access
   network, it is likely for MN to attach to different MAs when MN moves
   in the network.  In order to keep service continuity, DMM network
   would keep MN's IP address for IP session, and routes the packets
   through the anchor of IP address.  The change of MA would bring about
   routing redundancy, so tunnel based routing optimization could be
   used to reduce the routing redundancy.

   For DMM network, When MN moves to a new MA, the tunnel for routing
   optimization could be set up between MN's MA and CN's MA (Figure 1),
   or between MN and CN (Figure 2).

            +--+
            |CN|
            +-|+
              |
              |
            +-|-+
            |MA3|=========||
          .'+---+         ||
         ,'               || RO tunnel
        /                 ||
       /                  ||
    +-`-+              +---+
    |MA1|--------------|MA2|
    +-|-+              +-|-+
      |                  |
      |                  |
      |                  |
     +|-+               +|-+
     |MN|  ---------->  |MN|
     +--+     move      +--+





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               Figure1: tunnel based routing optimization 1


                       +--+
             +--------+|CN|=========||
             |         +--+         ||
             |                      ||
             |                      || RO tunnel
             |                      ||
             |                      ||
             |                      ||
   +---------+------------+   +-----||-------------+
   |        ++--+         |   |     ||             |
   |        |MA1|         |   |     ||             |
   |        +-+-+         |   |     ||             |
   |          |     +     |   |     ||             |
   |         ++-+         |   |    +--+            |
   |         |MN|  ------------->  |MN|            |
   |         +--+       move  |    +--+            |
   |                      |   |                    |
   +----------------------+   +--------------------+

   network of MA1                           network of MA2



               Figure2: tunnel based routing optimization 2

3.2.  IP changing

   In mobile IP network, the reason of non-optimal route is that in
   order to provide service continuity for MN, network always guarantees
   the consistency of MN's IP address when MN moves in network.  But in
   today's network there are a lot of applications that don't need
   service continuity, e.g. web service, DNS; and for the applications
   which though need service continuity, but they deal with service
   continuity in other layers, e.g. application layer, transport layer
   etc, and not depends on network layer.  So for these applications,
   the consistency of IP address will cause unnecessary non-optimal
   route for them.

   But for some other applications, they need mobility support from
   network layer, and in order to keep service continuity the IP address
   of MN must not be changed during the whole service session.

   So in order to provide optimal path for service traffics from
   applications that don't require IP address consistency, when MN moves
   to a new MA, DMM network could assign new IP address for MN, and then



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   MN could use current MA's IP address for these applications; for the
   applications that require IP address consistency, when MN moves to a
   new MA, DMM network should allow MN to use the IP address assigned by
   previous MA to make sure the address for these applications not
   change.

   For the traffic that requires the consistency of IP address, other
   routing optimization methods such as tunneling and local routing
   could be implemented.

3.3.  Local Routing

   Local routing is another routing optimization method that could be
   used in the situation that MN and CN are in the same network region.
   In the same region means MN and CN are under control of the same
   mobility management entity, e.g. mobility anchor.

   When MN and CN are in the same region, their traffic path might be
   shortened significantly by local routing.  For example, there is a
   local routing function in PMIPv6 [2] protocol as shown in Figure 3.
   When MN and CN are under the control of the same MAG, the local
   routing path could be set up between MN and CN through the MAG, and
   then packets will transported along the path of MN--MAG--CN without
   passing through LMA.

             +----------+
             |   LMA    |
             +----------+



              +---------+
     |------->|   MAG   |<-----|
     |        +---------+      |
     |                         |
     |                         |
     |                         |
     |                         |
   +--V------+             +----V----+
   |   MN    |             |   CN    |
   +---------+             +---------+


                     Figure3: Local Routing in PMIPv6

   Because in DMM network, MA would be deployed towards to the access
   network, so when MN and CN are under the same MA, local routing
   method would provide a optimal path for packets between MN and CN.



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   An example of local routing for DMM network is shown in Figure 4.

                    +---------+
           |------->|   MA    |<-----|
           |        +---------+      |
           |                         |
           |                         |
           |                         |
           |                         |
        +--V------+             +----V----+
        |   MN    |             |   CN    |
        +---------+             +---------+


                      Figure4: Local Routing for DMM




































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4.  Conclusions

   This document discusses three kinds of method for routing
   optimization in DMM network, these methods aims to provide optimal
   traffic route in DMM network, and they would be suitable for
   different situations and different traffics.













































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5.  Security Considerations

   Security related issues are not considered in current document.
















































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6.  IANA Considerations

   There have been no IANA considerations so far in this document.
















































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7.  References

7.1.  Normative References

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

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

   [3]  Perkins, C., Johnson, D., and J. Arkko, "Mobility Support in
        IPv6", RFC 6275, July 2011.

7.2.  Informative References

   [4]  Chan (Ed.) et al., "Requirements for Distributed Mobility
        Management", draft-ietf-dmm-requirements-12 (work in progress),
        Dec 2013.

   [5]  CJ. Bernardos et al,, "PMIPv6-based distributed anchoring",
        draft-bernardos-dmm-distributed-anchoring-03 (work in progress),
        Oct 2013.

   [6]  W. Luo, J. Liu,, "PMIP Based DMM Approaches",
        draft-luo-dmm-pmip-based-dmm-approach-02 (work in progress),
        July 2013.

   [7]  H. Chan, P. Seite, K. Pentikousis, A. Dutta,, "Distributed
        Mobility Management Framework", draft-chan-dmm-framework-03
        (work in progress), Oct 2013.

   [8]  M. Liebsch, P. Seite, G. Karagiannis,, "Distributed Mobility
        Management - Framework & Analysis",
        draft-liebsch-dmm-framework-analysis-02 (work in progress),
        Oct 2013.

   [9]  D. Liu et al,, "Distributed Mobility Management: Current
        practices and gap analysis",
        draft-ietf-dmm-best-practices-gap-analysis-02 (work in progress)
        (work in progress), Oct 2013.











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Author's Address

   Xinpeng Wei
   Huawei Technologies

   Email: weixinpeng@huawei.com













































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