Distributed Mobility Management Protocol for WiFi Users in Fixed Network
draft-sarikaya-dmm-for-wifi-00

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Authors Behcet Sarikaya  , Li Xue 
Last updated 2014-07-03
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Network Working Group                                        B. Sarikaya
Internet-Draft                                                Huawei USA
Intended status: Standards Track                                  L. Xue
Expires: January 4, 2015                                          Huawei
                                                            July 3, 2014

Distributed Mobility Management Protocol for WiFi Users in Fixed Network
                   draft-sarikaya-dmm-for-wifi-00.txt

Abstract

   As networks are moving towards flat architectures, a distributed
   approach is needed to mobility management.  This document defines a
   distributed mobility management protocol.  Protocol is based on
   mobility aware virtualized routing system with software-defined
   network support.  Routing is in Layer 2 in the access network and in
   Layer 3 in the core network.  Smart phones access the network over
   IEEE 802.11 (Wi-Fi) interface and can move in home, hotspot and
   enterprise buildings.

Status of This Memo

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   This Internet-Draft will expire on January 4, 2015.

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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   carefully, as they describe your rights and restrictions with respect

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   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  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Overview  . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Detailed Protocol Operation . . . . . . . . . . . . . . . . .   4
     4.1.  Layer 2 Mobility in Access Network  . . . . . . . . . . .   4
     4.2.  Layer 3 Mobility and Routing in Core Network  . . . . . .   5
   5.  IPv4 Support  . . . . . . . . . . . . . . . . . . . . . . . .   7
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   7
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   7
     9.2.  Informative references  . . . . . . . . . . . . . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   Centralized mobility anchoring has several drawbacks such as single
   point of failure, routing in a non optimal route, overloading of the
   centralized data anchor point due to the data traffic increase, low
   scalability of the centralized route and context management
   [I-D.ietf-dmm-requirements].

   In this document, we define a routing based distributed mobility
   management protocol.  The protocol assumes a flat network
   architecture as shown in Figure 1.  No client software is assumed at
   the mobile node.

   IP level mobility signaling needs to be used even when MN is
   connected to a home network or a hotspot.  Distributed anchors in the
   protocol are called Unified Gateways and they represent an evolution
   from the Broadband Network Gateway (BNG) currently in use.

   .

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    Cloud                        _.---------+----------.
                      ,' ' ---''Virtualized Control Plane---'-.
                     (    +---+          +---+         +---+   `.
                      `.  |VM1|          |VM2|         |VM3|      )
                          +---+          +---+         +--,+    ,'
    IP Routers              |     _.---------+----------.
    with SDN Clients       ,----''           |           `---'-.
    and Agents         ,-'  |               |                \ `-.
                    ,'      |              |                '   `.
                   (        |    IP Network|                 \     )
                    `.     |               |                  '  ,'
                      `-. |                 ;                  ,\'
                         ;-----. ---------+------------------
                    +-------+         +-------+      +-------+
                    |  UGW  |         |  UGW  |      |  UGW  |
                    +-------+         +-------+      +-------+
                   ,'                     |                    `.
                  (             Access Network                    )
                   `.                     |                    ,'
                    +-----+           +-----+        +-----+
                    | RG  |           | RG  |        | RG  |
                    +-----+           +-----+        +-----+
                  +-----+                          +-----+
                  | MN  | ----move---------------> | MN  |
                  +-----+                          +-----+

               Figure 1: Architecture of Wi-Fi DMM Protocol

2.  Terminology

   This document uses the terminology defined in
   [I-D.matsushima-stateless-uplane-vepc].

3.  Overview

   This section presents an overview of the protocol.  See also
   Figure 1.

   Access routers (AR) are Unified Gateways (UGW) that are the access
   network gateways that behave similarly as Evolved packet Core (EPC)
   Edge Router (EPC-E) in [I-D.matsushima-stateless-uplane-vepc].  UGW
   is configured an anycast address on the interface facing the
   Residential Gateway (RG).  RGs use this address to forward packets
   from the users.  The fixed access network delivers the packets to
   geographically closes UGW.

   Wi-Fi smart phone, the mobile node (MN) is assigned a unique prefix
   using either Stateless Address Auto Configuration (SLAAC) or by a

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   DHCP server which could be placed in the cloud.  In case of SLAAC, RG
   is delegated the prefixes by DHCP server using [RFC3633].

   Prefix assignments to MNs are consistent with the prefixes assigned
   to UGWs that are shorter than /64.  These prefixes are part of the
   operator's prefix(es) which could be /32, /24, etc.

   The mobile node can move at home or in a hot spot from one Access
   Point (AP) to another AP and MN mobility will be handled in Layer 2
   using IEEE 802.11k and 802.11r.

   When MN moves from one UGW into another UGW, IP mobility signaling
   needs to be introduced.  In this document we use Handover Initiate/
   Handover Acknowledge (HI/HAck) messages defined in [RFC5949].
   Handover Initiate message can be initiated by either previous UGW
   (predictive handover) or the next UGW (reactive UGW).  In reactive
   handover, RG establishes a new connection with the next UGW when MN
   moves to this RG and provides previous UGW address.  This will
   trigger the next UGW to send HI message to the previous UGW.
   Previous UGW sends HAck messages which establishes a tunnel between
   previous and next UGWs.  Previous UGW sends packets destined to MN to
   the new UGW which in turn sends them to MN.

   Note that the mobility signaling just described is control plane
   functionality.  Control plane in our document is moved to the cloud,
   thus mobility signaling happens at the cloud, possibly between two
   virtual machines (VM).

   Upstream packets from MN at the new UGW are sent as usual but
   downstream packets may need special path establishment if MN's prefix
   is not hosted at the new UGW.  In this case Software-Defined
   Networking (SDN) is used.  SDN allows Routing Information Bases (RIB)
   in a subset of the upstream routers to be modified to enable the
   downstream packets to be routed to the new UGW but not to the
   previous UGW.

4.  Detailed Protocol Operation

   In this section, Layer 2 and Layer 3 mobility procedures are
   explained.

4.1.  Layer 2 Mobility in Access Network

   In the access network, RG MAC address acts as an identifier for the
   MN.  Access network switches are controlled by SDN.  Controller to
   Switch interface uses Extensible Messaging and Presence Protocol
   (XMPP)[RFC6121].  XMPP is based on a general subscribe-publish
   message bus.  SDN controller publishes forwarding instructions to the

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   subscribing switch.  Forwarding instructions could be Open Flow like
   match-forward instructions.

   Access network is organized as interconnected switches.  The switch
   connected to the RG is called egress switch.  The switch connected to
   the UGW is called ingress switch.  IEEE 802.1ad standard for VLAN (Q-
   in-Q) is used in the access network, where S-VLAN denotes RG groups,
   and C-VLAN determines traffic classes.  One S-VLAN tag is assigned to
   create one or more VLAN paths between egress and ingress switches.

   MN mobility in the access network can be tracked by keeping a table
   consisting of MN IP address and RG MAC address pairs.  In this
   document SDN controllers keep the mobility table.  This table is used
   to select proper S-VLAN downstream path from ingress switch to egress
   switch and upstream path from egress switch to ingress switch.

   After a new MN with WiFi associates with RG, RG sends an Unsolicited
   Neighbor Advertisement (NA) messages upstream.  This NA message is
   constructed as per [RFC4861] but the Source Address field is set to a
   unicast address of MN.  NA message is received by SDN controller and
   it enables SDN controller to update the mobility table.  SDN
   controller selects proper path including S-VLAN and ingress switch to
   forward the traffic from this MN.  The controller establishes the
   forwarding needed on these switches.

4.2.  Layer 3 Mobility and Routing in Core Network

   MN moving from one RG to another may eventually require MN moving
   from one UGW to another.  This is Layer 3 mobility.

   Predictive handover happens when MN just before leaving the previous
   RG (pRG) for the next RG (nRG) MN is able to send an 802.11 message
   containing MN MAC address and nRG MAC address, e.g. learned from
   beacons to the pRG (called Leave Report in Figure 2. pRG then sends a
   handover indication message to pUGW providing MN and nRG addresses
   (called Leave Indication) and this could happen between two
   respective virtual machines in the cloud.  This message results in
   pUGW getting nUGW information and then sending Handover Initiate
   message to nUGW, which also could happen in the cloud. nUGW replies
   with Handover Acknowledge message.  pUGW sends any packets destined
   to MN to nUGA after being alerted by the control plane.  MN moves to
   nRG and nUGW is informed about this from Layer 2 mobility
   Section 4.1. uGW delivers MN's outstanding packets to MN.

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           MN         P-RG       N-RG        (P-UGW)     (N-UGW)   Cloud
            |   Leave   |          |            |           |        |
       (a)  |--Report-->|          |            |           |        |
            |           |          |            |           |        |
            |           |       Leave           |           |        |
       (b)  |           |------indication------>|           |        |
            |           |          |            |           |        |
            |           |          |            |           |        |
       (c)  |           |          |            |----HI---->|        |
            |           |          |            |           |        |
            |           |          |            |           |        |
       (d)  |           |          |            |<---HAck---|        |
            |           |          |            |===========|        |

                       Figure 2: Predictive Handover

   Reactive handover handover happens when MN attaches the new RG from
   the previous RG (called Join Report in Figure 3.  MN is able to
   signal in 802.11 association messages previous RG MAC address.  nUGW
   receives new association information together with pRG information,
   possibly in the cloud (called Handover Indication). nUGW finds pUGW
   address and sends HI message to pUGW, again happening between two
   virtual machines in the cloud. pUGW after receiving indication from
   the cloud server delivers any outstanding MN's packets to nUGW which
   in turn delivers them to MN.

           MN         P-RG       N-RG        (P-UGW)     (N-UGW)   Cloud
            |   Join    |          |            |           |        |
       (a)  |--Report------------->|            |           |        |
            |           |          |       Handover         |        |
       (b)  |           |          |------Indication------->|        |
            |           |          |            |           |        |
       (c)  |           |          |            |<----HI----|        |
            |           |          |            |           |        |
       (d)  |           |          |            |----HAck-->|        |
            |           |          |            |           |        |
       (e)  |           |          |            |<--------->|        |
            |           |          |            |           |   data |
       (f)  |           |          |            |===========|        |

                        Figure 3: Reactive Handover

   Note that Handover Initiate and Handover Acknowledge messages used in
   this document carry only a subset of parameters defined in [RFC5949].
   Also no involvement with the Local Mobility Anchor (LMA) is needed.

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   After handover, SDN route establishment in upstream routers needs to
   take place.  I2RS Agent as XMPP Client in nUGW and in pUGW inform the
   handover to I2RS Clients as XMPP Server upstream.  I2RS Agent at pUGW
   removes any routing information for MN.  XMPP Clients and Servers
   engage in structured request-response interactions.  These
   interactions are needed for these purposes: I2RS Client publishes the
   new route for this MN to nUGW at the router upstream.  I2RS Agent at
   nUGW adds new routing information for this MN into its RIB.

   As a result for MNs that handover, upstream routing that takes place
   is not modified up to the lowest level of routers.  The lowest level
   of routers handle the mobility but proper modifications so that the
   packets reach the right Unified Gateway.  One way to achive this
   could be using host routes.

5.  IPv4 Support

   IPv4 can be supported similarly as in vEPC
   [I-D.matsushima-stateless-uplane-vepc].  UGW stays as IPv6 node
   receiving from all RGs IPv6 packets and forwarding them upstream.

   IPv4 MN is supported at the RG.  RG has B4 functionality of DS-Lite
   [RFC6333] or CLAT entity for 464XLAT [RFC6877].  RG encapsulates IPv4
   packets in DS-Lite or translates IPv4 packets in 464XLAT into IPv6
   packets making sure that UGW stays IPv6 only.

6.  Security Considerations

   TBD.

7.  IANA Considerations

   TBD.

8.  Acknowledgements

   TBD.

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.

   [RFC3633]  Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic
              Host Configuration Protocol (DHCP) version 6", RFC 3633,
              December 2003.

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   [RFC4861]  Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
              "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
              September 2007.

   [RFC5949]  Yokota, H., Chowdhury, K., Koodli, R., Patil, B., and F.
              Xia, "Fast Handovers for Proxy Mobile IPv6", RFC 5949,
              September 2010.

   [RFC6121]  Saint-Andre, P., "Extensible Messaging and Presence
              Protocol (XMPP): Instant Messaging and Presence", RFC
              6121, March 2011.

   [RFC6333]  Durand, A., Droms, R., Woodyatt, J., and Y. Lee, "Dual-
              Stack Lite Broadband Deployments Following IPv4
              Exhaustion", RFC 6333, August 2011.

   [RFC6877]  Mawatari, M., Kawashima, M., and C. Byrne, "464XLAT:
              Combination of Stateful and Stateless Translation", RFC
              6877, April 2013.

9.2.  Informative references

   [I-D.ietf-dmm-requirements]
              Chan, A., Liu, D., Seite, P., Yokota, H., and J. Korhonen,
              "Requirements for Distributed Mobility Management", draft-
              ietf-dmm-requirements-17 (work in progress), June 2014.

   [I-D.matsushima-stateless-uplane-vepc]
              Matsushima, S. and R. Wakikawa, "Stateless user-plane
              architecture for virtualized EPC (vEPC)", draft-
              matsushima-stateless-uplane-vepc-02 (work in progress),
              February 2014.

   [I-D.ietf-i2rs-architecture]
              Atlas, A., Halpern, J., Hares, S., Ward, D., and T.
              Nadeau, "An Architecture for the Interface to the Routing
              System", draft-ietf-i2rs-architecture-04 (work in
              progress), June 2014.

Authors' Addresses

   Behcet Sarikaya
   Huawei USA
   5340 Legacy Dr. Building 175
   Plano, TX  75024

   Phone: +1 469 277 5839
   Email: sarikaya@ieee.org

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   Li Xue
   Huawei
   NO.156 Beiqing Rd. Z-park, Shi-Chuang-Ke-Ji-Shi-Fan-Yuan,
   Beijing, HaiDian District  100095
   China

   Email: xueli@huawei.com

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