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					Mobility and Future
Internet
 Jeonghoon Mo @ WINE LAB
 Information and Communications University

                                             WINE LAB.
                                               ICU
Overview
   Introduction
   Mobility Solutions
       Application Layer
       Link Layer
       Network Layer
       Transport Layer
   Other Issues
       Host Identity Protocol (HIP)
       Network Mobility
   Summary


                                       2
Future Internet
   We do not know what it is as of now …
   There are many research initiatives on the Future Internet
       GENI, FIRE, FIF, …
       Clean Slate Approach
   Initiatives
       Korea
           Future Internet Forum, July, 2006
       US
           GENI (Global Environment for Network Innovation) August 2005
           FIND (Future Internet Design) December 2005
       Europe
           FIRE (Future Internet Research and Experimentation Activities)



                                                                             3
Issues with Current Internet
   QoS
       Real time audio/video
   Complexity
       Complicated BGP, Routers
   Management
       Hard to control, deployment issues, robustness
   Business Model
       Network Neutrality, google, yahoo, at&t, KT
   Security
       DDoS, packet filtering, Firewall,
    


                                                         4
Mobility
   Mobility is the key issues in the future Internet as people asks
    for convenience
       Anywhere, Anytime, Any devices
   In cellular based networks, handoff is mature technique
       Handoff in GSM networks
       Handoff in CDMA networks
   In IP based networks, handoff is immature
       WiMax, Wi-Fi
   Vertical handoff, NEMO are being pursued…
   Sensors, wearable computing adds new requirements
   Mobile LAN or PAN (NEMO)
       Mobile Vehicle, Mobile Human


                                                                       5
Different Types of Mobility
   Scale
       Pico
       Micro
       Macro
       Global
   Network
       Vertical Handoff
       Horizontal Handoff
   Moving Entity
       Host mobility
       User Mobility
       Application Mobility
       Network Mobility
                               6
What do we mean by supporting?
   What kinds of mobility scenarios should
    we support?
       Talking on a VoIP phone while walking down
        the street?
       Navigating with a laptop in a car?
       Using a laptop in an airplane?
       Taking laptop from home to work?
       Walking around lab or campus?
       Something we haven’t thought of yet??
How to handle Mobility?
   Where can we address this problem?
       Physical layer? (sure; very limited)
       Link layer
       Network layer
       Transport layer
       “Something higher” (often called session)
       Application layer




                                                    8
How to handle Mobility?
   Where can we address this problem?
       Physical layer? (sure; very limited)
       Link layer
       Network layer
       Transport layer
       “Something higher” (often called session)
       Application layer




                                                    9
Try #1: No Network Support
(Applications are on their own)
   Let them disconnect and reconnect when they
    arrive at a new location.
       Network support needed: None / DHCP
       Your SSH sessions die.  Your streaming media
        probably gets interrupted.
       Some applications have already worked around this:
         Your Web browser doesn’t care

         Your IMAP mail reader probably doesn’t care
Dealing with disconnection
   Possible to code many applications to deal
    with disconnection
       It’s all about trying to resume and managing
        state (we’ll come back to this)
       But should the burden be placed on every
        application developer?
So – Application?
   What components are affected?
       Any application that wants to work
   What timescales does it support?
       End-to-end application communication. Seconds?
   What geographic/logical bounds does it place on mobility?
       None
   What overhead does it impose?
       Lots of programmer overhead
   How does it affect or interact with other aspects of the
    architecture?
       Nothing’s changed
How to handle Mobility?
    Where can we address this problem?
           Physical layer? (sure; very limited)
           Link layer
           Network layer
           Transport layer
           “Something higher” (often called session)
           Application layer




2007/1/22                                               13
Try #2: Link-layer mobility
   Have the link layer mask mobility
       E.g., the campus 802.11 wireless. You can move
        anywhere and keep the same MAC and IP address
   Completely transparent. No OS/App support
    needed. Brilliant!
   Fast & Local: Only switches near moving client
    must be updated.
   But – only local! Can’t move out of your subnet.
So – Link?
   What components are affected?
       The local switching infrastructure
   What timescales does it support?
       Pretty durned fast
   What geographic/logical bounds does it place on mobility?
       Can only move within local subnet
   What overhead does it impose?
       Little
   How does it affect or interact with other aspects of the
    architecture?
       Could encourage ideas like making all of KAIST a single
        broadcast domain. Oops, too late. 
How to handle Mobility?
   Where can we address this problem?
       Physical layer? (sure; very limited)
       Link layer
       Network layer
       Transport layer
       “Something higher” (often called session)
       Application layer




                                                    16
IP Layer Mobility
   Allow hosts to take their “home” IP address with
    them wherever they go.
   Advantages:
       Potentially global mobility scope (not limited to subnet like
        link layer)
       Transparent to applications and layers above IP
   How can we do it?
       (Many ways, each with own costs)
Brute Force: IP routing
   If node leaves home, send out (global?) routing
    announcement pointing to new location
       In theory, “just works”
       Example: Boeing’s “Connexion” announced a /24 into
        BGP for every supported airplane and moved the
        announcement to the gateway the plane was closest
        to
       Why? Latency concerns over really long flights (start
        in SF, end in London)
       Already have high latency from using satellites. Ow.
Brute force 2
   May be feasible for Boeing
   But wouldn’t scale for single IP addresses
       Every AS in world would have routing entry for every
        mobile user in the world? Ouch!
   Problem: Having the whole world maintain state for
    every user
   Alternative: Keep state local, by…
Mobile IP (& others):
   Same as other problems in Computer Science
       Add a level of indirection
   Keep some part of the network informed about
    current location
       Need technique to route packets through this location
        (interception)
   Need to forward packets from this location to mobile
    host (delivery)
Mobile IP
   RFC 3220
   has many features we’ve seen:
       home agents, foreign agents, foreign-agent registration,
        care-of-addresses, encapsulation (packet-within-a-packet)
   three components to standard:
       indirect routing of datagrams
       agent discovery
       registration with home agent




                                                                    21
IP Mobility: Principles
   Core network routing transparency
       Routers and switches are un-aware of mobility


   Host-controlled location update to effect routing path change
       Responsibility rests on the Mobile Node (MN)


   Adheres to the “end-to-end” model
       Minimal network support
       Intelligent host




                                                                    22
Solution Requirements
   Roaming:
       Roaming: Packets need to reach the current location of a
        Mobile Node
   Handover:
       Connection (session) end-point must remain constant even
        though the IP address changes
       Connection end-point must be able to handle change of IP
        address




                                                                   23
 Mobile IP: indirect routing

                                                 foreign-agent-to-mobile packet
      packet sent by home agent to foreign          dest: 128.119.40.186
      agent: a packet within a packet

      dest: 79.129.13.2   dest: 128.119.40.186




Permanent address:
128.119.40.186

                                                            Care-of address:
                                                                 79.129.13.2
           dest: 128.119.40.186
           packet sent by
           correspondent
                                                                               24
 Mobile IP: agent discovery

     agent advertisement: foreign/home agents advertise service
      by broadcasting ICMP messages (typefield = 9)
                       0               8             16          24

                           type = 9    code = 0               checksum
                                       =9                     =9
H,F bits: home                                                                     standard
and/or foreign agent                         router address                       ICMP fields


R bit: registration
required               type = 16           length         sequence #
                                                       RBHFMGV
                           registration lifetime                      reserved
                                                         bits                    mobility agent
                                                                                 advertisement
                                      0 or more care-of-                           extension

                                          addresses
                                                                                                  25
Mobile IP: registration example

                                                                  visited network: 79.129.13/24
  home agent          foreign agent
HA: 128.119.40.7     COA: 79.129.13.2      ICMP agent adv.
                                                                                Mobile agent
                                            COA: 79.129.13.2                  MA: 128.119.40.186
                                            ….

                                           registration req.
                   registration req.        COA: 79.129.13.2
                    COA: 79.129.13.2        HA: 128.119.40.7
                    HA: 128.119.40.7        MA: 128.119.40.186
                    MA: 128.119.40.186      Lifetime: 9999
                    Lifetime: 9999          identification:714
                    identification: 714     ….
                    encapsulation format
                    ….



                   registration reply
           time     HA: 128.119.40.7       registration reply
                    MA: 128.119.40.186
                    Lifetime: 4999          HA: 128.119.40.7
                    Identification: 714     MA: 128.119.40.186
                    encapsulation format    Lifetime: 4999
                    ….                      Identification: 714
                                            ….
                                                                                            26
Mobile IP Issues
   Route Optimization
       In order to always use HoA, packets need to be routed
        through the Home Agent
       introduces sub-optimal routing and hence potentially longer
        delay
       Direct communication between the MN and its
        correspondents should be possible
   Authentication
       Registration messages
       Binding cache updates
   Must send updates across network
       Handoffs can be slow

                                                                  27
Mobile IP Optimization
   Fast Handoff
       Handoff delay is too long
       Can we reduce it?
       FMIP, FMIPv6
   Hierarchical Handoff
       Frequent Binding Update incurs burden on
       Let’s handle the local movements inside the local network




                                                                    28
Handoff Delay Illustration




                             29
Fast Handover Protocol
   Allows a MN to learn new Router information when
    still attached to the current router
       enables fast movement detection
       expedites new address configuration
       facilitates immediate transmission upon new link
        establishment
   Allows a MN to receive packets sent to its previous
    IP address until
       Binding Update to Home Agent is completed
       Binding Update to the correspondent is completed
   Involves tunnel establishment triggered by MN
    signaling
                                                           30
Fast Handover Illustration




                             31
Delays with Fast Handover




                            32
Hierarchical MIP:
Macro Mobility and Micro Mobility
   Macro Mobility
       Domain-level, Mobile IP-based
   Micro Mobility
       Cell area, Hierarchical MIP


                                        Home Agent
Components of Cellular Network


            recall:                               correspondent
                                  wired public
                                  telephone
                                  network

                          MSC                          MSC

                                 MSC
                                                              MSC
                                                 MSC




                      different cellular networks,
                      operated by different providers
2007/1/22                                                           34
Handling mobility in cellular networks
   home network: network of cellular provider you subscribe to
    (e.g., Sprint PCS, Verizon)
     home location register (HLR): database in home network
       containing permanent cell phone #, profile information
       (services, preferences, billing), information about current
       location (could be in another network)
   visited network: network in which mobile currently resides
     visitor location register (VLR): database with entry for each
       user currently in network




                                                                  35
 GSM: indirect routing to mobile

                                        home
                        HLR
                                        network                       correspondent
                              2
                                    home
                                    Mobile
home MSC consults HLR,             Switching
gets roaming number of              Center
mobile in visited network
                                                               1               call routed
                                                                               to home network
                                                       3           Public
                                  VLR                              switched
                                         Mobile
                                                                   telephone
                                        Switching
                                                                   network
                                         Center
                              4
                                                       home MSC sets up 2nd leg of call
                                                       to MSC in visited network
             mobile
             user                                   MSC in visited network completes
                                   visited          call through base station to mobile
                                   network                                                 36
 GSM: handoff with common MSC

                                            Handoff goal: route call via
                                             new base station (without
                                             interruption)
          VLR Mobile                        reasons for handoff:
               Switching
                Center                          stronger signal to/from new
                                                 BSS (continuing connectivity,
          old           new
                                                 less battery drain)
          routing    routing                    load balance: free up
old BSS
                               new BSS
                                                 channel in current BSS
                                                GSM doesn’t mandate why
                                                 to perform handoff (policy),
                                                 only how (mechanism)
                                            handoff initiated by old
                                             BSS
                                                                        37
  GSM: handoff with common MSC

                                             1. old BSS informs MSC of impending handoff,
                                                provides list of 1+ new BSSs
                                             2. MSC sets up path (allocates resources) to
                                                new BSS
              VLR Mobile                     3. new BSS allocates radio channel for use by
                   Switching                    mobile
                    Center 2                 4. new BSS signals MSC, old BSS: ready
                      4
          1                                  5. old BSS tells mobile: perform handoff to new
                           7
               8                                BSS
                                     3
old BSS   5                    6             6. mobile, new BSS signal to activate new
                                   new BSS      channel
                                             7. mobile signals via new BSS to MSC: handoff
                                                complete. MSC reroutes call
                                             8 MSC-old-BSS resources released


                                                                                      38
GSM: handoff between MSCs

                                          anchor MSC: first MSC
                                           visited during call
home network
                       correspondent          call remains routed through
 Home                                          anchor MSC
 MSC
                                          new MSCs add on to end of
anchor MSC
                    PSTN                   MSC chain as mobile moves
        MSC                                to new MSC
                MSC            MSC        IS-41 allows optional path
                                           minimization step to shorten
                                           multi-MSC chain


               (a) before handoff

                                                                     39
GSM: handoff between MSCs

                                          anchor MSC: first MSC
                                           visited during call
home network
                       correspondent          call remains routed through
 Home                                          anchor MSC
 MSC
                                          new MSCs add on to end of
anchor MSC
                    PSTN                   MSC chain as mobile moves
        MSC                                to new MSC
                MSC            MSC        IS-41 allows optional path
                                           minimization step to shorten
                                           multi-MSC chain


               (b) after handoff

                                                                         40
Mobility: GSM versus Mobile IP
      GSM element                     Comment on GSM element                Mobile IP element
Home system               Network to which the mobile user’s              Home network
                          permanent phone number belongs
Gateway Mobile            Home MSC: point of contact to obtain            Home agent
Switching Center, or      routable address of mobile user. HLR:
“home MSC”. Home          database in home system containing
Location Register (HLR)   permanent phone number, profile
                          information, current location of mobile user,
                          subscription information
Visited System            Network other than home system where            Visited network
                          mobile user is currently residing
Visited Mobile services   Visited MSC: responsible for setting up         Foreign agent
Switching Center.         calls to/from mobile nodes in cells
Visitor Location Record   associated with MSC. VLR: temporary
(VLR)                     database entry in visited system,
                          containing subscription information for
                          each visiting mobile user
Mobile Station Roaming    Routable address for telephone call             Care-of-address
Number (MSRN), or         segment between home MSC and visited
“roaming number”          MSC, visible to neither the mobile nor the
                          correspondent.
                                                                                                41
How to handle Mobility?
   Where can we address this problem?
       Physical layer? (sure; very limited)
       Link layer
       Network layer
       Transport layer
       “Something higher” (often called session)
       Application layer




                                                    42
TCP Migrate
   Transport-layer solution
   Idea: No IP support; just have transport layer
    dynamically re-bind endpoints
Migrate Architecture



    Location Query                              Location Update
    (DNS Lookup)                             (Dynamic DNS Update)
                      DNS Server


                     Connection Initiation

                     Connection Migration

  Correspondent
                                                      Mobile Host
       Host                                             foo.bar.edu
                                    yyy.yyy.yyy.yyy    xxx.xxx.xxx.xxx
Migrate
   Advantages:
       (Mostly) transparent to applications
           Unless they know their IP address and use it, e.g., peer-to-
            peer apps.
       Keeps state and modifications entirely at endpoints
       No triangle routing! All communication is direct
   But:
       Requires TCP support / only works for TCP
           Not true in general: “Host ID Protocol” – HIP – can work with
            both, but requires more invasive IP stack changes
       Slower timescales than link-layer migration (several
        RTTs)
Summary
   Solution Space
       Application layer
         No changes in other layers

         Burden on software developers

       Link layer
         Fast but not scalable

       Network layer (Mobile IP)
         Extensive work, MIPv4, MIPv6, FMIPv6, HMIP

       Transport layer
         Transparent but slow




                                                       46
Other Issues
   Network Mobility (NEMO)
   Host Identity (HIP) protocol




                                   47
Network Mobility Support

   The vehicle changes its point of
    attachment to the Internet
       Host Mobility
         Each node maintains Internet
          access                         Host Mobility Support
         Each host must perform
          Mobile IPv6
       Network Mobility
         Only the mobile router(MR)
          maintains Internet access                 Mobile Router

         Nodes can be located behind
          the MR
                                         Network Mobility Support


                                                                    48
Host Identity Protocol
   Considerable recent work: Give each host a unique
    identity
       Simplifies mobility
       Also simplifies multi-homing! (Many related issues)
       Deployment Issue
   Idea:
       IP address: changes with location
       HIP does not change
The Protocol Stack


      Application-specific identifiers   Application Layer

    Pairs <IP address, Port#> +
                                         Transport Layer
    Transport Protocol ID

    Host Identity (HI)                     Host Identity


    IP addresses                          Network Layer


    Link layer addresses                  Data Link Layer
APPENDIX




           51
WiBro Network Model




                                                   52
         (source: Mobility For WiBro, KRNET2005)
WiBro Mobility
   Support up to 60Km/h
   L2 Handoff
       Inter-sector Handoff less than 150msec
       Inter- IP subnet Handoff less than 1sec
   L3 Handoff
       Mobile IP for seamless session




                                                  53
Handoff in WiBro
   WiBro spec. supports three types of Handoff
       Hard Handoff
         Serviced by only one serving BS at a time instant

       Soft Handoff
         Serviced by one or more BSs at a time instant

         Macro diversity gain

         Seamless HO

       FBSS (Fast Anchor Base Station Selection)
         Serviced by only one serving BS at time instant

         But, fast switching between target BSs

         Macro diversity gain , Seamless HO




                                                              54
Hard handoff (Fast Handoff)




                              55
Fast anchor Base Station Selection
   BS selection
                                                     CQICH
       By the physical-layer            BS A                          BS B
        fast-feedback channel                                 User
   User
                                                BS A CINR        BS B CINR
       Report the target BS
        by CQICH (6 bits)
       Index to a 3-bit BS ID
   Base
       Response by using                                                      Time
        Anchor BS Switch IE              BS A > BS B            BS A < BS B
   Tightly synchronized
    operation
       between BS and user
       ASR (Anchor Switch Reporting)
        slot = M frames
       Switching period = L ASR slots
                                           ASR slot, M = 4 frames
                                           Switching period, L = 2 ASR slots
                                                                               56

				
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