Documents
Resources
Learning Center
Upload
Plans & pricing Sign in
Sign Out

CSE-302 Mobile-IP-Final

VIEWS: 4 PAGES: 62

mobile computing

More Info
									 Mobile IP


Dr. R. B. Patel
The benefit of Mobile IP


“
“Mobile IP provides an IP node the ability to
  retain the same IP address and maintain
   uninterrupted network and application
     connectivity while traveling across
                 networks ”
                                           ”
Which Applications
    The objective

    Maintaining continuous IP connectivity
    while crossing network boundaries, e.g.
         subnets or between networks
            Gateway A
            171.68.0.0                     Host B
                         Internet     Gateway C
                                      140.31.0.0
Mobile Router
 171.68.69.0
 171.68.70.0                    Mobile Router
                                 171.68.69.0
                                 171.68.70.0
The Possibilities

Many Networks Roaming




                        Mobile Routers
     Internet
       Internet Engineering Task Force
       (IETF) Proposed Standard
• Approved by the Internet Engineering Steering Group
    (IESG) in June 1996; published proposed standard in
    Nov. 1996
•   Mobile IP is an IETF proposed standard solution for mobility at Layer 3 IP
        – RFC2002/3220 - Mobile IP
        – RFC2003 and RFC2004 - Tunnel encapsulation
        – RFC2005 - Mobile IP applicability
        – RFC2006 - Mobile IP MIB
•   Associated RFCs
        – RFC1701 GRE – Generic Routing Encapsulation
        – RFC3024 - Reverse Tunneling for Mobile IP

        –Internet Engineering Task Force (IETF) develops and
        promotes Internet standards, cooperating closely with the
        W3C and ISO/IEC standards bodies and dealing in particular
        with standards of the TCP/IP and Internet protocol suite. It is
        an open standards organization, with no formal membership
        or membership requirements.
World Wide Web Consortium (W3C)
• World Wide Web Consortium (W3C) is the main
  international standards organization for the World
  Wide Web (abbreviated WWW or W3).
• Founded by Tim Berners-Lee at MIT and currently
  headed by him, the consortium is made up of
  member organizations which maintain full-time staff
  for the purpose of working together in the
  development of standards for the World Wide Web.
  As of 29 March 2012, the World Wide Web
  Consortium (W3C) has 351 members.
   The Problem with Mobility
                                           “Connect to
           Where is 171.68.69.0???         171.68.69.24”

            Gateway A
            171.68.0.0                        Host B
      ?                    Internet      Gateway C
                                         140.31.0.0
Mobile Router
 171.68.69.0
 171.68.70.0                       Mobile Router
                                                 X
                                    171.68.69.0         SEND
                                    171.68.70.0
• Gateway A replies to Host B with an Internet Control Message
  Protocol (ICMP) unreachable
       • Gateway C blocks router from joining network
• Routing Protocol rejects duplicate network advertisements
  Mobile IP Solution
        Mobility Binding Table:
        MR            CoA
        171.68.69.0 140.31.2.1

                                                   Host B
                              Internet         Foreign Agent
              Home Agent                       COA 140.31.2.1
Mobile Router 171.68.60.1
 171.68.69.0
 171.68.70.0                           Mobile Router
                                        171.68.69.0
                                        171.68.70.0
• Mobile Router sends Registration Request [RRQ] to Home Agent (HA)
• Home Agent forwards packets to Mobile Router via Care of Address
  [CoA]
Operator Benefits


• All applications work without
modifications (unlike
application/transport layer mobility)
• Operator can control handover
policies
• Access link independent (unlike link
layer mobility)
      “IETF Standard RFC 3344!”
Solution in a Nutshell

• A mobile node has a “home address”
  for the end-to-end communications,
  but also uses a temporary “care-of
  address” on access networks for
  routing purpose.
• A home agent maintains a mobility
  binding of home address and care-of
  address.
Mobile IP Network Elements

  1. Mobile Node (MN): Mobile IP enabled clients
     identified by home address or NAI (notebooks,
     cell phones, PDAs) updates CoA via registrations
  2. Home Agent (HA): Mobile IP enabled gateway
     acts as location database for MNs
  3. Foreign Agent (FA): Mobile IP enabled gateway
     [Optional] off-loads CPU processing of
     encapsulation/decapsulation, enforces local
     network administration policy, allows for billing
     of MNs, conserves IP address space, reduce
     access link usage
Mobile IP Key Concepts


• How does the Mobile Node find out where it is?
    Mobility Agent Advertisements—facilitates discovery of
    Mobility Agents (MN may solicits on demand)
• How does the Mobile Node inform the Home Agent of its current
  location?
    Via Registration—updates mobility binding after successful
    authentication using security association between MN and
    HA
• How does the Mobile Node receive packets from the Home
  Agent?
    Tunneling—Home agent adds IP header to direct packets to
    CoA, where decapsulation occurs
Mobile IP Activities Example


     Mobility Binding Table:
     MN               CoA
     171.68.69.24     140.31.2.1

         Home Agent
         171.68.69.1                                Host B

                                   Internet   Foreign Agent
  Host A
171.68.69.24                                    140.31.2.1


                                                          Host A
                                                        171.68.69.24
 • MN learns about FA and registers CoA
 • HA maintains MN location database and
   tunnels traffic to FA
Mobile IP Terminology

                                             CN
                       Internet
     HA                                FA
•   Mobile Router (MR)
•   Home Agent (HA)
•   Foreign Agent (FA) [1 Hop Away from MR]          MR
•   Care of Address (CoA) [Tunnel Endpoint]
•   Correspondent Node (CN)
•   Security Association (SA) [SPI/Key]
•   ICMP Router Discovery Protocol (IRDP) [Advertisement]
•   Registration Request (RRQ)
 Step 1: Agent Discovery
                                               Edited slide from original by
           Dest Addr      Src Addr             Lawrence Searcy, Cisco Systems

           MR Addr      FA Intfc Addr
                Advertisement
                Includes COA
                                        FA    HA



           Src Addr       Dest Addr                                   MR
  MR
           MR addr        224.0.0.2                                 1.1.1.7
1.1.1.7
                 Solicitation




   • MR sends out advertisement request (Solicitation) to
     “all router” multicast address 224.0.0.2
   • FA responds with unicast advertisement to MR
          Response includes Care-of Address
Options in FA advertisements
       •   R    Registration required. Registration with this foreign
       •       agent (or another foreign agent on this link) is required
       •       even when using a co-located care-of address.

       •   B    Busy. The foreign agent will not accept registrations
       •       from additional mobile nodes.

       •   H    Home agent. This agent offers service as a home agent on
       •       the link on which this Agent Advertisement message is
       •       sent.

       •   F    Foreign agent. This agent offers service as a foreign
       •       agent on the link on which this Agent Advertisement
       •       message is sent.

       •   M    Minimal encapsulation. This agent implements receiving
       •       tunneled datagrams that use minimal encapsulation.

       •   G    GRE encapsulation. This agent implements receiving
       •       tunneled datagrams that use GRE encapsulation.

       •   r   Sent as zero; ignored on reception. SHOULD NOT be
       •       allocated for any other uses.

       •   T   Foreign agent supports reverse tunneling.
 Step 2: Registration Request

                                     FA                               HA



 MR       Src Addr    Dest Addr             Src Addr      Dest Addr        1.1.1.7
1.1.1.7   MR Addr    FA Intfc Addr        FA Intfc Addr    HA Addr
          Src Port    Dest Port             Src Port      Dest Port
          random          434                  434           434
                  RRQ                                RRQ
          Includes COA from FA                   Includes COA


  • MR retrieves CoA from Advertisement and
    sends in RRQ
  • FA checks requested services and either
    rejects and replies or forwards the RRQ to HA
Options in RRQ
       •   S       Simultaneous bindings. If the 'S' bit is set, the mobile
       •             node is requesting that the home agent retain its prior
       •             mobility bindings


       •       B      Broadcast datagrams. If the 'B' bit is set, the mobile
       •             node requests that the home agent tunnel to it any
       •             broadcast datagrams that it receives on the home network.


       •       D      Decapsulation by mobile node. If the 'D' bit is set, the
       •             mobile node will itself decapsulate datagrams which are
       •             sent to the care-of address. That is, the mobile node is
       •             using a co-located care-of address.


       •       M      Minimal encapsulation. If the 'M' bit is set, the mobile
       •             node requests that its home agent use minimal
       •             encapsulation [34] for datagrams tunneled to the mobile
       •             node.


       •       G      GRE encapsulation. If the 'G' bit is set, the mobile
       •             node requests that its home agent use GRE encapsulation
       •             [16] for datagrams tunneled to the mobile node.


       •       r     Sent as zero; ignored on reception. SHOULD NOT be
       •             allocated for any other uses.


       •       T     Reverse Tunneling requested
 Step 2: RRQ Reply
            Dest Addr     Src Addr           Dest Addr     Src Addr
            MR Addr     FA Intfc Addr           FA       HA Intfc Addr
            Dest Port     Src Port           Dest Port    Src Port
            Orig Port        434               434            434

                  RRP Reply                        RRP Reply

                                        FA                          HA



 MR                                                                      1.1.1.7
1.1.1.7
           Foreign Agent                                 Home Agent
   •      FA sees MR is                  •     HA authenticates MR
          authenticated
                                         •     Sends RRP
   •      Forwards RRP to
          MR                             •     Proxy ARPs for MR

   •      Brings up tunnel               •     Brings up tunnel and
                                               adds host route
MR States

MR has five states that it can be in:
• Unknown – MR has not heard any agent
  advertisements and does not know where to send
  registration requests (RRQs)
• Isolated – MR has heard an agent advertisement
• Pending – MR has sent an RRQ and is waiting for a
  registration reply (RRP) from HA
• Registered – MR has been accepted and received the
  RRP from HA, which has set up a binding table entry,
  tunnels, and routes for the MR
• Home—MR is on its home network
Step 3: Routing
                                                    Correspondent
           Home                                     Host
           Agent


                                          Foreign
                                          Agent

                                                      Mobile
                                                      Router


• Traffic is sent as usual to the home subnet
• The home agent intercepts the traffic while the Mobile
  Router is registered as away
• Traffic is tunneled to the CoA of the MR and
  forwarded to MR
• Traffic from the Mobile Networks can go directly to the
  correspondent host = “Triangle Routing”
Mobile Network Routing – Packet Flow

                                            Mobile
                                            Networks
                                                                        Node on MR


                                                         Mobile Router




                                         Foreign Agent

                    Internet

Mobile
Networks
appear to                                                  Edited slide from original
                               Correspondent Node
be here     Home Agent
                                                           by Lawrence Searcy, Cisco
                                                           Systems
Mobile Network Routing – Packet Flow

                                               Mobile
                                               Networks
                                                                     Node on MR


                                                            Mobile Router



                   HA-FA Tunnel

                                            Foreign Agent

                     Internet

Mobile
Network
appears
                                  Correspondent Node
to be here   Home Agent
Mobile Network Routing – Packet Flow

                                                     Mobile
                                                     Networks
                                                                       Nodes on MR

                                      HA-MR Tunnel            Mobile Router

                                   FA WAN

                   HA-FA Tunnel

                                              Foreign Agent

                     Internet

Mobile
Network
appears
                                  Correspondent Node
to be here   Home Agent
Mobile Network Routing – Packet Flow

                                                     Mobile
                                                     Networks
                                                                       Node on MR


                                      HA-MR Tunnel            Mobile Router

                                   FA WAN

                   HA-FA Tunnel

                                              Foreign Agent

                     Internet

Mobile
Network
appears
                                  Correspondent Node
to be here   Home Agent
Mobile Network Routing – Return Packet Flow

                                                     Mobile
                                                     Networks

                                                                      Node on MR
                                      HA-MR Tunnel            Mobile Router

                                   FA WAN

                   HA-FA Tunnel

                                              Foreign Agent

                     Internet

Mobile
Network
appears
                                  Correspondent Node
to be here   Home Agent
  Tunneling

   • HA double encapsulates the packets,
     creating two tunnels:
        HA to FA
        HA to MR
   • FA strips outer header and forwards to MR
   • MR strips inner header and forwards to
     node on mobile network
     Outer Header               Inner Header
                                                        Original Packet
      HA       FA             HA             MR
100.100.100.1 30.30.30.1   100.100.100.1   65.1.1.1   <src> <dest> Data
Tunneling cont…

 • HA dynamically creates tunnel(s) as MRs
   and Mobile Hosts register
 • Tunnels are handled as interfaces
 • HA Routing Table shows Tunnels as
   interfaces
 • So “Tunneling” involves
    –Encapsulation
    –Interfaces in routing table
 HA State – Routing Table
Home_Agent_#show ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
    D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
    N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
    E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
    i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area
    * - candidate default, U - per-user static route, o - ODR
    P - periodic downloaded static route
Gateway of last resort is not set
   110.0.0.0/8 is variably subnetted, 10 subnets, 2 masks
M      110.10.11.0/24 is directly connected, Mobile0
M      110.10.11.237/32 [3/1] via 10.10.10.97, 00:57:28, Tunnel2
M      110.10.11.245/32 [3/1] via 10.10.10.129, 03:01:54, Tunnel0
10.0.0.0/8 is variably subnetted, 14 subnets, 3 masks
C     10.10.10.32/27 is directly connected, FastEthernet0/0
C     10.10.10.76/30 is directly connected, Loopback0
O IA 10.10.10.96/27 [110/11] via 10.10.10.36, 00:57:35, FastEthernet0/0
M      10.10.11.112/28 [3/1] via 110.10.11.237, 03:55:57, Tunnel1
O IA 10.10.10.128/27 [110/2] via 10.10.10.74, 00:57:35, FastEthernet0/1
M      10.10.11.144/28 [3/1] via 110.10.11.245, 03:55:57, Tunnel5
MR Routing



• Once MR is registered, routing is
  disabled on the MR’s roaming
  interfaces.
• When MR is home, routing is
  resumed on the interfaces (bindings
  and tunnels are no longer needed).
Mobile Router Timers
• Agent Solicitation-By default it is off, but if
  configured, keeps track of when to send next
  solicitation
• Agent Advertisement-Based on IRDP lifetime. As
  advertisements are received, timer is restarted. When
  timer expires, agent removed from agent table.
• Registration-Keeps track of when to send
  registrations before the registration lifetime expires.
  MR re-registers until a reply is received.
• Registration lifetime-Based on granted lifetime. As
  replies are received, timer is restarted. When timer
  expires, there is no more registration.
• Hold down-By default it is off, but if configured, MR
  waits for timer to expire before using an agent heard
  on that interface.
Mobile IP
Features
Mobile Router Features


 Co-located Care-of Address
 Reverse tunneling
 Preferred interfaces
 Hold down timer
 Agent solicitation
Mobile Router Features


 MR redundancy
 MR Asymmetric Links
 MR Dynamic Networks
 Identification mismatch adjustment
 Sequence number detection
Co-located Care-of Address Support


   MR                                      HA

• Care-of Address resides on Mobile Router
  itself
   –Rather than on the Foreign Agent
• Does away with the need for Foreign Agents
• Two IP-in-IP tunnels are created: HA-Co-
  located address, HA-MR
   –HA-Co-located address tunnel is only used for
   routing
   –Tunnel “Interfaces” added in Routing table
Co-located Care-of Address cont.


    MR                                 HA


• Static Co-located Care-of Address
  support uses the address statically
  configured on the roaming interface as
  care-of address
   –Used for fixed-IP address connections,
   e.g. Cellular Data Modem- Cellular Digital
   Packet Data (CDPD) network.
Static Co-located Care-of Address
Co-located Care-of Address cont.


    MR                             HA

 • CCoA can be Static or Dynamic


 • Dynamic Co-located Care-of Address
   support uses Dynamic Host
   Configuration Protocol (DHCP) or
   Internet Protocol Control Protocol
   (IPCP) to obtain a care-of address for
   the roaming interface
Reverse Tunneling

• Normally, routers route packets by looking
  at the destination address only.
• A security measure against attacks (such
  as spoofing), ingress filtering on a router
  checks the source and destination
  addresses on a packet to make sure that
  they are topologically correct.
• This poses a problem for Mobile IP
  because the source address of a packet
  from a mobile node does not belong to the
  network from which it emanated.
Mobile Network Routing – Packet Flow


                                                    Mobile Network
                                                                         Node on MR


                                     HA-MR Tunnel               Mobile Router

                                  FA WAN

                   HA-FA Tunnel

                                             Foreign Agent

                     Internet

Mobile
Network
appears
to be here   Home Agent         Correspondent Node
Reverse Tunneling

 • Reverse tunneling satisfies ingress filtering
 • Packets from the mobile network are sent
   back to the HA through the tunnel
 • HA de-capsulates the packets and forwards
   them to their destination through normal
   routing
 • Thus, the received packets’ path is
   topologically correct
Mobile Network Routing – Reverse Tunneling


                                                        Mobile Network
                                                                                      Node on MR
                                            Roaming
                                            Interface

                                     HA-MR Tunnel                   Mobile Router

                                  FA WAN

                   HA-FA Tunnel

                                             Foreign Agent

                     Internet

Mobile
Network
appears                                                                  Edited slide from original
to be here   Home Agent         Correspondent Node
                                                                         by Lawrence Searcy, Cisco
                                                                         Systems
 Preferred Interfaces

• By default, the Mobile Router sends data out
  the active interface with the highest
  bandwidth.
• If the bandwidth on multiple interfaces is
  equal, then the interface with the higher IP
  address is preferred.
• Priority can be configured on mobile router
  interfaces (default 100).
• MR prefers to register with higher priority
  interface.
• Uses – least-cost routing, preferential routing
Asymmetric Links

• Mobile Router can route traffic
  unidirectionally over half-duplex links
   Especially for a satellite environment
• MR configured to send traffic to a
  downlink router even though it hears
  advertisements on another interface
• FA configured to advertise foreign-
  agent service out only one interface, the
  uplink interface connected to MR
 Asymmetric Links

                                                    MR sends RRQ to HA
FA advertises service on                            via FA using its uplink
its uplink to MR’s downlink


               Downlink         Uplink   Downlink          Uplink
                       ADVT
                                                           RRQ
    RRP
Home Agent      Foreign Agent                           MR

                                              Then tunnels are
    RRP is sent to FA,                        set up between HA-FA,
    which forwards it to                      HA-MR’s downlink
    MR on its uplink.                         interface
Dynamic Mobile Networks

•Mobile Networks can register with Home
Agent dynamically (as opposed to static
network configuration on HA)
•Critical Vendor/Organization Specific
Extension (CVSE) is appended to the RRQ
by MR, which contains the mobile network
information
•Re-registrations do not append CVSE
Dynamic Mobile Networks cont.

•When mobile network is added/deleted,
MR immediately sends another re-
registration with CVSE
•HA processes RRQ with CVSE by
adding/deleting mobile network(s) and
creating/deleting routes to the mobile
network via MR
•If mobile network already exists HA
ignores the request
Dynamic Mobile Networks cont. 2


•FA needs to be able to process RRQs
with CVSE in order to forward them on
to HA.
•Dynamic and Static Networks can be
configured at the same time for an MR.
NOTE: CVSE is being replaced by AVSE
(standards-based) in near future
      Mobile IP
in real deployments
Mobile IP and GPRS Similarities

   GGSN        IP Network
                            SGSN
              GTP
                                   MT
    HA
               IP Network
                            FA
          IPinIP/GRE/UDP
                                   MN
Mobile IP and GPRS Integration
                     BSC

                              BTS

                                                 AP




      Serving GPRS                RADIUS                WLAN
      Support Node                Server
                                                        Hotspot
      (SGSN)
                  GPRS
               Backbone
                 Network    GTP
               (IP-Based)
                                               Internet

                             Gateway
                             GPRS
                             Support Node
              Home Agent     (GGSN)         Foreign Agent function can be
                                            added to GGSN and WLAN
                                            Access Router, though Mobile IP
                                            works without FA as well.
3GPP WLAN
Interworking Scenarios

 •   6 Scenarios identified which corresponds to incremental steps in terms of
     services and operational features
          1.   Common billing and Customer care
                no impact on 3GPP specs as such; access to Open internet
          2.   3GPP system based access control and charging with access to
                UMTS/GSM authentication (based on EAP-SIM/AKA methods)
          3.   Access to 3GPP system PS based services (e.g. IMS, Streaming,
               MMS, etc.)
                bearer path to the home domain (current GPRS model)
          4.   Service Continuity
                L3 Mobility introduction (e.g. Mobile IP technology)
          5.   Seamless service provision
          6.   Access to 3GPP CS Services (no use case so far)
 •   UMTS R6 includes scenario 2 & 3
 •   UMTS R7 will consider scenario 4 (mobility)
WLAN/GPRS Seamless Mobility
Scenario 4 (Tentative)

      Applications

                                     PDG                         Dual-mode handsets
                                     (FA)                       with L3 Mobility support
                                            WLAN 802.11
                                              Access
                                             Network
                        Mobility
                         (HA)
              IP Core
                         CMX
                                          GPRS/UMTS
                                   GGSN(FA)
 Content                                              SGSN
                                                                 RAN

                                                          RNC
Reiterate Benefit

 • Mobile IP operates at network layer,
   independent of link layer access
   technologies, allowing migration and
   coexistence of various access networks
   while providing seamless mobility
   transparently to the user
 • Proven mobility across satellite, WLAN,
   GPRS, CDMA2000 1xRTT, Flash OFDM,
   iDEN, CDPD, etc.
Differences between Mobile IPv4 and
Mobile IPv6


• Mobile IPv6 leverages enormous IPv6 address
  space
• Mobile IPv6 is integrated into base IPv6 protocol
• MNv6 automatically obtain CoA after Router
  Advertisement received
• No Foreign Agent in Mobile IPv6
• Registrations are protected by IPSec in Mobile IPv6
• Built in route optimization between MNv6 and CNv6
Security implications of Mobile IP


 • Access authentication independent
   of Mobile IP
    PPP CHAP for dial up
    802.1x for WLAN
 • Service authorization
    Mobile IP security association for
    registrations
QOS Implications of Mobile IP




    • DSCP copy to tunnel header
    • Per MN session policing
Mobile IP Scalability and Flexibility



• Demonstrated deployment of millions
  of MNs
• Mobile IP used for macro-mobility
  and micro-mobility
References


• Books
  MOBILE IP The Internet Unplugged, ISBN
  0-13-856246-6 James D. Solomon
• Cisco Mobile IP Web Page
  http://www.cisco.com/go/mobile_ip
• IETF Mobile IP Working Group
  http://www.ietf.org/html.charters/mobilei
  p-charter.html
Cisco Wireless Convergence
  1 Access               2 Control                      3 Services
 Access Networks          Network Manager Agg.          Off Net Services
  Venue Owners            Auth./ Access Control
                         Service / Content Billing
                                          Billing
                                          Authent.      Content     Corporate
          GPRS                                          Provider     Intranet

                                 Cisco Mobile
                                 Exchange       L2TP
                   GGSN
                                                GRE     Internet      Wireless
           3G      802.11                                              ASP
                                                IPSec
                   WiMAX
                                                MPLS
                   VPN
                                                IPV4
                   Other
          WLAN                                  IPV6
                                                        Streaming   Localization



         WiMAX                                           On Net Services
                            Mobile Internet Edge
Next-Generation IP Infrastructure
All-IP Multimedia Mobile Network
                   Hosted         Presence                                     Handsets with VoIP &
           CCM   Applications                                                  dual-mode support &
    Corp                                    Home               Visited           Mobility support
    AAA                                     AAA                 AAA

                                                              WLAN 802.11
                                                                Access
                      Session control                (FA)      Network
                           (SIP)        Mobility
                                         (HA)
                            IP Core                          Visited
                                                              AAA

                                            CMX           GPRS/UMTS/
                                                   GGSN(FA)/ CDMA
                                                    PDSN                   SGSN
                                                                                         RAN
                                        V
                                                                                   RNC

  Enterprises      PSTN Gateway                             PLMN
                                                                         MSC/VLR
                                   MSC/VLR


  Unified IP-based infrastructure allows for uniform delivery of services
  across consumer, enterprise and carrier domain

								
To top