ECE544: Communication Networks-II, Spring 2007

1. ECE544: Communication Networks-II, Spring 2007 D. Raychaudhuri Lecture 8 Includes tutorial materials from C. Perkins & D. Reininger

2. Today’s Lecture • Mobility in networks • Mobile IP • Mobile ATM, 3G

3. Mobility in Cellular Networks

4. Cellular Concept of Mobility • Users have a home system but can register at visited systems to make and receive calls – Single Number Service • Users can roam among systems during a call and the call is handed-off without being dropped.

5. Home Location Register – Maintains current customer Location and service profile HLR AC Authentication Center – Authenticates users VLR Visitor Location Register- Maintains temporary information on Visiting users. Functional Elements Home System Visited System

6. 3) The VLR sends a registration message to the HLR. HLR/AC Old VLR VLR 2) VLR queries previous VLR for user’s (actually the user’s smart card) permanent ID. Visited System 1) Visited system detects handset, handset transmits temporary ID assigned by previous system. Handset GSM Registration

7. Mobile Data Networks

8. Mobile Networks: IP Approach • Mobile IP based on the notion that today’s Internet protocols will evolve to provide most voice/data services: • Connectionless protocols offer lower complexity implementation • Distributed mobility management (no MSC!) • Needs further enhancements for flow QoS support Radio Microcell 1 IP ACCESS POINT IP TERMINAL IP Pkts w/ DLC segments IP packets IP HOST/SERVER IP ROUTER + Mobility Ext Radio Air Interface IP/RSVP + “M” Standard IP Radio Microcell 2

9. Mobile Networks: ATM Approach • Mobile ATM a candidate architecture for telco scenarios where an ATM access network is available: • Support for service integration & flow QoS • Connection-oriented framework suitable for dynamic handoff • May be used for micro-level mobility, with mobile IP for macro-level Radio Microcell 1 ATM ACCESS POINT Mobile TERMINAL MAC PDU’s ATM cells HOST/SERVER ATM SWITCH + Mobility Ext IP services + voice Radio Air Interface Mobile ATM “M” UNI/NNI IPOA Radio Microcell 2

10. RSVP + Mob Ext Application Data TCP/UDP/RTP IP Network Layer (incl.. Mob IP) Radio link control .. Flow # 1 n Wireless Control Data Link Control (or “LLC”) Medium Access Control Multiplexed user data Radio Transport Convergence Layer Radio PHY Radio Physical Medium Dependent Layer Radio Signal Mobile Networks : “+M” Protocol Stacks Optional Signaling, etc. + mobility ext Application Data Control Plane User Plane ATM Adaptation Layers ATM Network Layer Radio link control Control Flow SIG VC n VC# 1 2 .. Wireless Control Data Link Control (or “LLC”) Radio Access Layers Medium Access Control Multiplexed user data Radio Transport Convergence Layer Radio PHY Radio Physical Medium Dependent Layer Radio Signal Wireless ATM Protocol Stack Wireless IP Protocol Stack

11. Mobile IPRefer to:http://computer.org/internet/v2n1/perkins.htMhttp://www.ietf.org/html.charters/mobileip-charter.htmlhttp://wwwtgs.ctit.utwente.nl/Docs/education/advanced/mobile/Tutorials/MobileIPv6.pdfSlides on Mobile IP at: http://ing.ctit.utwente.nl/WU4/Documents/47

12. Name, Address, Routing • Name: is a location independent identifier of a host • Address: indicates where a given host is located. • Route: tells how to get to a destination

13. Mobility Problem: The Internet Viewpoint • Internet addresses are assigned in a topologically significant manner. • A mobile host must be assigned a new address when it moves. • Change host address  connection breaks. • Retain host address  routing fails. • Host address must be preserved regardless of its location.

14. Constraints • Inter-operability with TCP/IP protocol suite. • Existing networking apps should run unmodified on mobile hosts. • System should provide Internet-wide mobility. • No modification on existing routing infrastructure should be required. • Solution should be independent of wireless hardware technology. • Solution should have good scaling properties.

15. IP’s subnet model vs. Mobility • Terminals move from one IP subnet to another, but have the wrong “subnet prefix” for the destination subnet. • Solution: two-tier IP addressing • The mobile keeps its static IP address, but borrows the service of a “care-of-address” on whatever IP subnet it happens to be visiting. • A “care-of-address”, offered by a mobility agent, can be shared by visiting mobiles.

16. Basic Mobile IP • How does it work? • Agent discovery: advertisement/solicitation • MH registration • Use of Care-of-Address (COA) • Proxy ARP (Address Resolution Protocol) • Packet tunneling • Triangle routing

17. Key components Home Address: MH’s permanent IP address, network ID of this address identifies the mobile’s home network. MH Home Agent: a router attached to the MH’s home network maintains current location information for the MH is responsible for forwarding packets destined for the MH when MH is away from home. HA HN Home Network: the network identified with a mobile node R1 R3 Route Optimization FN FN R2 MH CH Foreign Network: a network, other than MA’s home network, that MH is currently attached to. Mobile Host: a host or router capable of changing its point of attachment to the Internet FA Corresponding Host: a host or router communicationg with a mobile node. Foreign Agent (FA) a router in the foreign network that the MH is visiting provides routing services to the MH while registred de-tunnels datagram to MH may serve as default router for outgoing packet from MH

18. Route Optimization • Provides a means for nodes to • cache the bindings of a mobile node • tunnel their own datagrams directly to the care-of-address • bypass mobile node’s home agent during datagram delivery • Allow datagrams sent based on an out-of-data cached binding, to be forwarded directly to the mobile node’s new care-of-address.

19. Terminology • Binding cache • a cache of mobility bindings of mobile nodes • maintained by CH for use in tunneling datagrams to those mobile nodes. • Binding update • a message indicating a mobile node’s current mobility binding and its care-of-address. • Registration lifetime • the time duration for which a binding is valid.

20. Route Optimization • Key features • Binding cache update • Smooth handoffs between foreign agents • New messages • binding update • binding request • binding warning • binding ack

21. Binding Cache Creation/Update • At CH, if no binding cache exists • datagrams will be routed to MH via basic mobile IP routing • home agent should then send a Binding Update message to the original source node • CH will then create a binding cache for the MH • At an FA, if MH has moved to a new FA and the old FA still receives tunneled datagrams • old FA send Binding Warning message to HA to advise the change.

22. Foreign Agent Smooth Handoff • As part of registration procedure, the mobile node may request its new FA to notify its previous FA on its behalf • a Previous Foreign Agent Notification extension is included in the Registration Request message • The new FA builds a Binding Update message and transmits it to the mobile node’s previous FA as part of registration, requesting an ACK from the previous FA • Security association between old FA and MH are used for authentication of the binding update message.

23. Mobile ATM Details

24. Mobile ATM: System Model • “M” UNI/NNI protocol extensions provide integrated & efficient support for mobility within ATM access network • Functions include: location mgmt, handoff control, mobile QoS/routing Location Mgmt provides mapping of A-> AL1, AL2 Connect (ATM Addr A) User Addr A (permanent) Crossover switch HO (BS1->BS2) Connection Before Handoff Initial Location AL1 ATM Network Terminal Movement Mobile ATM Access Network BS1 Handoff supports Dynamic rerouting Of active connections BS2 Rerouted Connection After handoff User Addr A Next Location AL2

25. Mobile ATM: Location Mgmt • Location management can be integrated into existing ATM connection procedures.... (external servers can also be used) • simple extensions to current CONNECT, RELEASE IE’s, etc. • no need for a-priori partitioning of mobile & static address space ATM Host (4) (3) setup release (foreign_addr, (foreign_addr) home_addr) (2) setup (home_addr) (1) update Current Home Foreign switch switch move

26. Mobile ATM: Handoff • Handoff can be implemented via modest extensions to existing ATM UNI/NNI signaling... • new signaling messages/IE’s for handoff initiation, COS select, etc. • provides high-performance, scalable solution (compared with external MSC, BSC, etc.) Crossover tear down ATM Switch (COS) subpath Host add subpath COS select (1) handoff handoff confirm request move

27. Mobile ATM: Use with Cellular • For mobile ATM infrastructure, a “proxy M-UNI” can be used at the AP for interworking with a non-WATM radio protocol... • GSM (or other cellular access protocol) converted to M-UNI at AP • Mobile ATM provides handoff and location mgmt to GSM user M UNI GSM GSM GSM GSM radio link GSM radio link Proxy M UNI M NNI GSM M NNI GSM/ATM gateway GSM radio air interface Terminal Movement HLR/VLR Mobile ATM Access Network Proxy migration M NNI GSM Network GSM GSM GSM radio link GSM radio link Proxy M UNI Handoff & loc mgmt within mobile ATM cloud provided By “M” UNI/NNI

28. Mobile ATM: Use with 3G/WLAN • Network part of broadband wireless system can be used as a generic infrastructure for various current & future radio access technologies --> platform for IMT2000/UMTS migration • Generic +M protocols supported by network routers/switches • Interworking function at AP converts to/from radio protocol AP IP/WLAN TERMINAL Wdata pkts SWITCH/ROUTER + Mobility Ext Wireless data air interface Generic “+M” Protocol To Internet or Cellular/PCS Network Gateways Cellular/PCS Air Interface

29. Today’s Homework - Read tutorial papers on mobile IP & ATM - Download and browse Mobile IP RFC