1. WIRELESS PROTOCOLS

2. The ISO OSI Reference Model A Network is a complex piece of hardware and Software.A Network is a complex piece of hardware and Software. Therefore, International Standard Organization (ISO) adopted a layered approach for networks.Therefore, International Standard Organization (ISO) adopted a layered approach for networks. The network is broken into seven layers, each of them has well-defined function such that each layer offers a service to the higher layer.The network is broken into seven layers, each of them has well-defined function such that each layer offers a service to the higher layer. The model is called ISO OSI (Open Systems Interconnect) Reference Model.The model is called ISO OSI (Open Systems Interconnect) Reference Model. IEEE defined a four layers model for LAN IEEE defined a four layers model for LAN

3. The OSI Reference Model Layers Application Data Link Presentation Network Physical Session Transport Physical Medium Application Data Link Presentation Network Physical Session Transport Host AHost B

4. IEEE 802 Model Layers

5. Protocol Definision Protocol: is a set of rules and conventions used by the layer to communicate with similar peer layer in another (remote) system.Protocol: is a set of rules and conventions used by the layer to communicate with similar peer layer in another (remote) system. Peer: The similar layer on a different machine.Peer: The similar layer on a different machine. –The peer processes communicate with each other using a protocol. A set of layers and protocols is called a network architecture.A set of layers and protocols is called a network architecture.

6. Key Features of a Protocol SyntaxSyntax –Concerns the format of the data blocks SemanticsSemantics –Includes control information for coordination and error handling TimingTiming –Includes speed matching and sequencing

7. Agents Involved in Protocol Communication ApplicationsApplications –Exchange data between computers (e.g., electronic mail) ComputersComputers –Connected to networks NetworksNetworks –Transfers data from one computer to another

8. Protocol Architecture Functions of physical layer:Functions of physical layer: –Encoding/decoding of signals –Preamble generation/removal (for synchronization) –Bit transmission/reception –Includes specification of the transmission medium

9. Protocol Architecture Functions of medium access control (MAC) Sub layer:Functions of medium access control (MAC) Sub layer: –On transmission, assemble data into a frame with address and error detection fields –On reception, disassemble frame and perform address recognition and error detection –Govern access to the LAN transmission medium Functions of logical link control (LLC) Sub Layer:Functions of logical link control (LLC) Sub Layer: –Provide an interface to higher layers and perform flow and error control

10. Separation of LLC and MAC The logic required to manage access to a shared-access medium not found in traditional layer 2 data link controlThe logic required to manage access to a shared-access medium not found in traditional layer 2 data link control For the same LLC, several MAC options may be providedFor the same LLC, several MAC options may be provided

11. MAC Frame Format MAC controlMAC control –Contains Mac protocol information Destination MAC addressDestination MAC address –Destination physical attachment point Source MAC addressSource MAC address –Source physical attachment point CRCCRC –Cyclic redundancy check

12. Logical Link Control Characteristics of LLC not shared by other control protocols:Characteristics of LLC not shared by other control protocols: –Must support multiaccess, shared-medium nature of the link –Relieved of some details of link access by MAC layer

13. LLC Services Unacknowledged connectionless serviceUnacknowledged connectionless service –No flow- and error-control mechanisms –Data delivery not guaranteed Connection-mode serviceConnection-mode service –Logical connection set up between two users –Flow- and error-control provided Acknowledged connectionless serviceAcknowledged connectionless service –Cross between previous two –Datagrams acknowledged –No prior logical setup

14. Differences between LLC and HDLC LLC uses asynchronous balanced mode of operation of HDLC (type 2 operation)LLC uses asynchronous balanced mode of operation of HDLC (type 2 operation) LLC supports unacknowledged connectionless service (type 1 operation)LLC supports unacknowledged connectionless service (type 1 operation) LLC supports acknowledged connectionless service (type 3 operation)LLC supports acknowledged connectionless service (type 3 operation) LLC permits multiplexing by the use of LLC service access points (LSAPs)LLC permits multiplexing by the use of LLC service access points (LSAPs)

15. IEEE 802.11 Services

16. Mobile IP Uses Enable computers to maintain Internet connectivity while moving from one Internet attachment point to anotherEnable computers to maintain Internet connectivity while moving from one Internet attachment point to another Mobile – user's point of attachment changes dynamically and all connections are automatically maintained despite the changeMobile – user's point of attachment changes dynamically and all connections are automatically maintained despite the change Nomadic - user's Internet connection is terminated each time the user moves and a new connection is initiated when the user dials back inNomadic - user's Internet connection is terminated each time the user moves and a new connection is initiated when the user dials back in –New, temporary IP address is assigned

17. Operation of Mobile IP Mobil node is assigned to a particular network – home networkMobil node is assigned to a particular network – home network IP address on home network is static – home addressIP address on home network is static – home address Mobile node can move to another network – foreign networkMobile node can move to another network – foreign network Mobile node registers with network node on foreign network – foreign agentMobile node registers with network node on foreign network – foreign agent Mobile node gives care-of address to agent on home network – home agentMobile node gives care-of address to agent on home network – home agent

18. Capabilities of Mobile IP Discovery – mobile node uses discovery procedure to identify prospective home and foreign agentsDiscovery – mobile node uses discovery procedure to identify prospective home and foreign agents Registration – mobile node uses an authenticated registration procedure to inform home agent of its care-of addressRegistration – mobile node uses an authenticated registration procedure to inform home agent of its care-of address Tunneling – used to forward IP datagrams from a home address to a care-of addressTunneling – used to forward IP datagrams from a home address to a care-of address

19. Discovery Mobile node is responsible for ongoing discovery processMobile node is responsible for ongoing discovery process –Must determine if it is attached to its home network or a foreign network Transition from home network to foreign network can occur at any time without notification to the network layerTransition from home network to foreign network can occur at any time without notification to the network layer Mobile node listens for agent advertisement messagesMobile node listens for agent advertisement messages –Compares network portion of the router's IP address with the network portion of home address

20. Move Detection Mobile node may move from one network to another due to some handoff mechanism without IP level being awareMobile node may move from one network to another due to some handoff mechanism without IP level being aware –Agent discovery process is intended to enable the agent to detect such a move Algorithms to detect move:Algorithms to detect move: –Use of lifetime field – mobile node uses lifetime field as a timer for agent advertisements –Use of network prefix – mobile node checks if any newly received agent advertisement messages are on the same network as the node's current care-of address

21. Co-Located Addresses If mobile node moves to a network that has no foreign agents, or all foreign agents are busy, it can act as its own foreign agentIf mobile node moves to a network that has no foreign agents, or all foreign agents are busy, it can act as its own foreign agent Mobile agent uses co-located care-of addressMobile agent uses co-located care-of address –IP address obtained by mobile node associated with mobile node's current network interface Means to acquire co-located address:Means to acquire co-located address: –Temporary IP address through an Internet service, such as DHCP –May be owned by the mobile node as a long-term address for use while visiting a given foreign network

22. Registration Process Mobile node sends registration request to foreign agent requesting forwarding serviceMobile node sends registration request to foreign agent requesting forwarding service Foreign agent relays request to home agentForeign agent relays request to home agent Home agent accepts or denies request and sends registration reply to foreign agentHome agent accepts or denies request and sends registration reply to foreign agent Foreign agent relays reply to mobile nodeForeign agent relays reply to mobile node

23. Wireless Application Protocol (WAP) Open standard providing mobile users of wireless terminals access to telephony and information servicesOpen standard providing mobile users of wireless terminals access to telephony and information services –Wireless terminals include wireless phones, pagers and personal digital assistants (PDAs) –Designed to work with all wireless network technologies such as GSM, CDMA, and TDMA –Based on existing Internet standards such as IP, XML, HTML, and HTTP –Includes security facilities

24. WAP Protocol Stack

25. WAP Programming Model

26. Wireless Datagram Protocol (WDP) Used to adapt higher-layer WAP protocol to the communication mechanism used between mobile node and WAP gatewayUsed to adapt higher-layer WAP protocol to the communication mechanism used between mobile node and WAP gateway WDP hides details of the various bearer networks from the other layers of WAPWDP hides details of the various bearer networks from the other layers of WAP Adaptation may include:Adaptation may include: –Partitioning data into segments of appropriate size for the bearer –Interfacing with the bearer network

27. Wireless Control Message Protocol (WCMP) Performs the same support function for WDP as ICMP does for IPPerforms the same support function for WDP as ICMP does for IP Used in environments that don’t provide IP bearer and don’t lend themselves to the use of ICMPUsed in environments that don’t provide IP bearer and don’t lend themselves to the use of ICMP Used by wireless nodes and WAP gateways to report errors encountered in processing WDP datagramsUsed by wireless nodes and WAP gateways to report errors encountered in processing WDP datagrams Can also be used for informational and diagnostic purposesCan also be used for informational and diagnostic purposes