Introduction of Computer Networking Professor Wei Chen Tennessee State University

Computer Network and Internet Regional ISP Company Network Local ISP Public Internet Internet/Intranet LAN (10/100 Mbps, 1/10 Gbps ) host (end system) Communication link transmitting rate router (packet switch) ISP Connection-oriented reliable/connectionless unreliable service multiplexing in circuit-switched networks (frequency-division multiplexing/time-division multiplexing) bandwidth (width of frequency spectrum) delay and packet loss Sever

ISO/OSI Reference Model Physical Layer Data Link Layer (Transfer of blocks across a link) Network Layer (Transfer of packets across network) Transport Layer (end-to-end transfer of message) Session Layer Presentation Layer Application Layer A p p l i c a t i o n P r o t o c o l T r a n s p o r t P r o t o c o l Computer Network Protocols Application Transport Network Link Physical Application Transport Network Link Physical # Link Physical Network Link Physical Source Destination Router Link-layer Switch

Application Layer Popular Network Applications Web Remote login (Telnet) File transfer (FTP) Multi-user networked game Internet phone Real-time video conferencing Network Application Architectures Client-server architecture (with fixed always-on sever) P2P architecture (decentralized) Hybrids of client-server and P2P Communicating Process and Socket Process and Socket: A process (analogous to a house) sends messages into, and receives messages from, the underlying network through its socket (analogous to a door). IP address and Port Number: IP address is a 32-bit quantity that uniquely identifies the host. Port number identifies the type of process. Application-Layer Protocols Type of messages (request, response) Syntax of message type, semantics of the fields Rules for determining when and how a process sends and responds to messages. Important Issues: Reliable data transfer, Band width, Timing

Transport Layer Provides for logical communication between application processes running on different hosts: (1) break the application messages into smaller chunks, (2) adding a transport-layer header to each chunk to create the transport- layer segment, and (3) then pass the segment to the network layer. Transport Layer in the Internet (TCP/IP) UDP (User Datagram Protocol) provides an unreliable, connectionless service, where the transport layer packet is called as segment. TCP (Transmission Control Protocol) provides a reliable, connection-oriented service, where the transport layer packet is called as datagram. TCP provides congestion control. Transport-layer multiplexing (gather data chunks at the source host from different sockets and pass to network layer) and demultiplexing (delivering the data in transport- layer to the correct socket) extend host-to-host services between two end systems to a delivery service between two processes running on the end system. Important Issues: Reliable data transfer, Congestion control

Example 1: TCP Segment Structure Source port #Dest port # Sequence number Acknowledgement number Data Header Length……Receive window Internet checksum Urgent data pointer Options 32 bits Example 2: UDP Segment Structure Source port #Dest port # Data LengthChecksum 32 bits

Network Layer Two important network layer functions Forwarding: transfers a packet from an incoming link to an outgoing link within a single router. Routing: involves all of a network’s routers, whose collective interaction via routing protocols (algorithms) determine the paths that packets take on their trips from source to destination node. Routing algorithms Local forwarding table

Version Header Length Type of serviceDatagram length (bytes) Versio16-bit IdentifierFlags13-bit Fragmentation offset Time to liveUpper-layer protocolHeader checksum 32-bit Source IP address 32-bit Destination IP address Options (if any) Data 32 bits IPv4 datagram format IPv6 datagram format Version Traffic class Flow label Pay-load length Next hdrHop limit 128-bit Source IP address 128-bit Destination IP address Data 32 bits

Link Layer A link-layer protocol (Ethernet, wireless LAN, token ring, PPP) is used to move a datagram over an individual link. It defines the format of the packets exchanged between nodes at the ends of the link, as well as the actions taken by these nodes when the packets are sent and received. Actions in Link layer sending and receiving frames including error detection retransmission flow control random access Multiple Access Protocols Channel partitioning protocols (Time division multiplexing, frequency-division multiplexing) Random access protocols Taking-turns protocols

Overall Communication Process ISO/OSI Reference Model Wireless Ad-Hoc Model Correlation-based Communication Layer Physical Layer Data Link Layer (Transfer of blocks across a link) Network Layer (Transfer of packets across network) Transport Layer (end-to-end transfer of message) Session Layer Presentation Layer Application Layer A p p l i c a t i o n P r o t o c o l T r a n s p o r t P r o t o c o l Communication Unit in A Sensor Node for Sensor Network

Correlation-based Communication Layer Hierarchical Communication/routing protocols Highest Level Physical Layer (Flat Communication Network) Fusion-Oriented Application Layer Lowest Level Communication Tasks Multicasting Broadcasting Global Synchronization System Maintenance Tasks Network Reconfiguration Structured (Hierarchical) Communication Network Static/Dynamic Grained-Clustering

Architecture of Sensor Nodes Data path Tradeoffs between power consumption, bandwidth, and latency Interrelationship between transmission rates, processor speed and power consumption. Interface between an application and its communication protocols Control and computing System Sensor System Communication System Power System System timers Data memory Power tracking unit RF Transceiver Sensor arrayMicro controller

Wireless Stands IEEE (Wi-Fi): Mainly used for the access between wireless devices and base stations. Possible for the access between wireless devices. IEEE (based on Bluetooth): Used for Ad-hoc network without base station. Types of Nodes in Sensor Networks (1)Homogeneous Sensor Network Uniform sensor nodes & sink nodes No base station (2) Heterogeneous Sensor Network Sensing nodes, processing nodes, mobile nodes, sink nodes Mixed with base station

Indoor m Outdoor m Mid range 200m-4km Long range 5Km-20Km (a,g) b UMTS/WCDMA,CDMA2000 IS-95 CDMA, GSM 54 Mbps 5-11 Mbps I Mbps 384 Kbps 56 Kbps Comparison between standards CAMA/CA: carrier sense multiple access with collision avoidance TDM: time division multiplexing Up to 1 Mbps Up to 54 Mbps Up to 11 Mbps Data rate TDM access Same as above Random access CSMA/CA MAC Protocol GHz802.11g 2.4 GHz802.15(based on Bluetooth) GHz802.11a GHz802.11b Frequency (unlicensed) standard

IEEE Frame Frame Control DurationAddress 1 Address 2 Address 3 Seq Control Address 4 PayloadCRC Bytes: MAC address of the station that transmits the frame MAC address of the destination station MAC address of the router interface Using for Ad-Hoc network Cyclic redundancy check

RF transceiver Protocol processing Application control Transmission power control Synchronizer Channel coding MAC (Media access control ) protocol Communication Unit

Radio transceiver Synchronizer (Global clock) No collision detection Each node has a distinguish ID. TDM access/Random access. Communication Unit (Based on b)

Software Sensor Nodes node ID node mode: sleeping, waking, charging communication range channel mode power level frame type: data, management, control memory size local clock physical location? global clock? QoS