Lect 1 Introduuction to Network.pdf

University of Science & Technology Faculty of Computer Science & Information Technology Department of information for communication and technology Mobile communications & wireless technology_ it 709 4year/sem 7 Tawffeeg Mohammed Tawfeeg Wireless...

University of Science & Technology Faculty of Computer Science & Information Technology Department of information for communication and technology Mobile communications & wireless technology_ it 709 4year/sem 7 Tawffeeg Mohammed Tawfeeg Wireless & Mobile Network  Course Contents Unit No Unit Description Unit.1 Introduction Unit 2 Wireless Transmission Media Unit 3 Wireless Links and Network Characteristics Elements of a wireless network Unit 4 WiFi Wireless LANs The 802.11 MAC Protocol Employ Collision-avoidance techniques. Dealing with Hidden Terminals WiMax and Bluetooth Unit 5 Mobility Management Mobility within the Same Subnet. Mobility Management & Mobile Routing Unit 6 Cellular Internet Access 2G,3G 4G,5G Unit 7 Mobile IP and Handoff in GSM. ICT Department 3 Textbooks Computer Networking: A Top Down Approach Fifth edition. Jim Kurose, Keith Ross Addison-Wesley, July ICT Department 4 2010.  Course Evaluation 25 Marks (Labs + Assignments) 15 Marks (Midterm Exam + quizzes+ Seminars) 60 Marks (Final Exam) ICT Department 5 OSI & TCP/IP Models ICT Department 6 The application Layer represents the interface between the user and the network ICT Department 7  The Application Layer (In the TCP/IP model) The application layer is an abstraction layer reserved for communications protocols and methods designed for process-to-process communications across an Internet Protocol (IP). Application layer protocols use the underlying transport layer protocols to establish process-to-process connections via ports. ICT Department 8  Some network applications E-mail Internet telephone Web Real-time video Instant messaging conference Remote login Massive parallel P2P file sharing computing Multi-user network games Streaming stored video clips ICT Department 9  Application architectures Client-server Peer-to-peer (P2P) Hybrid of client-server and P2P ICT Department 10  Creating a network app Write programs that application transport network – run on different end systems data link physical and – communicate over a network. – e.g., Web: Web server software communicates with browser software No software written for application application transport devices in network core transport network network data link data link – Network core devices do physical physical not function at app layer – This design allows for rapid app development ICT Department 11  Processes communicating Process: program running Client process: process within a host. that initiates communication within same host, two Server process: process processes that waits to be communicate using contacted inter-process communication  Note: applications with (defined by OS). P2P architectures have processes in different client processes & server hosts communicate by processes exchanging messages ICT Department 12  Sockets process host or sends/receives server host or server messages to/from its controlled by socket process app developer process socket similar to door socket socket – sending process shoves TCP with buffers, Internet TCP with message out door variabl buffers, es variabl – sending process relies on es transport infrastructure controlled by OS on other side of door which brings message to socket at receiving process ICT Department 13  Addressing processes For a process to receive Identifier includes both messages, it must the IP address and port have an identifier numbers associated A host has a unique32- with the process on the bit IP address host. Q: does the IP address Example port numbers: of the host on which the – HTTP server: 80 process runs suffice for identifying the – Mail server: 25 process? More on this later Answer: No, many processes can be running on same host ICT Department 14  Transport services and protocols  Transport layer provides logical application transport communication between app network data link processes running on different hosts physical  transport protocols run in end systems  send side: breaks app messages into segments, passes to network layer  rcv side: reassembles segments application transport into messages, passes to app network data link layer physical  more than one transport protocol available to apps  Internet: TCP and UDP ICT Department 15  Network layer  transport segment from sending to receiving host application transport network  on sending side encapsulates data link physical segments into datagrams network network data link data link network physical data link physical  on receiving side, delivers physical network data link network data link physical segments to transport physical network network layer data link physical network data link physical  network layer protocols in data link physical every host, router network data link physical network network data link  router examines header fields data link physical physical in all IP datagrams passing through it ICT Department 16  Link layer terminology:  hosts and routers: nodes global ISP  communication channels that connect adjacent nodes along communication path: links  wired links  wireless links  LANs  layer-2 packet: frame, encapsulates datagram data-link layer has responsibility of transferring datagram from one node to physically adjacent node over a link ICT Department 17 Questions These slides are adapted from Computer Networking: A Top Down Approach Jim Kurose, Keith Ross Addison-Wesley March 2012 ICT Department 18