Lecture-01-overview tcp-ip stack-part 1

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Wireless Networking Concepts Dr. Nguyen Tuan Nam Outline •  Overview of network background and technology –  Important concepts in computer networking –  Security •  Introduction to wireless network –  –  –  –  –  –  –  –  Cellular network 802.11 WEP WiMax WAP Bluetooth and security in Bluetooth J2ME MANET WNC 2010 2 Prerequisites of this Course •  Computer Networking WNC 2010 3 Assignments & Grading •  2 exams –  Midterm 20% –  Final exam (40%) •  Projects (30%) –  Individual –  Coding/Presentation •  Quiz –  10% •  Students responsible for going to class & take notes •  Extra credit for advanced projects and class participation •  Fun & creative WNC 2010 4 Exams (closed notes, closed books) •  Questions mostly discussed in class, so don’t skip lecture J •  Midterm –  Basic concepts from Computer Networking course –  Plus all topics discussed from today until that day •  Final exam –  All lectures –  Lab material given by your TAs WNC 2010 5 Project/Presentation •  Projects WNC 2010 6 Overview •  TCP/IP layers •  Important properties of a network protocol •  Important concept in computer network WNC 2010 7 TCP/IP Layers Dr. Nguyen Tuan Nam Quiz 1 •  What happen when you open a website like www.yahoo.com ?? •  Hints: (DNS look up, TCP connection, what happen in each layer) WNC 2010 9 Network Stacks/Layers •  OSI 7-layer model –  –  –  –  –  –  –  Physical Data link Network Transport Session Presentation Application •  TCP/IP stack –  5 layers •  Each layer: –  Only uses functions of the layer below –  Export functionality to layer above –  Why divides it into layers? WNC 2010 10 The 5 Layers Application HTTP, FTP, SSH Network aware program Transport TCP, UDP End-end connections & Reliability Network IP Path Determination (Logic Adr) Data Link Ethernet, Wi Fi 802.11, Bluetooth, ATM MAC and LLC (Phys Adr) Physical Media, Signal, Bin Transmission Wire, Radio, Fiber Optic, Acoustic WNC 2010 11 Physical Layer •  Most complex layer •  Define the means of transmitting raw bits –  Bit stream converted to physical signal •  Main responsibilities: –  Definition of Hardware Spec: shapes and properties of electrical connectors –  Encoding and signaling –  Data transmission and reception –  Topology and physical network design •  Pretty much about hardware •  Example: repeater WNC 2010 12 Illustration . . . 0101011101010111010101010101 . . . Physical signal (wave, voltage, light pulses) WNC 2010 13 Data Link Layer •  Put data into frames –  Ethernet frames –  Local delivery of frames between devices on the same LAN –  Start/end of the frame •  Time based •  Character counting •  Bit pattern –  Frame header contains info about the frame –  Hop-to-hop frame delivery •  Physical Address: –  MAC address –  Identify which computer in the subnet –  Source and Destination Addresses •  Collision Avoidance/Detection –  Frame collision –  Can be reliable/unreliable transmission WNC 2010 14 Illustration Frame 3 Frame 2 Frame 1 010…0111 0101…110 101…0101 00FF00AA00BD 00FF00AA00BE | Start | MAC addresses | Content | End | MAC address: _ unique address, uniquely identify an adapter in LAN 6 bytes in hexadecimal First 3 bytes: manufacture, Last 3 bytes: serial number WNC 2010 15 Illustration 2 00FF00AA00BA MAC: flat address, specify nothing about the network structures Switch 00FF00AA00BB Hub 00FF00AA00BC 00FF00AA00BD WNC 2010 16 Quiz •  Do 2 adapters (computers) in a LAN (local area network) need to have the same MAC address prefix? 00FF00AA00BA 00FF00 Switch 00FF00AA00BB Hub 00FF00AA00BC 00FF00AA00BD WNC 2010 17 Quiz •  Can 2 adapters (computers) in a LAN (local area network) have the same MAC address? 00FF00AA00BA Switch 00FF00AA00BB Hub 00FF00AA00BA 00FF00AA00BD WNC 2010 18 Quiz •  Can a computer have 2 network adapters? 00FF00AA00BA Switch 00FF00AA00BB 00FF00AA00BC Hub 00FF00AA00BC Switch Hub 00FF00AA00B9 00FF00AA00BD WNC 2010 19 Switch/Bridge vs Hub •  Hub: –  Repeater –  Take incoming data packet in 1port –  Copies it to all other ports –  No filtering or redirection of data •  Switch/Bridge: –  Layer 2 –  Only forward packet to the correct adapter WNC 2010 20
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