Computer Communication & Networks Intoduction Computer Communication & Networks Course Instructor: Mr. Asjad Amin Text Book: Computer Networks A Top-Down Approach Featuring Internet 3rd Edition By James F. Kurose && Keith W.Ross

Goals of The Course This course is to provide a combined applied/theoretical background in Data Communications & Networks, focusing the fundamentals of good science and creative engineering

Teaching Goals Prepare and Reward good students because Networks impact quality of life Unskilled practitioners are dangerous ! Skilled practitioners are valuable Improve the student skills in Network design & Analysis Molding the general minds to Engineering cat Amplifying IQ

Non Goals of the Course This course is not intended to Train you as a Network Administrator Focus on the implementation specifics of a particular Vendor Provide Cisco/Alcatel/3com/Novell certification But it may make these things easier to learn once you know the general principles and the “Big Picture”

Text Book Why this Text? In today's time this book is considered as one of the finest equipped with all the modern technology information Seven of the top 10 engineering universities of the world are using Kurose as Text Book

Text Book Stanford University (World Rank # 2) http://www.stanfordcourses.com/CS144 University of Michigan (World Rank # 4) http://irl.eecs.umich.edu/jamin/courses/eecs489/ University of California – Berkeley (World Rank # 5) http://inst.eecs.berkeley.edu/~ee122/fa08/ Harvard University (World Rank # 6) http://www.eecs.harvard.edu/cs143/ Georgia Institute Technology (World Rank # 7) http://www.ece.gatech.edu/academics/courses/course_outline.php?prmCourse=ECE3076 University of Texas – Austin (World Rank # 8) http://www.cs.utexas.edu/users/vin/Classes/CS386M-Fall04/ University of California – San Diego (World Rank # 9) http://ece-classweb.ucsd.edu/winter09/ece158a/info.htm

Slides Courtesy of Kurose & Ross Most of the Slides that will be used during the course are provided by Kurose & Ross

Data Communication Data Communication Data Compression Error Detection & Correction

Data Compression Objective: To reduce the size of data so that the usage of storage hardware could be made efficient There are a hundred of techniques used to achieve the above objective but for our course we will study just two of them. These are the two most commonly used Data Compression techniques

Data Compression These two techniques are Lempel-ZIV Algorithm Run Length Encoding

Lempel-ZIV Algorithm At start prefix = NULL Input = 101011011010101011 Divide the Input string into groups with each group containing A Prefix + one new bit At start prefix = NULL The first bit, a 1, has no predecessors, so it has a NULL prefix and one new bit itself 1,01011011010101011 Same goes for the 0 that follows since it can’t be expressed in terms of the only existing prefix 1,0,1011011010101011

Lempel-ZIV Algorithm Continuing in this way we eventually divide the whole string in groups 1,0,10,11,01,101,010,1011 Since we found 8 phrases, we will use a 3 bit code to label the null prefix & the first seven phrases (000,1) (000,0) (001,0) (001,1) (010,1) (011,1) (101,0) (110,1) Thus the coded version of Input String is Output = 00010000001000110101011110101101

Run Length Encoding Count + A bit Input = 11111111111110000000000000000011111 Divide the Input string into groups with each group containing Count + A bit This can be represented as (13,1) (17,0) (5,1) (01101,1) (10001,0) Output = 011011100010

Thank You