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This text explores essential characteristics and concepts of communication links in internet technology. It emphasizes key metrics such as speed, latency, jitter, and packet loss rate that define link performance. Additionally, it discusses various types of connection technologies, including terrestrial, satellite, and wire-line options, while addressing the global disparities in internet access between developed and developing nations. This work seeks to inform users about the importance of these characteristics in digital communication and data transmission, fostering better application development and content creation practices.
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Link characteristics Skills: none Concepts: Link characteristics -- technology, length, speed, latency, jitter and packet loss rate, units of measure for amount of data and connection speed, link trends and the gap between developed and developing nations This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 License.
Where does this topic fit? • Internet concepts • Applications • Technology (communication) • Implications • Internet skills • Application development • Content creation • User skills
Link characteristics Computer 2 Computer 1 Link technology Link length Link speed Latency, jitter and packet loss rate
Wireless connection technologies Terrestrial radio Satellite radio
Wire-line connection technologies Copper, twisted pair (electronic) Copper, coaxial cable (electronic) Fiber (optical)
Only use wireless links when a wired connection is not convenient or possible.
Link characteristics Computer 2 Computer 1 Link technology Link length Link speed Latency, jitter and packet loss rate
Link characteristics Computer 2 Computer 1 Link technology Link length Link speed Latency, jitter and packet loss rate
What are some unit of measure for … Length? Weight? 0101010101001011010010111001010101010010101010001010101010101010100101010010101010010010010010101010010001010101011101001010010101010 Data?
Units of measure for quantity inches, meters, millimeters, miles, nanometers, light years, etc. pounds, ounces, grams, kilograms, tons, nanograms, milligrams, etc. 0101010101001011010010111001010101010010101010001010101010101010100101010010101010010010010010101010010001010101011101001010010101010 bits, bytes, kilobytes, kilobits, terabits, megabits, gigabytes, etc.
Units of measure for time hours, days, weeks, years, centuries, seconds, microseconds, nanoseconds, and so forth
Rate = quantity per unit of time Distance traveled per unit of time
Units of measure for data transmission rate Transmission rate = amount of data per unit of time
Units of measure for data transmission rate Transmission rate = amount of data per unit of time
Units of measure for data transmission rate Transmission rate = amount of data per unit of time
The Internet Home
Link characteristics Computer 2 Computer 1 Link technology Link length Link speed Latency, jitter and packet loss rate
Jitter Which has the lowest jitter?
The link from your home to the Internet ? Home LAN The Internet LAN router ISP router
Global view PingER at Stanford University http://bit.ly/mnruYf
Summary Computer 2 Computer 1
Self-study questions • We discussed several characteristics of a communication link. Without looking back, do you recall what they were? • Name two units of measure for each of the following: • Weight • Length • Rate at which you run • Amount of data • Rate of data transmission • The general form of a unit of measure for velocity is distance/time. What is the general form of a unit of measure for data transmission speed? • What unit of measure would you use for a quantity of water? • What unit of measurement would you use for the rate at which water flows through a hose? • When you walk, you typically travel at rate of about 4 miles per hour. Convert that to miles per second. • When you walk, you typically travel at rate of about 4 miles per hour. Convert that to feet per second. • How many bits in a megabyte? • How long would it take to transmit a 100 megabit file over a 100 megabit/second link? • How long would it take to transmit a 100 megabit file over a 10 megabit/second link? • How long would it take to transmit a 100 megabit file over a one gigabit/second link? • How long would it take to transmit a 100 megabyte file over a 100 megabit/second link? • How long would it take to transmit a 100 megabit file over a 100 megabyte/second link? • How long would it take to transmit a 132 megabyte file over a 12 megabit/second link? • What are the speed, technology, length and monthly cost of the link from your home to your Internet service provider? • We saw that Internet links are often asymmetric – faster in one direction than the other. Why is the transmission rate from your ISP to your home faster than the other direction?
Resources Test ping times: http://pingtest.net Test data transmission rate: http://speedtest.net A more detailed link test with hints to improve performance by adjusting TCP parameters: http://ndt.anl.gov Current data on Verizon network performance: http://www.verizonbusiness.com/about/network/latency/ The 2010 Stanford report on Internet performance:http://www.slac.stanford.edu/xorg/icfa/icfa-net-paper-jan10/report-jan10.doc Aladdin Nassar, Worldwide Inventory of Last-mile Bandwidths & Network Latencies:http://velocityconf.com/velocity2010/public/schedule/detail/14075 Project PingER: http://www-iepm.slac.stanford.edu/pinger/