The Free Internet. Questions to Ponder On. Packet Switching Network. Circuit Switch vs Packet Switch. Circuit Switching

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1 The Free Internet CCST9015 Feb 15, 2012 Questions to Ponder On 1. Think of 5 things that you get for free from the Internet. 2. Think of 5 things that you get for free in real life. Dr. Hayden Kwok-Hay So Department of Electrical and Electronic Engineering 2nd semester, 2012 CCST Dr. H. So 2 Getting Information across the Globe When you request a web site, how does the information get across the Internet? Packet Switching Network One of the major innovations of the Internet was the use of a packet switch network for communication Information are divided into small pieces called packets before they are sent across the network At the receiving end, the information is reconstructed using all received packets The network is responsible for delivering the packet correctly 3 2nd semester, 2012 CCST Dr. H. So 4 Circuit Switch vs Packet Switch Two important ways of network communication: Circuit switching dedicated circuit per connection e.g. telephone network (PSTN Public Switched Telephone Network) Packet switching Data sent through the network in discrete packets e.g. Internet Circuit Switching End-to-end resources reserved for exclusive use by each connection Network resources (e.g., bandwidth) divided into pieces Pieces allocated to each connection Guaranteed performance Resource piece idle if not used by owning call (no sharing) 5 6

2 Packet Switching A B 10 Mbs Ethernet queue of packets waiting for output link D statistical multiplexing 1.5 Mbs Each end-end data stream divided into packets Different users share the same resource as needed Excessive queuing might cause packet drop E C Packet Routing Getting packets from one computer to another Each data packet must be marked with the destination Just like the address on a postcard The header of a packet stores all the information about the content of the packet The payload contains the actual data The machine that decides how to route a packet in the network is called a router. 7 8 Internet Routers Surprisingly, the Internet routing protocol is relatively simple. Each stop between router is called a hop. Each router only knows the general direction on where to route a packet A hierarchal routing idea Example: Send a packet form the USA to Rm 516, Dept of EEE, HKU, HK 1. Send to HK 2. Postman (router) at HK sends to HKU 3. Router at HKU sends to EEE 4. Router at EEE sends to Rm Internet structure: network of networks a packet passes through many networks! Tier 3 Tier 1 Tier-2 Tier-2 Tier 1 Tier-2 NAP Tier 1 Tier-2 Tier-2 10 Visualizing Internet Routes Traceroute A standard tool to look for all the intermediate routers to a remote site Interesting website that provides visualization of routes Is packet switch always better? Great for bursty data e.g. Web browsing resource sharing Excessive congestion: packet delay and loss Q: How to provide circuit-like behavior? bandwidth guarantees needed for audio/video apps still an unsolved problem 11 Internet traffic going out of New York (2008) 12

3 Question: The core of the Internet is a vast structure consisting of tens of thousands of computers, servers and communication links. Who is paying for all these infra-structures? A. Users B. Government C. Military D. Big companies E. Universities Service Agreement What are you paying for when you sign up for an? Speed? Unlimited access? Amount of data? Guarantee of service? 2nd semester, 2012 CCST Dr. H. So 13 2nd semester, 2012 CCST Dr. H. So 14 Performance Pledge Speed Guaranteed? 1.5M, 3M, 6M, 10M, 30M services? In theory, it stands for the maximum throughput (bandwidth) you should get But Latency vs Throughput If you get 100Mbps speed but only after 1day of latency, will you want the service? Very few advertise on their latency performance Guaranteed? The speed ratings are maximum speed that you would ever reach. In other word, the will cap your service at that speed But that doesn t mean you will always get that speed 2nd semester, 2012 CCST Dr. H. So 15 2nd semester, 2012 CCST Dr. H. So 16 Network Latency Speed Guaranteed? (2) Recall that Internet is made of many other network that your cannot control As a result, your can never guarantee any speed to any place on the Internet The speed rating is often defined between your home and the HKIX, the Hong Kong Internet Exchange 2nd semester, 2012 CCST Dr. H. So 17 2nd semester, 2012 CCST Dr. H. So 18

4 Speed Guaranteed? Maintaining the end-to-end quality of service (QoS) on Internet is still a very difficult research question Some success in reality, but still largely unsolved Unlimited Access? Most s offer unlimited access in Hong Kong Only some mobile Internet plan are charged on the actual transfer volume Recall the notion of free : Since you can transfer unlimited amount of data with a fixed price, each byte of data transfer is essentially free 2nd semester, 2012 CCST Dr. H. So 19 2nd semester, 2012 CCST Dr. H. So 20 SmarTone Incident SmarTone Hong Kong decided to stop offering its unlimited data plan starting Feb 9, Reasons: OFTA states that any Unlimited usage plan shall not be subject to any limitation in the name of FUP SmarTone considers traffic control management and FUP are indispensable to safeguard stable network operations and quality for all In effect, Unlimited usage plans can no longer be offered Fair Usage Policy Many cellular network and carries out traffic control to the user s connection to the Internet Limiting the speed of data transfer Limiting the amount of data transfer Limiting the content of transfer, such as BT Argument: since all user shares the same networking resources, to be fair to all user, they must limit the usage of some users to ensure other users stable connections 2nd semester, 2012 CCST Dr. H. So 21 2nd semester, 2012 CCST Dr. H. So 22 A few days later SmarTone Hong Kong decided to resume offering of its unlimited data plan starting Feb 13, Reasons: in the light of market & regulatory developments Open Question IF each byte of data transfer is free, and the performance is not guaranteed, then what are you paying the for? Under this new policy, customers on unlimited and other plans who reach 5GB of data fair usage within a single billing period will be given lower priority to access the network resources for the remainder of that billing period. 2nd semester, 2012 CCST Dr. H. So 23 2nd semester, 2012 CCST Dr. H. So 24

5 Administrivia Quiz 1 Quiz 1 grades available on Moodle Mean: 70.8/100 SD: 18 Hard copy available during tutorial session this week nd semester, 2012 CCST Dr. H. So 26 Administrivia Quiz 2 Quiz 2 in 2 weeks (Feb 29, 2012) 15 minutes during the beginning of lecture Covers materials since Quiz 1 Same rules as Quiz 1 Remember: 4 quizzes in class, but only the best 3 counts towards your final grade Administrivia Homework Homework 1 is released Individual homework Due in 3 weeks Start early! Submit through Moodle Mandatory plagiarism check through integrated Turnitin function Recall: Zero tolerance in plagiarism Cite and quote references appropriately 2nd semester, 2012 CCST Dr. H. So 27 2nd semester, 2012 CCST Dr. H. So 28 Administrivia - Project Project topics posted Pick your project preference by end of Friday, Feb 17. Pick 5 projects out of the list Fill in your preference in the online form Project groups will be formed according to your choice Groups will be formed with students from the same tutorial sessions Wikipedia Blackout First time in history Entire US site unavailable for 24 hours Protest against the pending passing of SOPA/ PIPA law in the US that may threaten the free flow of information on the Internet. 2nd semester, 2012 CCST Dr. H. So 29 2nd semester, 2012 CCST Dr. H. So 30

6 SOPA/PIPA Stop Online Piracy Act A bill submitted to the US House of Representative Protect IP Act A bill in Senate similar to SOPA Proposed to pass laws that allow court orders to shutdown Internet sites and infrastructure that enables or facilitates online piracy It is so vague that it can mean the entire Internet Massive reaction from online community Massive blackout on Jan 18, 2012 Including sites like Wikipedia, Wordpress, Goolge, Mozilla foundation 2nd semester, 2012 CCST Dr. H. So 31 How does SOPA work? Source: Khan Academy 2nd semester, 2012 CCST Dr. H. So 32 Results of SOPA/PIPA? The bills get postponed But new, similar bills are being constantly being pushed by the media companies Music, Movie A continue battle among media companies and technology companies and general public Business vs Ideologies Price Results from tutorial Movie (theater) Movie (online) 1 CD 1 song from Internet An application (smartphone) An application (computer) A dinner meal Item A mobile phone Internet access for 1 month trip to HKU 1 month of newspaper subscription 1 handbag/backpack 1 pair of earrings 2nd semester, 2012 CCST Dr. H. So 33 2nd semester, 2012 CCST Dr. H. So 34 Free digital media content Digital media contents (photo, music, movie) can be reproduced and redistributed infinitely online Has a marginal cost of almost 0 The natural pricing tends to be zero User do not perceive the incremental cost Unlike physical objects Oranges, apples Online Piracy Piracy is a real issue: Content can be copied and redistributed easily User: why pay when there are free alternatives? Easily available before content released officially, if at all 2nd semester, 2012 CCST Dr. H. So 35 2nd semester, 2012 CCST Dr. H. So 36

7 Who is the culprit? User who pirates and distributes the content? User who download the content? Media companies? Technology companies that provide the facilities for pirating/distributing the content? The technology itself? Viable Alternatives Free software/tools by design Free open source software Free services Technology as a tool Use Internet as a distribution tool 2nd semester, 2012 CCST Dr. H. So 37 2nd semester, 2012 CCST Dr. H. So 38 Technology as Tools Technologies are simply tools that enhance our productivity Same as a hammer, or a car Embrace new opportunities make available Youtube may be a breeding ground for pirated content because it allows any user to upload any content It has rule that remove illegal content It is successful because it allows easy distribution of content (legal & illegal) Free by design Being free does not imply low quality Example: Linux operating system Wikipedia 2nd semester, 2012 CCST Dr. H. So 39 2nd semester, 2012 CCST Dr. H. So 40 Ex: Linux OS Linux was originally developed by Linus Torvald in 1991 Designed to be free and open source from the beginning Today: Major competitor against MS windows in servers Super computing world Major player in embedded systems: e.g. Android, network router Youtube as a distribution platform Instead of using traditional platforms such as TV, radio All promotion, distribution using Youtube Low cost (free) Reach global audience Example: Jayesslee 2nd semester, 2012 CCST Dr. H. So 41 2nd semester, 2012 CCST Dr. H. So 42

8 Online Broadcasting Treat Internet as the equivalent of radio wave/cable/tv signal Broadcast (original) contents directly on the Internet May also complement traditional broadcasting medium E.g. mytvb.com Bits and Bytes In modern digital systems, data are managed as binary numbers Engineers refers each binary unit of information (i.e., a 1 or a 0 ) as a bit But since one bit contains very little information, most electronic systems manage groups of bits. In particular, one of the the most used groupings is the unit of a byte, which stands for a group of 8 bits. To avoid confusion, I usually use: upper case (B) to stands for a byte, and Lower case (b) to stands for a bit 2nd semester, 2012 CCST Dr. H. So 43 2nd semester, 2012 CCST Dr. H. So 44 SI, Binary and IEC units When a large number of bits/bytes are referred, they are usually attached with special prefixes. As there is a lack of widely adopted standard, the SI prefixes are often misused (intentionally?). SI Pronounce SI meaning Customary Binary meaning k kilo 10 3 = 1, = 1,024 Ki Ex: 1 DVD stores 4GB, 1CD stores ~700MB IEC M mega 10 6 = 1,000, = 1,048,576 Mi G giga Gi T tera Ti P peta Pi E exa Ei 2nd semester, 2012 CCST Dr. H. So 45