2/8/12 The Internet CCST9015 Feb 8, 2012 What does 1000M and 200M mean? Dr. Hayden Kwok-Hay So Department of Electrical and Electronic Engineering 2 Charging for Internet One is charging for speed (How fast the apples are delivered to you, but you can eat as many as you want) Another one is charging for amount of data (Number of apples you can eat per month) What does 1GB mean? Are they charging for the same Internet? Which way is more realistic Which way is more fair 3 4 5 6 Conceptual Picture of the Internet Each computer thinks it is directly connected to another one through a magic cloud. 1
2/8/12 Internet structure: network of networks Tier 3 Tier-2 Tier-2 Tier 1 Internet in 2003 Tier 1 Tier 1 Tier-2 7 Internet Basics Inter -Net Distributed management Defines layers of services 9 ARPANET Advanced Research Projects Agency Network Project active during early 70s Commonly referred as the predecessor of the Internet A large-scale research effort involved multiple Universities to construct a communication network Before the Internet, each University and military unit has their own network Different standards Some of them work only when the computers are physically close to each other Src: http://www.computerhistory.org DEC s PDP-10 Networking was a niche 10 Enable communication among different private networks and computers from different vendors with different standard and performance physically located at different locations to communicate Fault tolerant Allows the overall network to operate despite failures in some parts Scalable Allows network to grow very large First operational packet-switch network 8 Design goals of the Internet Simple point-to-point connections Connections between computers Security Application services (e.g. world wide web, email, gopher, usenet) Tier-2 Tier-2 Back in The Internet is a network that connects millions of of computing devices throughout the world. The Internet is formed by connecting many different networks. NAP 11 12 2
2/8/12 Same Internet? Internet of Things Earlier question: Is the computer and the mobile phone connected to the same Internet? Modern mobile phones, especially smartphones, are examples of advance embedded systems As powerful as a desktop computer 10 years ago For example, both smartphone and a laptop can connect to the Internet using WiFi Answer: (Mostly) Yes Except if you have an older phone with WAP access Researchers predicts the future will be an age of Internet of Things Everything will be connected to the Internet Even TV, refrigerator, microwave oven, lightbulb 13 Who owns the Internet? 14 Discussion Billions of computers are connected to the Internet Q: Are they all part of the Internet? A: Technically all computers connected to the Internet is part of the Internet The Internet is made up of millions of computers. When you pay for the Internet, what are you exactly paying for? A. B. C. D. E. Each computer can be configured to perform certain core task of the Internet As a result, the Internet is a distributed effort, with distributed ownership Email service The world wide web The electricity charge of the servers A right to access to the Internet The software that connects to the Internet More next 15 Internet-in-a-Box Circa 1994, by Spry Contains all software to connect to the Internet Mosaic browser Dial-up access Whole Internet Guide 16 What are you really paying for? When you pay your Internet service provider () or your mobile phone company, you are paying for your access to the Internet. But what kind of service are you really getting in return? Photo source: computerhistory.org 17 18 3
SmarTone Incident SmarTone Hong Kong decided to stop offering its unlimited data plan starting Feb 9, 2012. 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 http://www.smartone.com/about/media_centre/press_release/press/2012/02/2012_02_02_340_chi.pdf 19 20 Administrivia Class is full Thu 4-5pm tutorial canceled Moved to other sessions Current active tutorial sessions: Wed 5pm-6pm Thu 3pm-4pm Thu 5pm-6pm Course web site: http://www.eee.hku.hk/~ccst9015 22 Measuring Network Performance Latency Measures the to get the first byte of data across a network Unit: seconds (s) Throughput Measures the aggregated amount of data transported over a period of Unit: byte per second (Bps) or bit per second (bps) Example: Mailing DVDs Mailing a DVD takes 1 day = 24 hours = 86400s Each DVD is 4GB Latency is 86,400s Throughput is an average value. If we mail 1 DVD everyday, then the throughput (bandwidth) is: 4GB / 86400s 46.2 kbps 370 kbps 23 24
Example: scaling up What if we mail 100 DVDs at the same? Latency remains the same: 86400s Bandwidth increases by 100 s 37 Mbps In other words, mailing 100 DVDs at the same has higher bandwidth than your average broadband internet access at home. 25 Physical Mail vs Network When the data transfer is large, traditional postal mail has much higher bandwidth than any Internet connection E.g. Amazon AWS Import/Export allows company to send data to the Internet cloud by physically sending hard drives. When is physical mail faster? Available Internet Connection Theoretical Min. Number of Days to Transfer 1TB at 80% Network Utilization When to Consider AWS Import/Export? T1 (1.544Mbps) 82 days 100GB or more 10 Mbps 13 days 600GB or more T3 (44.736Mbps) 3 days 2TB or more 100 Mbps 1-2 days 5TB or more 1000 Mbps < 1day 60TB or more 26 Which network is better? Which network is better? (A) Network A has low latency and low throughput Network B has high latency, high bandwidth Network C has moderate latency, moderate throughput, and unpredictable performance Network A is the best for short, bursty traffic, such as web browsing. Think of the first yellow packet as all you need for 1 web page Email, IM (MSN messenger, gtalk,etc) are all examples of short bursty traffic 27 28 Which network is better? (B) Which network is better? (C) Network B has the longest latency (longest wait ) But once the data arrive, it has the highest bandwidth Network B is best for streaming data E.g. youtube, and any other streaming data Network C is difficult to classified Network C is the most realistic model of today s s capability 29 30
Discussion Question: Internet Traffic by % Which of the following types of traffic is most common on the Internet? A. Web pages B. Video C. Pictures D. Twitters, Weibo and other microblog E. Apps download 31 Source: The Web Is Dead. Long Live the Internet Wired, Aug, 2010 http://www.wired.com/magazine/2010/08/ff_webrip/ 32 Internet Traffic - Denormalized total internet traffic rose then from about 1 exabyte to 7 exabytes between 2005 and 2010. Source: Is the Web Really Dead? http://www.boingboing.net/2010/08/17/is-the-web-really-de.html 33 Internet Traffic Summary Video content is on a very rapid rise More than half (51%) of today s Internet traffic is for video Followed closely by peer-to-peer (P2P) traffic and web But Recall the Internet was designed with bursty traffic like the web in mind (and many traffic that has pretty much extinct) 34 What about P2P? Peer-to-peer communication is a relatively new model for data communication Example: bittorrent Opposite to the traditional server-client model Used mainly for file download/upload Latest: P2P streaming Such as PPStream, etc Server-Client Model Client Can you give me file A? Ok, part 1 of A A2 A1335 Server 35 36
P2P traffic A21 A220 A198 A903 A2 A38 A458 A998 A5 A246 A180 A23 A380 A772 A55 A7 Where can I find peers who have A? A235 A117 List of Peers A6 A89 P2P Traffic vs Server-Client P2P Equal portion of uplink and downlink Each client connects to many computers Essentially no one has the entire file Except seeder in some cases Server-Client Mostly downlink Each client connects to 1 computer Files centrally located Servers always contain the entire file 37 38 Is the Internet Designed for P2P? The Internet core network actually does not care so much about uplink and downlink The Internet core, being a dumb network, doesn t even know if a client is connected to many other computers To certain extent, the Internet works fairly well with P2P traffic But Many s are not very happy with P2P traffic Discussion Question: Given what you have learned about network resource sharing and traffic pattern, do you think the /Mobile Phone company should be allowed to control the traffic of their Internet user in the name of fair use? 39 40 Service Agreement What are you paying for when you sign up for an? Speed? Unlimited access? Amount of data? Guarantee of service? http://www.ofta.gov.hk/en/consumer_interest/ppbroadband.html Performance Pledge http://www.netvigator.com/netvigator2003/pledge/technical.html 41 42
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 Network Latency http://www.hkbn.net/2010/eng/en_service1_5a.html 43 44 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 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 45 46 In conclusion The true performance of a network must be evaluated by both its latency and throughput The core network of the Internet is designed to deliver best effort service, not guaranteed service The Internet with its original design has no provision of performance guarantee Local only guarantee service to exchange, before it enters the Internet 49