Network and Mobile Compung in the 20th Century and Beyond

COMP 1400 Memorial University Winter 2015 What’s the : “nuts and bolts” view

PC • millions of connected computing mobile network server devices: – hosts = end systems global ISP laptop – running network apps home v communication links network § fiber, copper, , regional ISP wireless satellite links § transmission rate: wired links

v Packet switches: forward packets router (chunks of data) institutional § routers and switches network

1-2 “Fun” internet appliances

Web-enabled toaster + weather forecaster

IP picture frame http://www.ceiva.com/

Tweet-a-watt: monitor energy use

Slingbox: watch, control cable TV remotely Internet refrigerator Internet phones

1-3 What’s the Internet: “nuts and bolts” view

mobile network • Internet: “network of networks”

– Interconnected ISPs global ISP • protocols control sending, receiving of msgs home – e.g., TCP, IP, HTTP, , 802.11 network regional ISP • Internet standards – RFC: Request for comments – IETF: Internet Engineering Task Force

institutional network

Introduction 1-4 What’s the Internet: a service view

mobile network • Infrastructure that provides services to applications: global ISP – Web, VoIP, , games, e- commerce, social nets, … home • provides programming network interface to apps regional ISP – hooks that allow sending and receiving app programs to “connect” to Internet – provides service options, analogous to postal service

institutional network

Introduction 1-5 What’s a protocol? human protocols: network protocols: • “what’s the time?” • machines rather than • “I have a question” humans • introductions • all communication activity in Internet governed by … specific msgs sent protocols … specific actions taken protocols define format, order when msgs received, or of msgs sent and received other events among network entities, and actions taken on msg transmission, receipt

1-6 What’s a protocol? a human protocol and a protocol:

Hi TCP connection request Hi TCP connection response Got the time? Get http://www.awl.com/kurose-ross 2:00 time

Q: other human protocols? 1-7 A closer look at network structure:

• network edge: mobile network – hosts: clients and servers – servers often in data centers global ISP

home v network access networks, physical regional ISP media: wired, wireless communication links

v network core: § interconnected routers § network of networks institutional network

1-8 versus packet switching allows more users to use network!

example: § 1 Mb/s link ….. N § each user: users • 100 kb/s when “active” 1 Mbps link • active 10% of time

• circuit-switching: – 10 users Q: how did we get value 0.0004? • packet switching: – with 35 users, probability > Q: what happens if > 35 users ? 10 active at same time is less than .0004 *

1-9 Packet Switching: queueing delay, loss

C A R = 100 Mb/s D R = 1.5 Mb/s B queue of packets E waiting for output link

queuing and loss: v If arrival rate (in bits) to link exceeds transmission rate of link for a period of time: § packets will queue, wait to be transmitted on link § packets can be dropped (lost) if memory (buffer) fills up

1-10 Protocol “layers”

Networks are complex, with many “pieces”: – hosts Question: – routers is there any hope of organizing structure of network? – links of various media …. or at least our discussion – applications of networks? – protocols – hardware, software

1-11 Internet protocol stack

• application: supporting network applications – FTP, SMTP, HTTP application

• transport: process-process data transfer transport

– TCP, UDP network • network: routing of datagrams from source to destination link – IP, routing protocols

• link: data transfer between physical neighboring network elements – , 802.111 (WiFi), PPP • physical: bits “on the wire”

1-12 source Encapsulation message M application

segment Ht M transport

datagram Hn Ht M network frame Hl Hn Ht M link physical link physical

switch

destination Hn Ht M network H H H M link M application l n t Hn Ht M physical Ht M transport

Hn Ht M network router Hl Hn Ht M link physical

1-13 Web and HTTP

Web has been the most important application on the Internet • web page consists of objects • object can be HTML file, JPEG image, Java applet, audio file,… • web page consists of base HTML-file which includes several referenced objects • each object is addressable by a URL, e.g., www.someschool.edu/someDept/pic.gif host name path name • carried by the HyperText Transfer Protocol

2-14 P2P applications

• no always-on server • arbitrary end systems directly communicate • peers are intermittently connected and change IP addresses examples: – file distribution (BitTorrent) – Streaming (KanKan) – VoIP (Skype)

2-15 Client-server vs. P2P: example client upload rate = u, F/u = 1 hour, us = 10u, dmin ≥ us

3.5 P2P 3 Client-Server 2.5

2

1.5

1

0.5 Minimum Distribution Time

0 0 5 10 15 20 25 30 35 N

2-16 Internet history

1961-1972: Early packet-switching principles

• 1961: Kleinrock - • 1972: queueing theory shows – ARPAnet public demo effectiveness of packet- – NCP (Network Control switching Protocol) first host-host • 1964: Baran - packet- protocol switching in military nets – first e-mail program • 1967: ARPAnet conceived – ARPAnet has 15 nodes by Advanced Research Projects Agency • 1969: first ARPAnet operational

1-17 Internet history

1972-1980: Internetworking, new and proprietary nets

• 1970: ALOHAnet in Hawaii Cerf and Kahn’s • 1974: Cerf and Kahn - internetworking principles: architecture for interconnecting – minimalism, autonomy - no networks internal changes required to interconnect networks • 1976: Ethernet at Xerox PARC – best effort service model • late70’s: proprietary – stateless routers architectures: DECnet, SNA, – decentralized control XNA define today’s Internet • late 70’s: switching fixed length architecture packets (ATM precursor) • 1979: ARPAnet has 200 nodes

1-18 Internet history

1980-1990: new protocols, a proliferation of networks

• 1983: deployment of TCP/ • new national networks: IP CSnet, BITnet, NSFnet, • 1982: smtp e-mail protocol defined • 100,000 hosts connected • 1983: DNS defined for to confederation of name-to-IP-address networks translation • 1985: ftp protocol defined • 1988: TCP congestion control

1-19 Internet history 1990, 2000’s: commercialization, the Web, new apps

• early 1990’s: ARPAnet late 1990’s – 2000’s: decommissioned • 1991: NSF lifts restrictions on • more killer apps: instant commercial use of NSFnet messaging, P2P file sharing (decommissioned, 1995) • network security to • early 1990s: Web – hypertext [Bush 1945, forefront Nelson 1960’s] • est. 50 million host, 100 – HTML, HTTP: Berners-Lee million+ users – 1994: , later • backbone links running at Gbps – late 1990’s: commercialization of the Web

1-20 Internet history 2005-present • Over a billion hosts – More and tablets • Aggressive deployment of broadband access • Increasing ubiquity of high-speed wireless access • Emergence of online social networks: – Facebook: over one billion users • Service providers (Google, Microsoft) create their own networks – Bypass Internet, providing “instantaneous” access to search, email, etc. • E-commerce, universities, enterprises running their services in “cloud” (eg, Amazon EC2)

1-21

Now and beyond

• Computers in your pocket, on your wrist and face • Machine to machine • Environment monitoring through the crowd • Healthy life styles and medical research • Ubiquitous computing – Ambient intelligence

“The most profound technologies are those that disappear. They weave themselves into the fabric of everyday life unl they are indisnguishable from it.”

Mark Weiser Chief Scienst, Xeros PARC The Computer for the 21st Century Scienfic American September 1991 1-24