Computer Networking

Yao Liang, Professor [email protected]

Dept. of Computer Science IUPUI Fall 2020

Introduction 1-1 Roadmap Computer networking is the area in Computer Science studying the principles of connecting computer devices via communication networks (e.g., ) 1.1 what is the Internet? 1.2 network edge 1.3 network core 1.4 protocol layers, service models 1.5 history

Introduction 1-2 What’s the Internet: “nuts and bolts” view

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

Packet switches: forward router packets (chunks of data) institutional network . routers and switches

Introduction 1-3 “Fun” internet appliances

Fitbit 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 Internet phones refrigerator 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 network  provides programming regional ISP interface to apps . hooks that allow sending and receiving app programs to “connect” to Internet . provides service options, analogous to postal service institutional network

Introduction 1-6 What’s a protocol?

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

Introduction 1-7 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?

Introduction 1-8 A closer look at network structure:

 network edge: mobile network . hosts: clients and servers global ISP . servers often in data centers home  access networks, physical network media: wired, wireless regional ISP communication links

 network core: . interconnected routers . network of networks institutional network

Introduction 1-9 Access networks

Q: How to connect end systems to edge router?  residential access nets  institutional access networks (school, company)  mobile access networks

Introduction 1-10 Enterprise access networks ()

institutional link to ISP (Internet) institutional router

Ethernet institutional mail, switch web servers

 typically used in companies, universities, etc  10 Mbps, 100Mbps, 1Gbps, 10Gbps transmission rates  today, end systems typically connect into Ethernet switch

Introduction 1-14 Wireless access networks

 shared wireless access network connects end system to router . via aka “access point” wireless LANs: wide-area wireless access . within building (100 ft) . provided by telco (cellular) . 802.11b/g (WiFi): 11, 54 Mbps operator, 10’s km transmission rate . between 1 and 10 Mbps . , 4G: LTE

to Internet

to Internet

Introduction 1-15 The network core

 mesh of interconnected routers  packet-switching: hosts break application-layer messages into packets . forward packets from one router to the next, across links on path from source to destination . each packet transmitted at full link capacity

Introduction 1-18 : 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:  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

Introduction 1-19 Two key network-core functions routing: determines source- forwarding: move packets from destination route taken by router’s input to appropriate packets router output . routing algorithms

routing algorithm

local forwarding table header value output link 0100 3 1 0101 2 0111 2 3 2 1001 1

dest address in arriving packet’s header Network Layer 4-20 Internet structure: network of networks

Question: given millions of access ISPs, how to connect them together?

access access net net access net access access net net access access net net

access access net net

access net access net

access net access net access access net access net net Internet structure: network of networks

Option: connect each access ISP to every other access ISP?

access access net net access net access access net net access access net net connecting each access ISP to each other directly doesn’t access access net scale: O(N2) connections. net

access net access net

access net access net access access net access net net Internet structure: network of networks

Option: connect each access ISP to a global transit ISP? Customer and provider ISPs have economic agreement.

access access net net access net access access net net access access net net

global

access access net ISP net

access net access net

access net access net access access net access net net Internet structure: network of networks

But if one global ISP is viable business, there will be competitors ….

access access net net access net access access net net access access net net ISP A

access access net ISP B net

access ISP C net access net

access net access net access access net access net net Internet structure: network of networks

But if one global ISP is viable business, there will be competitors …. which must be interconnected Internet exchange point access access net net access net access access net net IXP access access net net ISP A

access IXP access net ISP B net

access ISP C net access net

access peering link net access net access access net access net net Internet structure: network of networks

… and regional networks may arise to connect access nets to ISPS

access access net net access net access access net net IXP access access net net ISP A

access IXP access net ISP B net

access ISP C net access net

access net regional net access net access access net access net net Tier-1 ISP Network map: Sprint (2019)

POP: point-of-presence to/from other Sprint PoPS links to peering networks … …

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

Introduction 1-33 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 . Ethernet, 802.111 (WiFi), PPP  physical: bits “on the wire”

Introduction 1-34 source message M applicatio Encapsulation segment Ht M n

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

switch

destination Hn Ht M network H H H M M applicatio l n t link Hn Ht M physical Ht M n Hn Ht M transport Hl Hn Ht M network router link physical 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 . ARPAnet has 15 nodes conceived by Advanced Research Projects Agency  1969: first ARPAnet operational . https://www.youtube.com/watch?v=kh ajeqHUQ7Q . https://www.youtube.com/watch?v=vu iBTJZfeo8 Introduction 1-37 Internet history

1972-1980: Internetworking, new and proprietary nets

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

Introduction 1-38 Internet history

1980-1990: new protocols, a proliferation of networks

 1983: deployment of  new national networks: TCP/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

Introduction 1-39 Internet history 1990, 2000’s: commercialization, the Web, new apps

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

Introduction 1-40 Internet history

2005-present: more new applications, Internet is “everywhere”

. ~18B devices attached to Internet (2017) • rise of (iPhone: 2007) . aggressive deployment of broadband access . increasing ubiquity of high-speed wireless access: 4G/5G, WiFi . emergence of online social networks: • Facebook: ~ 2.5 billion users . service providers (Google, FB, Microsoft) create their own networks • bypass commercial Internet to connect “close” to end user, providing “instantaneous” access to search, video content, … . enterprises run their services in “cloud” (e.g., Amazon Web Services, Microsoft Azure) Summary

you now have:  Concepts, overview, “feel” of networking  More depth, detail to have CSCI43600  And CSCI43300 Introduction to Internet of Things

Networking in Future :  Internet of Things  Wireless sensor networks  5G communications  Cognitive and smart networks  Better network security  …

Introduction 1-42