Kick starting science ... Computer networking (TDDD63): Part 1 - PDF document

2015-09-20 Kick starting science ... Computer networking (TDDD63): Part 1 … Niklas Carlsson, Associate Professor http://www.ida.liu.se/~nikca/ What do you have in the future? What do you have in the future? … well, cable into wall … How does it keep going? 1

2015-09-20 What happens there? What happens there? Or maybe more realistically … • Work at company … Important problem faced every day How do we build services that are … by many companies, including … Efficient Secure Reliable 1-12 2

2015-09-20 In the computer network part we How do we build scalable, efficient, will look at things such as … secure, and reliable services? How do we communicate with a How do we find out who to talk to? machine across the world? How do we avoid sending too much for How do we find a path? the receiver and network to handle? 3

2015-09-20 What happens at our machine? Inside the What happens at our machine? Inside the network? Along the path? network? Along the path? Roadmap • What is the Internet? • Network Edge • End systems, access networks, links • Network Core So let’s start the lecture … • Packet switching, network structure • Protocol Layers, service models • Network Security • History What’s the Internet: “Nuts and Bolts View” Roadmap • What is the Internet? • Network Edge • End systems, access networks, links • Network Core • Packet switching, network structure • Protocol Layers, service models • Network Security • History 4

2015-09-20 What’s the Internet: “Nuts and Bolts View” What’s the Internet: “Service View” Today’s service/company landscape include ... Today’s service/company landscape include ... 1-27 1-28 Today’s service/company landscape include ... Today’s service/company landscape include ... Network operators Equipment manufacturers Equipment manufacturers (also sell services and help (also sell services and help Operate networks) Operate networks) 1-29 1-30 5

2015-09-20 Today’s service/company landscape include ... Today’s service/company landscape include ... Content delivery networks Enterprise solutions Enterprise solutions and network service and network service (e.g., data center (e.g., data center solutions and cloud solutions and cloud providers) providers) 1-31 1-32 Today’s service/company landscape include ... Some common applications today … • World Wide Web (WWW) • Remote login (telnet, rlogin, ssh) End user services (e.g., • File transfer web-based social • networks, search, Peer-to-peer file sharing communication, and • Cloud computing/services streaming) • Instant messaging (chat, text messaging, etc.) • Live and video-on-demand streaming • Internet phone (Voice-Over-IP) • Distributed games • … 1-33 34 … and tomorrow Today’s end hosts … The 2020 vision  Everything that can be connected will be connected  50B devices (perhaps more like 500B ...)  IoT and smart cities  Machine-to-machine  High-definition 3D streaming to heterogeneous clients 35 6

2015-09-20 … and tomorrow’s Internet of Things! Roadmap A Closer Look at Network Structure • What is the Internet? • Network Edge • End systems, access networks, links • Network Core • Packet switching, network structure • Protocol Layers, service models • Network Security • History Access Networks and Physical Media Access Net: Digital Subscriber Line (DSL) 7

2015-09-20 Access Net: Cable Network Access Net: Home Network Wireless Access Networks Enterprise Access Networks (Ethernet) Host: Sends Packets of Data Physical Media 8

2015-09-20 Physical Media: Radio Roadmap • What is the Internet? • Network Edge • End systems, access networks, links • Network Core • Packet switching, network structure • Protocol Layers, service models • Network Security • History The Network Core Packet-Switching: Store-and-forward Two Key Network Functions Packet Switching: Queueing Delay, Loss 9

2015-09-20 Internet Structure: Network of Networks Internet Structure: Network of Networks Internet Structure: Network of Networks Internet Structure: Network of Networks Internet Structure: Network of Networks Internet Structure: Network of Networks IXP- 3rd party company sets up an exchange point where multiple ISPs Tier 1 ISPs can peer together (about 300 IXPs) Peering Link - all traffic between two ISPs travels through one direct connection 10

2015-09-20 Internet Structure: Network of Networks Internet Structure: Network of Networks Tier-1 ISP: Sprint Internet Structure: Network of Networks POP: ISP to ISP Sets of routers in the provider’s network Google private network bypasses Google has over 50 data centers some with upper tiers by peering with lower tiers over 100,000 servers, all interconnected via connections where customer ISPs can connect into provider ISP directly Googles private TCP/IP network What’s a Protocol? Roadmap • What is the Internet? • Network Edge • End systems, access networks, links • Network Core • Packet switching, network structure • Protocol Layers, service models • Network Security • History 11

2015-09-20 What’s a Protocol? What’s a Protocol? A Human A Human A Computer Protocol Protocol Network Protocol Protocol “Layers” What's a Protocol? Problem Scenario More Problems Web Email Bittorrent VoIP Bittorrent Bittorrent Application endpoints • This is a nightmare scenario may not be on the • Huge amounts of work to add new apps or media same media • Limits growth and adoption 802.11 Ethernet Ethernet 802.11 Bluetooth Cellular 12

2015-09-20 Solution: Use Indirection Layers, Protocols, Interfaces • Web Email Bittorrent VoIP Networks organized as a stack of layers • Offer services to the layer above it using a well- defined interface (programming language analogy: API libraries hide details while providing a service) • Reduces design complexity • O(1) work to add new apps, media Magical Network Abstraction • Protocols: Logical “horizontal” conversations at any • Few limits on new technology Layer layer (between peers) API API API • Data Transfer: each layer passes data & control information over the interfaces (between neighboring layers) Ethernet 802.11 Bluetooth Cellular Internet Protocol Stack The Hourglass HTTP, FTP, RTP, IMAP, Jabber, … TCP, UDP, ICMP IPv4 Ethernet, 802.11x, DOCSIS, … Fiber, Coax, Twisted Pair, Radio, … 76 Layering: logical communication Layering: logical communication data application application transport transport transport network network link link physical physical network ack network application link application link transport physical transport data physical network network link link data physical physical application application application application transport transport transport transport transport network network network network link link link link physical physical physical physical 13

2015-09-20 Layering: physical communication Encapsulation: Layering and data data Each layer takes data from above application • adds header information to create new data unit transport network • passes new data unit to layer below link physical network source destination application link transport physical message application application network M link transport transport data physical application application network network transport transport link link network network physical physical link link physical physical Encapsulation: Layering and data Encapsulation: Layering and data Each layer takes data from above Each layer takes data from above • adds header information to create new data unit • adds header information to create new data unit • passes new data unit to layer below • passes new data unit to layer below source source destination destination message message M application application M application application transport transport segment transport transport segment H M H M t t network network network network datagram H H M n t link link link link physical physical physical physical Encapsulation: Layering and data Encapsulation: Layering and data Each layer takes data from above Each layer takes data from above • adds header information to create new data unit • adds header information to create new data unit • passes new data unit to layer below • passes new data unit to layer below source source destination destination application message application message M application M application transport transport segment transport transport segment H H M M t t network network network datagram network datagram H H M H H M n t n t link link link link H H H M H H H M frame H H H M n t frame l l n t l n t physical physical physical physical 14