Internet Overview: roadmap

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Internet Overview roadmap

• 1.1 What is the Internet?
• 1.2 Network edge
• end systems, access networks, links
• 1.3 Network core
• network structure, circuit switching, packet
  switching
• 1.4 Delay, loss and throughput in Internet
• 1.5 Protocol layers, service models
• 1.6 Networks under attack security

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How is the Internet Organized

• A hierarchical structure.
• hosts combine to form a Local Area Network (LAN).
• LANs combine to form an Autonomous System (AS)
• Autonomous Systems combine to form the Internet.

Internetworked networks Internet !
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Whats the Internet nuts and bolts view

• millions of connected computing devices hosts
  end systems
• running network apps

• communication links
• fiber, copper, radio, satellite
• transmission rate bandwidth

• routers forward packets (chunks of data)

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Whats the Internet operational view

• Internet network of networks
• Requires sending, receiving of messages
• protocols control sending, receiving of messages
• e.g., TCP, IP, HTTP, Skype, Ethernet etc.
• Design of protocols is the key for Internet

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Whats the Internet an operational view

• a human protocol and a computer network protocol

human protocol
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Whats the Internet an operational view

• human protocols
• specific msgs sent
• specific actions taken when msgs received, or
  other events

• network protocols
• machines rather than humans
• all communication activity in Internet governed
  by protocols

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Whats a protocol?

• a human protocol and a computer network protocol

human protocol
Internet protocol example
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Whats the Internet an operational view
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We have studied a high-level overview of the
Internet!Now, A closer look at the Internet
structure!
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Components of Internet

• Hosts (end-users)
• e.g. computers

• access networks, physical media wired, wireless
  communication links

• network core
• interconnected routers
• network of networks

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The network edge

• End-users (hosts)
• run application programs
• e.g. Web, email

• client/server model
• client host requests, receives service from
  always-on server
• e.g. Web browser/server email client/server

• peer-peer model
• minimal (or no) use of dedicated servers
• e.g. Skype, BitTorrent

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Access networks and physical media

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

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Residential access point to point access

• Dialup via modem
• up to 56Kbps direct access to router
  (conceptually)
• ADSL asymmetric digital subscriber line
• up to 1 Mbps home-to-router
• up to 8 Mbps router-to-home
• ADSL deployment happening

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Residential access cable modems

• HFC hybrid fiber coax
• asymmetric up to 10Mbps upstream, 1 Mbps
  downstream
• network of cable and fiber attaches homes to ISP
  router
• shared access to router among home
• issues congestion
• deployment available via cable companies, e.g.,
  MediaOne, CableVision

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Institutional access local area networks

• company/univ local area network (LAN) connects
  end system to edge router
• Ethernet
• shared or dedicated cable connects end system and
  router
• 10 Mbps, 100Mbps, Gigabit Ethernet
• deployment institutions, home LANs happening now

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Wireless access networks

• shared wireless access network connects end
  system to router
• wireless LANs
• radio spectrum replaces wire
• e.g., 802.11b/g (WiFi) 11 or 54 Mbps
• wider-area wireless access
• next up (?) WiMAX (10s Mbps) over wide area

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The Client/Server Model

• Client/server model is a basic design for
  Internet applications
• server - is the information provider
• client - is the information consumer
• example
• web server and a client running web browser
• a CNN web server simultaneously serves thousands
  of clients.
• In this class, we will also learn how to
  construct Web pages at the client end!

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Summary What have we learnt?

• What is Internet?
• Components
• Operational view
• System (structure) view
• Client-server and peer to peer model
• Access Networks

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Next Up

• 1.1 What is the Internet?
• 1.2 Network edge
• end systems, access networks, links
• 1.3 Network core
• network structure, circuit switching, packet
  switching
• 1.4 Delay, loss and throughput in Internet
• 1.5 Protocol layers, service models
• 1.6 Networks under attack security