lecture 1 internet n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Lecture 1 Internet PowerPoint Presentation
Download Presentation
Lecture 1 Internet

Loading in 2 Seconds...

play fullscreen
1 / 30

Lecture 1 Internet - PowerPoint PPT Presentation


  • 98 Views
  • Uploaded on

Lecture 1 Internet. CPE 401 / 601 Computer Network Systems. slides are modified from Dave Hollinger and Daniel Zappala. Network. “ ... communication system for connecting end-systems” End-systems a.k.a. “hosts” PCs, workstations dedicated computers network components.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

Lecture 1 Internet


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
lecture 1 internet

Lecture 1Internet

CPE 401 / 601Computer Network Systems

slides are modified from Dave Hollinger and Daniel Zappala

network
Network

“ ... communication system for connecting end-systems”

End-systems a.k.a. “hosts”

PCs, workstations

dedicated computers

network components

Internet

multiaccess vs point to point
Multiaccess vs. Point-to-point
  • Multiaccess means shared medium.
    • many end-systems share the same physical communication resources (wire, frequency, ...)
    • There must be some arbitration mechanism.
  • Point-to-point
    • only 2 systems involved
    • no doubt about where data came from !

Internet

lan local area network
LAN - Local Area Network
  • connects computers that are physically close together ( < 1 mile).
    • high speed
    • multi-access
  • Technologies:
    • Ethernet 10 Mbps, 100Mbps
    • Token Ring 16 Mbps
    • FDDI 100 Mbps

Internet

wan wide area network
WAN - Wide Area Network
  • connects computers that are physically far apart. “long-haul network”.
    • typically slower than a LAN.
    • typically less reliable than a LAN.
    • point-to-point
  • Technologies:
    • telephone lines
    • Satellite communications

Internet

man metropolitan area network
MAN - Metropolitan Area Network
  • Larger than a LAN and smaller than a WAN

- example: campus-wide network

    • multi-access network
  • Technologies:
    • coaxial cable
    • microwave

Internet

internetwork
Internetwork
  • Connection of 2 or more distinct (possibly dissimilar) networks.
  • Requires some kind of network device to facilitate the connection.

Net A

Net B

Internet

the internet

PC

Mobile network

server

Global ISP

wireless

laptop

cellular

handheld

Home network

Regional ISP

access

points

wired

links

Institutional network

router

The Internet
  • millions of connected computing devices: hosts = end systems
    • running network apps
  • communication links
    • fiber, copper, radio, satellite
  • routers: forward packets (chunks of data)

Internet

the internet1
The Internet

Internet Mapping Project, Bill Cheswick

Internet

a network of networks
A Network of Networks
  • roughly hierarchical
    • Tier-1 ISPs provide national, international coverage
    • Tier-2 ISPs provide regional coverage
    • Tier-3 and lower levels provide local coverage
  • any tier may sell to business and residential customers
  • any ISP may have a link to any other ISP (not strictly hierarchical)

Internet

many different internet service providers
Many Different Internet Service Providers
  • Each network is independent
  • Interoperability requires using Internet standards: IP, TCP
    • the Internet is global and must run these standards
    • your private intranet can do whatever you want it to do

Internet

internet design goals
Internet Design Goals
  • primary goal: interoperability among existing networks
    • a network of networks
    • obey administrative boundaries
  • secondary goals
    • fault tolerance
    • multiple transport protocols
    • support a variety of networks
    • distributed management
    • cost effective, low effort for host attachment, accountability
  • first three were more important, so remaining four did not receive as much attention
  • no mention of security

Internet

internet design principles
Internet Design Principles
  • minimal assumptions about services network should support
    • ability to send packets
    • no reliability or security
  • end-to-end principle
    • keep the core of the network as simple as possible,
    • put complex functionality at the edges
    • exception: significant performance improvement

Internet

network models
Network Models
  • Using a formal model allows us to deal with various aspects of Networks abstractly.
  • We will look at a popular model (OSI reference model).
  • The OSI reference model is a layered model.

Internet

layering
Layering
  • Divide a task into pieces and then solve each piece independently (or nearly so).
  • Establishing a well defined interface between layers makes porting easier.
  • Major Advantages:
    • Code Reuse
    • Extensibility

Internet

interface and peer to peer protocols

Process

Process

Interface Protocols

Transport

Transport

Peer-to-peer Protocols

Network

Network

Data Link

Data Link

Interface and Peer-to-peer Protocols
  • Interface protocols describe communication between layers on the same endpoint.
  • Peer-to-peer protocols describe communication between peers at the same layer.

Internet

what s a protocol
What’s a protocol?

human protocols:

  • “what’s the time?”
  • “I have a question”
  • introductions

… 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

Internet

what s a protocol1

TCP connection

response

Get http://www.awl.com/kurose-ross

Got the

time?

2:00

<file>

time

What’s a protocol?

a human protocol and a computer network protocol:

Hi

TCP connection

request

Hi

Q: Other human protocols?

Internet

protocol
Protocol
  • An agreed upon convention for communication.
    • both endpoints need to understand the protocol.
  • Protocols must be formally defined and unambiguous!
  • Protocols define
    • format,
    • order of msgs sent and received among network entities,
    • actions taken on msg transmission, receipt
  • We will study lots of existing protocols and perhaps develop a few of our own.

Internet

programs processes
Programs & Processes
  • A program is an executable file.
  • A process or task is an instance of a program that is being executed.
  • A single program can generate multiple processes.

Internet

client server
Client - Server
  • A server is a process - not a machine !
  • A server waits for a request from a client.
  • A client is a process that sends a request to an existing server and (usually) waits for a reply.

Internet

client server examples
Client - Server Examples
  • Server returns the time-of-day.
  • Server returns a document.
  • Server prints a file for client.
  • Server does a disk read or write.
  • Server records a transaction.

Internet

servers
Servers
  • Servers are generally more complex (more interesting).
  • Basic types of servers:
    • Iterative - server handles one client at a time.
    • Concurrent - server handles many clients at a time.
  • We will study the differences later.

Internet

thought exercise
Thought Exercise
  • Come up with an example of a layered system.
  • Describe the interface and peer-to-peer protocols for your example.

Internet

layering example federal express
Layering Example: Federal Express

Addressed

Envelope

Letter

  • Letter in envelope, address on outside
  • FedX guy adds addressing information, barcode.
  • Local office drives to airport and delivers to hub.
  • Sent via airplane to nearest city.
  • Delivered to right office
  • Delivered to right person

Addressed

Envelope

Letter

Internet

layered software systems
Layered Software Systems
  • Network software
  • Operating systems
  • Windowing systems

Internet

unix is a layered system
Unix is a Layered System

Applications

Libraries

System Calls

Kernel

Internet