Lec 1 internet overview
This presentation is the property of its rightful owner.
Sponsored Links
1 / 46

Lec 1: Internet Overview PowerPoint PPT Presentation


  • 81 Views
  • Uploaded on
  • Presentation posted in: General

Lec 1: Internet Overview. ECE5650. Intenet. Physical Connectivity Topology Access network and physical media Layered Internet Protocol Stack History. millions of connected computing devices: hosts = end systems running network apps communication links fiber, copper, radio, satellite

Download Presentation

Lec 1: Internet Overview

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


Lec 1 internet overview

Lec 1: Internet Overview

ECE5650

Overview


Intenet

Intenet

  • Physical Connectivity

    • Topology

    • Access network and physical media

  • Layered Internet Protocol Stack

  • History

Overview


What s 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)

router

workstation

server

mobile

local ISP

regional ISP

company

network

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

Overview


What s the internet a service view

Distributed applications:

Web, email, games, e-commerce, file sharing

Network protocols: used by applications tocontrol sending, receiving of msgs:

TCP, IP, HTTP, FTP, PPP

Internet standards

RFC: Request for comments

IETF: Internet Engineering Task Force

Communication services provided to apps:

Connectionless unreliable

connection-oriented reliable

What’s the Internet: a service view

Overview


A closer look at network structure

network edge: applications and hosts

network core:

routers

network of networks

access networks, physical media: communication links

A closer look at network structure:

Overview


The network edge

end systems (hosts):

run application programs

e.g. Web, email

at “edge of network”

Programs in end-systems use the serivce of the Internet to send msgs to each other

client/server model

client host requests, receives service from always-on server; e.g. web, email

peer-peer model:

minimal (or no) use of dedicated servers

e.g. Gnutella, KaZaA, Skype, BitTorrent

The network edge:

Overview


The network core

Physical connectivity of local area networks

mesh of interconnected routers

Logical connectivity: how is data transferred through net?

The Network Core

Overview


Internet structure network of networks

roughly hierarchical

at center: “tier-1” ISPs or Internet backbone networks (e.g., MCI, Sprint, AT&T, Cable and Wireless), national/international coverage, connect to large tier-2 ISPs and to all tier-1 ISPs and many customer networks.

NAP

Tier-1 providers also interconnect at public Network Access Points (NAPs).

Tier-1 providers interconnect (peer) privately

Internet structure: network of networks

Tier 1 ISP

Tier 1 ISP

Tier 1 ISP

Overview


Commercial internet isp connectivity

Commercial Internet ISP Connectivity

  • Roughly hierarchical

    • Divided into tiers

    • Tier-1 ISPs are also called backbone providers, e.g., AT&T, Sprint, UUNet, Level 3, Qwest, Cable & Wireless

  • An ISP runs (private) Points of Presence (PoP) where its customers and other ISPs connect to it

    • E.g., MCI has 4,500 PoP

    • called private peering

  • ISPs also connect at (public) Network Access Point (NAP)

    • called public peering

Overview


Internet structure network of networks1

“Tier-2” ISPs: smaller (often regional) ISPs

Connect to one or more tier-1 ISPs, possibly other tier-2 ISPs

NAPs (Network Access Points) are complex high-speed switching networks often concentrated at a single building. Operated by 3rd party telecom or Internet backbone ISP-1.

PoPs (Points of Presence) are private group of routers within each ISP and used to connect it (peer it) with other up/down/equal ISPs and is the new trend in connectivity.

NAP

Tier-2 ISPs also peer privately with each other, interconnect at public NAPs or private POPs.

Tier-2 ISP pays tier-1 ISP for connectivity to rest of Internet, tier-2 ISP is customer of

tier-1 provider

Tier-2 ISP

Tier-2 ISP

Tier-2 ISP

Tier-2 ISP

Tier-2 ISP

Internet structure: network of networks

Tier 1 ISP

Tier 1 ISP

Tier 1 ISP

Overview


Internet structure network of networks2

“Tier-3” ISPs and local ISPs

last hop (“access”) network (closest to end systems)

Tier 3

ISP

local

ISP

local

ISP

local

ISP

local

ISP

local

ISP

local

ISP

local

ISP

local

ISP

NAP

Local and tier- 3 ISPs are customers of

higher tier ISPs

connecting them to rest of Internet

Tier-2 ISP

Tier-2 ISP

Tier-2 ISP

Tier-2 ISP

Tier-2 ISP

Internet structure: network of networks

Tier 1 ISP

Tier 1 ISP

Tier 1 ISP

Overview


Internet structure network of networks3

a packet passes through many networks!

Tier 3

ISP

local

ISP

local

ISP

local

ISP

local

ISP

local

ISP

local

ISP

local

ISP

local

ISP

NAP

Tier-2 ISP

Tier-2 ISP

Tier-2 ISP

Tier-2 ISP

Tier-2 ISP

Internet structure: network of networks

Tier 1 ISP

Tier 1 ISP

Tier 1 ISP

Overview


Tier 1 isp e g sprint

Tier-1 ISP: e.g., Sprint

Introduction


Att global backbone ip network

ATT Global Backbone IP Network

From http://www.business.att.com

Overview


Michnet statewide backbone

MichNet: Statewide Backbone

  • Nation’s longest-running regional network

  • An 2.5 Gigabit (OC48c) backbone, with 24 backbone nodes

  • Two diverse 2.5 gigabit (2x OC48) to chicago

  • www.merit.edu/mn

Overview


Lec 1 internet overview

Overview


Intenet1

Intenet

  • Physical Connectivity

    • Structure

    • Access network and physical media

  • Layered Internet Protocol Stack

  • History

Overview


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

Keep in mind:

bandwidth (bits per second) of access network?

shared or dedicated?

Access networks and physical media

Overview


Residential access point to point access

Dialup via modem

Uses existing telephony infrastructure; Home is connected to central office

up to 56Kbps direct access to router (often less)

Can’t surf and phone at same time: can’t be “always on”

Residential access: point to point access

central office

telephone

network

Internet

homedial-up

modem

ISPmodem

(e.g., AOL)

home

PC

Overview


Lec 1 internet overview

telephone

network

  • ADSL: asymmetric digital subscriber line

    • up to 1 Mbps upstream (today typically < 256 kbps)

    • up to 8 Mbps downstream (today typically < 1 Mbps)

    • FDM: 50 kHz - 1 MHz for downstream

      4 kHz - 50 kHz for upstream

      0 kHz - 4 kHz for ordinary telephone

Existing phone line:0-4KHz phone; 4-50KHz upstream data; 50KHz-1MHz downstream data

Internet

home

phone

DSLAM

splitter

DSL

modem

central

office

home

PC

Overview


Residential access cable modems

HFC: hybrid fiber coax

asymmetric: up to 30Mbps downstream, 2 Mbps upstream

network of cable and fiber attaches homes to ISP router

homes share access to router so communication activity is visible to each other.

deployment: available via cable TV companies

Residential access: cable modems

Overview


Residential access cable modems1

Residential access: cable modems

Diagram: http://www.cabledatacomnews.com/cmic/diagram.html

Overview


Cable network architecture overview

Cable Network Architecture: Overview

Typically 500 to 5,000 homes

cable headend

home

cable distribution

network (simplified)

Overview


Cable network architecture overview1

Cable Network Architecture: Overview

cable headend

home

cable distribution

network (simplified)

Overview


Cable network architecture overview2

server(s)

Cable Network Architecture: Overview

cable headend

home

cable distribution

network

Overview


Cable network architecture overview3

C

O

N

T

R

O

L

D

A

T

A

D

A

T

A

V

I

D

E

O

V

I

D

E

O

V

I

D

E

O

V

I

D

E

O

V

I

D

E

O

V

I

D

E

O

5

6

7

8

9

1

2

3

4

Channels

Cable Network Architecture: Overview

FDM:

cable headend

home

cable distribution

network

Overview


Company access local area networks

company/univ local area network (LAN) connects end system to edge router

Ethernet:

shared or dedicated link connects end system and router

10 Mbs, 100Mbps, Gigabit Ethernet

LANs: chapter 5

Company access: local area networks

Overview


Wireless access networks

shared wireless access network connects end system to router

via base station aka “access point”

wireless LANs:

802.11a/b/g (WiFi): 11 Mbps ~54Mbps

802.11n: 100~200Mbps (theoretically up to 300Mbps)

wider-area wireless access

provided by telco operator

3G ~ 384 kbps

Will it happen??

WAP/GPRS in Europe

WiMAX

~100Mbps

~10 miles

router

base

station

mobile

hosts

Wireless access networks

Overview


Home networks

Typical home network components:

DSL or cable modem

router/firewall/NAT

Ethernet

wireless access

point

Home networks

wireless

laptops

to/from

cable

headend

cable

modem

router/

firewall

wireless

access

point

Ethernet

Introduction


Physical media

Bit: propagates betweentransmitter/rcvr pairs

physical link: what lies between transmitter & receiver

guided media:

signals propagate in solid media: copper, fiber, coax

unguided media:

signals propagate freely, e.g., radio

Twisted Pair (TP)

two insulated copper wires

Category 3: traditional phone wires, 10 Mbps Ethernet

Category 5: 100Mbps Ethernet

Physical Media

Introduction


Physical media coax fiber

Coaxial cable:

two concentric copper conductors

bidirectional

baseband:

single channel on cable

legacy Ethernet

broadband:

multiple channels on cable

HFC

Physical Media: coax, fiber

Fiber optic cable:

  • glass fiber carrying light pulses, each pulse a bit

  • high-speed operation:

    • high-speed point-to-point transmission (e.g., 10’s-100’s Gps)

  • low error rate: repeaters spaced far apart ; immune to electromagnetic noise

Introduction


Physical media radio

signal carried in electromagnetic spectrum

no physical “wire”

bidirectional

propagation environment effects:

reflection

obstruction by objects

interference

Physical media: radio

Radio link types:

  • terrestrial microwave

    • e.g. up to 45 Mbps channels

  • LAN (e.g., Wifi)

    • 11Mbps, 54 Mbps

  • wide-area (e.g., cellular)

    • 3G cellular: ~ 1 Mbps

  • satellite

    • Kbps to 45Mbps channel (or multiple smaller channels)

    • 270 msec end-end delay

    • geosynchronous versus low altitude

Introduction


Intenet2

Intenet

  • Physical Connectivity

    • Topology

    • Access network and physical media

  • Layered Internet Protocol Stack

  • History

Overview


What s a protocol

human protocols:

“what’s the time?”

“I have a question”

introductions

network protocols:

machines rather than humans

all communication activity in Internet governed by protocols

What’s a protocol?

A protocol is a set of rules that govens how two or more communicating parties are to interact. It defines:

- msg format

- order of msgs sent & received

- actions taken on msg transmission & receipt

Overview


Protocol layers

Protocol “Layers”

Networks are complex!

  • many “pieces”:

    • hosts

    • routers

    • links of various media

    • applications

    • protocols

    • hardware, software

  • Layered Protocol

    • Modular approach to network functionality

    • Examples:

      • Taking an airplane trip

      • Mailing service

Overview


Internet protocol stack

application: supporting network applications

FTP, SMTP, HTTP

transport: process-process data transfer

TCP, UDP

network: host-host data transfer

IP

link: data transfer between neighboring network elements

PPP, Ethernet

physical: bits “on the wire”

application

transport

network

link

physical

Internet protocol stack

Overview


Encapsulation

network

link

physical

link

physical

M

M

Ht

Ht

M

M

Hn

Hn

Hn

Hn

Ht

Ht

Ht

Ht

M

M

M

M

Hl

Hl

Hl

Hl

Hl

Hl

Hn

Hn

Hn

Hn

Hn

Hn

Ht

Ht

Ht

Ht

Ht

Ht

M

M

M

M

M

M

source

Encapsulation

message

application

transport

network

link

physical

segment

datagram

frame

switch

destination

application

transport

network

link

physical

router

Overview


Characteristics of layering

Characteristics of Layering

  • Layering positives:

    • Each layer relies on services from layer below and exports services to layer above

    • Interface defines interaction

    • Hides implementation - layers can change without disturbing other layers (black box)

  • Layering negatives: duplicate functionality and inter-dependency.

Overview


Internet history

1961: Kleinrock - queueing theory shows effectiveness of packet-switching

1964: Baran - packet-switching in military nets

1967: ARPAnet conceived by Advanced Research Projects Agency

1969: first ARPAnet node operational

1972:

ARPAnet demonstrated publicly

NCP (Network Control Protocol) first host-host protocol

first e-mail program

ARPAnet has 15 nodes

Internet History

1961-1972: Early packet-switching principles

Overview


Initial arpanet

Initial ARPANET

  • 1965-1968

    • ARPANET plan, implemented by BBN (Bolt, Beranek, Newman): packet switch to build IMP

  • 1969

    • ARPANET commissioned: 4 nodes, 50kbps

Overview


Initial expansion of the arpanet

Initial Expansion of the ARPANET

Dec. 1969

July 1970

Mar. 1971

Apr. 1972

Sept. 1972

Overview

RFC 527: ARPAWOCKY; RFC 602: The Stockings Were Hung by the Chimney with Care


Internet history1

1970: ALOHAnet satellite network in Hawaii

1973: Metcalfe’s PhD thesis proposes Ethernet

1974: Cerf and Kahn – archi. for interconnecting networks

Initially, named NCP

Later, split to TCP/IP

late70’s: proprietary architectures: DECnet, SNA, XNA

late 70’s: switching fixed length packets (ATM precursor)

1979: ARPAnet has 200 nodes

Cerf and Kahn’s internetworking principles:

minimalism, autonomy - no internal changes required to interconnect networks

best effort service model

stateless routers

decentralized control

define today’s Internet architecture

2005 ACM Turing Award

“A protocol for packet network interconnection”, IEEE Trans. on Communications Technology, vol.22(5), 627-641

Internet History

1972-1980: Internetworking, new and proprietary nets

Overview


Internet history2

1983: deployment of TCP/IP

1982: SMTP e-mail protocol defined

1983: DNS defined for name-to-IP-address translation

1985: FTP protocol defined

1988: TCP congestion control

new national networks: Csnet, BITnet, NSFnet, Minitel

100,000 hosts connected to confederation of networks

Internet History

1980-1990: new protocols, a proliferation of networks

Overview


Internet history3

Early 1990’s: ARPAnet decommissioned

1991: NSF lifts restrictions on commercial use of NSFnet (decommissioned, 1995)

1992, 1 million hosts

early 1990s: Web

hypertext [Bush 1945, Nelson 1960’s]

HTML, HTTP: Berners-Lee

1994: Mosaic, later Netscape

late 1990’s: commercialization of the Web

Late 1990’s – 2000’s:

more killer apps: instant messaging, peer2peer file sharing (e.g., BitTorrent, YouTube)

network security to forefront

Today:

400 million users, 150 countries

backbone links running at 10 Gbps

Internet History

1990, 2000’s: commercialization, the Web, new apps

Overview


Growth of the internet

Growth of the Internet

Number of Hosts on the Internet:

Aug. 1981 213

Oct. 1984 1,024

Dec. 1987 28,174

Oct. 1990 313,000

Jul. 1993 1,776,000

Jul. 1996 19,540,000

Jul. 1999 56,218,000

Jul. 2004 285,139,000

Jan. 2005 317,646,000

Jul. 2005 353,284,000

About 2B users out of 6.8B people,

from 16M in 1995, 350M in 2000,1B in 2005

Overview


Summary

Summary

  • Physical Connectivity

    • Topology

    • Access network and physical media

  • Layered Internet Protocols

  • History

Overview


  • Login