Copyright 2005 John Wiley & Sons, Inc10 - 1 Business Data Communications and Networking 8th Edition Jerry Fitzgerald and Alan Dennis John Wiley & Sons,

Copyright 2005 John Wiley & Sons, Inc 10 - 1

Business Data Communications and Networking

8th Edition

Jerry Fitzgerald and Alan Dennis

John Wiley & Sons, Inc

Prof. M. UlemaManhattan College

Computer Information Systems


Chapter 10

The Internet


Outline

• How Internet works

– Architecture

• Internet Access Technologies

– DSL and cable modem

– Wireless Access

• Internet Governance

• Internet 2


Internet

• Most used network in the world

• Not one network, but a network of networks

• Made up of thousands of networks of – National and state government agencies,

– Non-profit organizations and for-profit companies.

• A rigidly controlled club – To exchange data, these networks must agree to use

Internet protocols

– TCP/IP MUST be supported by all networks

• Unrestricted applications and contents– Developed freely


Internet’s Hierarchical Structure

• National Internet Service Providers (ISPs)– Provide services to their customers and sell

access to regional ISPs and local ISPs

• Regional ISPs– Connect with National ISPs– Provide services to their customers and sell

access to local ISPs

• Local ISPs – Connected to National or Regional ISPs– Sell access to individuals


Internet’s Access Points• Network Access Points (NAPs)

– Connect National ISPs together

– Sometimes large regional and local ISPs also have access directly to NAPs

• Indiana University, for example, which provides services to about 40,000 individuals, connects directly to the Chicago NAP

– About a dozen NAPs in the U.S.– Run by common carriers such as Sprint and AT&T

• Metropolitan Area Exchanges (MAEs)– Connect Regional ISPs together– About 50 such MAEs in the U.S. today

Copyright 2005 John Wiley & Sons, Inc

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AccessNetworks

Core Networks

Connectivity and Processing

Transit Net

Transit Net

Transit Net

PrivatePeering

NAP

PublicPeering

InternetDatacenter

PSTNRegional

WirelineRegionalVoiceVoice

CellCell

Cell

CableModem

LAN

LAN

LAN

Premises-based

WLAN

WLAN

WLAN

Premises-based

Operator-based

H.323Data

Data

RAS

Analog

DSLAM

H.323


Basic Internet Architecture


Packet Exchange Charges

• Peering

– ISPs at the same level usually do not charge each other for exchanging messages

• Higher level ISPs charge lower level ones

– National ISPs charge regional ISPs which in turn charge local ISPs

• Local ISPs charge individuals and corporate users for access


Connecting to an ISP

• Done by through ISP’s Point of Presence (POP)– A place ISP provides service to its customers

• Individual users – Typically through a dial-up line using the PPP protocol

• Handled by the ISP’s modem pool– Userid and password checked by Remote Access

Server (RAS)

• Once logged in, the user can send packets over the phone line

• Corporate users – Typically access the POP using a T-1, T-3 or ATM OC-3

connections provided by a common carrier

• Cost = ISP charges + circuit charges


ISP Point-of Presence

Modem Pool

Individual Dial-up Customers

Corporate T1 Customer

T1 CSU/DSU

Corporate T3 Customer

T3 CSU/DSU

Corporate OC-3 Customer

ATM Switch

Layer-2 Switch

ISP POP

ISP POP

ISP POP

NAP/MAE

RemoteAccess Server

ATM Switch

Inside an ISP POP


ATM Switch

RouteServer

Router

ISP A

Router

ISP B

Router

ISP C

Router

ISP D

ISP E

ATM Switch

ISP F

ATM Switch

Inside an Internet NAP (Chicago)One of the busiest (4 Gbps; 140 ISPs)

Used to exchange routing information through BGP


Internet Backbones in 2002

• Backbone circuits for national ISPs– OC-48 and OC-192 (10 Gbps) becoming common

– To be converted to OC-192 (10 Gbps) by 2005

– OC-768 (40 Gbps) and use OC-3072 (160 Gbps) in experiment stage

• Aggregate Internet traffic– Growing rapidly

– Expected to reach 40 Terabits per second (Tbps) by 2007.

– NAPs and MAEs becoming bottlenecks

• Requiring larger and larger switches


Sprint’s Internet Backbone• A national ISP in North America

• Circuits: mostly ATM OC-12; few OC-48 and OC-192


Internet Access Technologies

• Most commonly used– 56K dial-up lines (individuals)

– T1 or T3 lines into ISPs (organizations)

• New access technologies– Commonly called “broadband access”

• Provide higher speed access

– Digital Subscriber Line (DSL)

– Cable Modems

– Fixed Wireless (including satellite access)

– Mobile Wireless (WAP)


Digital Subscriber Line (DSL)

• A family of point-to-point technologies

• Designed to provide high speed data transmission over traditional telephone lines– Traditional telephone lines (local loop)

• Limited capacity due to telephone and switching equipment at the end offices

• Constrained by 4 KHz voice channel

• Much higher bandwidth possible (with new technology based equipment DSL)

• Requires changing telephone equipment; not rewiring the local loop

• Not available in all locations in the US– More wide spread in Asia, Europe and Canada


Local Carrier End Office

Line Splitter

Customer Premises

Telephone

DSL Modem

Hub

Computer Computer

Local Loop

MainDistribution

Frame

CustomerPremises

CustomerPremises

Voice Telephone Network

DSL AccessMultiplexer

ATM Switch

ISP POP

ISP POP

ISP POP

ISP POP

DSL Architecture


Types of DSL• Asymmetric DSL (ADSL)

– Uses three FDM channels• 4 KHz analog voice channel• A simplex data channel for downstream traffic• A slower full-duplex data channel for Upstream traffic

– Size of digital channels

• Depends on the distance (CPE-Office) (up to 18,000 ft)

• Most common (T1): 1.5 Mbps down; 384 Kbps up

• Very high data rate DSL (VDSL)– Designed for local loops of 4500 ft or less (1000 ft ideal)

– Also uses three FDM channels as in ADSL

– Size of digital channels (distance sensitive)

• Most common (1/4OC1): 12 Mbps down; 1.6 Mbps up


Type Maximum Lengthof Local Loop

MaximumDownstream

Rate

Maximum Upstream Rate

T1 18,000 feet 1.5 Mbps 384 Kbps

E1* 16,000 feet 2.0 Mbps 384 Kbps

T2 12,000 feet 6.1 Mbps 384 Kbps

E2* 9,000 feet 8.4 Mbps 640 Kbps

* E1 and E2 are the European standard services similar to T1 and T2 services in North America

ADSL Data Rates


VDSL Data Rates


Cable Modems

• A digital service offered by cable television companies

• Data Over Cable Service Interface Specifications (DOCSIS)– Most common protocol used for cable modems

– Not a formal standard

• Offers vary (depends on the quality of cable plant)– In theory: downstream: 27-55Mbps; upstream: 2-10 Mpbs

– Typical: downstream: 1.5 -2 Mbps; upstream 0.2 – 2 Mbps

– A few cable companies offer downstream services only

• Upstream communications using regular telephone lines


Cable Modem Architecture• Similar to DSL (with one main difference):

– DSL: point-to-point technology

– Cable modems: use shared multipoint circuits

• All messages on the circuit heard by all computers on the circuit security issue

• 300 – 1000 customers per cable segment

• Type of equipment used– Cable Modem Termination System (CMTS)

• Used for upstream traffic only

• Converts data from DOCSIS to Internet protocols

– Fiber Node with an Optical Electrical (OE) converter

– Combiner (for downstream traffic only)

• Combines Internet traffic with TV video traffic


Cable Company Distribution Hub

Cable Splitter

Customer Premises

TV

Cable Modem

Hub

Computer Computer

SharedCoaxCable

System

Combiner

CustomerPremises

CustomerPremises

TV VideoNetwork

Cable Modem

TerminationSystem

ISP POP

Cable CompanyFiber Node

Optical/ElectricalConverter

Downstream

Upstream

Router

Cable Company

Fiber Node

Basic Cable Modem Architecture


Fixed Wireless• Requires “line of sight” access between transmitters

– Requires tall buildings and towers

– Common use: provide Internet access to multi-tenant buildings (apartment buildings, hotels, etc.,)

• Types of FWA– Point-to-point types

• Used to connect only two locations

– Point-multipoint types

• Allow access by a limited number of stations

• Designed as an alternative to DSL, cable modems

• Data access speeds – Range from 1.5 to 11 Mbps


Fixed Wireless Architecture


Mobile Wireless

• Allows users to access the Internet from any location

• Next major challenge in networking: Widespread mobile high speed Internet access

• Current Mobile wireless technologies– Slow access speeds compared to DSL,cable modem

– WLAN: Higher speed, but limited range and locations

– Wireless Application Protocol (WAP)

• Based on Wireless Application Environment (WAE) and Wireless Markup Language (WML)

• Streamlines HTTP and HTML for use in the very limited low speed and small screens of mobile devices


WAP Architecture


Future Access Technologies• Passive Optical Networking (PON)

– Also called Fiber to the Home

– Potential of optical fiber communications to end users

• Possibility of thousands of channels (with WDM)

– Doesn’t require electricity, thus “passive”

– Limits its maximum distance (about 10 miles)

– No standards yet

• Ethernet to the Home – Yipes.com is now doing this in several large US cities

– Gives home users 10BaseT or 100BaseT connections

– A TCP/IP router installed into the customer’s network connect to an Ethernet MAN

– No protocol conversion required


Internet Governance

• No one operates the Internet

• Closest thing: Internet Society (ISOC)– Open membership professional society

– Over 175 organizational and 8000 individual members in over 100 countries

– Mission: “Open development, evolution and use of the Internet for the benefit of the people in the world.”

– ISOC work areas

• Public policy:– Involves in debates in copyright, censorship, privacy

• Education– Training and education programs

• Standards


ISOC Standard Bodies

• Internet Engineering Task Force (IETF)– Concerned with evolution of Internet architecture and

smooth operation of Internet

– Work through groups (organized by topics)

– Request For Comments (RFC): basis of Internet standards

• Internet Engineering Steering Group (IESG)– Responsible for management of the standard process

– Establishes and administers rules in creating standards

• Internet Architecture Board (IAB)– Provides strategic architectural oversight, guidance

• Internet Research Task Force (IRTF)– Focus on long-term specific issues


Internet 2

• Many new projects designing new technologies to evolve Internet

• Primary North American projects– Next Generation Internet (NGI) funded by NSF

• Developed very high performance Backbone Network Service (vBNS)

– Run by WorldCom

– University Corporation for Advanced Internet Development (UCAID) with 34 universities

• Developed Abilene network (also called Internet 2)

– Advanced Research and Development Network Operations Center (ARDNOC) funded by Canadian government

• Developed CA*Net


Backbone for Internet 2


Features of Future Internet

• Access via Gigapops, similar to NAPs– Operate at very high speeds (622 Mbps to 2.4 Gbps)

using SONET, ATM and IPv6 protocols

• IPv6 not IPv4

• New protocol development focuses on issues like – Quality of Service

– Multicasting

• New applications include– Tele-immersion

– Videoconferencing


Implications for Management

• Concern about traffic slowing down Internet

– New fiber based circuits deployment overbuilt

• Many new broadband technologies for high speed Internet access

– Simple to move large amount of data into most homes and business richer multimedia apps

• Which access technology to dominate?

– Challenge: Figure out which one


Copyright 2005 John Wiley & Sons, Inc.

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Copyright 2005 John Wiley & Sons, Inc10 - 1 Business Data Communications and Networking 8th Edition Jerry Fitzgerald and Alan Dennis John Wiley & Sons,