Broadband Technology
Cable modem & DSL
Cosc 513
Professor: Dr. Anvari
By
Ching-Jen Hsueh
106003
Broadband Technology
Contents
I. Introduction
II. The Advantages of Dial-up modems
III. The Advantages of Broadband Connection
IV. Cable Modem
V. DSL
VI. Security Issues
VII. Summary
VIII. Reference
Broadband Technology
Introduction
1. Broadband Technology
A kind of wide-spread, high-speed Internet access
2. Broadband Connections
Cable model, DSL (ADSL, SDSL), T1& ISDN,
and Satellite
Broadband Technology
Advantages of Dial-up modems:
1. Dial-up is cheap and everywhere
a. cost free~$30
b. no distance limitation
2. An unwired PC is safer
Broadband Technology
Advantages of Broadband Connections:
1. Broadband Internet service is “Always-on”
You don’t have to dial in your ISP’s server, just lunch your browser and
you’re there.
2. Broadband Internet service is faster
Cable and DSL connections generally deliver an average min of around
150 Kbps and max 1~2 Mbps, versus the max of 53.3 Kbps for dialup Internet services.
Broadband Technology
Disadvantages of Broadband Connections:
1. Broadband does not well spread
2. Security issues
3. Cost
Cable Modem
• Cable access is the most widely available and
most commonly used broadband technology in
U.S.
• Cable Web access is faster than dial-up and less
complex to install than DSL
• Cable modems work via a 6-MHz channel slot
with the cable signal to deliver burst download
speeds of up to 5 Mbps.
Cable Modem
Cable Modem
Cost
$40~$50 a month
$200~$300 installation fee
Downstream200Kbps~1.2Mbps
(Theoretical Max 7Mbps)
Upstream 100~200Kbps
SubscribersEstimated in 2000: 3.4million
Estimated in 2004: 13.7million
Cable modem
Features of Cable Modem:
1. Shared bandwidth
2. Upload speed is lower than download
speed
3. Available in residential areas, often not in
downtown or commercial areas
Cable Modem
DSL(Digital Subscriber Line)
• DSL is the second –most-popular broadband
service in U.S., trailing cable modem access
• DSL delivers digital data through phone lines
• DSL boasts faster connection times, high
throughput, and cheaper subscription costs
• DSL is available in metropolitan areas and their
surrounding suburbs.
DSL(Digital Subscriber Line)
Downstream SpeedUpstream SpeedDistance Limitation
ADSL
Asymmetric144Kbps~2.2Mbps 90Kbps~640Kbps
ADSL(G.Lite) Asymmetric
1.5Mbps
384Mbps
18,000 feet
22,000 feet
SDSL
Symmetric 160Kbps~2.3Mbps 160Kbps~2.3Mbps
22,000 feet
HDSL
Symmetric
1.544Mbps
1.544Mbps
12,000 feet
IDSL
Symmetric
144Kbps
144Kbps
Max 35,000 feet
VDSL
Asymmetric
13~52Mbps
1.5~2.3Mbps
4,500 feet
ADSL( Asymmetric Digital Subscriber Line)
1. Asymmetric data transmission
Different downstream and upstream
2. The farther the line, the slower the rate
3. You phone line does double duty
Use different frequency for voice and data
ADSL( Asymmetric Digital Subscriber Line)
ADSL
Cost
$40~$80 a month
$200~$400 installation fee
Downstream 144Kbps~2.2Mbps
(Theoretical Max 8Mbps)
Upstream 90~640Kbps
Subscribers Estimated in 2000: 1.97million
Estimated in 2004: 12.2million
Security of Broadband
1. “Always on” access means always
exposed
2. Hardware protection
NAT (Network Address Translation)
3. Software protection
Firewall software such as ZoneAlarm pro,Norton
Personal Firewall
Summary
ADSL
Cost
$40~$80 a month
$200~$400 installation fee
Downstream 144Kbps~2.2Mbps
(Theoretical Max 8Mbps)
Upstream 90~640Kbps
Subscribers Estimated in 2000: 1.97million
Estimated in 2004: 12.2million
Advantages Dedicated service
(not shared)
Cable Modem
$40~$50 a month
$200~$300 installation fee
200Kbps~1.2Mbps
(Theoretical Max 7Mbps)
100~200Kbps
Estimated in 2000: 3.4million
Estimated in 2004: 13.7million
Always-on
No distance limitation
Higher availablity
DisadventagesLimitation in the distance from CO
Shared bandwidth
Security issues
Broadband Technology
Reference
1. Computer Networks 3rd edition
2. www.pcworld.com
3. www.verizon.com
4. www.excite.com
5. www.sisco.com
6. www.lucent.com
7. www.3com.com
8. www.com21.com
9. www.zonelabs.com
10. www.zonealarm.com
11. www.norton.com
By Andrew S. Tanenbaum
Broadband Technology
The End
Thank you!