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!