2. COMPUTER NETWORKING 2 LECTURE 5: CABLE MODEMS

3. Cable Modems

4. What are Cable Modems?  The cable TV plant dedicates a standard cable TV channel to data transfer for Internet and multimedia services.  A computer equipped with a cable modem is then connected to the cable TV network using the same type of hook-up used for a television.  Once connected, the cable modem tunes to the channel set aside for data transfer to access the Internet.

5. How Fast are Cable Modems?  Phone Modem connection is about 50 kbit/s and is used point-to-point.  EtherNet (LAN) connection is 10 Mbit/s or 100Mbit/s and is used to connect many computers that can “talk” directly to each other.  Cable Modem connection is something in between. Speed is typically 3-50 Mbit/s and the distance can be 100 km or more.

6. How Fast are Cable Modems?  the speed of the cable modem depends on a few things. First it depends on how many users are on the system since the cable technology is a "shared" bandwidth. Too many users using too much throughput can drain this “shared” technology. bandwidth  The second factor to cable modem speed is a limit on the cable modem itself. Some cable providers will limit the upload or download speed on the cable modem, and this could affect your connection speed

7. How Do Cable Modems Work?  Cable modems receive digital information carried over the cable TV network and passes it through to the computer via a standard 10BaseT Ethernet interface.

8. Cable Modem Connection

9. How secure is a Cable Modem?  Cable connections are not 100% secure in any instance like many other connections on the Internet.  A general rule is to keep passwords long and turn off any service that you don't absolutely need running.  A firewall type application should be used to keep a network as secure as possible.

10. Cable Modems vs. ADSL  There is one major advantage that ADSL has over cable modems. Cable modems use a shared networking technology where all the cable modems share a single pipe to the Internet. This pipe speed will fluctuate depending on the number of subscribers on the network.  When ADSL is used, the pipe to the Internet is solely "yours", and is not shared along the way to a central office. This allows for a more consistent speed, and this speed does not typically fluctuate like cable modem networks.