ComputaShop

Cable Modems - speeds, connection sharing, security, etc.

Cable modems may be the most readily available broadband internet connection followed closely by DSL (anyone have some stats?). They can reach nearly every home that has access to digital cable television. At about $40-$50 per month, cable modems are still a premium service over traditional phone lines.

Speeds:

Cable modems boast some of the fastest download speeds. Most cable modem companies cap the download bandwidth at 1.5Mbps but some people have reached speeds of up to 3 or 4 Mbps. I could count on about 500-800Mbps throughput in a community that has had cable modems for a while. The upload speeds are fairly slow and are limited to 64 or 128Mbps. Unlike DSL, you can not yet purchase different service levels to increase the bandwidth available.

Shared Bandwidth

Cable modems work by assigning upload and download 'channels' to communities of people in your neighborhood. Although your download speed might be capped at 1.5Mbps, that bandwidth is shared by many people in your neighborhood. If someone runs a streaming audio server or other server that sends a lot of data, they could tie up the upload channel for 20 or 30 people making their Internet access much slower than it should be.

Network Security

Cable modems put your computer in the same 'logical' network neighborhood as your neighbors. All the computers directly connected to a cable modem in your neighborhood think they are on the same LAN and try to communicate with each other. These computers then show up in Microsoft's Internet neighborhood ready to be browsed. If network shares are presented to your cable modem neighborhood, you can bet that someone is going to 'browse' the neighborhood and try to access your shares. That is one of the reasons it is SO important to have a software or hardware firewall with a cable modem.