Identification
Category 5e cables, or "Cat 5e" cables, are specifically structured cables used in computer networks. When someone mentions the term "Ethernet cable," they are referring to this type of cable, or slightly newer variations such as "Cat 6" and "Cat 6a," which have greater bandwidth minimums. These cables replaced the earlier "Category 5" cable in 2001 and consist of a pair of copper cables that are twisted around each other.
Lengths
Ethernet cables range from a few feet to well more than 100 feet, but most types of Ethernet cables cannot exceed 328 feet. For connecting game consoles or computers to a modem or router, this range is more than sufficient.
Reliability
Ethernet cables are sturdy and reliable, with a plastic exterior protecting the twisted pairs of wires underneath. The cables are able to withstand getting bent and stepped on and may have longer lifespans than the computers and gaming consoles to which they are connected. However, it is not unheard of for cables to go bad after years of use and abuse. Replacing a bad cable will almost certainly cost you less than $20.
Right Cable for PS3
A new PS3 always comes with an Ethernet cable. If you bought a used PS3 without an Ethernet cable, you can purchase a 5- to 25-foot cable at an electronics store. Some online merchants carry Ethernet cables that claim to be made specifically for the PS3, but you will likely find a cheaper deal somewhere if you purchase an ordinary Ethernet cable.
Determining the Length
If your computer's modem is in a different room from your PS3, you will need a long Ethernet cable that can run from one room to another. A 50-foot or even 100-foot cable may be necessary. You may want to take crude measurements of the distance between your PS3 console's normal spot and the modem, even if it is in the same room. If you need a long cable, it might make more sense to run wirelessly. The price of wireless routers has plummeted over the years.