said by Unlimited Access :
Oh I see.
You can stay online as long as you want, but you can't use all of your bandwidth bandwidth during that time online.
And to further explain as I mentioned cable is a shared resource. Your node is capable of handling about 40 Gbs of bandwidth. Depending on how many users are behind your node, every other users bandwidth for a given time is affecting everyone else on that node. If you're on a 6 GB account and downloading constantly you're using about 24% of the available bandwidth for that node. Multiply any other users who might be downloading at the same time and before long every users bandwidth behind the node will be affected and their speeds will suffer. The nodes do have burst capabilites but that is only for short periods. With 6 and 8 GB accounts as the norm it doesn't take long for a node to become saturated.
And Comcast does not provide the backbone. They have to pay for the bandwidth they use as well. They pay based on some kind of 95% plan. Someone else may be better able to explain that. But suffice to say bandwidth is not free so Comcast simply figures an average for each user and is billed accordingly. Go over that arbitrary amount and you risk "The Letter", which you didn't appear to get, and possible cut-off.