why do downloads occur at faster rates along the download process?
In: Technology
I’m going to tell you about uploading, even though you asked about downloading. That’s because I think the explanation is easier to follow from an uploader’s point of view. But the thing is, uploading and downloading are really just two sides of the same coin.
One computer’s download is another computer’s upload!
When you upload something, you don’t know how quickly you’ll be able to send packets to the receiver. This depends on a ton of possible factors. Packets on the Internet travel across often ten or more “links” between different computers owned by different companies. Any of these “links” might be shared between many users, or have degraded / interrupted performance for a variety of reasons.
Your performance is determined by the slowest link in the chain, but you have no idea how fast that is (and a link’s available speed can change over time).
So when you upload something, you start sending packets slowly, then if no packets are lost, you send them faster. You keep checking if all the packets arrived safely, and send them faster and faster until you start losing packets. Then you assume the available speed is just under the speed that resulted in failures, so you dial it back just a bit to try to hit that “sweet spot” where you’re sending as fast as you can without losing packets. (But if you keep sending packets successfully, you periodically try sending faster to see if you still lose packets. After all, the speed limit might have increased.)
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