Uploading kills my Download speed

[spannermonkey]

Hi all, when uploading a video e.g. to YouTube or sharing large files I noticed my download speed drops from 50Mbps to next to nothing, I've asked Virgin Media engineers but they never got back! help if you can.

 

[herrwizo]

That's how things work when uploading at max speed - it limits download as well, because downloading process also needs some of the upload bandwidth for sending requests, acknowledgments etc. The best you can do is limit upload speed - even 99% would probably allow enough for download to work normally, but reduce it to 95% or 90% if that's still not enough. Just don't use ALL of the upload bandwidth at 100%. There are various free utilities for limiting up/down bandwidth, you can choose any you like.

 

[Kewlx25]

It's an issue with bufferbloat. In order to download, you need to upload ACK packets to indicate that you've successfully downloaded. If your upload is too saturated, you will have massive amounts of latency and possibly some packetloss, both of which will be hugely detrimental to your download. Your ISP has too large of buffers on your cable/dsl modem for the speed they are providing you. Rule of thumb is a buffer should not hold more than 10ms of traffic.

You need to be able to ratelimit your upload to keep it from getting out of control. This is called "Traffic Shaping".