One of my interests recently has been around network quality and how well protocols such as TCP cope with noise. Having just spent a week trying to use internet in various backpackers, network quality has come to the front of my brain again.

When a router can’t forward traffic as quickly as it’s getting it, it starts dropping packets. TCP takes advantage of this to measure link capacity – it increases the amount of traffic being sent until it starts losing packets then reduces the speed again. This generally works very well, but has an issue with packet loss not related to the data being sent. Many networks just have noise or lose packets randomly, and TCP will tend to back right off to a trickle when this happens completely unnecessarily.