Introduction

slow internet problems is the result of congestion control
loss-based congestion control keeps buffers full and causes memory bloat.
slowest link in a route determines data delivery rate
queue shrinks only when departure rate exceed arrival rate
TCP views arbitrarily complex routes as a single link
Characterizing bottlenecks
- TCP runs at peak performance when bottleneck packet arrival is the bottleneck bandwidth and the total data in flight is equal to the BW-D product
- bottleneck bandwidth and round trip propagation are constantly changing - so they must constantly be estimated
- RTT = RT_prop + n_t
  - n_t is noise introduced by queues along path
- estimate of bottleneck bandwidth is the delivery rate of packets.
- bottleneck bandwidth calculated by max delivery rate in a sliding window (6-10 RTTs)
- impossible to know both bottleneck bandwidth and RTprop at the same time
sometimes acks are grouped together, causing delays in updates to bottleneck bandwidth
- set cwnd_gain to a alrger value (2) to account for additional RTT time.

set cwnd_gain to a alrger value (2) to account for additional RTT time.