- A new TCP flow should start with a small congestion window (slow start) to avoid overloading network
- Initial congestion window is 1 MSS
- So, initial sending rate is MSS/RTT
- Could be pretty wasteful:
- Might be significantly less than actual bandwidth
- Linear increase takes long time to get to actual bandwidth
- Slow-start phase (really should be called “fast start”)
- Sender starts at a slow rate, but increases rate exponentially until first loss (double)
SSTHRES = Slow-start threshold