Taming the elephants: New TCP slow start

Standard slow start does not work well under large bandwidthdelay product (BDP) networks. We find two causes of this problem in existing three popular operating systems, Linux, FreeBSD and Windows XP. The first cause is that because of the exponential increase of cwnd during standard slow start, heavy packet losses occur. Recovering from heavy packet losses puts extremely high load on end systems which renders the end systems completely unresponsive for a long time, resulting in a long blackout period of no transmission. This problem commonly occurs with the three operating systems. The second cause is that some of proprietary protocol optimizations applied for slow start by these operating systems to relieve the system load happen to slow down the loss recovery followed by slow start. To remedy this problem, we propose a new slow start algorithm, called Hybrid Start (HyStart) that finds a “safe” exit point of slow start at which slow start can finish and safely move to conges...

• Type: Journal
• Year: 2011
• Where: CN
• Authors: Sangtae Ha, Injong Rhee
• Keywords: Blackout Period, CN 2011, Congestion Avoidance, Congestion Window, Distributed And Parallel Computing