$cat /proc/sys/net/ipv4/tcp_retrans_collapse 1 $
Try to send full-sized packets during retransmit. This is enabled by default.
TCP smart Framing, or TCP-SF for short, enables the Fast Retransmit/Recovery algorithms even when the congestion window is small. Without modifying the TCP congestion control based on the additive-increase/multiplicative-decrease paradigm, TCP-SF adopts a novel segmentation algorithm: while Classic TCP always tries to send full-sized segments, a TCP-SF source adopts a more flexible s segmentation algorithm to try and always have a number of in flight s segments larger than 3 so as to enable Fast Recovery. We motivate this choice by real traffic c measurements, which indicate that today's traffic is is populated by short-li flows, whose only means to recover from a packet loss is by triggering a Retransmission Timeout. The key idea of TCP-SF can be imple- mented on top of any TCP flavor, , from Tahoe to SACK, and re- quires modifications s to the server TCP stack only, and can be easily coupled with recent TCP enhancements. The performance of the proposed TCP modification were studied by means of simulations, live measurements and an ana- lytical model. In addition, the analytical model we have devised has a general scope, making it a valid tool for TCP performance evaluation in the small window region. Improvements are remark- able under several buffer management schemes, and maximized by byte-oriented schemes.
TCP Smart Framing: A Segmentation Algorithm to Reduce TCP Latency Marco Mellia, Member, IEEE, Michela Meo, Member, IEEE, and Claudio Casetti