Techniques for Improving Performance of Web Access and Asymmetric Networks
This distribution includes BSD/OS 3.0 source code corresponding to
various techniques for improving the performance in the context of
Web access, and separately, asymmetric networks.
These techniques include:
This distribution includes the following:
- TCP session: Performs integrated congestion control and loss
recovery for a set of TCP connections between a pair of hosts. This cuts
down packet loss rate, improves the chances of data-driven loss recovery,
and on the whole makes the performance of each connection more
- TCP fast start: Re-starts an idle TCP connection using congestion
window, RTT, and other TCP state variables cached in the recent
past. This improves the effectiveness of techniques such as
However, to guard against performance
degradation in case the cached information is stale, packets sent
during the fast start phase are assigned a high drop priority and
are subject to special loss recovery procedures.
- TCP asym: Performs ack congestion control to avoid
congesting a bandwidth-constrained ack path, as in common in
asymmetric-bandwidth networks (e.g., cable modem networks). Also,
the IPTOS_LOWDELAY flag is set for ack-only packets
(acks-first scheduling), which is useful in the presence of
bidirectional traffic in the asymmetric network.
For questions/comments, please contact:
Venkata N. Padmanabhan
- allsrc.zip: all .c and .h files from the
netinet, net, kern and sys
directories. In addition to the three techniques listed above, this
includes source code for many other orthogonal optimizations developed by
the Daedalus Research Group
at UC Berkeley.
- A separate distribution for each of the techniques containing only the
relevant files. For each, we include links to both the zipped version and the