The TIME_WAIT state in TCP and Its Effect on Busy Servers
Theodore Faber
Joe Touch
Wei Yue
University of Southern California/Information Sciences Institute
4676 Admiralty Way
Marina del Rey, CA 90292
Phone: 310-822-1511
{faber,touch,wyue}@isi.edu
Abstract - Hosts providing important network services such as HTTP and
FTP incur a per-connection memory load from TCP that can adversely
affect their connection rate and throughput. The memory requirement
is directly tied to the number of connections; caching and other
sharing methods will not alleviate it. We have observed HTTP
throughput reductions of as much as 50% under SunOS 4.1.3 due to this
loading. This paper advocates off-loading the memory requirements to
the growing number of clients. This reduces server memory
requirements as connection rate at that server grows due to increases
in the number of clients and the bandwidth available on the network.
Our approaches control server memory load better with growing client
load than per-transaction techniques such as persistent HTTP
connections. Our approaches also interoperate with persistent
connections to take advantage of their other benefits. This paper
describes the causes of the memory loading, called TIME-WAIT
loading,and defines three methods of alleviating it that scale with
increasing number of clients. We present measurements of the systems
and a comparison of their properties.