van@HORSE.EE.LBL.GOV (Van Jacobson) (06/14/91)
A new tech report (LBL-30840):
"Measurements and Models of Wide Area TCP Conversations"
by Vern Paxson, LBL Computer Systems Engineering Group
is available for anonymous ftp from ftp.ee.lbl.gov (128.3.254.68),
file tcpmeasurements.ps.Z (this is a 1MB compressed postscript file).
This study is similar to that described in the recently
announced paper by Danzig, et.al., of USC. However, a much more
efficient means of data capture was employed (described in the
paper) which allowed the collection & analysis of every
conversation in to and out of the LBL campus over a period of
two months, rather the the two hour period of the USC study.
This greater temporal scope allowed the investigation of
long-term TCP/IP traffic variation (i.e., hourly, daily, weekly
and monthly). It also allowed a detailed investigation of the
geographic distribution of traffic. (This and other studies
have shown that there is substantial short term correllation in
conversation patterns and it is not possible to reliably assess
geographic distribution from samples spanning less than a few days.)
The abstract of the paper is attached.
- Van
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Abstract
This paper describes measurements of all of the wide area
network TCP conversations between the Lawrence Berkeley
Laboratory (LBL) and the rest of the world for the months of
November, 1990, and March, 1991. Some 500,000 conversations
were recorded, encompassing 11 different major protocols. We
look at aggregate characteristics of these conversations, both
overall and by TCP protocol (e.g., smtp, ftp), computing the
distributions of amount of data transferred, network bandwidth
used, conversation lifetimes and conversation interarrival
times. Temporal traffic variation is also investigated, showing
the variation of number of active conversations and network
bandwidth utilization over periods of 24 hours, 7 days and 30
days. Long term variation is also investigated by separately
analyzing November and March data (which reveals a 10-20%
increase in almost all aggregate traffic characteristics in just
four months). We classify each conversation geographically and
discover that the connectivity of the conversations was
remarkably rich, including traffic to 48 of the 50 states in the
U.S. and 23 foreign countries. Finally, we develop a number of
models for describing conversations of the various protocols.
From these models we can more readily assess how each protocol
is used and how the use changes as network utilization grows.