(Georgia Institute of Technology, 2002-10)
He, Qi; Ammar, Mostafa H.; Riley, George F.; Fujimoto, Richard M.
In discrete-event network simulation, a significant portion
of resources and computation are dedicated to the creation
and processing of packet transmission events. For
large-scale network simulations with a large number of
high-speed data flows, the processing of packet events is
the most time consuming aspect of the simulation. In this
work we develop a technique that saves on the processing
of packet events for TCP flows using the well established
results showing that the average behavior of a TCP flow is
predictable given a steady-state path condition. We exploit
this to predict the average behavior of a TCP flow over a future
period of time where steady-state conditions hold, thus
allowing for a reduction (or elimination) of the processing
required for packet events during this period. We consider
two approaches to predicting TCP’s steady-state behavior:
using throughput formulas or by direct monitoring of
a flow’s throughput in a simulation. We design a simulation
framework that provides the flexibility to incorporate
this method of simulating TCP packet flows. Our goal is
1) to accommodate different network configurations, on/off
flow behaviors and interaction between predicted flows and
packet-based flows; and 2) to preserve the statistical behavior
of every entity in the system, from hosts to routers to
links, so as to maintain the accuracy of the network simulation
as a whole. In order to illustrate the promise of this idea
we implement it in the context of the ns2 simulation system.
A set of experiments illustrate the speedup and approximation
of the simulation framework under different scenarios and for different network performance metrics.