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A TCP/IP network is described by nodes, links, and traffic classes.
Nodes represent end-hosts, routers, and switches. Links interconnect nodes
and are bi-directional. Traffic classes represent end-to-end TCP and UDP
connections. |
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NetSolver computes link metrics such as average buffer occupancy, utilization,
and loss rate at time t, and traffic-class metrics such as achieved throughput
at time t. To do this, NetSolver models the TCP/IP network by a time-dependent
queueing network and numerically solves the queueing differential equations
using an approximation technique called the Z-iteration. |
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A TCP source is modeled by a time-dependent stochastic source whose
current rate is determined by its profile and the current network
state. The profile is an empircally-obtained function expressing the instantaneous
throughput of the source in terms of instantaneous roundtrip time and instantaneous
loss rate. Different TCP implementations have different profiles, which
translates to significant differences in performance. In Net Solver 1.0,
the user may choose between the TCP Reno implementations in NetBSD 1.2
and in the ns simulator. |

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The user can easily compare results computed by NetSolver against those
obtained by the ns network simulator. Specifically, NetSolver can
generate the ns script of a network, run ns, and include
the results in graphs. |
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For more information:
Profiles
of some TCP Reno implementions
Evaluations
of some TCP/IP networks and comparisons against ns simulations
Z-iteration numerical
solution method
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