## Grants and Contracts Details

### Description

Network simulation is an indispensable tool for researchers seeking to understand the principles of
network architecture and protocol design. A key parameter in any moderate to large-scale simulation is the
topology, Le., the way the nodes ofthe network are organized and connected to each other. "Good" models
for topology are essential for good simulations.
The PIs have developed graph modeling software that currently is widely used as a tool for generating
topologies, particularly models of large internetworks. The Georgia Tech Internet Topology Models (GTITM)
package allows researchers to construct model topologies whose structure arguably resembles the
node-level structure of the Internet: routers or switches, connected by (bidirectional) links, and grouped into
domains. The GT-ITM software is included with "ns2" [2], the defacto open-source standard for network
simulation.
Despite the wide-spread use of GT-ITM, in general, and its transit-stub model, in particular, a number
of critical and fundamental questions remain unanswered about network topology modeling. For example,
Topology models. Recent data indicates that the current Internet topology has some properties that
exchanges where many transit domains come together are lacking. Are there "better" techniques to
generate topologies intended to model the Internet? More fundamentally, how should a topology
generation technique be evaluated (i.e., how is "better" measured)?
Topology scaling. Although strides are being made in supporting large-scale simulations [33], most
researchers will continue to simulate their protocols on topologies that are smaller than the target
scaling that can provide the fundamental
grounding for configuring topologies of various sizes?
. Topology use. Our primary interest in topology modeling is to provide a foundation for large-scale
simulations. Facilitating the use of topologies in simulations must go beyond providing theoretically
sound models, however, and include a set of complementary tools for graph visualization, routing table
construction, etc. What visualization tools are useful to researchers and assist in accurate intuitive
understanding of underlying topology? How can different routing policies be effectively reflected in
routing table construction?
Wepropose (1) to address these and other fundamental questions in the area of topology modeling and
(2) to reflect our understanding in a set of topology tools and benchmarks made available to the research
community at large. This work will build on our prior experience in modeling internetworks.
The proposed work will contribute to fundamental understanding in the area of topology modeling. Our
work will include a set of evaluation criteria to assess the quality of a topology generation method and
improvements in topology models. Our work will also produce an evolutionary theory of topology scaling,
with implications for efficient simulation using topologies that are smaller than the target. In addition to
contributions to fundamental understanding, a central component of the proposed work is a set oftools and
benchmarks to be made available to the research community at large, following in the tradition of the GTITM
suite. These tools will allow other researchers to generate topologies, assess the quality of candidate
topology modeling methods, utilize benchmarks based on current and future technologies, and interact with
a visualization of topology.

Status | Finished |
---|---|

Effective start/end date | 9/1/00 → 5/31/05 |

### Funding

- National Science Foundation: $112,382.00

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