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Dola Saha wins Grace Hopper Scholarship

Dola Saha, a Ph.D. student working on Software Defined and Cognitive Radio networks, is a winner of a 2011 Grace Hopper Scholarship. As a scholar, she will be receiving a scholarship of $10,000 and is invited to attend the Scholars’ Retreat on July 27 – 29 at the Googleplex in Mountain View, CA.

ModelNet @ Colorado

ModelNet is a network emulation platform developed by Ken Yocum at UCSD that allows the experimenter to run real code atop a hypothetical network with assigned bandwidth, latency, queue length, and other link properties. In contrast to other emulation platforms such as Emulab, ModelNet runs entirely on commodity hardware and, thus, can be deployed easily and cheaply on just a few machines. Also, there’s no contention for experimental resources with other researchers; it’s your own, private testbed!

In short, ModelNet consists of 1) one or more FreeBSD “emulator” machines that are responsible for emulating the virtual network topology, and 2) one or more Linux “virtual node” machines that have multiple virtual network interfaces, each of which act as a distinct “virtual end-host” located in the virtual network topology.

Kevin Bauer used ModelNet to improve congestion and flow control in Tor, as part of his Ph.D. thesis work.


  • The primary ModelNet documentation, detailing installation, configuration, and experiment setup and deployment can be here.
  • An excellent installation resource is available here.

Machine Setup

Our ModelNet setup is very simple. We have two machines, both located in the Systems Lab machine room:

  • Supermicro “slab” (8 core, 24 GB RAM, 1 TB disk) “virtual node” machine. This machine is assigned a static IP address of on eth1 and an internal IP address of on eth0. The eth1 interface should be used primarily as a control channel, to access the machine for configuration and experiment setup via ssh. eth0 is used for all communication with the modelnet emulator machine. For machine identification purposes, NICs: 00:30:48:f5:f1:f0 and 00:30:48:f5:f1:f1.
  • Dell PowerEdge 2650 running FreeBSD 6.3 – this is an “emulator.” This machine uses only a single network interface that is statically configured to It uses the machine as a gateway to access the Internet at large. For machine identification purposes, NIC: 00:11:43:35:a3:2f.

IMPORTANT:  The address space is reserved for ModelNet’s internal routing. Do not use this address space on the ModelNet machines’  VLAN.

ModelNet Code

The latest version of the ModelNet code (as of 4/7/2011) with Kevin’s patches is available here:  Download

See the above documentation for compilation, installation, and configuration details.

PlanetLab Site Details

PlanetLab is a global research network that supports the development of new network services. Since the beginning of 2003, more than 1,000 researchers at top academic institutions and industrial research labs have used PlanetLab to develop new technologies for distributed storage, network mapping, peer-to-peer systems, distributed hash tables, and query processing.

University of Colorado operates two nodes in the PlanetLab testbed:

Each node runs PlanetLab-BootCD-4.2 software with statically configured IP addresses. Both machines (pictured) are HP DC7900 models with Intel Core 2 Quad, 4GB RAM, 500GB disk. The machines are physically located in the Systems Lab machine room.

All administrative tasks can be performed by logging in to the PlanetLab website. This includes slice creation, user creation, software updating, and other maintenance tasks.

Each site appoints a technical contact who is responsible for maintaining the site’s nodes and responding to inquiries from PlanetLab’s management.

Our site’s technical contact person is Sears Merritt ( Please direct any questions related to our PlanetLab site to him.