\reviewtitle{An Integrated Experimental Environment for Distributed
  Systems and Networks}
\reviewlabel{white02netbed}
\reviewauthor{Brian White, Jay Lepreau, Leigh Stoller, Robert Ricci, Shashi
Guruprasad, Mac Newbold, Mike Hibler, Chad Barb, and Abhijeet
Joglekar}

Netbed tries to combine the best of three experimentation approaches:
simulation, live networks, and emulation.  It is a descendant of
Emulab.  Emulation is a hybrid approach that subjects real
applications, protocols, and operating systems to a synthetic network
environment.  One goal in particular is automatic parameter-space
studies.

Netbed uses nodes allocated from clusters for emulation and uses
geographically-distributed nodes.  The former are called ``emulation
nodes'' and are temporarily dedicated to an individual user.  The
latter are ``wide area nodes'' and are shared among Netbed users.

Netbed works by creating a virtual (user-specified) topology that
virtualizes hostnames, IP addresses, links, and nodes.  Currently
Dummynet is used to control cluster behavior.

Resources are divided into three categories: (1) local-area; these
nodes can function as edge nodes, traffic generators, or routers; each
machine has five network interfaces (one is used for control
messages), (2) Dummynet and VLANs emulate a wide-area within
local-areas, (3) distributed resources connected via Internet2,
DSL, and cable modems, and (4) Simulated resources, these are accessed
through ns's emulation facility, \emph{nse}.

The paper includes validation experiments.  It also provides a
comparison to PlanetLab.  They say they are looking into providing
access to PlanetLab via Netbed's interface.