Emulab is a network testbed, giving researchers a wide range of environments in which to develop, debug, and evaluate their systems. The name Emulab refers both to a facility and to a software system. The primary Emulab installation is run by the Flux Group. There are also installations of the Emulab software at more than two dozen sites around the world, and Emulab is used as the base for other testbeds including GENI, PRObE, and DETER. Emulab is widely used by computer science researchers in the fields of networking and distributed systems. It is also designed to support education, and has been used to teach classes in those fields.

Emulab is a public facility, available without charge to most researchers worldwide. It provides integrated access to a wide range of experimental environments:

Emulation: An emulated experiment allows you to specify an arbitrary network topology, giving you a controllable, predictable, and repeatable environment, including PC nodes on which you have full "root" access, running an operating system of your choice.

Live-Internet Experimentation: Using the GENI and PlanetLab testbeds, Emulab provides you with a full-featured environment for deploying, running, and controlling your application at hundreds of sites around the world.

802.11 Wireless: Emulab's 802.11a/b/g testbed is deployed on multiple floors of an office building. Nodes are under your full controland may act as access points, clients, or in ad-hoc mode. All nodes have two wireless interfaces, plus a wired control network.

Software-Defined Radio: USRP devices from the GNU Radio project give you control over Layer 1 of a wireless network - everything from signal processing up is done in software.

Emulab unifies all of these environments under a common user interface, and integrates them into a common framework. This framework provides abstractions, services, and namespaces common to all, such as allocation and naming of nodes and links. By mapping the abstractions into domain-specific mechanisms and internal names, Emulab masks much of the heterogeneity of the different resources.